A Study of Meadow-Crop Diseases in New York 



115 



TABLE 33. 



Effect of Sulfur and Copper-Lime Dusts Upon Ccnidial Germination 

 of Hei.minthosporium Triseptatum 



TIMOTHY SMUT 



Scant attention in this investigation was devoted to timothy smut 

 because of the excellent discussion of the disease by Osner (1917). An 

 attempt was made to culture the smut, using the method of Christensen 

 and Stakman (1926:981) by which they immersed corn-smut spores in 

 1-per-cent copper-sulfate solution and removed them at intervals up to 

 seventy-two hours and made streak plantings with them on potato agar. 

 No success crowned this effort probably because a period of after-ripening 

 is necessary for the germination of these spores, as pointed out by Davis 

 (1924 b). Davis (1928) has published a note on physiologic specialization 

 of the fungus. 



SILVER TOP 



Sporotrichum poae Pk., described originally by Stewart and Hodgkiss 

 (1908), causes what they call silver top on blue-grass, orchard grass, and 

 timothy. The disease is rather common in June as the grasses are heading. 

 It frequently accompanies the killing of the heads, which stand out promi- 

 nently among the green ones. Several attempts to culture the fungus 

 failed. Stewart, however, did culture it. 



POWDERY MILDEW 



Powdery mildew of grasses is common, but it seems to play a minor 

 role in the meadow-crop economy in this State. Sulfur will keep it easily 

 in check. To discuss in detail the enormous amount of work of Reed, 

 Salmon, and others on specialization of the fungus is outside the scope of 

 this paper. 



PIRICULARIA LEAF SPOT OF FOXTAIL 



Piricularia (/risen, the cause of piricularia leaf spot of foxtail, (Setaria 

 lutescens (Wieg.) (Hub.), is a common and a destructive disease in the 

 State. The spots, watersoaked at first, are unmistakable. Later there 

 is an irregular margin on old spots of raw umber color (Ridgway, 1912) and 

 a center of light neutral gray to pallid purplish gray. In some cases the 

 spots occur on leaf sheaths. 



