Cotton Rust. 



SUMMARY. 



Cotton Rust is primarily a physiological disease. It is 

 induced when any sudden check to active growth so lowers 

 the vitality of the plant as to permit the attack of Macros- 

 2)orium nigricantiwn^ Alternari s;;. Cercospora gossypina or 

 other fungi that are facultative parasites and that spot and 

 destroy the leaves. 



It has also been called Black Rust, Yellow Leaf Blight, 

 and Mosaic Disease. 



It occurs throughout the older cotton states. It is worse 

 on old worn sandy lands, but it may occur on any land when 

 the humus is exhausted, also sometimes on wet poorly 

 drained lands, and occasionally on any character of soil under 

 unfavorable weather conditions. 



It may usually be entirely prevented by ameliorating the 

 soil conditions, giving better drainage, incorporating more 

 vegetable matter in the soil, and by supplying abundant plant 

 food in complete fertilizers, especially those rich in potash. 



The cheapest and most available method of soil improve- 

 ment is by green manuring with cow peas and other legu- 

 minous crops, supplemented by mineral fertilizers and the 

 feeding of much more live stock. 



On some soils potash salts act as an almost complete pre- 

 ventive of cotton rust. 



Sulphate of potash, muriate of potash and kainit seem 

 to be equally effective in proportion to the per cent, of potash 

 contained. 



At present prices, the muriate is the cheapest form in 

 which to apply potash. 



