California growers can help reduce navel orangeworm (NOW) pressure next season by taking advantage of predicted El Nino rains.
Wet weather is predicted for California this winter especially in December and January. Integrated Pest Management Advisor Emily Symmes says nut growers can plan ahead and take advantage of that rain for NOW management.
UC IPM Guidelines: Removal of Mummy Nuts
Remove mummy nuts from trees before bud swell by mechanically shaking the tree or by hand poling. Trees should be cleaned to less than two mummies per tree by February 1 in the Sacramento Valley, and fewer in the San Joaquin Valley where lack of winter storms or bird and squirrel activity does not favor natural removal of the mummies. If possible, determine the percentage of infested mummies and the presence of live larvae or pupae. Mummy removal is even more important during periods of drought because survival of the overwintering larvae in the mummies tends to be greater than in wet years. Blow or sweep fallen mummy nuts to the row center and destroy them by discing or flail mowing by March 15 where ground cover is not present. Moist orchard floor conditions provided by winter-resident vegetation and rain will enhance mortality of navel orangeworms in mummy nuts that have fallen from trees. Get all the navel orangeworm information at the UC IPM website.