STRAWBERRY LEAF SPOT 107 



STRAWBERRY LEAF SPOT 



{^Sphaerella fragariae, Tul.) 



The leaves of cultivated strawberries are too frequently 

 attacked by this fungus, which is widely distributed. 

 Small dusky spots first appear on the upper surface; as 

 these continue to increase in size for some time, and run 

 into each other, large blotches are often formed. The 

 central part of each blotch changes to a pale grey or almost 

 white, and is bordered by a reddish line. Next, minute 

 white tufts of mould appear on the white central spots; 

 these constitute the conidial condition of the fungus — 

 once considered as a distinct species called Batnularia 

 tulasnei. 



Later in the season the higher stage of the fungus 

 appears on the white patches, under the form of minute 

 black points ; these are perithecia containing spores pro- 

 duced in asci. Minute sclerotia are also formed in the 

 fading leaves. 



Conceptacles resembling the perithecia in form are 

 sometimes present, containing myriads of very minute 

 conidia. 



The ascospores and sclerotia germinate the following 

 season ; the spores thus produced start the disease again. 

 If the leaves become badly diseased, the crop of fruit is 

 materially affected, if not completely lost ; moreover, the 

 plants become so weakened through loss of leaves that they 

 are comparatively worthless the following season. 



Preventive Means. — The disease can be checked by 

 spraying with Bordeaux mixture. If the disease has 

 existed previously, spraying should commence when the 

 leaves unfold, and be repeated at intervals as required 



