Evaluations of novel, synthetic compounds for control of the soybean cyst nematode (Heterodera glycines Ichinohe)

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Knips, Angela
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Plant Pathology and Microbiology
The Department of Plant Pathology and Microbiology and the Department of Entomology officially merged as of September 1, 2022. The new department is known as the Department of Plant Pathology, Entomology, and Microbiology (PPEM). The overall mission of the Department is to benefit society through research, teaching, and extension activities that improve pest management and prevent disease. Collectively, the Department consists of about 100 faculty, staff, and students who are engaged in research, teaching, and extension activities that are central to the mission of the College of Agriculture and Life Sciences. The Department possesses state-of-the-art research and teaching facilities in the Advanced Research and Teaching Building and in Science II. In addition, research and extension activities are performed off-campus at the Field Extension Education Laboratory, the Horticulture Station, the Agriculture Engineering/Agronomy Farm, and several Research and Demonstration Farms located around the state. Furthermore, the Department houses the Plant and Insect Diagnostic Clinic, the Iowa Soybean Research Center, the Insect Zoo, and BugGuide. Several USDA-ARS scientists are also affiliated with the Department.
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The first objective of this study was to determine the effects of four novel compounds on Heterodera glycines population densities in laboratory, growth chamber, and field microplot environments. Experimental test compounds were 2-hydroxymethylenecyclopentanone (compound AA), 2-(l-ethoxycarbonyl-l-hydroxymethylene)cyclopentanone (compound Va), 1-cyano-l-hydroxy-2-propene (compound CHP), and methyl pelargonate (compound MP). In the laboratory, H. glycines eggs were incubated in test solutions and transferred to fresh solution every two days for 20 days. Hatched second-stage juveniles (J2) were counted after each transfer. Heterodera glycines egg hatch was less in all test compounds relative to hatch in water. Aqueous treatments were applied to soil in growth-chamber pots and field microplots prior to planting with H. glycines-susceptible soybeans. Heterodera glycines eggs and J2 were extracted from soil and root samples and counted. The effect of the compounds on nematode population densities and soybean development in growth chamber and field microplot experiments was not consistent. The second objective was to evaluate hatch and mobility responses of H. glycines J2 to the compounds using a laboratory hatch study, mobility assay, and contact toxicity assay. In the laboratory hatch study, contact and volatile activities of the compounds were assessed by incubating eggs directly in treatment solution or in water exposed to vapors of a compound. Egg hatch was inhibited by direct incubation in all four compounds. Eggs incubated in water were inhibited from hatching in the presence of CHP and MP, suggesting volatile effects. Both contact and volatile inhibition of hatch by CHP and MP was irreversible to some extent. For the mobility assay, avoidance by H. glycines J2 to 10, 100, and 1,000 parts per million (ppm) of the compounds was determined. Heterodera glycines J2 were repelled by 100 and 1,000 ppm AA, 100 ppm Va, and 10 and 100 ppm CHP. In a contact toxicity assay, mobility rates of J2 were compared after one or twenty-four hours of incubation in 100 ppm of the compounds. Nearly 100% of nematodes incubated in CHP were immobile after each incubation period. Although the compounds affected egg hatch and juvenile mobility under controlled, laboratory conditions, they did not have consistent, adverse effects on H. glycines in soil experiments.

Mon Jan 01 00:00:00 UTC 2001