TlIK BULI.KTIN. 



75 



well, therefore, for the pruncr to carry a cloth saturated with a solution of 

 corrosive sublimate and to wipe the pruning knife witii this after each cut. If 



Fig. 42— Pear blight, healthy and diseased twigs. 



these directions are followed carefully the disease can to a very large extent be 

 brought under control. 



WILT. 



Cotton. — Cotton wilt may be recognized by sudden wilting of the plants, the 

 wilting often beginning between the veins of the leaves. Plants siiowing wilted 

 leavcs^if cut crosswise near the ground reveal darkened strands running length- 

 wise through the stem. The root is also more or less decayed. A furtlior symptom 

 of this disease is that it occurs in spots in the field, and tliat these spots occupy 

 the same location year after year, and enlarge as time goes by. The disease 

 is caused by a fungus in tlie soil which gains entrance to the plant tluough its 

 roots, grows into the water vessels, plugs them and thus cut off the water 

 suppl3\ No treatment is known except to employ resistant plants on soils in- 

 fected with this disease. 



Coicpea. — Cowpea wilt differs from the cotton wilt in that the leaves fall, leaving 

 the stalk bare. In its other symptoms it resembles the cotton wilt, and the remedy 

 consists in planting only resistant varieties. The most serviceable is the iron pea. 



