Acrolein (2-Propenal): A Potential Alternative to Methyl Bromide

Abstract

Vegetable producers face a variety of pest species that can negatively impact the performance of their crops. Nematodes, plant diseases, and several weed species, notably nutsedges (Cyperus spp.), are common problems in most areas where vegetables are commercially produced. Historically, growers have relied heavily on methyl bromide to fumigate their fields. Methyl bromide is a general biocide that effectively controls many fungi, bacteria, nematodes, and weeds. However, methyl bromide has been identified as an ozone-depleting compound. As a result, its use has been restricted as specified in the Montreal Protocol, which went into effect January 1, 1989. Currently there are no alternatives that can replace methyl bromide on a one-to-one basis. With the loss of methyl bromide, growers are forced to rely on compounds that may not be as effective at controlling pest species, and substantial losses in yield and quality can occur. Research was initiated at Auburn University, Alabama to evaluate the potential for acrolein to be considered a viable methyl bromide alternative. Acrolein currently has registration as an aquatic herbicide (Magnacide H®). It provides excellent control of aquatic vegetation in irrigation canals in many countries, including the United States. The pesticidal properties of acrolein when applied to soils are unknown. Research focused on herbicical efficacy against yellow nutsedge (Cyperus esculentus L.) and crop tolerance, focusing on tomato (Solanum lycopersicum L.), bell pepper (Capsicum annuum L), and strawberry (Fragaria x ananassa Duchesne). Greenhouse and field trials were conducted to evaluate acrolein rates ranging from 0 to 896 kg ai/ha applied as a fumigant application in greenhouse studies or when applied through irrigation drip lines in field experiments. Acceptable levels of control (>70%) for yellow nutsedge were achieved with acrolein rates of 448 kg ai/ha and higher. Enhanced growth of yellow nutsedge was observed at lower rates, indicating control of soil pathogens or a stimulation of beneficial organisms. Crop tolerance for all crops tested was excellent when planting was delayed 2 weeks after application. Earlier planting dates resulted in poorer plant health, particularly at rates higher than 448 kg ai/ha. Tomato yields were equivalent to methyl bromide at rates of 448, 672, and 892 kg ai/ha. Pepper yields with acrolein were equivalent to methyl bromide at 224 and 448 kg ai/ha, the only rates tested. Strawberry tolerance to acrolein was excellent when applied preplant. Strawberry yield was higher in plots receiving 448 kg ai/ha acrolein than with methyl bromide. Acrolein applied to strawberries after transplanting was too injurious at all rates evaluated and would not be advisable in sandy soils with low organic matter.