By John Wood, Certis USA Regional Manager-Southern CA, Central Valley, Desert

Q. Is a survey of my orchards for ants really necessary?

A. Using almonds as an example, ants can consume 1 percent of your almond yield per day on an average yield of 2,000 lbs. That means your financial loss can be upwards of $40/day/acre. So if you grow tree nuts, a survey of your orchard floor for ant colonies is a good idea and absolutely necessary if you have a history of ant damage. If you raise soft shell varieties of almonds and especially if you irrigate with drip and micro-sprinklers, ants are going to be a concern.  

UC IPM recommendations call for surveying your orchard floor by selecting five survey areas per block of the orchard, about 1,000 sq. ft. each. This includes the soil area from mid-alley to mid-alley beneath trees. UC IPM suggests counting the number of active colonies in each of the five areas per block of the orchard. The total of ant colonies in a 5,000 sq. ft. area indicates the potential amount of damage that may occur at harvest (refer to the table below).

A survey form developed by UC IPM is available here.

Q. Do I use insect sprays to control ants or baits?

A. Insecticides that control ants are available as contact sprays or bait materials. There are major differences between the two. Contact sprays control only the ants that come in contact with the insecticide. Baits, however, actually take advantage of normal ant feeding behavior. When baits are spread on soil, worker ants collect the bait and carry it to the ant nest. The insecticide spreads through the colony killing the entire nest, including the queens.

Certis USA’s Seduce^® is a soil-applied granular bait that contains the active ingredient spinosad for the control of ants (cutworms and earwigs, too). Seduce is available in highly compressed easy-to-apply granules that are formulated to be effective up to 4 weeks. It has a 4-hour reentry interval and is the only ant bait that can be used up to the day of harvest.

In tree nuts, apply Seduce banded to the berm at a banded rate of 6 to 14 lbs. per acre. Broadcasting Seduce down the middles also is effective, but at an increased rate of 22 lbs. per acre.