UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

The anthracnose disease of daphne mezereum caused by Marssonina daphnes (Desm et Rob.) Mag Menzies, James David 1939-12-31

You don't seem to have a PDF reader installed, try download the pdf

Item Metadata

Download

Media
UBC_1939_A4_M3_A4.pdf [ 18.69MB ]
Metadata
JSON: 1.0105233.json
JSON-LD: 1.0105233+ld.json
RDF/XML (Pretty): 1.0105233.xml
RDF/JSON: 1.0105233+rdf.json
Turtle: 1.0105233+rdf-turtle.txt
N-Triples: 1.0105233+rdf-ntriples.txt
Original Record: 1.0105233 +original-record.json
Full Text
1.0105233.txt
Citation
1.0105233.ris

Full Text

' THE ANTHRACNOSE DISEASE.' OT DAPHNE "MEZEREUM c a u s e d by M a r s s o n i n a daphnes  (Desm. e t R o b . ) Mag  by lames D a v i d Menzies  -o0o~  A T h e s i s s u b m i t t e d f o r the Degree  of  MASTER OE SCIENCE I N AGRICULTURE i n the  Department of  BOTANY  -oOo-  THE UNITERSITY OE B R I T I S H . COLUMBIA April,  1959  I  CONTENTS Acknowledgements  Ill  The S u s c e p t  . . «  Plants affected  . . .  1  Parts affected  .  Varietal susceptibility The D i s e a s e  .  . . . . . . . . . . . . .  . . . . . . . . . .  Names  2 2  . . . . . .  4  . . . . . . . . . . . . . . . . .  4  H i s t o r y and r a n g e  4  Economic importance Symptomatology  1  . . . . . . . . . . .  6  . . . . . . . . . . . . . . . . . . . .  6  M o r p h o l o g i c a l symptoms On t h e l e a v e s  . . . . . . . . . . . . .  7  . . . . . . . . . . . . . . .  7  On t h e b l o s s o m s O n t h e stems  7  . . . . . .  On t h e bud s c a l e s  . . . . . .  8  . . . . . . . . . . . . .  8  G r o s s symptoms  • •  Etiology  8 9  Name, h i s t o r y a n d c l a s s i f i c a t i o n o f p a t h o g e n e  . .  Morphology o f pathogene Pathogenicity  11  . .  L i f e h i s t o r y o f pathogene The p r i m a r y c y c l e s  9  . . . . . . . . . . .  12  . . . . . . . . . . . .  13  . . .  The s e c o n d a r y c y c l e s  . . . . .  13  . . . . . . . . . . . .  14  II  Etiology  (continued)  Pathological histology Cultural studies Epiphytology Control  17  . . .  . . . .  . .  . . . . . . . . . . . .  Exclusion Eradication  . . . . . . . . . . . . . . . . . . .  20 2  2  2  4  2  4  25  Protection  25  1937 e x p e r i m e n t  . . . . . . . . . . . . . .  25  1938 e x p e r i m e n t  . . . . . . . . . . . . . .  28  Summary  51  Bibliography Illustrations  . . . . . . 6  . . . . . . . . . . . . . . . . . .  52 .  55  III  ACKNOWLEDGEMENTS D u r i n g t h e t h r e e y e a r s t h a t t h i s w o r k h a s been- i n p r o g r e s s I have r e c e i v e d v a l u a b l e a s s i s t a n c e and c o operation f o r which I wish to thank those r e s p o n s i b l e . am p a r t i c u l a r l y  i n d e b t e d t o D r . F. D i c k s o n of the  of Botany, U n i v e r s i t y of B r i t i s h C o l u m b i a , direction this  s t u d y was m a d e .  difficult  Department  u n d e r whose  Dr. Dickson r e a d i l y  v a l u a b l e a d v i c e and e n c o u r a g e m e n t ,  I  gave  a s s i s t e d i n t h e more  p a r t s o f t h e w o r k a n d d i d some o f t h e  photography.  I a l s o w i s h t o thank D r . A . F. B a r s s o f the Department  of  H o r t i c u l t u r e f o r a u t h o r i z i n g t h e u s e o f daphne p l a n t i n g s  on  t h e campus f o r s p r a y i n g e x p e r i m e n t s and f o r s u p p l y i n g t h e s p r a y i n g equipment and 3abor f o r t h e s e t e s t s . Eastham, P r o v i n c i a l P l a n t P a t h o l o g i s t ,  M r . J . W.  supplied  valuable  d a t a and was most g e n e r o u s i n a l l o w i n g me t h e u s e o f excellent  reference l i b r a r y .  Newton, M r . H. F.  his  I w i s h t o t h a n k a l s o D r . "Wm.  O l d s and M r . W a l t e r J o n e s , a l l o f  Dominion Department o f A g r i c u l t u r e ,  the  a n d many o t h e r members  o f the s t a f f s o f the U n i v e r s i t y and t h e Department  of  A g r i c u l t u r e whose names a r e o m i t t e d o n l y f o r b r e v i t y . exchange o f i n f o r m a t i o n a n d d a t a w i t h t h e s e men h a s g r e a t l y i n the p r e p a r a t i o n of t h i s  paper.  The  aided  THE ANTHRACNOSE DISEASE OF DAPHNE MEZEREUM c a u s e d by M a r s s o n i n a daphnes  (Desxn. e t R o b . ) M a g .  The h a r d y o r n a m e n t a l , Daphne mezereum, i s a border p l a n t i n the southern coast regions of Columbia.  W e l l known f o r i t s  pink or white  familiar  British  spikes  of  p e r f u m e d f l o w e r s , w h i c h a p p e a r i n J a n u a r y o r F e b r u a r y when few o t h e r p l a n t s a r e i n b l o o m , and f o r i t s b e r r i e s and waxy f o l i a g e  brilliant  d u r i n g t h e summer, t h i s  red  shrub  b e c o m i n g i n c r e a s i n g l y p o p u l a r i n p a r k s and p r i v a t e  gardens.  However, w i t h i n t h e l a s t t h r e e y e a r s t h e p r o p a g a t i o n this  s h r u b has b e e n s e r i o u s l y t h r e a t e n e d by t h e  is  of  sudden  o c c u r r e n c e o f an a n t h r a c n o s e o r l e a f - s p o t t i n g d i s e a s e ,  which  p r i o r to t h i s  This  t i m e had b e e n unknown i n N o r t h A m e r i c a .  disease repeatedly defoliates completely k i l l s  the p l a n t s ,  stunts  t h e b l o o m and u s u a l l y k i l l s  young  The w o r k r e p o r t e d h e r e i n was u n d e r t a k e n t o s t u d y d i s e a s e u n d e r l o c a l c o n d i t i o n s and, i f practical control  or  possible,  seedlings.  this to  find  measures.  THE SUSCEPT Plants affected. Daphne mezereum. immune.  The d i s e a s e has b e e n f o u n d o n l y on  O t h e r s p e c i e s o f Daphne a r e  Attempts to i n f e c t a r t i f i c i a l l y  apparently  D. cneorum and  D. l a u r e o l a h a v e been u n s u c c e s s f u l , and b e d s o f t h e  former,  g r o w i n g u n d e r n e a t h s e v e r e l y i n f e c t e d b u s h e s o f D. mezereum, have remained c o m p l e t e l y f r e e o f t h e d i s e a s e d u r i n g years of observation.  three  The numerous o t h e r s p e c i e s o f  daphne  h a v e n o t b e e n t e s t e d s i n c e t h e y a r e grown o n l y r a r e l y B r i t i s h Columbia. literature  T h e r e i s no r e f e r e n c e  on t h i s d i s e a s e t o i t s  i n the  in  scanty  o c c u r r e n c e on o t h e r  species.. Parts affected.  The most a p p a r e n t i n j u r y c a u s e d by  daphne a n t h r a c n o s e i s t o t h e l e a v e s .  The l e s i o n s a r e  b u t u s u a l l y v e r y numerous a n d c h a r a c t e r i s t i c a l l y along the m i d - r i b ,  small  located  r e s u l t i n g i n d e f o l i a t i o n of the  plant.  A s many a s t h r e e c r o p s o f l e a v e s h a v e b e e n d e s t r o y e d i n one s e a s o n , l e a v i n g t h e p l a n t v e r y weak i n t h e f a l l to winter  injury.  and  subject  S i n c e t h e daphne i s u s e d a s a n o r n a m e n t a l  shrub the u n s i g h t l y appearance of the s p o t t e d l e a v e s , without d e f o l i a t i o n ,  s e r i o u s l y reduces i t s  Flower i n f e c t i o n ocours i n the s p r i n g , deformed b l o o m . current  attractiveness.  c a u s i n g r e d u c e d and  Stem i n f e c t i o n s h a v e b e e n o b s e r v e d on t h e  s e a s o n ' s new g r o w t h b u t t h e y r a r e l y k i l l  Spindly suckers,  starting late  i n the f a l l ,  b a c k by l e s i o n s o f t h e a n t h r a c n o s e .  the  have been  shoot. killed  M a t u r i n g buds become  i n f e o t e d i n the f a l l but are not k i l l e d .  Lesions  f o r m e d on t h e bud s c a l e s b u t t h e f u n g u s r e m a i n s until  even  are  dormant  spring before' s p o r u l a t i n g . Varietal  varieties  susceptibility.  Although there are  several  o f Baphne mezereum r e c o r d e d b y Kew G a r d e n s ,  only  t h e p i n k f l o w e r e d f o r m and a w h i t e f l o w e r e d D. mezereum l a r .  variety,  a l b a , a r e known i n B r i t i s h - C o l u m b i a .  Of  t h e s e two t h e p i n k f o r m i s much more commonly g r o w n . these v a r i e t i e s are very s u s c e p t i b l e t o the  Both  disease.  O c c a s i o n a l l y a d a r k p i n k f o r m i s f o u n d , w h i c h , a l t h o u g h by no means immune, i s c o n s i d e r a b l y more r e s i s t a n t common p i n k .  than the  N u r s e r y m e n r e p o r t t h a t when daphnes  are  r a i s e d f r o m seed a s m a l l p e r c e n t a g e o f t h e p l a n t s w i l l of the dark form.  T h i s s t r a i n i s c h a r a c t e r i z e d by  flowers which are almost red i n c o l o u r .  be  larger  The dormant buds  a r e o f a r e d d i s h t i n g e a n d t h e p e t i o l e s and m i d - r i b s  of  t h e l e a v e s a r e a l s o r e d d e r t h a n t h o s e o f t h e common p i n k form. A n o t h e r p e c u l i a r daphne i s y e t has not been i d e n t i f i e d .  