Effectiveness of Benomyl and Benomyl-Folicote Treatments in Reducing Ozone Injury To Pinto Beans

Abstract

The body of information presented in this paper is directed to individuals interested in effects of air pollution on vegetation. The effectiveness of the systemic fungicide benomyl (methyl i-(butylcarbamoyl)-2-benzimidazolecarbamate) and the ahtitranspirant Folicote (hydrocarbon paraffin wax emulsion) in reducing ozone injury to plants of Phaseolus vulgaris L “Pinto 111” was determined in a series of experiments. Treatments included incorporating benomyl with soil; drenching a benomyl suspension on the soil with or without a surfactant; and spraying the foliage with benomyl, Folicote, or a mixture of benomyl and Folicote. Eleven-day-old plants of “Pinto 111” were grown in a soil mixture of Hagerstown silty clay loam-peat-perlite (2-1-1) and were fumigated under controlled conditions with 25 pphm of ozone for 4 hours. Temperature during exposure was maintained at 30°C, relative humidity at 78%, and light intensity at approximately 650 ft-c. Results of the fumigation were evaluated 3 days following exposure by determining the percentage area of injured tissue. Fumigated control plants showed flecks on 50-55% of the leaf area. 99% protection was obtained when benomyl was used as a soil amendment at a concentration of 160 μg/g soil on an air dry soil weight basis. Partial protection was obtained at lower concentrations. Higher benomyl quantities were needed to obtain the same results when applied as a soil drench, although protection was improved when a surfactant was added to the suspension. No significant protection was obtained when a water suspension containing 250 mg/1 benomyl was sprayed on the foliage. 99% protection was obtained when plants were sprayed with a Folicote solution alone (10 ml Folicote/1 water). The data demonstrate that ozone injury to plants may be reduced by chemical protectants added to the soil and as a foliar spray.