By Joel Siegel, Ph.D., Entomologist, USDA Agricultural Research Service

Q: How have navel orangeworm (NOW) pressures and flight timing changed in recent years on the West Coast, and what are the most effective control strategies at almond hull split?

Almond acreage has expanded in recent years, with many new trees being planted in existing almond- growing areas. This increase in the number of trees has the potential to increase NOW populations, which means  growers need to do a better job of pest management.

In the southern part of the San Joaquin Valley, NOW pressures have become heavier and more predictable, so growers have adjusted their product rotation and application techniques. Growers on the northern end of the valley, where NOW appearance had been sporadic, are seeing more regular, longer NOW pressures and need to alter their budgets and spray plans accordingly.

Scout and Spray for NOW Control

Growers should begin monitoring almond trees in mid- June for early signs of hull split. Protecting the nut crop from second-generation NOW egg-laying is critical at hull split, and the first spray should be made at or before 1 percent hull split.

It’s better to err on the side of caution and make the first application several days early than to be several days late. Almond blanks split about five days before intact almonds, so that’s a good sign for growers to prepare for the first spray. DuPont™ Altacor® insect control is a good option because its duration of activity provides some flexibility in that first application, and it can be used again 10 to 14 days later for optimal results.

In areas with heavy NOW pressure, employing two 4.5-ounce applications of Altacor®, made 10 to 14 days apart, beginning at early hull (1 percent hull split) is an effective way to combat NOW. This “two shot” strategy allows growers to apply two layers of residual protection to almond hulls and shells that are at various stages of splitting and exposure, providing a one-two punch against second-generation NOW.

For more information on how Altacor® can help you control NOW, talk to your DuPont retailer or visit altacor.dupont.com.

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