A Study of Meadow-Crop Diseases in New York 75 



fields, or seed that has been cleaned mechanically, and disinfection of the 

 seed with formalin solution, 1 ounce to 3 gallons of water, for fifteen 

 minutes. Hegyi (1915) recommends treating the seed with 1-per-cent 

 copper-sulfate solution. 



Unfortunately, no data on the sensitiveness of this fungus to fungicides 

 have been obtained because the spores are so small that they are distin- 

 guished with great difficulty from the dust particles on slides. This fact 

 makes fungicidal tests in the laboratory difficult and unsatisfactory. It 

 may be said, however, that in the two seasons of field dusting with sulfur 

 no control of anthracno.se was apparent in the plots. Apparently this 

 fungus, like Glomerella rufcmaculans and other anthracnose fungi, is 

 tolerant of sulfur. 



The production of resistant varieties is commonly assumed to be the 

 panacea for control of this malady, but no good ones as yet have been 

 discovered. Miss Sampson (1928:111) advances some evidence to show 

 that much of the apparent resistance which has been observed is in reality 

 only klenducity, because propagants that she took from field-resistant 

 and field-susceptible plants were all affected alike when placed under 

 optimum conditions for infection. 



STAGONOSPORA LEAF SPOT 



The disease for which the name Stagonospora leaf spot is proposed, is 

 widespread in this State, occurring most plentifully on alsike clover. It 

 occurs in New York on white, red, alsike, and sweet clovers, as well as on 

 yellow trefoil and alfalfa. It has not been collected as yet on hop clover. 

 Because of a confusion of names of the causal organism, records of the 

 disease are difficult to identify in the literature, but it undoubtedly occurs 

 on other suscepts also. 



The lesions, which vary considerably in diameter, are circular or oval to 

 irregular in .shape. Diagnosis is made easy by the light-brown to white 

 center and the dark-brown margin of the spots. Comparisons with 

 Ridgway's (1912) color standards give: for the center of the spot, deep 

 olive buff to pallid brownish drab on white clover, white to tawny olive on 

 sweet clover, pale smoke gray on alsike clover; for the margin of the spot, 

 buffy brown on white clover, bister on sweet clover, and brownish drab on 

 alsike clover. In some instances the spots tend to show faint concentric 

 zones of the same color as the margin. These have been observed on all 

 suscepts except sweet clover. This tends to confuse the spot with the 

 Macrosporium leaf spot, but the signs described in the following para- 

 graphs and the papery aspect of the center of the older lesions differentiates 

 the lesions in such cases. 



Greenhouse inoculations with single spore cultures isolated from alfalfa, 

 as shown in figure 17, A, result in spots on alfalfa seedlings that are 



