TIME TO CONSIDER
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Almond Facts
MAY | JUNE 2016
The goal is to find a balance that relies primarily on
natural enemies supplemented by miticides as needed.
Growers who want to conserve and promote predators
should avoid broad spectrum insecticides, particularly early
in the season, and avoid prophylactic and preventative
miticide applications that do not provide enough food for
mite predators to become established in the spring.
In determining when to time the first mite spray
application, a presence/absence monitoring protocol has
been developed. Monitoring should occur weekly, and prior
to mid-June should focus on hot-spots within the orchards.
After mid-June, the whole orchard should be randomly
sampled. When sampling trees, 15 leaves from a minimum
of five trees should be selected. Leaves should be randomly
chosen from the inside and outside of the canopy. Examine
both sides of the leaves looking for pest mites and predators.
Note the number of leaves on each tree with pest mites
and their eggs, and the number of leaves with predators.
There is no need to count the mites. Once completed,
compare the numbers with the guidelines provided in the
“Don’t Treat” and “Treat” columns on the sampling form
provided at the webspinning spider mite link of the UC
Almond Pest Management Guidelines (
.
edu/PMG/selectnewpest.almonds.html)
Many miticide options exist for cases where a treatment is
required. Each miticide has its strengths and weaknesses,
and for that reason options should be discussed with a pest
control advisor. For almond growers in the San Joaquin
Valley that plan on using miticides containing abamectin,
keep in mind that new regulations require that only low-
VOC formulations be used between May 1 and October
31, 2015 and 2016. More details on this new regulation and
all miticide options can be found in the UC Almond Pest
Management Guidelines
/
selectnewpest.almonds.html).
Spray Rig Speed
Spray coverage for almond trees is based on the height
and density of the tree. If the height of the tree is under 10
feet, adequate spray coverage can be attained at almost
any reasonable speed. For taller orchards, however, slower
speeds have been shown to increase coverage. Research
trials have shown that a difference of a 1/2 MPH (2.0
MPH vs. 2.5 MPH) can reduce the coverage by 30 percent
for trees 18 feet or higher. Traveling at 3.25 MPH, less
than 2 percent coverage was achieved at a height of 20 feet.
This reduction reduces the concentration of the pesticide
deposited, increasing the chance of resistance formation,
loss of crop due to disease/insect damage, and tractor/rig
damage. For maximum coverage and pesticide efficacy,
spray rig speeds should be operated no faster than 2 MPH.
Final Thought
As we prepare for an earlier than normal harvest, remind
your work crews to be careful with the heat and around
machinery. Long, hot days – especially when short on
sleep – slow our reflexes and reduce the ability to make
decisions. Work with the crews and contractors to ensure
that there is adequate shade and water, and rules regarding
pesticide usage are being followed. If personally spraying
or harvesting late, have somebody check in every few hours
to make sure you are safe.
Figure 3: Fire ant mounds in an almond orchard.
Mounds tend to be at the edge of the wetting
profile and are found in groups of three or more.
Photo credit: David Doll.
