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Controlling Pecan Weevil with Beneficial Fungi: The Impact of Fungal Species and Fertilizer Regimes

David I. Shapiro-Ilan, Wayne A. Gardner, Lenny Wells, Ted E. Cottrell, Robert W. Behle, Bruce W. Wood
Pecan grower 2013 v.24 no.4 pp. 54-64
Beauveria bassiana, Curculio caryae, Metarhizium brunneum, Trifolium incarnatum, ammonium nitrate, biological control agents, entomopathogenic fungi, fertilizer application, insect control, mortality, nitrogen fertilizers, pecans, pests, poultry manure, soil, tree nutrition
The pecan weevil, Curculio caryae (Horn), is a key pest of pecan. Prior research indicated the potential for using entomopathogenic fungi to suppress pecan weevil in the soil. We compared the efficacy of two fungal species, Beauveria bassiana (GHA strain) and Metarhizium brunneum (F52), in their ability to cause pecan weevil mortality. Results indicated that B. bassiana is superior to M. brunneum regardless of application method; consequently, the potential for applying B. bassiana to control pecan weevil was further explored. Specifically, the impact of different fertilizer regimes on the persistence of B. bassiana (GHA) in soil was determined. B. bassiana was applied to soil in a pecan orchard following one of several nitrogen-enhancement treatments—i.e., ammonium nitrate, crimson clover, poultry litter, clover plus poultry litter, and a no-fertilizer control. Fertilizer treatments did not impact B. bassiana persistence. We conclude that standard fertilizers for nitrogen management, when applied according to recommended practices, are unlikely to negatively impact survival of B. bassiana when the fungus is applied for suppression of emerging pecan weevil (Shapiro-Ilan et al., 2013). Additional research on interactions between beneficial fungi and fertilizer amendments (or other tree nutrition or soil management practices) is merited.