STRAWBERRY DISEASES 



423 



amass themselves beneath the cuticle of either surface of the 

 leaf, and from these masses conidiophores bearing conidia 

 arise. These spores develop, are scattered and produce in- 

 fections through- 

 out the summer; 

 with the advent 

 of winter conidial 

 formation ceases, 

 but the mycelium 

 remains alive in 

 the leaves until 

 the following 

 spring. At this 

 time a new crop of 

 conidia develop, 

 which begin the 

 cycle anew by in- 

 fecting again the 

 strawberry plants. 

 Should any of 

 these spores per- 

 chance fall on the common cinquefoil, the disease would be 

 produced. It should also be mentioned that this plant acts 

 as a weed-host, carrying the fungus through the winter and 

 furnishing a source of the inoculum in the spring, as does the 

 strawberry plant itself. 



It has been noted that conidial production ceases in the fall 

 and that the winter is spent as mycelium in the old leaves. 

 Toward winter the fungus makes preparations for other means 

 of hibernation. Masses of mycelium appear on the surface 

 of the leaf; these are sclerotial bodies which are capable of 

 producing conidia in the spring following. A third means 

 of over-wintering is by the perithecia; these arise in the fall, 

 but remain immature until March or April, when mature asco- 



FIG. 123. Strawberry leaf-spot. 



