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Bull. Spec. CORESTA Congress, Jerez de la Frontera, 1992, p. 122, A18, ISSN.0525-6240

Effect of MH application time on methanol soluble and insoluble residues in flue-cured tobacco

SELTMANN H.; SHEETS T.J.; MEYER S.A.
USDA-ARS, Crops Research Lab, Oxford, NC, USA

Field experiments were conducted for two years with maleic hydrazide (MH) in a chemical sucker control program to determine the relationship between the degree of control and the time of day that the MH was applied; and to determine the relationship between the degree of control and the levels of methanol soluble (70%), methanol insoluble (filter cake), and total MH in fresh and cured leaves from the same plants. Decapitated plants were treated with the labelled rate of MH at 200, 600, 1000, 1400, 1800, and 2200 h. Fresh leaf samples for the MH residue analyses were taken 24 h after each application. The degree of sucker control was determined after harvest was completed. MH was determined spectrophotometrically in the two methanol fractions and in the whole tissue of both the fresh and cured leaf samples. Residues of MH in the soluble and insoluble fractions and in the total (whole) tissue were highest from applications made at 1000 and 1400 h and lowest at 200 and 600 h. The degree of sucker control tended to correlate with residues.