Developing Alternatives to Methyl Bromide - A Focus on Acrolein (2-Propenal). (Paperback)

Methyl bromide, a soil fumigant with biocidal action, is used in agriculture to control weeds, fungi, bacteria, nematodes, and arthropods. Production of many agricultural commodities including strawberry (Fragaria x ananassa Duchesne), tomato (Solanum lycopersicum L.), pepper (Capsicum spp. L.), and certified sod rely heavily on its usage. Due to methyl bromide's active role in atmospheric ozone depletion, its usage will be phased-out according to the guidelines of the United Nation's Montreal Protocol. Currently, there are no effective alternatives to methyl bromide, leaving these agricultural industries with inadequate means of weed, insect, and pathogen control. In efforts to develop novel alternatives to methyl-bromide, -enal compounds with pesticidal effects similar to that of methyl-bromide, were tested at Auburn University for efficacy. Several compounds from this group have potential as pesticides, however acrolein was chosen for further investigation and development. Acrolein is currently labeled as an aquatic herbicide for use in irrigation canals, however little has been done to explore the nematicidal effects of acrolein or to develop strategies and methods to use it in agriculture as an alternative to methyl-bromide. Primary areas of focus in preliminary testing were herbicidal effects on a variety of difficult agronomic weeds and nematicidal effects on two economically important nematodes of Alabama: root-knot nematode (Meloidogyne spp. Kofoid and White) and reniform nematode (Rotylenchulus reniformis Linford and Oliveira). Greenhouse and microplot studies provided data pertaining to necessary dosimetry and methods of applications required to control plant parasitic nematodes and agricultural weeds. Herbicidal efficacy. In greenhouse trials, morningglory (Ipomoea lacunose L, /I.hederacea Jacq.), sicklepod (Senna obtusifolia (L.) H. S. Irwin and Barneby), jimsonweed (Datura stramonium L.), large crabgrass ( Digitaria sanguinalis (L.) Scop.), and yellow foxtail (Setaria glauca L. P. Beauv.) were controlled with acrolein rates =250 mg for complete control. Since approximately 150% more acrolein was required to control this species, it was decided to explore combinations of acrolein with yellow nutsedge-specific herbicides in attempts to reduce rates. Combinations of acrolein with halosulfuron, s-metolachlor, EPTC, and propionic acid were successful for reducing rates; however, it was also found that when applied in the same drench, metam sodium and acrolein were antagonistic. Nematicidal effects. Results from greenhouse trials indicated that drench applications of acrolein at rates 50 to 100 mg/kg soil effectively controlled the reniform nematode. Control of root-knot by drench application in greenhouse studies required rates of 60 to 200 mg/kg soil. Acrolein was also effective at controlling stubby-root (Paratrichodorus minor (Colbran) Siddiqi) and spiral (Helicotylenchus dihystera (Cobb) Sher.) nematodes. Rates required to control plant parasitic nematodes did not drastically affect microbivorous nematode populations. Soil Enzymatic Activity. In general, as acrolein doses were increased, there was a reduction in soil catalase, alpha-glucosidase, beta-glucosidase, alpha-galactosidase, beta-galactosidase, sulfatase, phosphatase, urease, and chitobiase activity. This is typical of broad-spectrum biocidal activity of a soil fumigant. Acrolein treatments resulted in a slight decrease in soil pH and a slight increase in soil electrical conductivity. Effects on Fungi, Bacteria, and Actinomycetes. Bacterial colonies decreased as rates of...