It  except t h a t t h e bloom i s p a l e r ,  f o u n d on t h e campus a n d a s is  s i m i l a r t o t h e mezereum  the branches t h i c k e r  and  more s p r e a d i n g and t h e l e a v e s i n more d e f i n i t e w h o r l s . daphne i s  c o m p l e t e l y immune t o a n t h r a c n o s e ,  according  This to  f i e l d o b s e r v a t i o n s and l a b o r a t o r y t e s t s a n d , a l t h o u g h n o t a s showy a s t h e common p i n k mezereum, i t may be v a l u a b l e a substitute.  E f f o r t s a r e b e i n g made t o d e t e r m i n e  v a r i e t y name o f t h i s  the  type.  B e c a u s e o f t h e s e v e r i t y o f t h e a n t h r a c n o s e on t h e f o r m o f daphne, n u r s e r y m e n who p r o p a g a t e t h i s s e e d w o u l d be w e l l a d v i s e d t o s e l e c t which i s  as  species  the dark pink  e q u a l l y b e a u t i f u l b u t more d i s e a s e  pink from  form  resistant.  4. THE DISEASE Names.  A l t h o u g h t h e c a u s a l f u n g u s o f daphne  n o s e was f i r s t  d e s c r i b e d i n 1843 > t h e r e i s  l i t e r a t u r e on t h e d i s e a s e i t s e l f . d i s e a s e f r o m Germany i n 1931 name.  The f i r s t  i n 1935•  Laubert  still  very  little  described  (7)  but d i d not g i v e i t  the  a common  p u b l i s h e d w o r k i n E n g l i s h was by G r e e n  He u s e d t h e name "Daphne L e a f S p o t " t o  the d i s e a s e .  anthrac-  (4)  describe  L o c a l names u s e d b y g a r d e n e r s and n u r s e r y m e n  i n c l u d e "Daphne B l i g h t " and " S c a b . " Anthracnose" i s  suggested as b e i n g the most.'accurate.  l e s i o n s are n e c r o t i c ing to Jenkins'  The name "Daphne  (6)  and h y p o p l a s t i c a n d t h e r e f o r e , classification,  c a l l e d an a n t h r a c n o s e .  the disease  T h i s name w i l l b e u s e d  The.  accord-  s h o u l d be throughout  t h i s paper. • • H i s t o r y and Range. The p a t h o g e n e was f i r s t  The d i s e a s e i s o f E u r o p e a n o r i g i n . d e s c r i b e d by D e s m a z i e r e i n  when i t was f o u n d on n a t i v e E u r o p e a n D. mezereum S y l l . E u n g . I l l : 498).  (7)  i n 1931  very i n j u r i o u s  (Sacc.  I n 191$ t h e a n t h r a c n o s e was  by Bubak and K a b a t on w i l d daphnes i n t h e T y r o l Laubert  1843,  reported  (1).  i n Germany d e s c r i b e d t h e d i s e a s e  as  i n n u r s e r i e s a n d gave a s h o r t d e s c r i p t i o n  symptoms a n d e t i o l o g y ,  G r e e n (4)  of  f o u n d t h e f u n g u s on t h e  c u l t i v a t e d daphne i n E n g l a n d b u t r e p o r t e d t h a t i t was v e r y r a r e and c e r t a i n l y n o t o f  economic  importance.  The most r e c e n t r e p o r t s i n d i c a t e t h a t t h e t r o u b l e known i n F r a n c e , S w i t z e r l a n d , I t a l y ,  Denmark,  Austria,  is  L a t v i a , H o l l a n d , G r e a t B r i t a i n and A u s t r a l i a , a s w e l l a s  in  B r i t i s h Columbia, Canada,  the  ( 4 ) , (3) and ( l l ) »  Apparently  disease i n t h e s e European c o u n t r i e s i s of minor s i n c e t h e r e i s p r a c t i c a l l y no l i t e r a t u r e subject.  importance  a v a i l a b l e on t h e  •  Daphne a n t h r a c n o s e - was f i r s t  reported i n  British  C o l u m b i a i n J u n e , 1 9 3 6 , when s p e c i m e n s were s e n t t o M r . J . W, E a s t h a m , P r o v i n c i a l P l a n t P a t h o l o g i s t , Nurseries,  L i m i t e d , Vancouver.  from L a y r i t z  M r . Eastham f o u n d - t h a t  the  d i s e a s e was s e v e r e on t h e daphnes a t t h i s n u r s e r y a n d a l s o at t h e i r nursery i n V i c t o r i a ,  A b o u t t h e same t i m e  the  d i s e a s e was n o t i c e d by D r . E . D i c k s o n , P r o f e s s o r o f  Botany  a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , on t h e D. mezereum p l a n t s on t h e campus o f t h e U n i v e r s i t y .  Further  investi-  g a t i o n s by t h e a u t h o r d u r i n g t h e same summer showed t h a t few p l a n t s  i n p r i v a t e gardens were d i s e a s e d but  i n f e c t i o n had n o t o c c u r r e d .  a  general  The s t u d i e s w e r e c o n t i n u e d  the  n e x t summer when i t was f o u n d t h a t t h e d i s e a s e h a d  spread  to gardens i n w i d e l y separated p a r t s of the c i t y .  In the  summer o f 1938 d i s e a s e d p l a n t s w e r e f o u n d i n a l l suburban n u r s e r i e s v i s i t e d .  S e v e r a l nurserymen  that t h e i r e n t i r e plantings of k i l l e d by t h i s spraying.  the reported  s e e d l i n g s t o c k had been  d i s e a s e i n s p i t e o f a t t e m p t e d c o n t r o l by  A number o f p l a n t i n g s  i n public parks  throughout  t h e c i t y have a l r e a d y been t a k e n o u t because o f t h e of the anthracnose.  At the present time the disease  ravages has  n o t been r e p o r t e d anywhere e l s e i n N o r t h . A m e r i c a . I t h a s n o t been p o s s i b l e  t o d e t e r m i n e when a n d how t h e  d i s e a s e was i n t r o d u c e d i n t o B r i t i s h C o l u m b i a . through the f i l e s  of the P l a n t  A check  Inspection Office  in  showed t h a t , a l t h o u g h t h e L a y r i t z N u r s e r i e s h a d n o t  Vancouver imported  daphnes f r o m a n y c o u n t r y w h e r e t h e d i s e a s e i s known f o r l e a s t two y e a r s p r i o r t o t h e o u t b r e a k , p a s t been i m p o r t e d from H o l l a n d . some o f t h i s spores of the Economic  It  t h i s p l a n t has i n quite possible  s t o c k was d i s e a s e d , o r a t l e a s t  carried  the  that  the  pathogene. importance.  The e c o n o m i c i m p o r t a n c e o f  daphne i n Canada i s n o t v e r y g r e a t . to m i l d ,  is  at  The p l a n t i s  the  confined  t e m p e r a t e r e g i o n s where t h e w i n t e r s a r e open and  t h e summers r e l a t i v e l y B r i t i s h Columbia.  c o o l and h u m i d , s u c h a s i n  southern  T h e r e a r e p r o b a b l y more daphnes grown  here than i n any o t h e r p a r t o f Canada. daphne i s o f d e f i n i t e  In t h i s area the  i m p o r t a n c e t o n u r s e r y m e n and g a r d e n e r s  and u n l e s s methods a r e f o u n d t o c h e c k t h e damages o f nose , the use o f t h i s h a v e t o be  anthrac-  s h r u b a s an i m p o r t a n t o r n a m e n t a l  will  discontinued* STICPTOMADOLOG-Y.  Symptoms o f t h e d i s e a s e a r e f o u n d on a l m o s t a l l of the p l a n t .  The b u d s , b l o s s o m s ,  s h o o t s a r e a l l a t t a c k e d by t h e  parts  l e a v e s , b e r r i e s and young  anthracnose.  The most d e s t r u c t i v e p h a s e o f t h e d i s e a s e o c c u r s o n t h e  7. leaves  (Plate I ) .  The f i r s t  symptoms o f i n f e c t i o n  minute dark green or b l a c k d o t s .  are  T h e s e u s u a l l y a p p e a r on  a r e a s o f the l e a v e s where f r e e w a t e r can a c c u m u l a t e . m i d - r i b o f a daphne l e a f  is  s u n k e n and i t  t h a t most o f t h e l e s i o n s a p p e a r .  is  The  in this  The T a c t t h a t  trough  the  lesions  a r e g e n e r a l l y c l u s t e r e d on t h e m i d - r i b a t t h e base o f l e a f b l a d e and on t h e s h o r t p e t i o l e a c c o u n t s f o r d e f o l i a t i n g a c t i o n of t h i s spots enlarge,  finally  disease.  the  the  W i t h i n a few days  t o a d i a m e t e r o f 1 t o 2 mm.,  and t u r n d a r k g r e y o r p a l e brown i n c o l o u r .  the  coalesce  The m a r g i n s  t h e s e l e s i o n s a r e v e r y d e f i n i t e and t h e s u r f a c e i s  of  slightly  raised.  The g r e y ,  erumpent n a t u r e o f t h e l e s i o n s a t  stage i s  due t o t h e f o r m a t i o n o f a g l i s t e n i n g , waxy mass o f  spores over the s u r f a c e .  The i n f e c t i o n s  remain i n  this  this  s t a g e u n t i l a r a i n o r h e a v y dew washes away t h e s p o r e m a s s e s , leaving shallow,  brown d e p r e s s i o n s w h i c h do n o t e n l a r g e  g e n e r a l l y p r o d u c e a new c r o p o f s p o r e s .  L e s i o n s have been  f o u n d on b o t h s i d e s o f t h e l e a v e s b u t t h e g r e a t e s t o c c u r s on t h e u p p e r  but  number  surface.  Blossom i n f e c t i o n i s completely k i l l e d flowers  c h a r a c t e r i z e d by m a l f o r m e d (Plate IT).  U s u a l l y the  or lesions  o c c u r on t h e c a l y x l o b e s c a u s i n g them t o c u r l and d i e .  