^ 6 ~ 



1^ in''Efu;]i,'T STRAiirs c tu^ jti^a cerry leaf 3 P or fufc-us 



It is well kr.ovm that some varieties of strav/berries are more susceptible f 

 the common leaf-spot disease than others. However, it \-as only recently that 

 several strains of the leaf-spot . fungus Qvlycophaerella fragariae ) were found, ^i.... 

 being decidedly more pathogenic to certain varietiee than other strains. The 

 follo\';ing is a digest of an article by A. G. Plalzidas (of the Louisiana Station) 

 in Phytopathology 38:12:938-992,1948. 



Seven isolates of thefimgus from different parts of the country ( Louisianr. , 

 Oregon, Llichigan, Maryland, Nev; York) sho;ved widely different pathogenic proper- 

 ties when inoculated into ten varieties of strawberries. In fact, no two 

 varieties reacted exactly alike to all of the strains. Wo tnvo strains beliaxvd 

 similarly on all of the varieties. One variety, Caledonia, v/as moderately or 

 highly susceptible to all seven straios. Clermont shov/ed no infection from four 

 strains, a trace from one strain, and heavy infection from two. Iloiraro 17 s]iou'<'' 

 a trace of infection from each of tv;o strains, v/hile U.S.D.A. Seedling No. 1021 

 yielded a trace of infection from only one of tliem. U.S.D.A. Seedling No, 1^"42 

 showed no infection from two strains, light infection from three ol-]iei-s, mui 

 neavy infection from the remaining tivo. One isolate (S1600) from New York, 

 produced moderate to heavy infection on all varieties except Ha'/nrd 17 and 

 •J.S.D.A, Seedling No, 1021 ~ only a trace on them. Strain S1610 (from louini .„■,.. 

 produced moderate' to heavy infections On all but tla'oe of the 10 varieties; no 

 infection on them, Clermont, liov/ard 17, and' U.S.D.A. Seedling No. 1021. In 

 contrast there was one strain of the fungus, the Oregon strain (S8?), that vm.- 

 wealcly parasitic on most of the varieties; producing heavy infection on one 

 (Caledonia), light infection on two, a trace on three, aiid none on four. Somt 

 varieties that remained free of infection under natural conditions took the 

 :"'iscase ^fhen inoculated artificially. Iloivard 17 and U.S.D.A. Seedling No. 1021 

 v.'ere almost immune to all strains even when heavily inoculated. Certain 

 v.?.rieties appear to merely escape the disease in the field by virtue of thoir 

 grwing habits, whereas 'Howard 17 and U.S.D.A. Seedling No. 1021 appear to 

 possess iiiarked inherent, "ch.emical" resistance to all fonus of the fungus, 



-_ 0. C, Boyd 



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This So-Calle d_ V^inter - The mean tcmporaturc in Amlicrst 

 during Uo'cember wa"s"' slightly above the freezing point, 

 »nd much of the month of January has seemed oven more 

 springlike. The writer set a fev; strav/berry plants on 

 January 8 (fall planting?) and on January 14, Howard 

 C-llmore of 'w'estboro brought .to a meeting two apparently 

 undejaaged Baldwin apples which lie picked in his orcliard 

 the previous daj/. No apple blossoms have been reported 

 to date. 



_-io\/_ Pnaning Ix^aflet - "Pruning Apple Trees" is the- title of a no'>. 

 leaflet wliioh wl'J 1 \,o rc;!,'\y for distribution in the very near 

 future. It covers hli<> prnniuj;; of bobh young and bearing trees ano. 

 is v;r;ll illustrated. A copy may bo obtained fnar. your County 

 S;:teuGion Offj.ce or from hho Ilai.ling Room at the University. 



