LEGUMINOUS FORAGE CROPS 153 



Among the numerous fungi attacking the clovers the fol- 

 lowing may be mentioned as being of more or less economic 

 importance : 



Powdery mildew, Erysiphe polygoni D. C. 

 Clover rust, Uromyces trifolii Hedw. 

 Downy mildew, Peronospora trifoliorum De Bary. 

 Leaf spot, Phyllachora trifolii (Pers.) Fckl. 

 Root fungus, Rhisoctonia liolacea Tul. 

 Damping off, Pythium debaryanum Hesse. 

 Leaf spot, Pseudopeziza trifolii Bernh. 

 Stem rot, Sclerotinia trifoliorum Eriks. 



163. Insect Enemies. More than 80 insects in the United 

 States and a much larger number in European countries are 

 known to do more or less damage to red clover. Wire worms 

 (C. A. 328), cutworms (C. A. 329), and white grubs (C. A. 

 330), being omnivorous feeders, may do serious injury to red 

 clover, as may also blister beetles, locusts and leaf hoppers. 

 None of them, however, can be considered specifically clover 

 insects. 



The most injurious insects confined to red clover and other 

 closely allied legumes are: 



The clover root borer, Hylastes trifolii Mull. 



The clover leaf weevil, Phytonomus punctatus Fab. 



The clover seed midge, Cecidomyia leguminicola Lint. 



The clover root borer is a small brown or black beetle one-eighth inch long, 

 which lays its eggs in the crown of the plants in spring. These hatch in 

 about a week, and the larvae burrow into and destroy the roots. The larvae 

 must find sustenance in the plant or perish. If, therefore, the clover is 

 plowed before the larvae are old enough to pupate say between June 15 and 

 July 1, immediately after cutting the first crop they will be destroyed. In 

 some sections a crop of buckwheat could be obtained. The beetle is single 

 brooded. , 



The clover leaf weevil is a large brownish and yellowish snout beetle 0.04 

 inch long. Adults and larvae feed upon the leaves of clover, the larvae 

 mostly in May and the beetles in July and August. A second brood of Karvae 

 appears in September: they pupate in October, emerge as beetles in November, 

 and hibernate when quite small within the clover stem. Aside from a rota- 

 tion of crops there is no practicable remedy. Fortunately, however, it is sb- 



