PLANT DISEASES AND PESTS 



377 



Remedy. The diseased limbs and twigs should be 

 removed as soon as discovered, always cutting several 

 inches below the noticeable affection to be sure to remove 

 all bacteria. Always disinfect the cut surfaces and also 

 the cutting instrument after each cut. The cankers in 

 which the bacteria live through the winter can be cut off 

 with a sharp knife. Cut well back into -the healthy bark, 

 scrape out the diseased parts 

 thoroughly, and sponge the 

 wound with corrosive subli- 

 mate solution, one part to 

 1,000 parts of water. After 

 the wound is dry, keep it 

 painted with good lead paint 

 until the wound is healed 

 over. 



261. Other Diseases of 

 Plants. There are many 

 other diseases caused by 

 parasitic plants. Bacteria 

 produce the diseases known 

 as blight of beans, cucumber 

 wilt, soft rot of turnips, black rot of cabbage, crown gall 

 of peaches, pears, and apples. 



Additional diseases caused by fungi are apple scab, 

 which passes the winter on fallen leaves; potato scab, 

 which is largely propagated by being planted with the 

 potato; and blight of potatoes. 



Apple scab attacks the leaves and young apples about 

 blossoming time. Spraying just before blossoming and 

 just after will largely control the scab. 



Potato scab lives over the winter on the potatoes and 

 also in the soil in which the potatoes grew. It can be 



SAN JOSE SCALE 

 Natural size on the left; much 

 enlarged on the right. 