If  t h e buds become i n f e c t e d b e f o r e t h e y open t h e y become m u m m i f i e d and r e m a i n t o s p r e a d t h e d i s e a s e t o t h e y o u n g l e a v e s w h i c h appear as soon as t h e b l o o m i n g p e r i o d i s The l e s i o n s on t h e b e r r i e s a r e s i m i l a r t o t h o s e on t h e  over.  8. l e a v e s but are s m a l l e r i n s i z e , 1 mm. i n d i a m e t e r .  seldom becoming l a r g e r  A normal b e r r y i s b r i g h t  a n d a b o u t 1 cm. i n d i a m e t e r .  red i n  than  colour  Severely infected berries  n o t c o l o u r a s c o m p l e t e l y and a r e  smaller i n s i z e .  do  Premature  b e r r y d r o p i s a p h a s e o f t h e d i s e a s e due more t o a weakened c o n d i t i o n of the p l a n t than to p e d i c l e Stem i n f e c t i o n s  on t h e c u r r e n t  occasionally found.  infections.  season's growth are  They a r e e r u m p e n t , o l i v e  c o l o u r and somewhat e l o n g a t e d v e r t i c a l l y . n e v e r more t h a n 2 mm. i n d i a m e t e r . kill  green  in  Such l e s i o n s  These i n f e c t i o n s  are  do n o t  t h e t w i g a n d a r e c o n s i d e r e d u n i m p o r t a n t compared t o  other phases of the  disease.  The l e s i o n s on t h e dormant bud s c a l e s a r e characteristic  (Plate I I I ) .  quite  They v a r y i n s i z e f r o m l e s s  t h a n 1 mm. i n d i a m e t e r t o e l o n g a t e d l e s i o n s 1 cm. i n  length.  The m a r g i n s o f t h e s e s p o t s a r e c l e a r l y d e f i n e d and r i n g e d by a w h i t e , p a p e r y f r i n g e o f t h e b r o k e n c u t i c l e a n d  epi-  dermis.  stroma-  The c e n t e r o f t h e s e l e s i o n s  l i k e and d i s t i n c t l y - e r u m p e n t .  is  coal-blaok,  Bud s c a l e i n f e c t i o n  i n t h e l a t e summer a s t h e buds a r e m a t u r i n g and t h e l e s i o n s c a n be f o u n d a t any t i m e d u r i n g t h e w i n t e r  occurs black before  t h e buds open and t h e s c a l e s f a l l . G r o s s symptoms on a s e v e r e l y i n f e c t e d p l a n t severe f r o s t i n j u r y .  resemble  The t e n d e r y o u n g l e a v e s w i l t  turn y e l l o w before dropping, w h i l e the o l d e r leaves  and show  dead o r f l a c c i d p o r t i o n s w h e r e t h e l e s i o n s have b e e n m o s t  numerous.  L a t e r on i n t h e s e a s o n , d e f o l i a t i o n i s t h e most  common g e n e r a l symptom.  Severely infected plants,  after  l o s i n g one c r o p o f l e a v e s , u s u a l l y do n o t p r o d u c e a new s e t b e f o r e t h e l e a v e s a r e k i l l e d o f f a g a i n .  full  As a  result  s u c h p l a n t s h a v e o n l y a w h o r l o f new l e a v e s a t t h e t i p s  of  the- stems a s c o n t r a s t e d t o t h e u s u a l h e a v y f o l i a t i o n o f  a  healthy p l a n t . straggly  The p l a n t s t h u s p r e s e n t a g e n e r a l  ragged,  appearance. ETIOLOGY  Name, H i s t o r y a n d C l a s s i f i c a t i o n o f t h e  Pathogene.  The c a u s a l o r g a n i s m o f t h e daphne a n t h r a c n o s e i s daphnes  Marssonina  (Desm. e t R o b . ) M a g . , a n i m p e r f e c t f u n g u s o f  family Melanconiaceae.  The e a r l i e s t  record of t h i s  the fungus  d a t e s f r o m 1843 when D e s m a z l e r e d e s c r i b e d t h e f u n g u s by t h e name o f S e p t o r i a daphnes Desm. e t R o b . Ill:  498).  (Sacc. S y l l ,  L a t e r Oudeman ( M a t . M y c . N e e r l . I I ,  p.  Fung. 28)  des-  c r i b e d a f u n g u s w h i c h he named G l e o s p o r i u m Daphne Oudem. The p a t h o g e n e was t r a n s f e r r e d by S a c c a r d o t o t h e Marssonia  ( s p e l l e d M a r s o n i a by S a c c a r d o ) w h i c h had been  e r e c t e d by F i s c h e r Ill:  769).  the t i t l e  genus  I n 1923 of the  ( R a b e n . F . E u r . n.1857) i n 1957 Magnus ( S e c . V . H6*hn, 1923)  (Sacc.  changed  genus t o M a r s s o n i n a b e c a u s e t h e  previous  name h a d b e e n p r e o c c u p i e d by a p h a n e r o g a m i c g e n u s . f o r e a t t h e p r e s e n t t i m e t h e a c c e p t e d name o f t h e i s M a r s s o n i n a daphnes different  (Desm. e t R o b . ) M a g .  Therefungus  An a p p a r e n t l y  f u n g u s , G l e o s p o r i u m m e z e r e l G k e . was  described  10.  f r o m E n g l a n d by Cooke i n I89O ( G r e v i l l e a  19:  p.8,  d i f f e r i n g f r o m M. daphnes i n h a y i n g n o n - s e p t a t e  18?0),  spores.  C o r r e s p o n d e n c e b e t w e e n t h e a u t h o r a n d D r . B i s b y o f Kew Gardens r e s u l t e d i n a r e - e x a m i n a t i o n o f C o o k e ' s material,  i n 1 9 3 7 , w h i c h showed t h a t ,  " G l e o s p o r i u m m e z e r e i Cooke i s daphnes  (Desm. e t R o b . ) S a c c .  original  t o quote D r .  Bisby,  i d e n t i c a l with Marssonina ....  M. daphnes i s  the  o l d e r name and i t w o u l d be a good t h i n g t o r e l e g a t e i m p e r f e c t l y d e s c r i b e d G. m e z e r e i t o s y n o n y m y . " the c o n f u s i o n r e s u l t e d from t h e f a c t t h a t  the  Apparently  immature  spores  o f t h e f u n g u s a r e n o n - s e p t a t e and a p p r o x i m a t e l y 1 5 X 6 u i n s i z e , which i s a Gleosporium character, a r e m o s t l y 1 - s e p t a t e a n d more u s u a l l y  but mature  20 u long,  spores  which  c h a r a c t e r s p l a c e t h e f u n g u s i n t h e genus M a r s s o n i n a . Connors i n the Canadian P l a n t D i s e a s e S u r v e y , the outbreak o f the disease i n B r i t i s h f i e d the fungus as G. m e z e r e i Cke.  1937,  C o l u m b i a and i d e n t i -  Later,  in  private  c o r r e s p o n d e n c e t h e i d e n t i f i c a t i o n was changed t o M . Grove  (5) in 1937,  Leaf Fungi, l i s t e d  reported  daphnes.  i n h i s monograph o f B r i t i s h Stem and G. m e z e r e i a s " p r o b a b l y a y o u n g s t a t e  M. d a p h n e s , " a l t h o u g h he d i d n o t examine C o o k e ' s  of  material.  Many s p e c i e s o f M a r s s o n i n a have b e e n f o u n d t o be t h e i m p e r f e c t s t a g e s o f b o t h Discomycetes and Pyrenomycetes, but t h e r e i s  s t i l l no p e r f e c t  stage of E.  Attempts to l o c a t e a perfect study.  daphnes k n o w n .  s t a g e w e r e made d u r i n g  F a l l e n l e a v e s were examined p e r i o d i c a l l y  during  the the  winter,  as were the b e r r i e s .  examined a t a l l  Bud s c a l e l e s i o n s  s t a g e s and t w i g l e s i o n s  t h e y were f o u n d .  were  s t u d i e d whenever  On none o f t h e s e s t r u c t u r e s was  any i n d i c a t i o n o f a p e r f e c t  stage.  there  The f a l l e n p a r t s  the p l a n t s always decayed i n the f i e l d l o n g b e f o r e time, p r e c l u d i n g the p o s s i b i l i t y on them i n " t h e  spring.  climates the leaves, ground u n t i l  It  of a p e r f e c t  forming humid  b e r r i e s and bloom would p e r s i s t  on t h e  spring.  Morphology of Pathogene.  The f r u i t i n g body o f  covers the whole of the s u r f a c e of the i n d i v i d u a l It  blooming  stage  i s possible that m less  of  M.daphnes lesion.  i s o f t h e t y p i c a l a c e r v u l u s t y p e and i s f o r m e d i n  epidermal l a y e r of the p l a n t t i s s u e  (Plate  IV , F i g .  the 1 )«  The s p o r e s a r e p r o d u c e d i n a g e l a t i n o u s m a t r i x on v e r y  short,  simple conidiophores.  to  They a r e o b o v a t e ,  s l i g h t l y bent  one s i d e , h y a l i n e and w i t h numerous g u t t u l a t i o n s Fig.  J ).  A b a s a l septum i s f o r m e d i n m a t u r e s p o r e s ,  two u n e q u a l c e l l s ,  spores i s  showed t h a t t h e  completely i n t r a - c e l l u l a r  The m y c e l i u m  and v e r y c h a r a c t e r i s t i c  the from  average  8 X 20 u , w i t h a r a n g e i n w i d t h  7 t o 9 u a n d i n l e n g t h f r o m 18 t o 21 u .  being a l t e r n a t e l y  making  M e a s u r e m e n t s on 100 s p o r e s  n a t u r a l l e s i o n s on daphne l e a v e s s i z e of the  VI ,  the l a r g e r a p i c a l c e l l u s u a l l y being  one t o p r o d u c e a g e r m - t u b e .  tortuous  (Plate  in  from is shape,  s w o l l e n and c o n s t r i c t e d , b r a n c h i n g and  ( P l a t e jy , F i g .  2 )«  This p e c u l i a r type of  i s found i n a l l t h e t i s s u e s a t t a c k e d and i n  culture.  mycelium  12. Pathogenicity.  Two a t t e m p t s t o i n f e c t h e a l t h y  daphne  p l a n t s i n ' t h e g r e e n - h o u s e w i t h M. daphnes f r o m s i n g l e c u l t u r e s were u n s u c c e s s f u l .  spore  T h i s m a y h a v e h e e n due t o  incorrect humidity r e l a t i o n s ,  h u t s i n c e t i m e and  were n o t a v a i l a b l e  this  to c o r r e c t  error,  the  facilities  green-house  t e s t s w e r e abandoned i n f a v o u r o f e x c i s e d l e a f ;  cultures.  