Welcome to our Ag Blog. Our field scouts will offer a unique ground-level perspective from the field to you as an independent field scout with the San Joaquin Sustainable Farming Project. Our mission is to promote sustainable farming systems throughout the Central Valley and provide you with the latest information about cotton, almond and alfalfa crops. From time to time, you'll also find guest posts from our project team and other contributors. This Blog is edited by Gilbert Mohtes-Chan.
Monday, March 13, 2017
Looking at Rain, Bugs and Pest Management This Season
Will the wet winter meanfarmers will be dealing with
fewer pest problems this season?
The answer is yes … and no.
crystal ball is a bit fuzzy,” Dr. Pete Goodell, extension adviser of University
of California Statewide Integrated Pest Management Program, told a group of
farmers at a recent field day.
Pete explains that in some instances the near-record
rains are likely to keep crop-threatening pests at bay, especially
overwintering populations. In other instances, it might not have much of an
Other factors come into play such as daily
temperatures, including the number of freezing nights.
Here’s Pete’s run down about the possible impact of
the rain on pests in alfalfa, cotton and almonds in 2017:
A warm January and February brought out weevils a little early this year.In the Fresno area, for example, January
recorded daytime highs averaging 2 degrees higher than normal, according to the
National Weather Service. It even hit 71 degrees on January 8.
Weevil larvae cause the most damage in alfalfa.
“They are out there,” Pete says about weevils. One
grower told the field day gathering that he recorded a count of 20 weevils per
sweep of a sweep net in one field.That’s about normal right now, Pete says. If
this was harvest time, the grower would want to start cutting the crop to avoid
damage to the plants.
According to UC IPM, weevils overwinter as adults in
field trash or other hiding places and come out in late winter or early
spring.That’s when adult females start
inserting eggs into alfalfa stems. It is the young larvae that feeds on the
plants and causes the most damage.
Growers should start monitoring for weevils now. Pest
management should be focused before the first cutting. “Control options are insecticides and early
harvest. Biological control is not effective at preventing economic damage in
most areas because populations of natural enemies are not sufficient to provide
control in the spring.” UC IPM says.
Armyworm: The rains will spur growth for host
plants. That means growers are likely to see larger worm populations this
Lygus bugs expect to be a problem for cotton this season.
Suppliers are reporting an increase in seed orders.
That bodes well for the California cotton market. Look for more planted acreage
due to anticipated increases in water availability this
– The flip side of the wet winter are weeds such as London rocket should thrive
this spring, providing a nice home for lygus. Pete says an extra generation of
lygus is likely to emerge in early summer as weeds dry out and the pest looks
for a new home such as cotton.“We’re probably going to see some widespread
outbreaks of lygus. I have no doubt about it. “Growers should check weeds for
the presence of lygus through the end of this month. This could be a really bad year for them.”
Mites and aphids: Pete says the winter impact on
these pests is uncertain. Whitefly tends to increase during a drought. “Ithas
to get really cold to freeze some of the overwintering insects out.”
Leaf-footed plant bugs can pose a problem in almonds.
plant bug – The forecast is unclear. The soggy soil won’t impact this pest because it
doesn’t overwinter in the ground. You need really freezing temperatures below
28 degrees to have an effect on the population. “They’re still out there,” Pete
Navel orangeworm (NOW) and peach twig borer – the
rain has been a positive to reduce the overwintering population. The same goes
for mites. “It’s not a nice environment for them,” Pete says.
We’ll have to wait and see how these predictions
play out. Meanwhile, Pete stresses that it is important for growers to remain vigilant and
keep monitoring their fields or orchards for pests.