Submitted to: Georgia Peanut Research Extension Report
Publication Type: Experiment Station
Publication Acceptance Date: 1/8/2003
Publication Date: 1/14/2003
Citation: Timper, P., Brenneman, T.B., Holbrook, Jr., C.C. 2003. Effectiveness of vapam for controlling root-knot nematodes in peanut. 2002 Georgia Peanut Research and Extension Report. p.64-66. Interpretive Summary: Interpretive Summary not required.
Technical Abstract: Both root-knot nematodes (Meloidogyne arenaria) and Cylindrocladium parasiticum, the causal agent of Cylindrocladium black rot (CBR) can cause devastating yield losses in peanut. The fumigant Vapam (metam sodium), which is recommended for suppression of CBR, also has nematicidal activity. However, there have been mixed reports about the effectiveness of this fumigant as a nematicide. Our objective was to evaluate the effectiveness of Vapam for controlling root-knot nematodes in susceptible and nematode-resistant peanut. The effectiveness of Vapam was compared to that of the standard single and split applications of Temik. Two nematode-resistant peanuts, the highly resistant COAN and the moderately resistant C209-6-49, were also included in the experiment. The experiment was conducted twice in a field naturally infested with M. arenaria but without a history of CBR. The treatments were laid out in a split-split-plot design with peanut genotype (Georgia Green, COAN, and C209-6-49) as the whole plots, fumigant (Vapam and No Vapam) as the subplots, and three Temik treatments (at planting + at pegging, at planting, and nontreated) as the sub-sub-plots. The Temik treatments had no affect on either yield or TSWV; however, they did reduce root galling in 2001 but not in 2002. Vapam, on the other hand, reduced galling on the susceptible and moderatley-resistant genotypes (Georgia Green and C209-6-49) in both years, but did not affect root galling on the resistant genotype (COAN). Vapam increased yields for Georgia Green in 2001, but not for the other genotypes. Georgia Green is more susceptible than the other genotypes to M. arenaria and probably suffered the greater yield loss from the nematode in untreated plots. In 2002, Vapam increased yields of C209-6-49 and COAN, but not Georgia Green. Because root galling was minimal in this year, suppression of the nematodes by Vapam probably had little effect on yield. Therefore, other factors may be involved in the yield enhancement of Vapam. The fumigant reduced the severity of TSWV in COAN. Vapam may have killed overwintering thrips in soil, thus reducing vector transmission of the virus. The yield enhancement of Vapam to C209-6-49 is more difficult to explain given that this genotype had low gall indices and TSWV. We have shown that Vapam is effective in reducing galling and yield losses from M. arenaria. Either Temik at pegging or a nematode-resistant cultivar may be needed for additional control in fields heavily infested with this nematode.