The method o f c u l t u r i n g t h e daphne l e a v e s was a m o d i f i c a t i o n o f t h a t u s e d by C l i n t o n and M c G o r m i c k l e a v e s were suspended o v e r a c u l t u r e s o l u t i o n i n dishes or t r a y s ,  on f l o a t i n g w a x e d - p a p e r .  it  petioles  i n the  T h i s method was f o u n d v e r y s a t i s f a c t o r y  h e l d t h e l e a v e s f r e e f r o m t h e s o l u t i o n and y e t  p e t i o l e s were always Immersed.  The l e a v e s were  The  Petri  The l e a f  p r o j e c t e d i n t o the s o l u t i o n through s m a l l s l i p s (Plate XI ).  (2).  paper since  the  held  s e c u r e l y i n t h e p a p e r and c o u l d be t r a n s f e r r e d ,  atomized  photographed w i t h ease.  sucrose  A l t h o u g h a two p e r c e n t  s o l u t i o n was u s e d i n e a r l y t r i a l s ,  i t was f o u n d t h a t  w a t e r k e p t t h e l e a v e s i n good h e a l t h f o r a t l e a s t  studies,  f o r the  t h i s medium was u s e d i n a l l  pure  s i x weeks„  S i n c e c o n t a m i n a t i o n s were e l i m i n a t e d by u s i n g w a t e r s i n c e two weeks were s u f f i c i e n t  or  and  pathogenicity  subsequent  I t was f o u n d n e c e s s a r y t o k e e p t h e c o v e r s on t h e plates i n order to maintain a s u f f i c i e n t l y  high  cultures. Petri humidity.  S a t i s f a c t o r y l i g h t i n g was o b t a i n e d f r o m n o r t h windows and a l l c u l t u r e s were k e p t i n t h e l a b o r a t o r y a t room t e m p e r a t u r e . I n o c u l a t i o n s on e x c i s e d l e a v e s r e a d i l y gave  infections  13.  a f t e r an i n c u b a t i o n p e r i o d o f t e n d a y s .  P a t h o g e n i c i t y was  d e m o n s t r a t e d i n one i n s t a n c e w h e r e s p o r e s f r o m a m o n o - s p o r i c c u l t u r e o f M . daphnes gave t y p i c a l i n f e c t i o n s leaves.  Subsequent r e - i s o l a t i o n s  lesions yielded cultures isolations.  from t h e s e  indistinguishable  on t h e  excised  anthracnose  from the  No d i f f i c u l t y was e x p e r i e n c e d i n  original  causing  i n f e c t i o n by a t o m i z i n g s p o r e s f r o m d i s e a s e d l e a v e s on t o leaves i n  the  culture.  L i f e H i s t o r y o f the Pathogene.  To u n d e r s t a n d t h e  c y c l e s o f t h e daphne a n t h r a c n o s e p a t h o g e n e i t  is  life  necessary  t o know t h e s e a s o n a l d e v e l o p m e n t o f t h e daphne p l a n t .  Under  l o c a l c o n d i t i o n s t h e daphne h a s a v e r y s h o r t p e r i o d  of  dormancy.  February,  U s u a l l y the f l o w e r s appear i n January or  before the opening of the l e a v e s .  The b l o o m i s  clustered  a l o n g the p r e v i o u s s e a s o n ' s growth, f o r m i n g a dense s p i k e flowers.  The b l o o m i n g p e r i o d i s r e l a t i v e l y p r o l o n g e d ,  f r o m a month t o s i x w e e k s .  By t h e end o f A p r i l t h e p l a n t  r e m a i n s so u n t i l l a t e  i n the winter.  b e r r i e s r i p e n i n the l a t e  lasting  G e n e r a l l y i n l a t e M a r c h t h e new  l e a v e s a p p e a r , m o s t l y f r o m l e a f buds among t h e d e a d o r flowers.  of  is  dying  in f u l l leaf  and  The b r i g h t  scarlet  summer a n d , on h e a l t h y  plants,  p e r s i s t w e l l into the w i n t e r . season's growth e n t e r a short p r i o r to the next season's The p r i m a r y c y c l e s .  The buds on t h e -  current  dormant p e r i o d i n t h e  fall  development. The l i f e  c o n s i s t s of a s e r i e s of c y c l e s ,  h i s t o r y o f M.  daphnes  none o f w h i c h c o n t a i n s  a  14. perfect  stage of the fungus  (Plate IX ).  t a k e s p l a c e on t h e b l o s s o m s .  The p r i m a r y  The i n o c u l u m i s  cycle  s u p p l i e d by  t h e s p o r u l a t i o n o f o v e r w i n t e r e d l e s i o n s on t h e bud  scales.  B e c a u s e t h e f l o w e r s a r e c l u s t e r e d c l o s e t o g e t h e r on t h e s t e m , the t r a n s f e r o f i n o c u l u m i s e a s i l y e f f e c t e d by  splashing  r a i n o r even a h e a v y dew, t h e d e n s e s p i k e a l s o  maintaining  a favourable high humidity for  spore g e r m i n a t i o n .  Because  the f r u i t i n g bodies are t y p i c a l a c e r v u l i water i s f o r spore d i s s e m i n a t i o n as a s o l v e n t  f o r the  m a t r i x i n w h i c h t h e s p o r e s a r e embedded. b o t h on t h e p e t a l - l i k e  gelatinous  Infections  c a l y x l o b e s and on t h e c a l y x  The r e s u l t i n g l e s i o n s p r o d u c e s p o r e s b e f o r e t h e drop.  essential  occur tube.  blossoms  T h i s i s t h e end o f t h e p r i m a r y c y c l e ; t h e r e i s  no  s a p r o g e n e s i s a s f a r a s i s known, t h e f a l l e n b l o o m p l a y i n g no f u r t h e r p a r t i n t h e l i f e  history.  The s e c o n d a r y c y c l e s .  The f i r s t  leaf  infection  c y c l e s commence w i t h t h e t r a n s f e r o f i n o c u l u m f r o m t h e d i s e a s e d blossoms t o the young l e a v e s .  The bud s c a l e s may  s u p p l y some i n o c u l u m f o r t h e s e c y c l e s b u t u s u a l l y t h e y h a v e dropped b e f o r e the l e a v e s open.  Because of the  close  a s s o c i a t i o n b e t w e e n t h e b l o s s o m s and t h e w h o r l s o f leaves i t  i s h a r d l y p o s s i b l e f o r the leaves  i n o c u l a t i o n from the d i s e a s e d bloom. that,  to  young  escape  I t has been n o t e d  as the l e a v e s open, the f l o w e r s drop and a r e h e l d  t h e w h o r l s o f l e a v e s i n t h e same manner t h a t t h e bud s c a l e s a r e h e l d by t h e b l o s s o m s .  in  loosened  R a i n and dew a r e  15. n e c e s s a r y b o t h f o r d i s s e m i n a t i o n and g e r m i n a t i o n . points of  severest  i n f e c t i o n on t h e l e a v e s a r e  where f r e e m o i s t u r e c a n a c c u m u l a t e . ,  The  invariably  F a l l e n d e b r i s and b l o o m  on t h e l e a f s u r f a c e s r e t a i n t h e m o i s t u r e ; t h e m i d - r i b b e n t - d o w n edges and l e a f water w i l l  t i p s h o l d drops of water; a f i l m  s t a y w h e r e two l e a v e s come i n c o n t a c t .  a r e a s a r e always t h e most s e v e r e l y a f f e c t e d .  surface of the l e a f lower surface. infections  s  of  These  There i s  r e l a t i o n between t h e stomata and t h e l o c a t i o n o f s i n c e most, but not a l l ,  trough,  no  infections  o f t h e l e s i o n s a r e on t h e u p p e r  while a l l  The r e l a t i v e  o f t h e s t o m a t a a r e on t h e  infrequency of the  under-leaf  i s p r o b a b l y due t o t h e a b s e n c e o f f r e e w a t e r on  t h e l o w e r s u r f a c e and t o t h e g r e a t e r d i f f i c u l t y inoculation.  of  The i n c u b a t i o n p e r i o d h a s b e e n f o u n d t o be  t e n days w i t h a r t i f i c i a l  inoculations  on e x c i s e d  leaves.  I n t h e f i e l d new i n f e c t i o n s a r e q u i t e e v i d e n t w i t h i n two weeks o f a r a i n y p e r i o d . pustules are present,  A t t h i s t i m e waxy,  the spores from which c o n s t i t u t e  i n o c u l u m f o r t h e r e p e a t e d summer The l e a f new l e a v e s  cycles continue into l a t e  continue to appear.  the  cycles. summer, a s l o n g a s  There i s a s t r i k i n g  between weather c o n d i t i o n s and t h e s e c y c l e s . spell,  sporulating  relation  During a dry  new, u n i n f e c t e d l e a v e s a r e p r o d u c e d and r e m a i n  healthy u n t i l after a r a i n .  Then a new g e n e r a l  a p p e a r s , f o l l o w e d by a n o t h e r  defoliation.  Other,  l e s s obvious,  infection  secondary c y c l e s appear d u r i n g  the  16. summer o n t h e s h o o t s and on t h e r i p e n i n g b e r r i e s .  As i n  o t h e r c y c l e s t h e r e i s a c l o s e a s s o c i a t i o n between t h e o f i n o c u l u m and t h e s u s c e p t i b l e t i s s u e *  source  The c y c l e on t h e  shoots apparently c a r r i e s the disease o v e r w i n t e r , ,  and,  a c c o r d i n g t o Green (4), t h e s e l e s i o n s  the  spring.  sporulate in  B e c a u s e o f t h e much g r e a t e r p r e v a l e n c e o f  infection,  the r o l e of twig l e s i o n s  hud-scale  i n i n i t i a t i n g the  flower i n f e c t i o n cycles i s r e l a t i v e l y unimportant. b e r r i e s are i n f e c t e d i n l a t e  appearing leaves, of the  primary  The  summer f r o m t h e d i s e a s e d  Some o f t h e s e d i s e a s e d b e r r i e s  spread the fungus t o  leaves.  