PEANUT DISEASES 297 



( G) Spraying for control of vector ( 107) . 

 (H) Grass mulching of soil (141). 



BACTERIAL WILT— SLIME DISEASE 



Importance. Bacterial wilt or "slime disease" i^, the first recorded 

 important disease of peanuts, was observed in the East Indies around 

 1905 with losses of at least 25 percent (23). The disease was investigated 

 extensively in the East Indies thereafter until 1937 when a gradual de- 

 crease in the importance of the disease was noted ( 154). Slime disease of 

 peanuts was reported, without estimates of importance, from various 

 regions and in South Africa the disease became of sufficient importance 

 for an extensive study to be made in 1930 (87). 



In the United States bacterial wilt of peanuts has generally been 

 regarded as of minor importance. The disease was noted in North Caro- 

 lina in 1912 when about 15 percent of Spanish peanuts on soil known to 

 be infested were diseased (47). Wartime plant disease surveys (1944) 

 reported some bacterial wilt of peanuts in the United States ( 13, 140) . 

 Experimental host range studies made in North Carolina in 1917 sub- 

 stantiated the general conclusion that the disease is relatively unim- 

 portant on peanuts in the United States since peanuts were placed in the 

 "very slightly susceptible" class (131). 



Description. As slime disease of peanuts was observed in the East 

 Indies, attacked plants usually wilted rather suddenly with leaves on dead 

 plants sometimes remaining green (23, 106). Slight, early infections, how- 

 ever, were usually overcome ( 106) . Apparently the disease developed pri- 

 marily in patches and general attacks over an entire field were very rare 

 (23). In contrast to this are the descriptions given from the United 

 States where the disease appears to be much milder (92, 136) . 



The attack of the causal organism is centered in the conducting cells 

 of the roots and stems (23). One diagnostic characteristic is a large 

 number of dead roots (106). Bacterial colonies form throughout the root, 

 main stem and lower branches (23) . These colonies are evident as streaks 

 of brown or black discolorations (23, 106). The original point of entrance 

 is possibly an insect wound or a lenticle (143). The infected tissue is 

 finally blackened with extensive plugging and necrosis. If young plants 

 are attacked the pods are invaded and remain small (106) or become 

 wrinkled and develop a spongy decay (23). Shells of well-developed 

 fruits have been found to contain the bacteria (106). When relatively 



" "Slime disease" is a general term applied to the effects of Bacterium solanaceamm on a 

 large number of hosts. 



