CONTROL OP GARDEN DISEASES AND INSECTS. 



27 



DOWNY MILDEW. 



Lima beans are sometimes attaclved by downy mildew, which 



the pods with a thick, felty, white growth. (Fig. 25.) 

 time this disease can be controlled by thorough 

 spraying with Bordeaux mixture. Apply when the 

 disease appears and repeat at 10-day intervals as 

 needed. Burn diseased pods. 



covers 

 If taken in 



The principal insect enemies of- beans are several 

 species of bean weevils. The cowpea w^eevil also at- 

 tacks beans when cowpeas are not available. Attack 

 begins in the field from eggs deposited in a joint in 

 the pod or opening through which the egg is thrust ; 

 the larva, or grub, develops within, and soon after 

 the beans are harvested the weevils begin to develop, 

 according to the temperature. A second generation 

 of the common bean w^eevil (fig. 26) may be sufficient 

 to destroy a crop of beans for either human consump- 

 tion or seed. Several generations may be produced 

 in a year. 



The bean weevils vary in color. The common bean 

 weevil is dull gray w'ith reddish legs. None of these 

 insects is much more than one-eighth of an inch long, and some are 

 shorter. 



Control. — Bean weevils can not be controlled in the field. They 

 breed continuously in dried seed, and it is therefore advisable to har- 



FiG. 25. — Downy 

 inilflew of Lima 

 beau. 



Fig. 26. 



-The common bean weevil {Bmchus ohtectus) : 

 c, pupa. (Jreatly enlarged. 



grub ; 



vest the crop and as soon as dry to fumigate with carbon disulphid. 

 See Farmers' Bulletin 799, " Carbon Disulphid as an Insecticide." 



