Sampling for Plant-parasitic Nematodes in Corn Strip Trials Comparing Nematode Management Products
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Protectant seed treatments are a new management option for plant-parasitic nematodes that feed on corn. Avicta from Syngenta Crop Protection became widely available for use on corn in the United States in the 2010 growing season, and Votivo from Bayer CropScience is now available for use on corn in the 2011 growing season. Many growers and agribusiness personnel working for co-ops, grain elevators, and seed and chemical companies are conducting strip-trial comparisons of nematode seed treatments in growers’ fields. Yield monitors in combines and/or weigh wagons can be used to collect yield data from multiplerow strips that stretch across an entire field. But some growers and agribusiness personnel also want to assess plant-parasitic nematode populations in these strip trials to gauge whether the seed treatments are affecting nematode numbers. Drawing conclusions about the effects of treatments on numbers of plantparasitic nematodes in strip trials is problematic because of the natural variability of nematode populations and their densities in the field. Plantparasitic nematodes are microscopic worms and their population densities can vary greatly over short distances. The variability in nematode population densities in two or more samples collected from the same treatment in a strip trial may be equal to or greater than the differences in nematode numbers in samples collected from two or more different treatments. And, if differences in numbers of nematodes from samples taken from different treatments are detected, one cannot assume that the differences are due to effects of the treatments. The inability to attribute differences in nematode numbers to treatment effects is especially true if only one sample is taken from each treatment. Multiple samples must be collected uniformly, consistently, carefully, and at the proper time in order to have a chance of detecting differences in nematode population densities among treatments.
This article is published as Tylka, G. L., Todd, T. C., Niblack, T. L., MacGuidwin, A. E., and Jackson, T. 2011. Sampling for plant-parasitic nematodes in corn strip trials comparing nematode management products. Online. Plant Health Progress doi: 10.1094/PHP-2011-0901-01-DG. Posted with permission.