46* THE farmers' HANDBOOK. 



Head Smut (Sorosporium reilianum). 



This soil-borne disease attacks sorghum as well as maize. When this 

 disease is present, it is therefore inadvisable to consider sorghum as an 

 entirely satisfactory successor to maize in a rotation, though for one to 

 follow the other is a better practice from the point of view of disease control 

 than continuous cropping with either. (See under Head Smut of maize, 

 page 426). 



Grain Smut (Sphacelotheca xorghi Lk. Clinton). 



This smut can be distinguished from Head Smut by reason of the fact that 

 it does not affect the whole of the panicle. Individual grains become 

 diseased and instead of giain there is found underneath the outer covering 

 membrane a mass of smut. The disease is conveyed to healthy seeds by the 

 wind or by contact with diseased panicles during threshing. Seedlings 

 become infected from spores borne in the seed. 



Methods of control recommended are : — 



1. Select seed from clean crops. 



2. Treat the seed before sowing with bluestone and lime as recom- 



mended for Bunt in wheat (see page 336). 



Leaf Spot or Anthracnose (Cqiletotrichum graminicolum Ces. Wils.). 



This disease causes light- coloured spots' outlined with red on the leaves 

 and stems of sorghum, and in the case of broom millet may seriously affect 

 the broom, discolouring it and causing it to become brittle. 



No methods of keeping the disease in check have been devised. It is 

 customary to harvest broom millet sufficiently early to prevent damage by 

 this disease, which is able to make its most rapid progress on the tissue of 

 the broom when it is nearly mature, especially under wet conditions. As a 

 disease in the leaves it is of little importance. 



Leaf Stripe (Helminthosporium). 



This disease attacks some varieties of sorghum, e.g., Early Amber Cane, 

 very badly, and is particularly prevalent in wet seasons. The characteristic 

 appearance of the disease is the death of portions of the leaf in spots or in 

 elongated areas, generally reddish or pink at the margin. The dead portions 

 are white or brown in colour. 



The disease is perpetuated by the growth of the fungus on old sorghum 

 trash in the soil and by the spread of the spores of the fungus from plant to 

 plant through the air. 



To control it, avoid a succession of sorghum crops on the same land, and 

 use a variety which, under the. conditions of the district concerned, is 

 normally free from the disease. Saccaline is freer from this disease than 

 Early Amber Cane. 



Rust (Puccinla purpurea Cke.). 



This disease gives rise to reddish or purple spots on the leaves, and on 

 these spots reddish or brown pustules occur and burs'', liberating the spores. 

 The disease sometimes reduces the yield of grain and fodder sorghums, and 

 is known to live on Johnson grass and Sudan grass. The selection of a 

 variety relatively resistant to attack is the only practicable method of 

 control. 



