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The relative toxicity of 2:4‐dichlorophenoxyacetic acid and 2‐methyl‐4‐chlorophenoxyacetic acid to annual weeds
Author(s) -
Ripper W. E.,
Baker C.
Publication year - 1952
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740031201
Subject(s) - mcpa , sodium , sodium salt , toxicity , chemistry , salt (chemistry) , 2,4 dichlorophenoxyacetic acid , high sodium , agronomy , botany , pesticide , biology , inorganic chemistry , organic chemistry
Results are presented showing differences in the relative toxicity of sodium MCPA (the sodium salt of 2‐methyl‐4‐chlorophenoxyacetic acid) and sodium 2.4‐D (the sodium salt of 2: 4‐dichlorophenoxyacetic acid) to Brassica alba sprayed in the field. The apparent toxicity ratio is shown to vary with: ( a ) the interval after spraying at which observations are made; ( b ) the dosage applied; ( c ) the incidence of rain after spraying; ( d ) the particular salt used. Spray droplets of sodium 2,4‐D dry out relatively completely, leaving a crystalline deposit, whereas those of sodium MCPA tend to dry to a non‐crystalline film. It is suggested that the observed variation in relative toxicity may be due to differences between the two materials in the facility with which they enter the leaf; sodium MCPA penetrates the more readily owing to the non‐crystalline nature of the spray deposit, and thus gives better results when rain follows after an interval which much decreases the efficacy of sodium 2,4‐D.