late-  and t h e c y c l e ends w i t h t h e f a l l a n d d e c a y  fruit.  The f i n a l  c y c l e o f t h e s e a s o n t a k e s p l a c e on t h e buds  formed i n t h e a x i l s  of the l e a v e s .  . In this  oase t h e  proximity  of i n o c u l u m t o s u s c e p t i b l e t i s s u e i s most s t r i k i n g l y rated.  Any r a i n f a l l i n g on t h e d i s e a s e d l e a v e s  t h e m i d - r i b and b a t h e s t h e a x i l l a r y spores.  In this  is practically fall.  the  illust-  i s d r a i n e d down  bud w i t h a s u s p e n s i o n  c y c l e the i n o c u l a t i o n i s  so s u r e t h a t  there  one h u n d r e d p e r c e n t b u d - s c a l e i n f e c t i o n i n  The c o n s t a n t  c l o s e p r o x i m i t y of the i n f e c t i o n  to the source of inoculum i n a l l  of the c y c l e s  e x p l a i n s the d e v a s t a t i n g nature of g e n e r a l f o l l o w i n g a p e r i o d of r a i n . in this  condition is  lesions  develop i n t o black,  the  courts  largely  infections  The h a b i t o f g r o w t h  i l l u s t r a t e d by P l a t e X . erumpent,  of  The b u d - s c a l e  stroma-like,  w i n t e r i n g b o d i e s w h i c h do n o t s p o r u l a t e u n t i l  resulting  over-  blossoming  17. time i n the s p r i n g  ( P l a t e I U , F i g s . 1 and 2 ) .  Spore  p r o d u c t i o n at t h a t time s u p p l i e s the inoculum f o r the of the primary c y c l e  start  again.  Pathological Histology.  Histological  s t u d i e s on t h e  r e l a t i o n b e t w e e n p a t h o g e n e a n d s u s c e p t were made on n a t u r a l l y i n f e c t e d m a t e r i a l except that  some o f t h e s t a g e s i n  p e n e t r a t i o n were o b t a i n e d f r o m a r t i f i c i a l excised  inoculations  on  leaves.  A m o d i f i c a t i o n o f t h e l a c t o - p h e n o l m e t h o d (9) o f c l e a r i n g and s t a i n i n g l e a v e s and o t h e r m a t e r i a l was u s e d w i t h good r e s u l t s . ' P o r t i o n s o f l e a v e s o r p e t a l s ,  bark o f young  t w i g s a n d b e r r y s k i n s w e r e t r e a t e d by t h e f o l l o w i n g m e t h o d : t h e f r e s h m a t e r i a l was b o i l e d i n a b s o l u t e a l c o h o l f o r f i v e m i n u t e s t o remove t h e c h l o r o p h y l l a n d o t h e r p i g m e n t s and t o f i x the t i s s u e ,  The t i s s u e was t h e n t r a n s f e r r e d t o  lacto-phenol for clearing.  I t was f o u n d t h a t when t h e  l a c t o - p h e n o l was h e l d a t a s l o w b o i l f o r „  hot  a few m i n u t e s  and  t h e n r a p i d l y c o o l e d t h e r e was l e s s d a n g e r o f a i r b u b b l e s i n the t i s s u e .  A few drops of c o t t o n - b l u e  s t a i n w e r e added t o  t h e l a c t o - p h e n o l , t h e c o n c e n t r a t i o n b e i n g d e t e r m i n e d by e x p e r i m e n t a t i o n and v a r y i n g w i t h t h e t i s s u e b e i n g t r e a t e d . The c l e a r e d a n d s t a i n e d m a t e r i a l was mounted on m i c r o s c o p e s l i d e s i n lacto-phenol or g l y c e r i n j e l l y  (8).  s l i d e s o f l e a v e s and p e t a l s t h e e p i d e r m i s was stripped off after  c l e a r i n g and s t a i n i n g .  I n making sometimes  Since the  stages of i n f e c t i o n a r e c o n f i n e d t o the e p i d e r m a l  early  layer,  18, t h i s t e c h n i q u e gave a c l e a r e r p l a n t c e l l s were l e f t s t a i n e d a dark b l u e ,  slide.  By t h i s method t h e  t r a n s p a r e n t and t h e f u n g u s t i s s u e was resulting i n very clear  differentiation.  I t was p o s s i b l e t o f o l l o w t h e c o u r s e o f m y c e l i u m down i n t o t h e spongy m e s o p h y l l a n d even t o s t u d y i n f e c t i o n s lower epidermal c e l l s  through the r e s t of the  in  leaf.  The s p o r e s a p p a r e n t l y become f i r m l y a t t a c h e d t o surface of the l e a f stance.  the  the  by t h e s e c r e t i o n o f some a d h e s i v e  sub-  E x a m i n a t i o n o f s p o r e s by t h e I n d i a - i n k method  (8)  showed t h a t t h e r e i s no t h i c k g e l a t i n o u s e n v e l o p e a r o u n d t h e spores.  S t a i n e d s p o r e s on t h e s u r f a c e o f l e a f m a t e r i a l w e r e  always surrounded by a d i f f u s e d s t a i n e d a r e a which would i n d i c a t e a fungus s e c r e t i o n .  TJngerminated s p o r e s on  leaf  m a t e r i a l t r e a t e d by t h e c l e a r i n g method d e s c r i b e d a b o v e w e r e not d i s l o d g e d i n the r a t h e r  strenuous  process.  Germination takes place from e i t h e r the l a r g e or s m a l l c e l l of the spore, but u s u a l l y germ-tube always o r i g i n a t e s is  the  from the l a r g e r .  The  from the s i d e of the spore whioh  i n contact w i t h the plant  surface.  tube i s formed immediately under the  A fine  penetration  s p o r e and p e n e t r a t e s  d i r e c t l y t h r o u g h t h e c u t i c l e and e p i d e r m a l c e l l w a l l . fact  t h a t t h e r e i s no h o r i z o n t a l g r o w t h o f a  germ-tube i s  strikingly  The  superficial  i l l u s t r a t e d by the f a c t  that  spores  h a v e been s e e n l o d g e d d i r e c t l y on a s t o m a t a l o p e n i n g and y e t t h e hyphae p e n e t r a t e d i r e c t l y t h r o u g h the s t o m a t a l o p e n i n g .  i n t o the guard c e l l r a t h e r Soon a f t e r  entering  the  than  19. epidermal c e l l 71,  Fig.  the hypha forms a s m a l l bulbous v e s i c l e  1)From  t h i s organ the t y p i c a l  (Plate  s w o l l e n hypha1  b o d i e s r a d i a t e t o t h e p e r i p h e r y of, t h e c e l l  (Plate  vT,  Fig.4).  A d j a c e n t c e l l s a r e p e n e t r a t e d o n l y when t h e i n v a d e d c e l l practically  f i l l e d w i t h hyphae.  s l o w l y and m a t u r e s i n g l e epidermal c e l l s wide is  The f u n g u s s p r e a d s  very  i n f e c t i o n s a r e s e l d o m more t h a n  (Plate IV,  Fig. l ) .  is  The p a l i s a d e  ten  layer  g e n e r a l l y p e n e t r a t e d and many o f t h e s e c e l l s h a v e b e e n  found c o m p l e t e l y  f i l l e d w i t h fungous t i s s u e .  mesophyll i s very r a r e l y  The  spongy  attacked from i n f e c t i o n s  on t h e  upper- s u r f a c e and no c a s e h a s b e e n s e e n w h e r e a n has p e n e t r a t e d c o m p l e t e l y t h r o u g h t h e l e a f . infections  occur over the m i d - r i b  infection  When t h e  t h e x y l e m e l e m e n t s become  c o m p l e t e l y f i l l e d w i t h hyphae w h i c h w o u l d e x p l a i n d e f o l i a t i n g a c t i o n of t h i s  disease.  the  As the l e s i o n s  mature  t h e e p i d e r m a l c e l l s a r e r u p t u r e d by t h e p r e s s u r e o f  the  fungous growth and the s ' p o r u l a t i n g l a y e r  (Plate  IV).  i s exposed  The i m m a t u r e s p o r e s a r e f o r m e d , b e f o r e t h e c u t i c l e  ruptured,  on s h o r t c o n i d i o p h o r e s .  the g e l a t i n o u s m a t r i x extrudes,  When t h e c u t i c l e  f o r the r e s t r i c t e d nature of the Histological  2. are  This  responsible  lesions.  e x a m i n a t i o n o f dormant b u d - s c a l e  show t h a t t h e b l a c k , e r u m p e n t  is  Fig.  I t has been n o t e d t h a t the c e l l w a l l s of i n v a d e d t i s s u e s  r e s p o n s e on t h e p a r t o f t h e p l a n t may be somewhat  S  breaks  a s shown i n P l a t e I ,  considerably t h i c k e r than those of healthy t i s s u e s .  Y  surface  is  sclerotial  lesions in nature,  20. ( P l a t e .VII, F i g s .  1 and 2 ) .  This structure  is  composed  almost e n t i r e l y of dark coloured c l o s e l y knotted mycelium. I n t h e s p r i n g t h e s u r f a c e o f t h e l e s i o n becomes a  sporulation  layer. Cultural Studies. mono-sporic  M. daphnes was o b t a i n e d i n  c u l t u r e by t h e f o l l o w i n g m e t h o d : a  suspension of spores from f r e s h l e a f on t o t h i n ,  dilute  l e s i o n s was  cleared agar i n P e t r i p l a t e s .  pure  streaked  Isolated  spores  were l o c a t e d w i t h a b i n o c u l a r m i c r o s c o p e and m a r k e d by  rings  o f I n d i a - i n k on t h e u n d e r s u r f a c e o f t h e p l a t e .  the  After  s p o r e s had g e r m i n a t e d t h e y were p i c k e d out w i t h a v e r y p o i n t e d p l a t i n u m n e e d l e and t r a n s f e r r e d t o t e s t - t u b e of potato-dextrose  agar.  A s e r i e s of  slants  A l t h o u g h t h e f u n g u s grew v e r y  s l o w l y on t h i s a g a r , s u f f i c i e n t obtained f o r the c u l t u r a l  fine-  single-spore  cultures  were  studies.,  d i f f e r e n t m e d i a were u s e d t o d e t e r m i n e  most s a t i s f a c t o r y one f o r g r o w t h o f t h e f u n g u s .  