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Title: EFFECT OF FOLIAR APPLIED PLANT ELICITORS ON MICROBIAL AND NEMATODE POPULATIONS IN THE ROOT ZONE OF POTATO

Author
item Collins, Harold
item Navarre, Duroy - Roy
item RIGA, E - WASHINGTON STATE UNIV
item PIERCE, F - WASHINGTON STATE UNIV

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2005
Publication Date: 7/1/2006
Citation: Collins, H.P., Navarre, D.A., Riga, E., Pierce, F.J. 2006. Effect of foliar applied plant elicitors on microbial and nematode populations in the root zone of potato. Communications in Soil Science and Plant Analysis. 37:1747-1759.

Interpretive Summary: Systemic acquired resistance is a process whereby a plant that successfully resists a pathogen becomes highly resistant to subsequent infection not only by the original pathogen, but also a wide variety of pathogens; this protection can last for weeks to months. Most SAR research has focused on resistance in leaves, so much less is known about the effectiveness of foliar applications of SAR compounds in the protection of plant roots. This study was conducted to determine if foliar SAR (BTH or harpin) applications exhibit a 'protection' response in the potato root system that influence rhizosphere microbial populations and activity, pathogens or nematodes. The foliar applications of both BTH and harpin had no stimulatory or inhibitory effects on major bacterial populations. The two elicitors significantly reduced the populations of two plant parasitic nematodes (lesion and root knot) by the end of the growing season. However, the reductions in nematode populations did not significantly lower the number of cull potatoes. Culls averaged > than 55% of total production in both years of the study.

Technical Abstract: Systemic acquired resistance is a process whereby a plant that successfully resists a pathogen becomes highly resistant to subsequent infection not only by the original pathogen, but also a wide variety of pathogens. This protection can last for weeks to months. Most SAR research has focused on resistance in leaves, so much less is known about the effectiveness of foliar applications of SAR compounds in the protection of plant roots. This study was conducted to determine if foliar SAR (BTH or harpin) applications exhibit a 'protection' response in the potato root system that influence rhizosphere microbial populations and activity, pathogens or nematodes. There was no significant difference in microbial biomass, culturable bacteria, Pseudomonas populations or N- mineralization potentials for any of the treatments for both years of the study. The foliar applications of both BTH and harpin had no stimulatory or inhibitory effects on major bacterial populations. Both BTH and harpin reduced the numbers of lesion nematodes by potato harvest. BTH significantly reduced the root knot nematodes, Meloidogyne chitwoodi, at the end of the season. In addition, BTH and Harpin reduced the nematode infection index in comparison to the control. All plant elicitors reduced the percent of culled potatoes in comparison to the control. The plant elicitors increased the densities of non-target free living nematodes in the soil in comparison to the control; however, the increase was not significantly different.