Winter is the time to remove and destroy mummy nuts that harbor navel orangeworm (NOW) larvae that can hatch in the spring and wreak havoc in the orchard. By removing the nuts and ensuring NOW don’t have a warm home in which to hibernate during dormancy, growers are eliminating both a shelter and food source for these overwintering pests. Winter sanitation, or mummy shaking, falls in line with the strategic and effective Integrated Pest Management (IPM) program for NOW, one that includes different tactics depending on the time of the year.
“Winter sanitation is the core of IPM programs,” said David Haviland, a UCCE farm advisor in Kern County who specialist in entomology and pest management.
Here are some quick tips to keep in mind when preparing to remove mummy nuts from the orchard:
- Mummy nuts become most obvious after trees have shed their leaves, and growers should look to knock all the mummies off the trees no later than Jan. 15.
- Optimal winter sanitation timing is when dew has formed or after it’s rained, as mummy nuts will have absorbed some moisture, making them easier to knock off the tree. In addition, a wet orchard floor helps to increase NOW mortality rates.
- Growers can remove mummy nuts by bringing the shaker through their orchards or hiring crews to knock mummies to the ground using long poles.
- To note: Both hard- and soft-shell varieties can harbor overwintering NOW, so growers must be sure to remove mummies in both types.
- Growers should aim to have fewer than two mummers per tree before bud swell (around Feb. 1) in the Sacramento Valley and Norther San Joaquin Valley. Growers in the mid-to-southern San Joaquin Valley should aim for less than one mummy per tree.
- Once on the ground, mummy nuts should be swept into windrows and destroyed, either with a flail mower or by disking them into the soil, by March 15.
Removing mummy nuts and reducing NOW levels using environmentally friendly techniques is key to helping the California almond industry achieve its Almond Orchard 2025 Goals, one of which is to increase adoption of environmentally friendly pest management tools by 25% by 2025.
ABC Chief Scientific Officer Josette Lewis said that when looking at the price a grower is paid for minimal NOW damage in their product, the cost of efficient winter sanitation pays for itself.
“As a grower, your return on investment comes from both a higher yield after shelling and a higher price premium at the handler,” Lewis said. “Without strong winter sanitation, yield loss occurs due to rejection of mummy nuts from the previous year as well as heavily NOW-damaged nuts from the current season. It’s best to be proactive and invest in this practice up front to save yourself from tough losses come August.”
To help remind growers to break the link between mummy nuts and NOW, the Almond Board of California created a parody song, "The Mummy Shake.” This year, the Almond Board will host its third annual Mummy Shake Video Contest, encouraging industry members to grab their families, get in the orchard and dance – or even sing! – along to The Mummy Shake. Record yourself jamming along to this “orchard smash” for a change to be this year’s contest winner and claim your prize of a $500 Amazon gift card.
For more information on the contest, please visit Almonds.com/MummyShakeRules.
