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Title: Nonchemical alternatives for managing phytoparasitic nematodes in peach: biological agents, solarization, preplant groundcovers

item Nyczepir, Andrew
item Kluepfel, Daniel

Submitted to: Southeastern Peach Convention Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 12/15/2007
Publication Date: 1/11/2008
Citation: Nyczepir, A.P., Kluepfel, D.A. 2008. Nonchemical alternatives for managing phytoparasitic nematodes in peach: biological agents, solarization, preplant groundcovers. In: Proceedings of the Southeastern Peach Convention, January 11-13, 2008, Savannah, Georgia. p. 12-15.

Interpretive Summary: Root-knot and ring nematodes are important pests of peach in the U.S. and other parts of the world. The ring nematode is the only plant-parasitic nematode that has been associated with predisposing trees to peach tree short life (PTSL) in the Southeast. Root-knot nematodes, on the other hand, cause stunted growth, loss of vigor, and early defoliation of one to two-year-old peach trees when recommended management practices are not followed. In the Southeast, preplant fumigation in combination with a resistant rootstock is recommended for increased tree longevity and maximum protection against these nematodes. However, in recent years growers have been faced with economic hardships which made it difficult to afford the costs associated with preplant fumigation and (or) not being able to get the land fumigated at the recommended time of year due to a conflict with managing other crops. Finding an alternative management strategy to preplant chemical control of these two nematodes is warranted. A field study was initiated to investigate the effect of soil solarization alone and in combination with a cocktail of 5 biocontrol agents delivered through irrigation system to manage ring nematode and PTSL. Results to date indicate that solarization has more of an effect on decreasing PTSL tree mortality than the biological control agents. A greenhouse study was initiated to examine the susceptibility of tall fescue to root-knot nematode. Results indicate that root-knot nematode did not reproduce nor produce root galls on tall fescue as compared to Lovell peach (i.e., root-knot nematode susceptible host). These data provide useful insights into 1) the benefits of soil solarization when establishing a peach orchard on a PTSL site in the Southeast and 2) the potential use of tall fescue rotation as an alternative to preplant chemical control of root-knot nematode prior to peach tree establishment.

Technical Abstract: In a field study, soil solarization alone and in combination with a cocktail of 5 Pseudomonas spp. (BG33R included) delivered through irrigation system will be investigated to manage ring nematode and PTSL. Soil treatments include: i) solarized soil alone; ii) solarized soil + biocontrol cocktail; iii) nonsolarized soil alone; iv) nonsolarized soil + biocontrol cocktail; v) solarized soil + wheat; vi) solarized soil + wheat + biocontrol cocktail; vii) nonsolarized soil + wheat; viii) nonsolarized soil + wheat + biocontrol cocktail; and ix) methyl bromide fumigated soil. Controls include, fumigated and nonsolarized unfumigated soil. Peach trees developed typical PTSL symptoms and died during the experiment. In May 2006 and 2007, more trees in the nonsolar treatment plots developed PTSL symptoms and died than in the solar treated plots or methyl bromide fumigated plots. Host susceptibility of endophyte-present (E+) and endophyte-absent (E-) tall fescue grass to Meloidogyne incognita (GA-peach isolate) were evaluated under greenhouse conditions. Tall fescue lines evaluated included, 1) Jesup EI (E+, wild-type endophyte present), 2) Jesup EF (E-, no endophyte present), 3) Max-Q (E+, but non-ergot producing endophyte), and 4) GA-5 (E+). Additionally, Lovell peach (i.e., root-knot nematode susceptible) was included as the reference control. Results indicate that all tall fescue lines tested were either poor or nonhosts for M. incognita and that the presence of the endophyte does not appear to effect nematode reproduction.