196 MUTATION AND PLANT BREEDING 



1960. Resistance occurs in a number of varieties, including milo, 

 hegari, and feterita. Among the parents of sorghum hybrids, Com- 

 bine White Feterita is highly resistant but not immune. Other 

 resistant parents are Wheatland, Plainsman, Caprock, and several 

 of the Redbines. Most of the kafirs are moderately susceptible and 

 Martin slightly so. The head smut resistance of a hybrid cannot 

 be predicted if one parent is resistant and one susceptible to the 

 fungus. Some parents, such as Caprock, are quite resistant them- 

 selves, but their hybrids with susceptible parents, such as Combine 

 Kafir Tx 3197, are susceptible. Combine White Feterita, Tx 09, 

 is also resistant, but its hybrid with Tx 3197 is quite resistant. 

 Most hybrids with two resistant parents are resistant. 



A destructive stalk rot of sorghum, caused by the fungus Macro- 

 phomina phaseoli (Maubl.) Ashley, is called charcoal rot. Severe 

 lodging results from the presence of the disease because the culms 

 break over close to the ground level when the pith of the lower 

 internodes rots away. The fungus, Fusarium moniliforme Sheldon, 

 produces symptoms that are sometimes quite similar to those pro- 

 duced by M. phaseoli, and there is a tendency to attribute the dam- 

 age to charcoal rot regardless of which fungus is responsible. Tullis 

 (42) reported on work done with moniliforme and cited the perti- 

 nent literature. Resistance to both these diseases exists in sorghum, 

 but the expression of susceptibility is variable from year to year 

 and it has been impossible to determine the mode of inheritance 

 of resistance to these stalk-rotting fungi. Breeding for resistance to 

 charcoal rot has not been very effective in sorghum up to the 

 present. 



Anthracnose of sorghum caused by Colletotrichum gramini- 

 colum (17) severely damages sorgo varieties grown in Mississippi. 

 Leaves are injured sometimes to the point of defoliation and rot- 

 ting causes a break-down of the tissues of the stalk. LeBeau and 

 Coleman (17) found resistance to the leaf phase of this disease in 

 recently introduced varieties from Africa. They found resistance to 

 the disease to be a simple dominant. 



The chinch bug, Blissus leucopterus (Say.), is a serious pest 

 on sorghum in some areas in certain years. In Texas and Oklahoma, 

 the insect migrates from grass pastures or barley fields to sorghum 

 by flying and the usual measures of building barriers to stop the 

 crawling insects is not effective. An effective breeding program to 



