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Seems like each year about this time we begin to think how unusual this produce
season is compared to previous years. Of course, every season is different. That’s
the complicated nature of farming and pest management; so many factors (some explained
and many unexplained) influence plant growth and insect pest activity and abundance.
I thought I’d share some of my recent observations of “unusual” insect activity
from research plots at the Yuma Ag Center (YAC), local commercial fields and conversations
with PCAs. Whitefly populations were the lightest we’ve seen in years, but have
been heavy in a few small areas. Many, like myself, believe this is due to the lower
cotton acreage this summer, but there could be other factors as well. Beet armyworm
pressure remains steady, but seems much lower than what I usually see this time
of the year. Cabbage looper numbers have been considerably lower from what we typically
see in lettuce and cole crops in October. There numbers seem to be increasing now.
Corn earworm larvae populations appear to be about normal relative to the past 3
or 4 years. So far, I have not had any complaints in regards to controlling these
worm pests, and all the standard Lep materials are performing up to par in my efficacy
trials. In contrast, diamondback moth larvae are very abundant in my broccoli trials.
They showed up earlier and in higher numbers than I typically see this time of the
year. Not sure why? Good news is, they remain easy to kill with standard materials.
Another interesting pest showing up is the Hawaiian beet webworm. They were very
abundant last year and PCAs have been sending me images from this season (see image
below). The larvae prefer spinach and beets and can cause damage if left untreated.
Again, easy to control. Western flower thrips are on the increase, consistent with
the warm weather. Adult and immatures are increasing on my lettuce plots, and several
PCAs have mentioned that they are quite abundant. Have also had some reports of
cowpea aphids showing up in lettuce. Experience has shown us that cowpea aphid will
begin to colonize lettuce about this time of the year, but never seems to amount
to much and colonies disappear when it gets colder. If the weather breaks in the
next week or so as anticipated, worm and thrips pressure should slow down considerably.
However, given our current and predicted El Nino weather pattern, all bets are off.
So, have your weather reports handy, and keep your eyes open for the unexpected.
Remember: When in Doubt-Scout.
Remember, When in Doubt . . . . . “SCOUT”
Click picture to listen to John’s update To contact John Palumbo go to: jpalumbo@ag.arizona.edu |
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For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
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