Submitted to: Southeastern Regional Peach Newsletter
Publication Type: Experiment Station
Publication Acceptance Date: November 14, 2003
Publication Date: December 1, 2003
Citation: Nyczepir, A.P. 2003. Preplant crop rotation for nematode control--a replacement for stacy wheat. Southeastern Regional Peach Newsletter. 3(5):9-10. Interpretive Summary: The most studied ring nematode species on Prunus is Mesocriconema xeonplax. This ring nematode is the only plant-parasitic nematode that has been associated with the peach tree short life (PTSL) disease complex in the southeastern United States. Tree loss due to PTSL in South Carolina alone was estimated at over $6 million per year. Previous research has shown that in two separate field plot trials preplant wheat cv. Stacy for 3 years suppressed the population density of the ring nematode, was shown to be as effective as preplant methyl bromide fumigation, and prolonged tree survival on PTSL sites. In recent years one of the major concerns to growers and researchers has been the availability of Stacy wheat seed for planting. Finding a replacement wheat variety(ies) that is as good or better than Stacy in suppressing ring nematode populations was investigated. Five commercial wheat varieties were evaluated for suppressing the ring nematode population density. The varieties tested were Pioneer 26R61, Pioneer 2691, Pioneer 2684, Coker 9663, and Coker 9835. Stacy wheat and Nemaguard peach were included as controls. Results indicate that most wheat cultivars tested were similar to Stacy in suppressing nematode reproduction. These data provide useful insights into the use of commercially available wheat cultivars that are suitable substitutes for Stacy wheat as a preplant alternative to chemical control of the ring nematode in peach orchard establishment.
Technical Abstract: Five commercially available wheat varieties were evaluated for host susceptibility to M. xenoplax, in the greenhouse. Stacy wheat and the ring nematode susceptible peach cultivar, Nemaguard, was used to verify nematode suppression and infectivity, respectively. Pots without plants were designated as a fallow treatment. The soil in each pot was infested with 2,000 ring nematode adults and juveniles. Ten replications of each plant species and five replications of fallow were arranged in randomized complete blocks on benches in an air-conditioned greenhouse. Six months after soil infestation, all test treatments were harvested and nematodes extracted from a 100-cm3 soil subsample and counted. The nematode reproduction factor [Rf = final population density (Pf) of all life stages divided by initial population density (Pi) was calculated as a measure of host susceptibility among the different plant treatments. Cultivars were grouped into three classifications based on the nematode Rf rating, as follows: nonhost, Rf = 0; poor host, Rf = 0.01 - 1.99; and suitable host; Rf > 2. The study was repeated once. In both tests, Nemaguard peach supported greater reproduction of ring nematode than the wheat varieties and fallow soil treatments. Most wheat varieties were similar to Stacy in subduing nematode reproduction. All wheat varieties were classified as either nonhosts (Rf = 0) or poor hosts (Rf = 0.01 - 1.99) to the ring nematode. No ring nematodes were detected in soil planted to Coker 9835 in either test.