Ants are always in the almond orchard — however, they aren’t as visible as they are now, advises Walt Bentley, regional IPM entomologist at the University of California Kearney Agricultural Research and Extension Center, Parlier.
While the timing to control ants is a month or two away, now is the time to monitor for insect activity, he says. Wait much longer and it will be more difficult to determine how to treat for the pest this summer.
“Now is the easiest time to see disruptions on the surface of the orchard floor as the ants open their colonies. Usually, the soil is moist enough in April and May that when ants mound soil around entrances to their colonies, it’s very visible. This is also when you can get the most accurate count of the population. Generally, if you see more than about three or four colonies per 1,000 square feet, it pays to put out bait later in the season to control them.”
A chart describing population densities and projected damage is available at www.ipm.ucdavis.edu/PMG/r3300411.html
Populations of the three ant species that feed on almondsappear to be increasing, Bentley says. From Fresno County south to Kern County two species threaten almonds — the California fire ant, which causes the most damage, and the slightly smaller, less common thief ant. In Merced, Stanislaus, and San Joaquin Counties, both the California fire ant and the pavement ant can cause damage. In the Sacramento Valley, the pavement ant is the predominant species.
Ants feed on nuts on the ground after they’ve been shaken from the tree; they seldom climb into trees to feed on nuts. Usually, this occurs when limbs touch the ground, providing easy access to split hull nuts. The longer nuts are on the ground, the more damage ants can do.
“Ants damage only the soft shell varieties, such as Nonpareil,” Bentley says. “Hard shells, such as Mission, Butte, Padre, and to some extent Carmel, are not fed upon. Don't bother to treat for ants if you have a hard shell orchard.”
Because conventional sprays kill only foraging worker ants, baits are the preferred method of control. Baits are taken back to the nest and weaken and kill the whole colony. But, bait products are slower acting than sprays, so they must be applied several weeks before harvest.
“Ants switch preference for food during the season,” Bentley says, “So, a particular type of bait might only be effective during certain periods. Follow label directions for timing of applications.
Each bait has a specific time interval, prior to shaking, to be applied. In applying baits, be sure to mow any cover prior to the application.”
More information is available in the IPM Guidelines for Almond at http://www.ipm.ucdavis.edu/PMG.
This year’s almond crop is another big one, estimated at 2 billion pounds for the second year in a row, and it is progressing nicely, according to the California USDA/NASS field office.
February was warm and dry, creating favorable bloom conditions. While the bloom period was shorter than last year, excellent weather made up for the shorter overlap, and bloom load was high. Chilling hours were plentiful. An early March frost resulted in some spotty damage in southern San Joaquin Valley and an early April hailstorm affected orchards in Merced County. Weather in the Sacramento Valley has been near ideal. A heavier than normal drop was reported in the San Joaquin Valley. a season of Disease and insect pressures have been low.
This year’s crop is 1.5 percent below last year's record production of 2.03 billion pounds. Yield, forecast at 2,560 pounds per acre acre, is down 4 percent from 2011’s record of 2,670 pounds per acre. Forecast bearing acreage for 2012 is 780,000.