Table  shows t h e m e d i a u s e d and t h e g r o w t h r e s p o n s e s o b t a i n e d t h r e e weeks a t a p p r o x i m a t e l y 22 d e g r e e s C .  The  the I after  "Difco"  a g a r s u s e d a r e c o m m e r c i a l p r e p a r a t i o n s and were made a c c o r d i n g t o the d i r e c t i o n s  on t h e c o n t a i n e r s .  was made f r o m t h e f o r m u l a g i v e n i n R a w l i n s f  Methods"  (?).  for one-half hour. T  o f w a t e r by  boiling  The e x t r a c t was f i l t e r e d and added t o  of hot 4 percent agar,  autoclaved.  "Phytopathological  The daphne t w i g a g a r was made by s t e e p i n g $0  grams o f d r i e d daphne t w i g s i n 500 c c ' s .  500 c c s .  Coon*s a g a r  s t r a i n e d , t u b e d and  The b e s t g r o w t h was o b t a i n e d on daphne t w i g a g a r  21. b u t e v e n t h a t medium gave v e r y s l o w g r o w t h .  P r u n e a g a r was  a l m o s t a s g o o d , a n d , s i n c e t h e daphne m a t e r i a l c o u l d n o t be e a s i l y o b t a i n e d , most o f t h e r o u t i n e the prune a g a r .  c u l t u r i n g was done on  More d e t a i l e d s t u d i e s o f c u l t u r a l  character-  i s t i c s w e r e abandoned b e c a u s e t h e s l o w g r o w t h o f t h e w o u l d n o t a l l o w f o r q u a n t i t a t i v e measurements o f  organism  growth  responses. Table I ,  The r e a c t i o n o f M . daphnes t o v a r i o u s m e d i a . Average diameter Final pH g r o w t h i n 5 w e e k s , A v e r a g e • on 4 c o l o n i e s . 5,1 9.75 9.37 8.25 8.57 8.95 mm. !  Medium. D i f co P r u n e A g a r "  Corn Meal Agar  "  Potato-dextrose  "  Malt Extract  " "  5.5 9.75 9-55 6.25 4.75 7.55 Agar  •_  "  7.21  "  5.0 6.00 •5.57" 4.87 5.00 5.51  "  Bean Pod A g a r  5.0 5.00 6.57; 5.00 5.00 5.54-  "  L i m a Bean A g a r  5.5 1.00 2.00 1.00 1.50 1.57  "  Coon's S y n t h e t i c  Agar  Agar  Daphne T w i g A g a r  A typical  brown m a r g i n .  7.00 8.00 6.22  5.1 n i l  nil  nil  c o l o n y on daphne t w i g a g a r i s  It  nil  nil  "  5-5 9.00 9-50 9.50 9.57 9.54  erumpent, w i t h a s l i g h t l y defined margin.  5.4  compressed,  c o n v o l u t e d s u r f a c e and a  clearly  i s almost b l a c k i n c o l o u r w i t h a narrow  The s u r f a c e o f m a t u r e c o l o n i e s  covered w i t h the waxy, w h i t e spore masses.  A  becomes characteristic  brown s t a i n p e r m e a t e s t h e a g a r s u r r o u n d i n g t h e c o l o n y , o u t a b o u t 1 cm. f r o m t h e m a r g i n .  fading  22. The s p o r e s g e r m i n a t e s l o w l y i n d i s t i l l e d w a t e r . II  shows t h e r e s u l t s o b t a i n e d f r o m a g e r m i n a t i o n s e r i e s  Van Tiegham c e l l s water.  a t v a r i o u s t e m p e r a t u r e s and u s i n g  Complete d a t a on t h e e f f e c t  t e m p e r a t u r e were not o b t a i n e d .  Table I I .  The e f f e c t  Temperature i n degrees C.  of n u t r i e n t ,  on spore  % Germination a f t e r 24 hours©  10  distilled  pH and  germination.  0  2.3  • •  7•6  . 24.2  32.5  20  52.4  75.0  25  0  (estim.)  0  b e t w e e n 20 and 25 d e g r e e s C.  a p p r o x i m a t e l y 70 degrees E.  for  % Germination a f t e r 48 h o u r s  3.0  spore germination l i e s  in  The optimum t e m p e r a t u r e  of temperature  . . '  if  Table  Very s l i g h t  the temperature i s below 15 degrees C.  or  germination  occurs  A t 25 d e g r e e s  C.  a n d a b o v e t h e s p o r e s were k i l l e d b e f o r e a n y s i g n o f g e r m i n a t i o n appeared.  T h i s i n f o r m a t i o n c a n n o t be  c o r r e l a t e d w i t h the temperature r e l a t i o n s  completely  of the disease  t h e f i e l d b u t does h e l p t o e x p l a i n why e p i p h y t o t i c s o f  in  the  a n t h r a c n o s e a r e a s s o c i a t e d w i t h h o t summer w e a t h e r . EPIPHYTOLOGY Weather c o n d i t i o n s a p p a r e n t l y p l a y a v e r y  important  part i n i n f l u e n c i n g the s e v e r i t y of the attacks of anthracnose.  The u n u s u a l l y l o n g p e r i o d o f a p p a r e n t  daphne health  23.  shown b y t h e p l a n t s b e t w e e n b l o s s o m i n f e c t i o n and g e n e r a l leaf  i n f e c t i o n seems t o be due t o u n f a v o u r a b l e w e a t h e r  d i t i o n s f o r the disease during that t i m e .  There i s  con-  certainly  a b u n d a n t i n o c u l u m p r e s e n t on t h e dead o r d y i n g b l o o m t o infect  the young l e a v e s which a r e a p p a r e n t l y v e r y  susceptible  a s shown by t h e s e v e r e a t t a c k s o f d i s e a s e on  late-appearing  l e a v e s i n t h e summer.  Vancouver  district  Weather c h a r t s of the  have b e e n c o n s u l t e d i n a n e f f o r t  t e m p e r a t u r e and h u m i d i t y c o n d i t i o n s w i t h epiphytotics.  The d a t e o f f i r s t  to  correlate  anthracnose  general leaf  i n f e c t i o n was  n o t e d d u r i n g 1937 and 1938 and s i n c e t h e i n c u b a t i o n i s approximately ten days, p r i o r to t h i s  date were  I n 1937 f i r s t May 2 9 .  period  the weather c o n d i t i o n s t e n days  studied.  general leaf  i n f e c t i o n was n o t i c e d on  From t h e w e a t h e r c h a r t s i t was f o u n d t h a t on May 17  a n d 18 t h e mean d a i l y t e m p e r a t u r e was 35 d e g r e e s accompanied by l i g h t p r e c i p i t a t i o n .  F,,  P r i o r to t h a t date  t e m p e r a t u r e h a d a t t a i n e d t h i s h e i g h t on two o c c a s i o n s , without r a i n .  T h e r e f o r e t h e s e two d a y s were t h e  the but  first  d u r i n g t h e y e a r when h u m i d i t y was h i g h and t e m p e r a t u r e 55 degrees or  higher.  In 1938 l e a f 15.  infeotion f i r s t  That y e a r the f i r s t  became g e n e r a l a b o u t May  two d a y s d u r i n g w h i c h  rain  a c c o m p a n i e d a t e m p e r a t u r e o v e r 55 d e g r e e s F . w e r e May 7 and 8 , w h i c h was one week p r i o r t o t h e f i r s t  epiphytotic.  i n 1 9 3 7 s u c h t e m p e r a t u r e s had b e e n r e a c h e d e a r l i e r  in  As the  24. season,, b u t n o t a c c o m p a n i e d by A l t h o u g h two y e a r s ' conclusive,  rainfall.  e v i d e n c e c a n n o t be  the f a c t s are worth r e p o r t i n g i n e x p l a i n i n g  i n c i d e n c e o f t h e d i s e a s e i n t h e summer. is  considered  Whether o r not  t r u e t h a t t e m p e r a t u r e s above 55 d e g r e e s F . ,  by'rain,  accompanied  in future  seasons.  One s u b s t a n t i a t i n g  i s o b t a i n e d from the spore g e r m i n a t i o n t e s t s .  7-5  it  a r e n e c e s s a r y f o r i n f e c t i o n w i l l h a v e t o be shown  by o b s e r v a t i o n s  F.  the  A t 59 d e g r e e s  t h e r e was J 2 p e r c e n t g e r m i n a t i o n i n 48 h o u r s b u t p e r c e n t a t 50 d e g r e e s F . ,  h u m i d i t y and w i t h a c o n s t a n t  fact  only  u n d e r optimum c o n d i t i o n s  of  temperature.  CONTROL Exclusion.  E x c l u s i o n a r y m e a s u r e s w o u l d be o f  definite  v a l u e i n p r e v e n t i n g t h e s p r e a d o f daphne a n t h r a c n o s e t o new areas. entirely  Long d i s t a n c e  spread of the disease i s  almost  e f f e c t e d by movement o f d i s e a s e d s t o c k and p r o b a b l y  was t h e method o f i n t r o d u c i n g t h e d i s e a s e t o B r i t i s h Columbia.  At present the adjacent  southern  state  of  W a s h i n g t o n i m p o r t s c o n s i d e r a b l e numbers o f daphnes  each  y e a r f r o m B. C.  daphne  S i n c e t h e r e h a s b e e n no r e p o r t o f  anthracnose i n that  state,  and s i n c e i t  is hardly  t h a t i n f e c t e d p l a n t s w i l l n o t be s e n t t h e r e  likely  eventually  u n l e s s o h e o k e d , i t w o u l d be i n t h e i n t e r e s t s o f  daphne  g r o w e r s i n W a s h i n g t o n t o b a n i m p o r t s o f daphnes f r o m i n fected areas.  Although there i s  still  s p r e a d o f t h e d i s e a s e down t h e c o a s t ,  the danger of exclusionary  natural  measures  25. would g r e a t l y reduce the danger of the d i s e a s e  becoming  established. Eradication.  Daphne a n t h r a c n o s e a p p e a r s t o be o f  an i n f e c t i o u s n a t u r e t h a t t h e r e i s l i t t l e  hope o f b e i n g a b l e  t o e r a d i c a t e t h e d i s e a s e i n d i s t r i c t s where i t established.  The a r e a i n v o l v e d i n B r i t i s h  s m a l l b u t t h e s u s c e p t p l a n t s a r e so w i d e l y w o u l d be p r a c t i c a l l y  easily  spread that  i s now  Columbia i s  Moreover,  every i n f e c t e d bush i n the  Protection. d i s e a s e where i t  The p r i m a r y p r o b l e m o f  i s made d i f f i c u l t  long s u s c e p t i b i l i t y However,  firmly  controlling  the  protecting  C o n t r o l by t h e u s e  by t h e e x t r e m e and summer-  of almost a l l  p a r t s of the  plants.  