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Almond Facts
MAY | JUNE 2017
IN YOUR ORCHARD
Ants
Fire ants and pavement ants are serious problems
where they are present. If in high populations, they can
consume between 1-2% of the crop within four days.
Fields should be scouted in mid-May and monitoring and
treatment information can be found in the
UC Almond Pest
Management Guidelines
. Baits containing growth regulators,
if needed, should be applied 1 month prior to harvest for
maximum effectiveness. If bait wasn’t applied, a broadcast
spray of organophosphate should be applied as close to
harvest as allowed to reduce foragers. Recently, a new
reduced risk bait with a shorter pre-harvest interval
was approved for almonds with the active ingredient
metaflumizone. This product can be applied later in the
season and has been shown to reduce problematic ant
populations. To further reduce ant damage, nuts should be
picked up as soon as possible after shaking.
Be mindful that not all ants present within the orchard feed
on almonds. A quick trick to distinguish “good ants” from
“bad ants” is to throw potato chips or a hot dog near the
mound. If consumed, it can be assumed that the colony will
also feed on almond kernels. Another trick is to stomp near
the mound to bring ants to the surface. If they swarm out
of the mound, are red in color with a black butt and bite,
they are mostly likely fire ants. Be on the lookout for red
imported fire ant which is being found in more areas – it
is likely these ants may damage crop at a higher level than
native fire ant populations. They are also quite aggressive!
Webspinning Spider Mite
Management in Almonds
As temperatures increase, monitoring for webspinning
spider mites should occur. The most common species
during the summer are Pacific and twospotted spider mite,
though on occasion strawberry spider mite can be found.
As adults, all three mites look and behave similarly, even
though Pacific spider mite is more difficult to control.
Webspinning spider mites overwinter in the orchard under
rough bark and ground litter. During the spring, usually
in March and April, migration will occur from these
places into the lower areas of the tree. These early-season
populations are typically small, do not reproduce quickly,
and often become prey to early-season natural enemies.
However, as temperatures warm in late May through
September, the populations increase rapidly, particularly
if natural enemies are absent. In favorable conditions,
a lifecycle can be completed in 7-10 days, with 8-10
generations a year.
The most important factor in spider mite management is
biological control. When natural enemies are abundant,
miticides are not needed. When natural enemies are
absent, control with even the best miticides can be
short-lived. 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
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. Monitoring
should occur in May during cooler
parts of the day when the ants are
active. Photo credit: David Doll.
