Radio frequency as a tool for pest control
In the United States, a cooperative effort by four Agriculture Research Service (ARS) laboratories and two universities aims to overcome technical barriers inhibiting the use of radio wave heating for controlling pests on a commercial scale in places such as orchards, packing houses and food plants. Electromagnetic waves of radio frequency can make molecules vibrate and heat up, in the same way that microwaves heat food. The hitch lies in eliminating pests without altering the taste or texture of the food they infest.


A team led by Mr. Juming Tang of Washington State University, and involving four ARS labs and the University of California-Davis, has been working on a four-year study to determine if radio waves could be used as an economical and environmentally friendly alternative to methyl bromide and other chemicals to effectively rid fruits and nuts of live insects. At Kika De La Garza Subtropical Agricultural Research Centre, entomologist Guy J. Hallman is investigating the use of radio frequency treatment of citrus against the Mexican fruit fly. In cooperation with a team led by Mr. Tang, Mr. James D. Hansen at ARS’ Yakima Agricultural Research Laboratory plans to “bathe” tubs full of apples and cherries with radio waves to determine exposure times that will eliminate codling moth larvae. At the ARS San Joaquin Valley Agricultural Sciences Centre, Mr. Judy A. Johnson is testing the use of this technology to rid walnuts, almonds, figs, pistachios and raisins of the wiggly larvae of the navel orangeworm, Indianmeal moth and codling moth. 


Website: www.ars.usda.gov 
Chitinase as replacement for methyl bromide
In the United States, researchers at the Agricultural Research Service and Kansas State University report that plants engineered genetically to kill insects may provide an alternative to the use of methyl bromide. The team incorporated an insect enzyme called chitinase to create insect-resistant transgenic tobacco and rice plants. Chitinase causes chitinous membranes in insect skin and gut tissue to disintegrate. Without this membrane, insects are vulnerable to microbial infections. Biotech firms are now working with the researchers to transform other plants such as corn, wheat and sorghum. 


Website: www.agriculture.com 
New methyl bromide substitutes
Researchers at the University of California-Riverside (UCR), the United States, report that liquid methyl iodide has the same spectrum of kill as methyl bromide. Moreover, methyl iodide is safer for workers to apply and remains in the atmosphere for 4-8 days, making it more ozone-friendly than methyl bromide, which remains for up to two years. Arvesta has bought licensing rights from UCR and is piloting its product ‘Midas’ through the registration process.


At the University of California Cooperative Extension, Mr. Hussein Ajwa has been testing the efficacy of iodomethane on strawberries. According to Mr. Ajwa, pound for pound iodomethane is more effective than methyl bromide. Iodomethane moves through the soil at 10 times higher pressure than methyl bromide and cab be used to propel chloropicrin, another fumigant, for controlling diseases.


Website: www.westernfarmpress.com 
Mustard plants suppress pests
According to the University of California Cooperative Extension (UCCE), the United States, mustard plants grown on farmlands have the potential to improve soil fertility and work like a fumigant to suppress soil-borne pathogens, nematodes and weeds. The mustard should be chopped, diced underground and irrigated, approximately 45-90 days after being planted, the time when adequate biomass is achieved during the bloom period, but before seeds develop. The amount of biomass and the degree of chopping and incorporation are critical in getting the maximum biofumigation effect. Mr. Grant Poole, agriculture and environmental issues farm advisor with UCCE, reports that preliminary research reveals a significant improvement in the soil quality of mustard cover crop plots over untreated control plots. 


Contact: Ms. Jeannette Warnert, UCCE, the United States. Tel: +1 (559) 2417 514


E-mail: jwarnert@ucop.edu


Website: www.unepie.org 
Liquid fumigant for farm-stored grains
At the Stored Grain Research Laboratory (SGRL), Australia, researchers are evaluating the use of ethyl formate as a multi-functional grain treatment tool for on-farm storage. The Grains Research and Development Corp. and the grains industry are funding this project. Ethyl formate is at present registered as a fumigant for dried fruit treatment. It occurs naturally in traces in soil, water, vegetation and a range of raw and processed foods, including fruit, vegetables, grain, beer and animal products like milk and cheese. Unlike phosphine, the only fumigant currently available for on-farm treatment of stored grains, ethyl formate kills insects rapidly and breaks down into non-poisonous, naturally occurring products – formic acid and ethanol. SGRL is investigating into the natural occurrence of ethyl formate in stored products, the behaviour of residues on different grains and safe practices in handling and application.


Successful trials using ethyl formate were undertaken on wheat, sorghum and navy beans stored in unsealed farm bins. Liquid ethyl formate was applied to the top of the grain through a PVC probe. This method of application was selected in order to maintain ethyl formate concentrations below the inflammability level, reduce vaporization and maintain an effective concentration for more than 10 h, and avoid liquid ethyl formate accumulating at the bottom of the bin. For wheat, the concentration of ethyl formate was maintained at effective levels for about two days. All insects and all stages of larvae were eliminated. Left for a further 3-5 days, ethyl formate residues in treated wheat were reduced to natural levels without the use of aeration.


Faba beans sorbed ethyl formate strongly and the residues persisted longer, but full control was achieved. For sorghum, insect mortality was high but not complete. Ethyl formate residues at 10ºC in sorghum persisted significantly longer than when treated at 20ºC. During application and fumigation, ethyl formate levels in the work environment did not exceed the worker safety level of 100 ppm. Unlike phosphine, which takes days to kill, ethyl formate kills within hours. 


Contact: Mr. Daphne Mahon, Australia. Tel: +61 (02) 6246 4104; Fax: +61 (02) 6246 4202


E-mail: Given_Name.Surname@csiro.au

Website: www.sgrl.csiro.au