Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 16, 1996
Publication Date: N/A
Interpretive Summary: Hay exported to Japan by ocean freight is valued at $240 million per year with an additional $90 million in income for the fright container industry. Hay exports have been jeopardized by rejections of hay upon arrival in Japan because weeds that serve as hosts for Hessian fly have been found when the bales were examined by Japanese inspectors. Hessian fly is an insect that is not found in Japan and a quarantine treatment for hay is needed to prevent the risk of an accidental introduction of the pest into their country. A multiple quarantine treatment using compression of bales and hydrogen phosphide fumigation was developed to control Hessian fly in timothy, alfalfa, oat, Bermuda grass, Sudan grass hays, and rye straw. Large-scale tests were conducted to demonstrate that the quarantine treatment caused 100% mortality of 76,000 insects in two tests. The tests fulfill regulatory agency requirements to certify the quarantine treatment. .Hay exported to Japan under the certification program will not be inspecte upon arrival at destination ports. The quarantine treatment ensures the Japanese government that accidental introductions of Hessian Fly will not occur through compressed hay exported from the U.S.A. Certified compressed hay will be more economical to ship and more competitively priced with hays exported from other countries such as Canada and Australia. The quarantine treatment is based on compression of bales which will help reduce dependency on chemical fumigants to control exotic pests in the future.
Technical Abstract: Hessian fly, Mayetiola destructor (Say), was reared in a greenhouse in Fresno, CA, which eliminated interstate shipments of test materials. Two large-scale tests fulfilled regulatory test requirements to confirm the efficacy of a multiple quarantine treatment using greater than or equal to 80 kg/cm2 compression and 60 g/28.3 m3 aluminum phosphide for 7 d at 22C, to control Hessian fly in compressed hay exported to Japan. A large-scale test with timothy, Phleum pratense, hay and a second test with alfalfa, Medicago sativa, combined with Sudan grass, Sorghum bicolor sudanensis, hays loaded in 76.2 m3 freight containers resulted in complete mortality of 38.957 and 37.345 Hessian fly puparia, respectively. These species of hay were representative of previously tested species including oat, Avena sativa, and Bermuda grass, Cynodon dactylon, hays and rye straw, Secale cereale. Copper plate corrosion values, bale temperatures, and fumigant concentrations were similar throughout the freight containers in both tests. Fumigant concentrations were lower in the second test than in the first test and were attributed to leakage. Hydrogen phosphide residues 1 d after fumigation and overnight aeration resulted in concentrations below the U.S. Environmental Protection Agency tolerance of 0.1 ppm. Hessian fly has not been reported as an economic pests of wheat in California for the past 20 years. Most Hessian fly puparia and pupae were located in wheat plants in the area below 1.9 cm above the bottom of the stem, an area below the cutting height of hay.