s p r a y i n g e x p e r i m e n t s h a v e b e e n made d u r i n g t h e  two summers i n an e f f o r t the l e a f  complete  recommended.  i s a l r e a d y w i d e s p r e a d i s one o f  t h e p l a n t s f r o m i n f e c t i o n by s p r a y i n g . of f u n g i c i d e s  is  so  whole'area  I n a r e a s where t h e d i s e a s e i s n o t y e t  e s t a b l i s h e d , * r o g u i n g out i n f e c t e d p l a n t s  it  by  the disease i s  w o u l d h a v e t o be l o c a t e d and d e s t r o y e d t o e f f e c t eradication.  still  scattered that  impossible to attempt c o n t r o l  destroying the diseased bushes.  such  last  t o c o n t r o l o r r e d u c e t h e damages o f  infections. 1937 e x p e r i m e n t .  In 1937 the author  on f i f t y m a t u r e p l a n t s on t h e U n i v e r s i t y  experimented  campus.  t h e b u s h e s were l e f t u n s p r a y e d a s c h e c k s and t h e were d i v i d e d i n t o t h r e e e q u a l g r o u p s . c l a s s i f i e d as t o s i z e ,  Five  of  remainder  E v e r y p l a n t was  v i g o u r a n d l o c a t i o n and t h e p l a n t s  in  26. each t e s t were as n e a r l y as p o s s i b l e equal i n a l l The s p r a y m a t e r i a l s u s e d w e r e Lime S u l p h u r ,  respects.  i n the form of  a c o m m e r c i a l p r e p a r a t i o n known a s M i c r o s u l , p r o d u c e d by t h e Lunavale Products L i m i t e d , Lancaster,. England; Mixture  i n the form of M i c r o n i z e d Burgundy,  Burgundy  p r o d u c e d by t h e  same company; and home-made B o r d e a u x M i x t u r e .  The c o n c e n -  t r a t i o n s used were: Micro sul  8 lbs.  M i c r o n i z e d Burgundy. Bordeaux M i x t u r e  p e r 100 g a l s .  4 l b s . p e r 100  gals.  .4-4-40  A s p r e a d e r a n d s t i c k e r known a s L e t h a l a t e W e t t i n g F l u i d , made by t h e L u n a v a l e P r o d u c t s L i m i t e d , was f o u n d t o be satisfactory.  Good c o v e r a g e was o b t a i n e d u s i n g 2 l b s .  L e t h a l a t e p e r 100 g a l l o n s o f s p r a y ,  a high  concentration  n e c e s s a r y b e c a u s e o f t h e v e r y waxy n a t u r e ' o f t h e Only h a l f  of  leaves.  t h i s amount o f s p r e a d e r was u s e d w i t h M i c r o n i z e d  Burgundy w h i c h i s  sold w i t h the spreader added.  T h r e e s p r a y s o f e a c h m a t e r i a l were a p p l i e d i n t h e most t h o r o u g h manner p o s s i b l e .  The d a t e s o f a p p l i c a t i o n w e r e  A p r i l 8, J u n e 4 and J u l y 1 3 .  A t t h e end o f t h i s  program  t h e e x p e r i m e n t h a d t o be d i s c o n t i n u e d ; t h e r e f o r e t h e  results  w e r e t a k e n on t h e amount o f c o n t r o l e f f e c t e d up t o t h a t B y t h e end o f May t h e c h e c k p l a n t s  showed g e n e r a l  infection  and were c o m p l e t e l y d e f o l i a t e d a t t h e c o n c l u s i o n o f  the  experiment. The Lime S u l p h u r s p r a y gave v e r y p o o r c o n t r o l ,  time.  the  •27. d e f o l i a t i o n b e i n g a l m o s t a s s e v e r e a s on t h e c h e c k s . M i c r o n i z e d B u r g u n d y gave f a i r  control.  A l t h o u g h t h e r e was  m o d e r a t e i n f e c t i o n , t h e d e f o l i a t i o n was much l e s s t h a n on t h e c h e c k s . control.  severe  The B o r d e a u x M i x t u r e gave t h e  At the time of the l a s t  l e s i o n s on t h e l e a v e s ,  The  best  s p r a y t h e r e were v e r y  t h e r e had been p r a c t i c a l l y  few  no  d e f o l i a t i o n a n d t h e p l a n t s were much more h e a l t h y t h a n t h e rest of the p l o t .  I n s p i t e o f t h e good c o n t r o l w i t h  t h e s e p l a n t s became i n f e c t e d l a t e r  Bordeaux,  i n t h e summer, and by t h e  end o f A u g u s t a l l t h e p l a n t s h a d b e e n d e f o l i a t e d . An i n t e r e s t i n g a f t e r - e f f e c t  of t h i s  s p r a y i n g program  was n o t e d a t b l o o m i n g t i m e t h e n e x t s p r i n g .  While  i f y i n g t h e p l a n t s f o r v i g o u r i t was o b s e r v e d t h a t w h i c h had been sprayed w i t h d i f f e r e n t differences  Table I I I .  The e f f e c t o f s p r a y t r e a t m e n t s on y e a r ' s bloom. Time o f B l o o m i n g L a t e Medium E a r l y  Bordeaux  100%  Burgundy  Che ok  Sulphur  The  results  III.  Treatment used 1937  Lime  plants  s p r a y s showed m a r k e d  i n e a r l i n e s s a n d amount o f b l o o m .  a r e shown i n T a b l e  class-  following  Amount o f Bloom Good Medium S l i g h t  0  0  80  66  34  0  73-  - 13  40  47  26  20  54  0  60  40  0  20  80  0  20 0  :  .  27  I t w i l l be s e e n t h a t t h e b e t t e r t h e s p r a y c o n t r o l t h e and more p r o f u s e was t h e b l o o m p r o d u c e d i n t h e s p r i n g .  later A  28* l o g i c a l e x p l a n a t i o n o f t h i s w o u l d he t h a t t h e B o r d e a u x and, to a l e s s e r  extent, the others,  by d e l a y i n g  spray,  defoliation  p r e v e n t e d t h e p l a n t s f r o m b e c o m i n g dormant a s e a r l y a s c h e c k s , b u t a t t h e same t i m e gave them more v i g o u r .  On t h e  o t h e r hand t h e b a d l y d e f o l i a t e d c h e e k s became dormant i n ' t h e f a l l and bloomed e a r l i e r however,  left  the p l a n t s  i n the s p r i n g .  the  earlier  The d i s e a s e ,  i n a weakened c o n d i t i o n ,  reflected  i n poor bloom. 1938  experiment.  The same p l o t o f p l a n t s was  s p r a y e d i n 1938 u s i n g o n l y t h e M i c r o n i z e d B u r g u n d y . ' was d i s c o n t i n u e d b e c a u s e , i n the previous year,  although i t  gave t h e b e s t  It  p o s s i b l e t h a t the Burgundy might g i v e s a t i s f a c t o r y t h e a p p l i c a t i o n s were more f r e q u e n t and t h e  continued l a t e r  control  t h e u n s i g h t l y r e s i d u e made i t  u n s u i t a b l e a s a s p r a y f o r an o r n a m e n t a l p l a n t .  if  i n the  Bordeaux  quite seemed control  spraying  summer.  Sprays were a p p l i e d on t h e f o l l o w i n g d a t e s : A p r i l May 4 , May 20  1  J u n e 9, J u l y 15 and A u g u s t 1.  On t h e  18,  first  s p r a y i n g t h e c o n c e n t r a t i o n o f M i c r o n i z e d B u r g u n d y was 1 l b . i n 8 g a l l o n s o f w a t e r , w h i c h i s much h i g h e r t h a n  the  recommended s t r e n g t h , b u t a c o n c e n t r a t i o n w h i c h gave f a c t o r y c o n t r o l o f r u s t on a n t i r r h i n u m s a t without  spray I n j u r y .  satis-  Saanichton,  T h i s s t r e n g t h d i d , however,  i n j u r e t h e daphnes and t h e s p r a y had t o be d i l u t e d  seriously in  subsequent a p p l i c a t i o n s  t o 1 l b . i n 40 g a l l o n s b e f o r e  the  i n j u r y was e l i m i n a t e d .  The s p r a y i n j u r y  leaves  s p o t s on t h e  29. were v e r y s i m i l a r i n appearance t o t h e l e s i o n s o f  the  a n t h r a c n o s e , m a k i n g o b s e r v a t i o n s on c o n t r o l d i f f i c u l t . p l a n t s so i n j u r e d w e r e g r e a t l y r e d u c e d i n v i t a l i t y ,  and  a l t h o u g h the subsequent s p r a y s d i d n o t cause b u r n i n g , p l a n t s were i n poor c o n d i t i o n f o r  group r e c e i v e d a l l  the  t h e d u r a t i o n o f t h e summer,  The p l a n t s w e r e d i v i d e d a s b e f o r e i n t o t h r e e The f i r s t  The  groups.  t h e s p r a y s ; t h e second group  was n o t s p r a y e d on A p r i l 1 8 ; a n d t h e t h i r d g r o u p was n o t s p r a y e d on A p r i l 18 n o r May 4,  Although the  between sprays were not r e g u l a r ,  intervals  a n e f f o r t was made t o  apply the sprays before threatened r a i n i n order to the best p r o t e c t i o n  possible,  Table IV.  R e s u l t s of s p r a y i n g experiment - 1938.  Amount o f Disease  Observed A p r i l 15 #1 2 3 4  No D i s e a s e  Observed &ay 12 1 2 3 4  6  4  3  5  3  Slight  6  4  5  Moderate  3  Severe  15 15 15 15 15 13 13  Observed May 25 1 2 3 4 3  Very S l i g h t  give  2  2  3  Observed July 5 1 2 3 4  1 7 1  8  13 15  3  1  6 6 14 15  E x p l a n a t i o n s - t h e f i g u r e s r e f e r t o t h e number o f p l a n t s o u t o f 1 5 . The f i g u r e s on t h e 5 c h e c k p l a n t s were m u l t i p l i e d by 3 t o be c o m p a r a b l e . # These numbers r e f e r t o t h e s p r a y t r e a t m e n t , thus: jfl - a l l 6 s p r a y s a p p l i e d . 