266 PLANT DISEASES 



Control. — Spray with bordeaux, 4-4-50, beginning about 

 August first, and making applications at intervals of ten days or 

 two weeks. 

 Beet. Heart-rot {Phomn betcc). — Leaves appear spotted late in 

 July, then wilt, and finally a dry heart rot appears. 



Control. — Destroy infected plants. Practice long rotation. 

 Treat seed with formalin, 1 pint in 30 gallons of water. 

 Leaf-spot (Cercospora beticola). — Ashen gray spots with reddish 

 borders occurring on leaves. In advanced stages, leaf becomes 

 much cracked and torn. 



Control. — Spray with bordeaux mixture, 4-4-50, at frequent 

 intervals. 

 Scab (Oospora scabies). — Fungus produces a scabby patch on the 

 root. The same disease as potato scab. 



Control. — Avoid planting beets after potatoes for several years. 

 Blackberry. Anthracnose. — See under Raspberry, p. 280. 

 Crown-gall or Root-gall (Bacterium tumefaciens) . — A bacterial 

 disease which soon ruins the bushes. 



Treatment. — Plow up and burn all bushes in a diseased patch. 

 Plant clean roots in a new place. 

 Red or Orange Rust. — See under Raspberry. 

 Brussels sprouts. Club-root. — See under Cabbage. 

 Cabbage. Club-root or Club-foot {Plasmodiophora brassicce). — 

 A contorted swelling of the roots of cabbage in the seed bed or 

 field, preventing the plant from heading and causing it to assume 

 a sickly color. Occurs on many allied plants — turnips, cauli- 

 flower, Brussels sprouts, chard, radish, wild mustard, etc. 



Control. — Destroy affected seedlings. Rotate crops, and do 

 not follow with other susceptible crops. Keep down weeds on 

 which disease occurs. Lime the soil at least eighteen months 

 before planting to cabbage, using at the rate of two tons of quick- 

 lime to the acre. 

 Black-rot (Bacillus campestre). — The bacteria causing this disease 

 get into the sap tubes, turn them black, and cause the leaves to 

 drop, thus preventing heading. 



Control. — Practice crop rotation. Soak the seed for fifteen 

 minutes in a solution of mercuric chloride, one tablet in a pint of 

 water. 



