Almond Season and Pests Are Right on Schedule in Valley

 It’s always nice to hear that the almond season is progressing well.

Trees are chock full of nuts. Weather has been warm. And, of course, pests are out in the orchards.

“Everything is on schedule for almonds, including the pests,” says field scout Jenna Mayfield.

Gumming occurring on the outside of the hull

Those bugs, she says, include leaffooted bugs and stink bugs. They are gumming things up onthe developing fruit. “It’s pretty widespread and extensive.”

On the technical side, the condition is called gummosis. 

Usually stink bugs and leaffooted bugs are considered infrequent pests in almonds. But the two pests do surface when weather and other conditions are right.

Stink bugs feed on almonds from early spring through July and can cause the kernel to abort. The pestwill migrate into the orchards when weeds or other host habitat start to dry up.

Stink bug feeds on almond. (UC IPM photo)

Both bugs will bore a pinhole in the hull and young kernel.  The gumming is clear oozing-like substance that can be found on various locations on the nuts.

Even if the pest doesn’t reach the kernel, too much feeding activity can trigger crop loss, fungi and bacterial infections and discoloration of the kernel. 

Jenna points out you need to split open a nut to determine if the bug penetrated the kernel. Damage is evident by finding a small pinhole caused from the pest’s feeding mouth part.

A leaffooted bug is on the prowl in this almond tree.

UC Integrated Pest Management says there are no treatment thresholds for stink bugs. Growers should base their treatment decision on the amount of damage. The decision to treat should be based on the appearance of damage and the extent of the damage. Stink bugs aren’t very mobile so sprays can be quite effective, according to UC IPM. Studies indicate one application cuts down the population enough that another treatment may not be necessary for three years.

Here’s what UC IPM says about the leaffooted plant bug pest: “The leaffooted bug overwinters in the adult stage in orchards or near orchards on native host plants, from which it migrates into orchards in March or early April in search of nuts on which to feed. Feeding by adult leaffooted bugs on young nuts before the shell hardens can cause the embryo to wither and abort, or may cause the nut to gum internally, resulting in a bump or gumming on the shell. It can also cause nut drop. After the shell hardens, leaffooted bug feeding can still cause black spots on the kernel or wrinkled, misshapen nutmeats. Varieties with softer shells such as Fritz, Sonora, Aldrich, Livingston, Monterey, and Peerless are more susceptible to plant bug damage for a longer period during the season.”

Slicing open an almond to look for bug damage.

Growers can be confused about what pest is creating the damage to their nuts since both the stink bug and leaffooted bug cause gumming on the hull. Gumming also can be caused by other factors.
Because the symptoms are similar, advisers recommend finding the actual pests or their egg masses. Check out UC IPM online for more information about monitoring and treating for stink bugs and leaffooted bugs in almonds.

Alfalfa field after harvest

Meanwhile, field scout Damien Jelen says alfalfa growers have wrapped up another cutting for the season. He expects many growers to start irrigating the fields this week. So far, there aren’t any significant pest issues.

In cotton, the young plants are moving into the true leaf development stage at many farms. Some growers are preparing for the first irrigation of the season.