Influence of tobacco flea beetle management on the development of black shank in tobacco
PI(s):
Semtner, Paul J
Investigators:
Johnson, Charles S. , Srigiriraju, Lakshmipathi
Abstract:
Black shank is a major soil-borne pathogen of tobacco. The objectives of this research are to determine the influence of early-season control of the tobacco flea beetle, a pest that damages young leaves and roots, on the development of black shank in tobacco. Imidacloprid for flea beetle control and metalaxyl, a fungicide commonly used for black shank management, are being assessed for their impact on the incidence of flea beetles and black shank. In a moderately-resistant cultivar, the use of imidacloprid applied as tray drench treatments provided effective early-season control of flea beetles, reduced flea beetle emergence from tobacco root systems, and reduced the number of plants with black shank symptoms by 40% to 50% compared with the untreated check and an early-season application of metalaxyl. This study may lead to improved insect management practices for reducing the incidence of black shank in problem fields.
Description:
Tobacco black shank, Phytophthora tabacum nicotianae, is
one of the most important soil-borne pathogens of tobacco in Virginia.
Previous research indicated that black shank is more severe in fields with
nematode problems. Recent observations conducted in cooperation with Dr.
Charles Johnson suggest that the insecticide imidacloprid (Admire) reduces the
incidence and severity of black shank in susceptible cultivars. Tobacco
treated with imidacloprid had much lower early season populations of the
tobacco flea beetle, flea beetle feeding damage and adult flea beetle
emergence from tobacco root systems than tobacco treated with the fungicide,
metalaxyl (Ridomil Gold0. or an untreated check. In addition, the incidence of
dead and wilted plants with symptoms of black shank were 40 to 50% lower in
plots treated with imidacloprid than in untreated plots or those treated with
a single application of Ridomil Gold or an untreated check. A single
late-season harvest of imidacloprid produced 5x higher yields in the
imidacloprid treated plots than in the untreated check. Although imidacloprid
does not control black shank directly, its use may help tobacco overcome
early-season insect feeding injury that reduces plant susceptibility to the
black shank fungus. This information will help farmers who have black shank in
their fields, especially those who plan to grow burley tobacco in
nontraditional areas where black shank is more severe.
Description last modified at 2007-07-31 16:18:05.0.
