Nov. 26, 2002
By Sara Goldman Smith
The almond PMA has completed its fourth year of reduced risk pest management in almonds with no increase in damage to the crop.
This past year, there were four treatment blocks plus an untreated control. All five blocks received the same Vanguard fungicide on Jan. 21, and the same weed control program. Based on the fact that in the last two years there has been less than 1% damage from Peach Twig Borer, there were no sprays of insecticide or Bt in any part of the orchard during the growing season. The 12.5 acre PMA block did not receive any additional fungicide treatments. Ten acres of the orchard received a dormant treatment with Diazinon, but the planned hullsplit spray on five of those acres was cancelled. Essentially, the orchard had almost 40 acres of untreated control and 10 acres of a dormant organophosphate spray, after the fourth year of the reduced pesticide study with no increased insect damage problems.
Each treatment block was inspected for mites every two weeks until July 30, with predatory mites outnumbering damaging mites in every case. In August, the webspinning mite levels began to rise, and near harvest, the trees were showing a little defoliation, but the grower opted not to treat for the mites in order to keep the populations of beneficial insects at a high level.
Although there are very few visible ant mounds in the orchard, every year, the nuts receive a small amount of damage from ants during the time they are on the ground after shaking. The PMA decided to sample for ants using vials baited with hot dogs in a grid evenly spaced throughout the orchard. In all, there were 90 samples, with 20 of them (or 22%) containing ants 1 ½ hours later. Twenty-two percent, or 20 out of 90 samples contained ants, which were about half pavement ants and half Southern fire ants. However, without a treatment threshold, it is hard to know what the next step should be. The Almond PMA continues to work on these issues- ant population levels, sampling methods, and treatment thresholds.
A harvest sample was collected from the Non-Pareils six days after shaking. The only damage found was from ants, as shown below: