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‘Circular No. 692) |i Le 
March 1944 > Washingeda D. KER 
UNITED STATES DEPARTMENT OF AGRICULTURE #9 : 
\\, Re ue aie 
Control of Bacterial Wilt (Bacterium sola- 
naceatum) of Tobacco as Influenced by 
Crop Rotation and Chemical Treatment 
of the Soil 
By T. E. Smrru, agent, Division of Tobacco Investigations, Burcau of Plant Industry, 
Soils, and Agricultural Engineering, Agricultural Research Administration, 
United States Department of Agriculture, and associate pathologist, North Carolina 
Agricultural Experiment Station } 
United States Department of Agriculture, Agricultural Research Admin- 
istration, Bureau of Plant Industry, Soils, and Agricultural Engi- 
neering, Division of ‘Tobacco Investigations, in cooperation with the 
North Carolina Department of Agriculture and the North Carolina 
Agricultural Experiment Station 
Page Page 
SLIM AT ye eee ee ae ROT eC pre eG ae 1 | Results with erop rotation—C ontinued. 
Geographic distribution of bacterial wilt .____- 2 Results on farmers’ fields.______-_________- 10 
Need of effective control.____________________- 3 Effect of susceptible weeds____.-___________ 10 
Outline of experimental work_________________ 3 Genetic resistance combined with rota- 
Control by crop rotation______________________ 3 CEL OM ee N  aneR E  pcmmeegieceer 12 
Crop rotation reeommended__________________ 4 Urea treatment combined with rotation _- 12 
Other control measures studied_______________ 5 | Chemical treatments of the soil______________- 14 
Results with crop rotation____-________________ 5 Tests with chloropierin._________________- 14 
Experiment on small plots________________ 5 Tests with complex organic compounds ___ 15 
Experiment on large plots________________ 7 | Modifications of cultural practices___________- 15 
Experiment on single-row plots__________- Oi uiterature: cited 2 verse ee ee ee ea a a 15 
PPPOE PPE PPP PBA LLL ALA ALAA AGL ALA LALLA ALAA ALAA OAL AGILE, 
SUMMARY 
Bacterial wilt, one of the most destructive diseases of tobacco, not 
only reduces the production of a crop in great demand by the armed 
services as well as by civilians but also results i in a waste of time and 
labor when both are urgently needed by the farmers who grow tobacco 
along with other crops. Wilt-control experiments carried on since 
1935 have brought about the completion of preliminary work with 
wilt-resistant strains of tobacco and with urea treatment of the soil, 
the most promising control measures now in sight, but these new 
methods have not been made available for commercial use. 
1 The author expresses appreciation for the help of E. G. Moss, senior agronomist and assistant director 
in charge of the Tobacco Branch Station of the North Carolina Agricultural Experiment Station, Oxford, 
N. C., and E. E. Clayton, senior pathologist, Division of Tobacco Investigations, Bureau of Plant In- 
dustry, Soils, and Agricultural Engineering; and for assistance in the survey work by M. F. Buell and 
ke Godfrey, formerly agents, Division of Tobacco Investigations. 
564056—44 
