DISEASES OF CROPS 



965 



SUGAR CANE 



Red Rot (Colletotrichum falcatum, Went.). — This is one of the most 

 destructive diseases of the sugar cane. It causes the plants to wilt and 

 finally a yellowing of the upper leaves. This is followed by a blackening 

 and dying of the eyes and a gradual discoloration on the outside extending 

 from the nodes. Upon splitting the canes, the fibro-vascular bundles are 

 found to show reddish discolor- 

 ations. 



Rind Disease (Trichosphae- 

 ria sacchari, Massee). — Although 

 this disease is not so severe as the 

 preceding one, it causes a prema- 

 ture yellowing and dying of the 

 plants. The joints become dis- 

 colored and shrunken and the 

 entire plant loses weight. Finally, 

 small black eruptions which are 

 thread-like in appearance appear 

 over the canes. 



The Pineapple Disease 

 (Thielaviopsis ethacetica, Went.). 

 — This disease is of comparatively 

 little importance, but it some- 

 times attacks the cuttings which 

 have been prepared for planting 

 and prevents their growth or 

 causes weak, unhealthy plants. 



Treatment. — The most satis- 

 factory treatment for these three 

 diseases is care in selection of 

 good healthy plants for cutting 

 and the treatment of these cut- 

 tings with Bordeaux mixture 

 before planting. 



When the grower has any 

 reason to suspect the appearance 



of these or other diseases, he should consult with the plant pathologist of 

 the experiment station in the state in which he is located. 



Other Diseases. — There are a number of other diseases of minor 

 importance. 



COTTON 

 Anthracnose (Golmerella gossypii, Southworth Edg.). — This disease 

 attacks stem, boll and leaves, causing dull, reddish-brown spots which are 



'Courtesy of Bureau of Plant Industry, U. S. Dept. of Agriculture 



A Young Cotton Plant Affected by 

 Cotton Wilt. 1 



