Poster Session: Integrated Pest Management

320-P

New products for management of lesion and ring nematode on walnuts.
B. B. WESTERDAHL (1), J. K. Hasey (2), J. A. Grant (3), L. W. Beem (4)
(1) University of California, Davis, CA, U.S.A.; (2) University of California Cooperative Extension, Yuba City, CA, U.S.A.; (3) University of California Cooperative Extension, Stockton, CA, U.S.A.; (4) Beem Consulting, Granite Bay, CA, U.S.A.

Two trials were conducted to determine the effectiveness of DiTera (a toxin produced by Myrothecium verrucaria) and Nema-Q (an extract of Quillaja, the soapbark tree) for management of lesion (Pratylenchus vulnus) and ring (Mesocriconema xenoplax) nematode on walnuts. In an orchard in Sutter County, CA, spring and fall treatments of DiTera at 56.1 kg/ha, and Nema-Q at 23.4 l/ha, were applied in a 50-percent banded spray followed by sprinkler irrigation, each year for four years to Chandler on seedling Paradox rootstock, and to own-rooted Chandler trees. Five individual tree replicates per treatment were compared to untreated controls in a randomized complete block design. On Paradox rootstock, both DiTera and Nema-Q increased walnut yields and produced more vigorous trees (p=0.05), but did not reduce nematode numbers. The second trial, conducted in San Joaquin County, CA, consisted of 17 treatments with 6 individual tree replicates per treatment in a randomized complete block design with rates of DiTera at 56.1, 28, and 14 kg/ha; rates of Nema-Q at 56, 37.4, 23.4, and 12 l/ha; combinations of the two products; and an untreated control. Products were applied in a 50-percent banded spray followed by drip irrigation to Chandler variety trees on Paradox rootstock. The combination treatments increased trunk circumference, and reduced populations of lesion and ring nematode (p=0.05). Individual treatments with each product reduced numbers of ring nematode (p=0.05).