Stink Bug Damage within Almonds

Green stink bug feeding on an almond hull. Note the multiple feeding sites.

Green stink bug feeding on an almond hull. Note the multiple feeding sites.

Stink bugs are found occasionally in almonds. They feed on the almond hulls from late April through July, causing gummosis and kernel abortion. Typically, multiple feeding points are found on an almond and within an area of the tree, with few feeding holes extending into the kernel after shell hardening. Even without reaching the developing kernel, excessive feeding can still cause crop loss, kernel discoloration, as well as infections of the fruit by yeast, other fungi, and bacteria.

There are several different species of stink bugs that affect almonds. Most common is the green stink bug, but the red-shouldered stink bug can also be found. These insects tend to move into the field during the spring when weed or crop hosts begin to dry up – which tends to be earlier in years of low winter rains. The green stink bug may also overwinter within the orchard. Eggs tend to be barrel-shaped and laid in clusters on hulls.

Feeding by stink bugs typically introduce opportunistic pathogens, which can damage the kernel or cause crop loss.

Feeding by stink bugs typically introduce opportunistic pathogens, which can damage the kernel or cause crop loss.

There are currently no treatment thresholds for stink bugs. The decision to treat should be based on the appearance of damage and the extent of the damage. Monitor the orchard for gummosis and try to observe the pest to separate it from feeding that may be caused by leaf footed plant bug. Unlike leaf-footed plant bug, stink bugs aren’t as mobile and sprays can be very effective. Use of a broad spectrum insecticide should reduce populations. Data suggests that an application typically reduces populations enough that another treatment may not be needed for three years.

More information can be found at the UC IPM Webpage for Stink Bugs.

Stink bug feeding in almond. Mote the multiple feeding sites with minimal gummosis.

Stink bug feeding in almond. Mote the multiple feeding sites with minimal gummosis. The multiple feeding sites and limited area of feeding area differentiates damage from leaf footed plant bug.

 

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