2 - - f i r s t spray omitted, 3 - second spray o m i t t e d . 4 - check - unsprayed.  30. Prom T a b l e I V i t w i l l be s e e n t h a t s p r a y s gave o n l y p a r t i a l the f i r s t  control.  even the whole  six  T h i s f a c t was o b v i o u s by  o f J u l y and t h e two s p r a y s f o l l o w i n g t h a t d a t e w e r e  of very l i t t l e use.  The p r o b a b i l i t y  of nurserymen or  g a r d e n e r s b e i n g w i l l i n g t o a p p l y more t h a n s i x s p r a y s remote; t h e r e f o r e the o n l y c o n c l u s i o n i s that w i t h Burgundy M i x t u r e i s not a p r a c t i c a l disease.  I n view of the r e s u l t s  year w i t h Bordeaux, effective  the  obtained d u r i n g the  probably t h i s  than Burgundy M i x t u r e .  be u s e d t o s a v e t h e p l a n t s e v e n i f  previous  s p r a y w o u l d be more Under c e r t a i n  it  conditions,  Bordeaux  destroyed  could  the  value.  There i s a s t r o n g p o s s i b i l i t y be a t t a c k e d i n t h e f a l l form.-  spraying  control for  such as i n s e e d l i n g p l o t s and i n n u r s e r i e s ,  ornamental  summer  is  t h a t t h e d i s e a s e can b e s t  at the time the bud-scale  A s t r o n g dormant o r p r e - d o r m a n t  or reduce the o v e r - w i n t e r i n g l e s i o n s .  lesions  spray might  control  One p r i v a t e  grower  r e p o r t e d t h a t he c o n t r o l l e d t h e a n t h r a c n o s e by d i p p i n g young infected plants,  d u r i n g November,  i n 10 g a l l o n s o f  solution.  plants  in his  experiment,  in a lye solution, 1 oz.  A l t h o u g h t h e r e were no c h e c k t h e r e p o r t i s a u t h e n t i c and may  i n d i c a t e t h e v a l u e o f a dormant s p r a y o r d i p .  It  is  t h a t t h i s w o r k c a n be s u p p l e m e n t e d i n t h e n e a r  future.  Prom t h e s e e x p e r i m e n t s t h e o n l y r e c o m m e n d a t i o n s c a n be made a r e t o u s e a s t r o n g dormant s p r a y j u s t the normal l e a f  drop i n the f a l l ,  followed i f  hoped  that after  n e c e s s a r y by  31. summer s p r a y s v / i t h B o r d e a u x M i x t u r e .  These summer  sprays  s h o u l d .commence- e a r l y i n May and c o n t i n u e d u r i n g t h e so s p a c e d t h a t t h e p l a n t the c r i t i c a l  periods of  is  completely  summer,  covered w i t h spray  at  rain. SOTMARY  The a n t h r a c n o s e o f t h e o r n a m e n t a l s h r u b . Daphne mezereum a d i s e a s e o f E u r o p e a n o r i g i n and p r e v i o u s l y unknown i n  North  A m e r i c a , has appeared and r e a c h e d s e r i o u s p r o p o r t i o n s southern B r i t i s h Columbia. type,  The d i s e a s e  is a leaf  the most s e r i o u s phase o f w h i c h i s  spotting  defoliation,  a c c o m p a n i e d by b l o s s o m b l i g h t a n d p r e m a t u r e b e r r y  i n g s h a v e b e e n c o m p l e t e l y k i l l e d and o l d e r p l a n t s  c a u s a l agent i s daphnes  (Desm. e t R o b . ) M a g .  plant-  greatly  i n ornamental v a l u e .  the M e l a n c o n i a c i o u s  .  drop.  T h i s t r o u b l e h a s become so s e v e r e t h a t y o u n g n u r s e r y  weakened, w i t h a g e n e r a l l o s s  in  The  fungus Marssonina  The f u n g u s G l e o s p o r i u m m e z e r e i  C k e , , p r e v i o u s l y b e l i e v e d t o be r e s p o n s i b l e f o r a n o t h e r  leaf  d i s e a s e o f d a p h n e , h a s b e e n p r o v e d t o be a synonym o f M. d a p h n e s . detail.  P a t h o l o g i c a l h i s t o l o g y has been s t u d i e d  The f u n g u s o v e r - w i n t e r s  buds i n t h e form o f s t r o m a - l i k e  in  on t h e s c a l e s o f t h e l e s i o n s , which  d u r i n g blossom time i n the s p r i n g .  Epiphytotics  sporulate o c c u r when  h i g h summer t e m p e r a t u r e s a r e a s s o c i a t e d w i t h r a i n . s p r a y i n g h a s n o t proved, t o be a n e f f e c t i v e  dormant  Summer  c o n t r o l , b u t hope  i s h e l d f o r t h e u s e o f a s t r o n g dormant s p r a y f o l l o w e d by summer s p r a y i n g w i t h B o r d e a u x M i x t u r e .  32,  BIBLIOGRAPHY Bubak, F. B i n B e i t r a g zur P i l z f l o r a vor T i r o l und Istrien.  Ann. Mycol. X I I : 205-220, 1914.  C l i n t o n , G, P. and Florence A. McCormick.  Rust  i n f e c t i o n of leaves i n P e t r i dishes. B u l l , Conn, A g r i c . Exp. Sta. 260: 475-510, 1924.  Connors, I . L. Sixteenth annual report of the-Canadian Plant Disease Survey.  Can. Dept. A g r i c . 1936.  Green, D. E. A l e a f spot of Daphne mezereum. Royal Hort. Soc.  J.. 60: I 5 6 - 8 ,  1935.  Grove, 11. B. B r i t i s h Stem and Leaf Fungi. V o l . 2. Cambridge U n i v e r s i t y Press.  1937•  Jenkins, A. E. A p p l i c a t i o n of the terms "Anthracnose" and "Scab" to plant diseases caused by Sphacelona and Gleosporium. 389-395,  Laubert, R.  Phytopaith 23' 1935.  A very i n j u r i o u s disease of Daphne mezereum (German t i t l e ) .  bau: 46: 1 3 8 ,  Der Blumen - und Pflanzen1931.  Lee, A* B. The Micrometrists Vade Mecum. Ninth e d i t i o n . P. Blakiston's Son and Co., P h i l a d e l p h i a , 1924.  Rawlins,  •  T, E.  P h y t o p a t h o l o g i c a l and  Research Methods.  Botanical  John W i l e y and Sons,  I n c . , London® Saccardo,  P-^-.  S y l l o g e Fungorum.  S t e v e n s o n , J. A .  1933, Vo/. /-zs <?v</  Foreign Plant Diseases.  Wash.-  U.S.D.A., 1  -0O0-  9  2  6  0  PLATE I . F i g . 1 .  L e a v e s o f Daphne mezereum i n f e c t e d Marssonina daphnes. culture.  Fig.  2.  I  J>.  I n f e c t e d daphne l e a f  The same  $  P h o t o g r a p h s by D r .  From e x c i s e d  leaf  s h o w i n g waxy  spore  1,  m a s s e s on l e s i o n s . Fig.  by  X  8.  showing k i l l i n g o f Dickson.  mid-rib.  PLATE I I .  Blossom  teds  o f D. mezereum.  % 6.  The t o p t h r e e ' b u d s a r e h e a l t h y , t h e b o t t o m show t h e l e s i o n s o f  anthracnose.  thr  PLATE I I  PLATE U T . '  Daphne anthracnose on the bud Eig.  l.  Overwintering  Fig.  2,  New  scales.  lesions.  l e s i o n s on f o l d e d  leaves.  PLATS I I I  Fig.  2 ,  PLATE I V .  -Fig.  1.  Semi-diagrammatic o f M. d a p h n e s ,  Fig.  2.  Camera l u c i d a  drawing o f a c e r v u l u s  i n cross  section.  drawing of young  infection  showing r a d i a t i n g hyphal b o d i e s .  PLATE  IY  PLATE V.  F i g . 1.  P h o t o m i c r o g r a p h o f cross s e c t i o n of a c e r v u l u s of Mv d a p h n e s .  X 500.  F i g . 2. Photomicrograph from cleared l e a f preparation showing r a d i a t i n g h y p h a l b o d i e s a t edge of l e s i o n .  X jjOQ.  PLATE Y  P i g . 2.  PLATE V T .  Morphology o f M, Figs.  1,  stages  daphnes.  2 , 4 a n d 5» camera l u c i d a d r a w i n g s  i n p e n e t r a t i o n o f t h e fungus i n t o  of  the  epidermal c e l l s o f t h e daphne l e a f . . 'Fig. 3 .  S p o r e s o f M. daphnes g r e a t l y  The a c t u a l s i z e o f s p o r e s i s  8 x 20 u .  enlarged.  P L A T E VI  PLATE Y H .  P h o t o m i c r o g r a p h s o f bud-scale Fig. 1 .  Free-hand s e c t i o n  lesions.  of a single  lesion,  showing c e l l s packed w i t h mycelium and i l l u s t r a t i n g the s t r o m a t i c nature o f the l e s i o n . X 100. F i g . 2.  P o r t i o n o f same l e s i o n X 500®  PLATE V I I  P i g . 2.  PLATE  VIII.  Figs.  1 and--2.  -Phot omioro graphs --of- young  petal infections showing epidermal c e l l s .  X 500®  hyphal bodies  in  PLATE  Fig.  Fig.  VIII  1.  2 .  PLATE I X .  Diagram showing the v a r i o u s c y c l e s o f M . on D. mezereum.  daphne  PLATE  IX  PLATE IX. DIAGRAMMATIC YEARLY CYCLE of Marssonina daphnes on Daphne mezereum.  scale  lesions.  PLATE X .  A s p r a y o f daphne bloom, i l l u s t r a t i n g t h e  dense  c l u s t e r s o f f l o w e r s i n c l o s e p r o x i m i t y t o the new l e a f  whorls.  Copies from N u t t h a l l ' s Shrubs."  "Beautiful  Flowering  PLATE X  %^K^~ •WBSEBBB A  SSL  PLATE X I .  Photographs o f e x c i s e d l e a f c u l t u r e s , the method u s e d t o support t h e Pig.  1.  A P e t r i dish  Eig.  2o  A tray culture,  leaves.  culture. showing minute  o f M . daphnes r e s u l t i n g f r o m inoculation. Photographed by D r .  showing  Dickson.  artificial  lesions  PLATE  Fig.  XI  2.  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Country Views Downloads
United States 12 1
China 9 36
Canada 5 1
Poland 2 0
Germany 2 0
Japan 2 0
City Views Downloads
Shenzhen 7 36
Ashburn 6 0
Windsor 5 1
Buffalo 3 0
Unknown 2 0
Swidnik 2 0
Beijing 2 0
Tokyo 2 0
Berlin 1 0
Satsop 1 0
Providence 1 0

{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}
Download Stats

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0105233/manifest

Comment

Related Items