Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2003
Publication Date: 8/10/2003
Citation: RIGA, E., MOJTAHEDI, H., COLLINS, H.P., WILSON, J. EDAPHIC AND BIOLOGICAL FACTORS IMPACTING METHAM SODIUM EFFICACY TO CONTROL ROOT-KNOT NEMATODES IN THE PACIFIC NORTHWEST. POTATO ASSOCIATION OF AMERICA PROCEEDINGS. 2003. G17, p. 35. Interpretive Summary:
Technical Abstract: Metam sodium products, including Vapam®, are important tools as effective nematicides for potato growers of the Pacific Northwest to control root-knot nematodes, i.e., Meloidogyne chitwoodi and M. hapla, and early die disease organisms, i.e., Verticillium dahliae. However, several fields throughout the State of Washington have been identified where metham sodium products fail to control root-knot nematodes. Extensive laboratory, greenhouse, and field studies indicated that certain edaphic factors like low soil moisture levels prior to fumigation and high silt content may impede the performance of the metham sodium products to control root-knot nematodes population in soil profile. Recently, we have obtained data to suggest that biological factors may also render metham sodium ineffective in soil from a 'problem' field. In these studies 100% M. chitwoodi survived in the 'problem' soil treated with Vapam. However, 100% of M. chitwoodi were controlled when the 'problem' soil was autoclaved or pasteurized prior to Vapam application. The performance of Vapam improved in soil samples that were previously irradiated or treated with methyl bromide. However, the residual population in these samples was higher than the known damage threshold of M. chitwoodi. Bacterial populations were determined following each soil treatment. Total culturalable bacteria, Pseudomonas, and fluorescent Psuedomonas declined in response to autoclaving and pasteurization and showed a significant increase following the methyl bromide treatment. The thermo-deactivation of Vapam blocking agent in this field soil suggests a living component which is not known at this time.