Be Sure To Make Time for Orchard Sanitation of Mummy Nuts
Joel Siegel is a USDA ARS entomologists and Parlier in Fresno County. “Yes, and again, in a perfect world, if everybody could sanitize perfectly, you could argue there'd be very little need for spraying because there wouldn't be any navel orangeworm,” noted Siegel.
“The reality is far uglier than that. So we're dealing with difficulties and getting in because of weather rain. And again, people have to make that commitment towards sanitation and the cost has gone up. So I'm hearing talk of $300 per acre and higher. So again, people have to factor that their world has changed,” he said.
When it comes to orchard sanitation, well, it's a numbers game. The higher the population at the beginning of the season, the higher the damage expected at the end of the season. The most effective way to reduce overwintering populations of navel orangeworm is sanitation. For every mummy nut left on the tree, that's equal to its percent damage. One mummy nut, 1% damaged. Five mummy nuts left in the tree is 5% damage. So the ultimate goal is to leave less than one mummy nut per tree, and then those nuts must be removed from the orchard or disc into the ground.