Vegetable and Field Crops 



243 



and the presence of pale bleached spots upon the foliage. 

 These spots are not definitely limited, nor does the tissue die 

 as it does in the case of other spinach leaf spots. 



Black-mold {Cladosporium macrocarpum Preuss) develops 

 primarily upon old leaves, and 

 renders the plant unsalable. The 

 spots are distinguishable from all 

 other spinach spot diseases by 

 their irregularity, indefiniteness, 

 and color. 



To control the three latter 

 spinach diseases, it is well to burn 

 diseased refuse, practice I'otation, 

 and employ preventive sprays 

 when the plants are young. 

 Spraying the edible leaves as the 

 plants approach maturity injures 

 the sale and is not permissible. 



Leaf-spot (Heterosporium va- 

 riahile Cke.). — -This disease was 

 especially injurious to spinach in 

 eastern Virginia during the win- 

 ter of 1908-1909, and has also 

 been noted in Connecticut, It 

 appears early in January and 

 continues to increase until the 

 spinach season is over. Numer- 

 ous leaf spots are produced, at 



first brown, later sooty, as the conidiophores and conidia 

 of the fungus develop. The older leaves usually show more 

 injury than the younger, but at times all leaves are seriously 

 affected. The presence of the fungus renders the leaves 

 unsalable, and much additional labor is required at harvest 

 time to trim off the injured leaves. 



The disease does not seem capable of attacking healthy, 

 vigorous plants, but usually follows injuries produced by 

 some other agencies. In Virginia it has been found to follow 



Fig. 133. — Spinach leaf 

 spotted by Heterosporium. 

 After Reed. 



