Potential impact of low levels of chlorsulfuron and other herbicides on growth and yield of nontarget plants

Abstract

Abstract-The influence of low application rates of chlorsulfuron on the growth and reproduction of four taxonomically diverse plant species (canola, smartweed, soybean, and sunflower) were examined. Exposures examined ranged from 1 ϫ 10 Ϫ3 to 8 ϫ 10 Ϫ3 of the recommended field rates for cereal crops and were approximately 1,000 times less than the highest exposure recommended by the U.S. Environmental Protection Agency. Each species received a single application at one of three different stages of reproductive development. Effects were determined by measuring the height and yield of mature plants. The comparative effects of four different herbicides (atrazine, chlorsulfuron, glyphosate, and 2,4-D) were determined in the same manner by exposing each test species to a single low dose at one of three critical stages of reproductive development.Chlorsulfuron reduced the yield of all plants tested, with the amount of reduction depending on the time and rate of application. Most noteworthy was its influence on canola and soybean, in which at critical stages in development, applications of 9.2 ϫ 10 Ϫ5 and 1.8 ϫ 10Ϫ4 kg/ha, respectively, reduced seed yields (dry wt) to 8 and 1% of those of controls without causing a significant change in vegetative growth. These low application rates are within the range of reported herbicide drift levels and suggest that chlorsulfuron may cause severe reduction in the yields of some nontarget crops if they are subjected to exposure at critical stages of development. Application of other herbicides at comparable rates and stages of plant development had no influence on either canola or soybean.

Comparison of the effects of glyphosate and atrazine herbicides on nontarget plants grown singly and in microcosms

“…Longer-term studies with different endpoints would be needed to determine the overall effect of glyphosate or atrazine on plant performance. Previous studies have found that significant herbicidal effects can become apparent a full year after spray [1,7] and that reproduction can be adversely affected [28,29]. It was evident that some recovery of biomass occurred for both terrestrial and wetland communities treated with atrazine.…”

Potato (Solanum tuberosum) greenhouse tuber production as an assay for asexual reproduction effects from herbicides

“…Even though in the present study NOEC and EC25 data were compared for plants treated with herbicides at the same chronological age ($14 DAE) for both plants in pots and plants in the field, there is no way to know whether tuber initiation occurred at the same time in the small pots as in the field. In other studies, there was no clear relationship between stage of plant development (preflowering to flowering) and herbicide sensitivity among four plant species [21]. Thus, although young seedling potato plants grown in small pots indicate the potential for effects on tuber production, the amount of reduction in tuber weight in relation to herbicide treatment may be different from the response of field-grown plants.…”

Test No. 227: Terrestrial Plant Test: Vegetative Vigour Test

“…The type and texture, % organic carbon, pH and salt content as electronic conductivity of the final prepared soil should be reported. The soil should be classified according to a standard classification scheme (13). The soil could be pasteurized or heat treated in order to reduce the effect of soil pathogens.…”