15 



of throwing out filaments, or germinating and affecting other 

 plants. Dessicating or drying the soil greatly increases the 

 activity of the sclerotia, and infection in the succeeding crop 

 is thereby materially increased. ^ 



A similar disease caused by a species of Sclerotinia, which 

 appears to be responsible for a large amount of damage to 

 tomatoes and other crops in the South, has been noted by P. 

 H. Rolfs^ in Florida, and attention has been called to this by 

 F. S. Earle-^ in Alabama. Since the disease has not proved to 

 be of great importance on tomatoes in Northern greenhouses 

 up to the present time, remedial measures are not urgently 

 needed ; but should it ever become so, soil sterilization will be 

 found efiicacious. and the treatment of the soil with formalin 

 may prove valuable.'* 



SCAB OR MILDEW 

 (Cladosporium fulvum, Cke.) 



This fungus is characterized by a velvety, mouse-colored 

 mildew-like growth forming irregular spots on the under sur- 

 face of tomato leaves. On the upper surface of the leaves these 

 spots are yellowish in color. The fungus penetrates the leaf 

 tissues and occasionally overruns the surface, thus causing much 

 injury. It attacks both field and greenhouse tomatoes, and while 

 we have never known of its completely killing the crop, it fre- 

 quently causes much injury. It is much more common and 

 severe in moist than dry weather. 



For the treatment of field crops the best remedy consists in 

 spraying with any good fungicide such as the Bordeaux mixture, 

 applied as occasion demands. For the control of the disease in 

 greenhouses, W. F. JMassey and A. Rhodes^ have recommended 

 the use of lime and sulphur applied to the steam or hot-water 

 pipes. The most successful method we have found for con- 

 trolling mildew consists in keeping the atmosphere of the house 

 dry. Our experiments have extended over a period of many 

 years, and we have carried through many crops without the 

 slightest trace of this mildew. It is a comparatively easy matter 

 to produce mildew in a house, and we have shown that by 

 covering individual plants with glass or a cloth and greatly 

 modifying the light and moisture conditions, mildew results. 



Watering or syringing the foliage should be done only on 



1. Mass. (Hatch) Agr. Exp. Sta., Bui. No. 69, 1900, p. 22. 



2. Fla. Agr. Exp. Sta., Ann. Rept., 1896, pp. 38—47; also Buls. Nos. 21 and 47. 



3. Ala. Agr. Exp. Sta., Bui. No. 108, 1900, pp. 28—32. 



4. Ohio Agr. Exp. Sta., Cir. No. — . 



5. N. C. Agr. Exp. Sta., Bui. No. 170, 1900, pp. 6—7. 



