Splitting Hulls Can Create Opening for Pests to Threaten Almonds Before the Harvest

You might say almonds are in the backstretch before harvest.

Field scout Jenna Mayfield reports almond hulls are starting to pull apart, signaling the first shaking of nuts off the trees is about a month or so away.

As the hull starts to split open, the shell is the only protection from pests trying to eat the almonds.

 “A lot growers are getting ready to do their hull split sprays,” Jenna says. That means some anxious days are ahead as growers do their calculations to determine the timing of their sprays to protect their crops from a second generation of navel orangeworm (NOW) egg laying.

Initial separation stage of the hull. (UC IPM photos)

Another top concern is spider mites. “They can flare up anytime,” Jenna says. While mites haven’t been a major issue right now, many growers are likely to hedge their bets and add miticides to their hull split spray so they can save money by avoiding a separate application.

Protecting the nut crop from NOW is critical at hull split, and the first spray should be made at or before 1 percent hull split.

The hull is split less than three-eighths of an inch wide.

Here’s what UC IPM says about hull split treatment: Time the spray to the beginning of hull split “if eggs are being laid on egg traps; otherwise time it to an increase in egg-laying on traps or the predicted initiation of egg-laying following hull split. Hull split is determined to begin when sound fruit in the tops of the trees begin to split.”

Initial drying of the hull.

“At this time, the nuts at eye level will be less mature than those at the top and have only a deep furrow in the hulls. Nuts in the top southwest quadrant of the tree split first. Blank nuts (usually 3 to 5 percent) will split one to two weeks ahead of sound nuts. Use a long-extension pole pruner to cut small branches from the top portion of five or six trees in the orchard to check whether hull split nuts are blank or sound.”

In this photo, the hull is completed dried out.

“Check for eggs on egg traps. If hull split has begun, but eggs are not being laid, wait until egg-laying starts. After hull split begins, egg-laying on traps may decrease due to competition of the traps with the new crop nuts. Therefore, if you do not see eggs on traps, use degree-days and apply a treatment at 1,200 degree-days from spring biofix,” UC IPM says.

Jenna says one grower is planning to do his hull split spraying this week. Others should follow suit this month. The first shaking will come a couple weeks after hull split application.

“We should see the first harvesting at the end of July or early August,” Jenna says.  

While growers are figuring out their hull split spraying schedule, they also are making sure the orchard floors are clear of leaves and debris ahead of shaking. They are a making sure ants are taken care of before harvest.