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• 1. [Article] Effect of two methylcarbamates on the toxiciity of isopropyl m-chlorocarbanilate (chlorpropham) to safflower (Carthamus tinctorius L.) and common buckwheat (Fagopyrum esculentum Moench.)

  Addition of the methylcarbamate compounds p-chlorophenyl N-methylcarbamate (PPG-124) and 1-naphthyl N-methylcarbamate (carbaryl) to various herbicides has resulted in reduced rates of degradation. Carbaryl ...

  Citation × Citation Citation Abstract Copy Title: Effect of two methylcarbamates on the toxiciity of isopropyl m-chlorocarbanilate (chlorpropham) to safflower (Carthamus tinctorius L.) and common buckwheat (Fagopyrum esculentum Moench.) Author: Kirkland, Kenneth Addition of the methylcarbamate compounds p-chlorophenyl N-methylcarbamate (PPG-124) and 1-naphthyl N-methylcarbamate (carbaryl) to various herbicides has resulted in reduced rates of degradation. Carbaryl affects the degradation of certain herbicides in both plants and soils while PPG-124 has only been demonstrated to affect degradation in soils. Both these materials are effective in increasing the persistence of isopropyl m-chlorocarbanilate (chlorpropham) in the soil. No work has been published on the possible effect of these compounds on the response of plants to chlorpropham or other carbahilate herbicides. Studies were conducted in a growth-chamber to investigate the effect of PPG-124 and carbaryl on the response of two test species to chlorpropham. One species, safflower (Carthamus tinctorius L. ), was chosen for its resistance to chlorpropham; the other, common buckwheat (Fagopyrum esculentum Moench. ) for its susceptibility. Plants were grown in Hoagland's solution to which the various treatments were added. This approach was used to avoid any soil effects such as differential adsorption and degradation of the chlorpropham. Four experiments were carried out with safflower and two with buckwheat. Varying doses and exposure periods to the chemicals were included but all experiments were of the same duration. The effects of mixtures of chlorpropham with PPG-124 or carbaryl were compared with those of individual treatments of the three compounds applied at the same time. Dry weights of roots and shoots were taken as indicators of plant response. The method of Colby (1967) was used to compute the expected response of the test species to the various mixtures. Comparisons of the expected with the observed responses indicated that both PPG 124 and carbaryl had an antagonistic effect on chlorpropham activity when applied to roots of safflower. In contrast, a slight synergistic effect at certain concentrations was noted when buckwheat was used as the test species. An explanation of these effects would require uptake and metabolism studies with labeled materials. The slight alterations in response to chlorpropham noted in these experiments probably would be masked in the field by the increased persistence of chlorpropham in soil treated with mixtures of this herbicide with PPG-124 or carbaryl. Title: Effect of two methylcarbamates on the toxiciity of isopropyl m-chlorocarbanilate (chlorpropham) to safflower (Carthamus tinctorius L.) and common buckwheat (Fagopyrum esculentum Moench.) Author: Kirkland, Kenneth Addition of the methylcarbamate compounds p-chlorophenyl N-methylcarbamate (PPG-124) and 1-naphthyl N-methylcarbamate (carbaryl) to various herbicides has resulted in reduced rates of degradation. Carbaryl affects the degradation of certain herbicides in both plants and soils while PPG-124 has only been demonstrated to affect degradation in soils. Both these materials are effective in increasing the persistence of isopropyl m-chlorocarbanilate (chlorpropham) in the soil. No work has been published on the possible effect of these compounds on the response of plants to chlorpropham or other carbahilate herbicides. Studies were conducted in a growth-chamber to investigate the effect of PPG-124 and carbaryl on the response of two test species to chlorpropham. One species, safflower (Carthamus tinctorius L. ), was chosen for its resistance to chlorpropham; the other, common buckwheat (Fagopyrum esculentum Moench. ) for its susceptibility. Plants were grown in Hoagland's solution to which the various treatments were added. This approach was used to avoid any soil effects such as differential adsorption and degradation of the chlorpropham. Four experiments were carried out with safflower and two with buckwheat. Varying doses and exposure periods to the chemicals were included but all experiments were of the same duration. The effects of mixtures of chlorpropham with PPG-124 or carbaryl were compared with those of individual treatments of the three compounds applied at the same time. Dry weights of roots and shoots were taken as indicators of plant response. The method of Colby (1967) was used to compute the expected response of the test species to the various mixtures. Comparisons of the expected with the observed responses indicated that both PPG 124 and carbaryl had an antagonistic effect on chlorpropham activity when applied to roots of safflower. In contrast, a slight synergistic effect at certain concentrations was noted when buckwheat was used as the test species. An explanation of these effects would require uptake and metabolism studies with labeled materials. The slight alterations in response to chlorpropham noted in these experiments probably would be masked in the field by the increased persistence of chlorpropham in soil treated with mixtures of this herbicide with PPG-124 or carbaryl. Close