Foxglove Aphids: In the past two weeks, foxglove aphid (FGA), has
increased dramatically in our untreated control lettuce plots here at the Yuma Ag
Center. We’ve also had reports from PCAs of difficulty in controlling FGA, which
is more abundant than I’ve seen in the past 5-6 years. In my opinion, this is the
reason more spray applications are necessary for FGA control this season. Green
peach aphids are also still prevalent in high numbers in our cole crops, but are
rapidly declining in lettuce. Because aphid species are inherently different in
their susceptibility to insecticides, the proper choice of product is important
for achieving adequate control. In my lettuce trials, Sequoia, Sivanto, and Beleaf
have provided the most consistent knockdown and residual control of FGA. For more
information on FGA and insecticide alternatives for the various aphid species please
view our Aphid Control Chart-2017
and Foxglove Aphid on
Desert Lettuce Crops
Thrips: In contrast, western flower thrips have been very light
this spring, largely due to heavier than average rainfall and cooler weather for
the past few weeks. However, as drier conditions prevail, PCAs should expect thrips
numbers to steadily increase with the warmer weather. This is particularly important
on late-lettuce where “bioconcentration" of thrips occurs each year as lettuce
acreage declines. Each time a lettuce field is harvested and disked, adult thrips
populations disperse from these areas into the next available lettuce field. As
the number of lettuce acres becomes reduced near the end of the season, this creates
a bottleneck effect that concentrates high numbers of thrips adults on the remaining
fields under production. This can often make chemical control very difficult, particularly
in March, as thrips adults may continually re-infest fields following spray applications.
See the Thrips Control Chart 2017
for more information.
Diamondback Moth (DBM): Reports of DBM infestations are still coming
in from PCAs as the season begins to end, and at the Yuma Ag Center, DBM can be
found on broccoli and cabbage in extremely high numbers. In fact, we were unable
to establish 2 acres of broccoli plots due to the extreme damage caused by larvae
on seedling plants. The entire 2 acres was essentially destroyed. Trap catches show
that DBM are still actively moving (see
DBM Trap Network). Thus, any late season brassica crops grown in the Yuma
Valley are susceptible to high DBM numbers, particularly with the warmer weather
to come. We have also found DBM infesting brassica seed crops, with the larvae feeding
on the developing seedpods. Products that are providing efficacy in the field include:
Radiant, Proclaim, Exirel, Entrust, Avaunt, Dibrom and XenTari. Avoid applying Coragen,
Voliam Xpress, Belt and Vetica due to DBM resistance to these products.
What stinkbug species is shown?
Areawide Diamondback Moth Trapping Network
In response to the recent outbreaks of Diamondback moth (DBM) , Plutella xylostella
in Yuma, we have established a pheromone trap network designed to monitor the activity
and movement of adult populations of DBM. PCAs have had difficulty controlling DBM
in cabbage, broccoli and cauliflower since October. Traps have been placed in Roll,
Wellton, Dome Valley, Gila Valley and Yuma Valley in locations where cole crops
are presently being grown or in areas where infestations were known to occur this
fall.
Click here to see results of DBM pheromone trap network.
Remember, When in Doubt . . . . . “SCOUT”
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