326 DISEASES OF ECONOMIC PLANTS 



worse upon late crops. There is no evidence that these 

 maladies can be carried by seed from rusted plants, though 

 such seeds should not be used for seed purposes, since they 

 do not have stored nourishment sufficient to give the 

 seedhng a vigorous start. 



Great difference in rust resistance has been shown ; thus 

 one variety was so badly affected as to yield only 2,f 

 bushels per acre, while a resistant variety under the same 

 conditions gave 38 1 bushels.^ 



The greatest hope lies in the use of varieties which can 

 resist the disease. A number of varieties of the different 

 kinds of grain are now known which possess sufficient 

 resistance to give good yields even when the rust is in its 

 worst epidemic form. Since serious epidemics of rust 

 must be looked forward to with certainty, the item of rust 

 resistance must have due weight in the selection of the 

 variety to be grown. 



Several varieties of oats, among them Texas and Georgia 

 Rust Proof, are known to possess valuable, though not 

 complete, resistance to the oat rust when grown in the 

 Southern States, though the same resistance is not main- 

 tained under the different climatic influences of the North. 



Early maturity in oats is of especial value in that it 

 enables the plant to evade the heaviest part of the rust 

 attack. Good drainage conduces to plants of more resist- 

 ance to rust, as does also good preparation of the seed bed 

 and extermination of weeds. Drilled wheat is better 

 lighted and better ventilated and resists rust better than 

 wheat that is broadcast. 



Wild grasses that harbor rusts identical with the rusts 



1 Carleton, M. A., U.S. Dept. Agr. Div. Veg. Phys. & Path. Bui. 16. 



