Pre-Season Vegetable Pest
Management Workshop

By Patrick Cavanaugh, Editor,
And Laurie Greene, Associate Editor

Sam Wang
On Wednesday, Imperial Valley growers and PCAs gathered at the UC Desert Research and Extension Center in El Centro to hear updates on pest management and spray techniques. It was all part of the preparation for the 2014 crop year.

The director of the center, Sam Wang, welcomed everyone and introduced all speakers.

Dr. Antoon Ploeg, Associate Nematologist and Associate Cooperative Extension Nematologist, UC Riverside, addressed nematode management in vegetable crops. He focused on three major nematode species including:

1.    Needle
2.    Root Knot
3.    Cyst

Needle nematode
Research shows that these nematodes live for approximately one year, but propagate during that time. Needle nematodes are present at all soil levels, but prefer deeper root-level soil and like warm weather. Thus, they are found worldwide in hot areas, including Imperial County and Mexico.

Antoon Ploeg
“Needle nematodes’ presence in a field tends to be unevenly dispersed, so scientists do not report levels per se; they report that the field either has or does not have nematodes,” Ploeg noted.

These parasites may propagate five times per season. They are found on many vegetable plants, and studies have analyzed nematodes in beans, tomatoes, pepper plants, cabbage, and brussel sprouts.

Root Knot nematode
Of the three different species mentioned that affect many crops in California, Ploeg said, “Root Knot nematodes are the most damaging of the nematodes, as they enter the roots and cause severe galling of the roots. They thrive in sandy soils.”

Ploeg noted that the industry is looking for new materials for protecting crops from this troublesome nematode. “We have Vydate and there are several novel materials in the pipeline. Some of those products look very promising.”

Cyst nematode
This nematode is particularly troublesome on Imperial Valley sugar beets and on cruciferous crops throughout the state.

Nematode control research is ongoing with work on anaerobic soil disinfestation—a practice of mixing compost matter in the soil that heats up to certain levels that kill the cyst nematode.

Eric Natwick, a UC Farm Advisor in Imperial County, spoke about new and old materials for pest control in cool season desert vegetables.

Eric Natwick
In looking at materials that control worms, whiteflies and aphids, Natwick asked two questions: “Are these newer materials as efficacious as the older materials?” and “Are the new materials better?”

Some of the newer worm control products include Anthranilic Diamide insecticides (Synapse, Coragen, Verimark, Volium Express); Spinosyns (Success and Radian); IGRs (Intrepid and Rimon) and others such as Torac.

Newer aphid controls include Movento, and Beleaf.

Newer whitefly control materials include Neonicotinoids, Movento Oberon, Coragen and Verimark & Exirel, Brigade (a pyrethroid), and Torac.

Pros and Cons of New vs. Old

The Pros of old vegetable insecticides include:
·      Less expensive
·      Broad Spectrum
·      Resistance Management partner
·      Fits existing IPM program

The Cons of old vegetable insecticides:
·      Worker safety issues
·      Environmental issues
·      Insecticide-resistance
·      Broad spectrum

The Pros of new vegetable insecticides:
·      Selective
·      More efficacious
·      Resistance rotation partner
·      Fits new IPM program
·      Environmentally friendly
·      Improved worker safety

The Cons of new vegetable insecticides:
·      More expensive
·      Too Selective

Natwick then considered the premixed in-the-can materials: Why? Or Why not?

Premixed in-the-can Pros:
·      Cheaper than “in-the-tank mixtures
·      Convenient for mixing and loading of the sprayer
·      New product for the company with old active ingredients (a.i.)
·      Broad spectrum insect control

Premixed in-the-can Cons:
·      Confound insecticide resistance management.
·      Environmental exposure of a.i. when pest is not present (always potential for environmental harm)
·      May not be more efficacious than one a.i.
·      Takes tank mix decision away fro PCA or grower (more important that PCAs keeping more control of input, need flexibility)

Milt McGiffen
Milt McGiffen, UC Riverside CE Vegetable Crops Specialist and Plant Physiologist spoke about nozzles, surfactants, and sprayer parts.

Nozzles are important to the private applicator because they:
·      Control the amount –GPA
·      Determine uniformity of application
·      Affect the coverage
·      Influence the drift potential

In a diverse agricultural region like Imperial Valley, there is a high potential for drift to injure crops.

What coverage is needed?

McGiffen spoke about spray nozzle basics incorporating the different types of nozzles and their spray patterns, which include flat fan, even fan, and modified flat fan.

“Droplet size less than 200 microns in size are highly driftable and should be avoided,” McGiffen said.

Factors affecting drift are drip size, nozzle type, nozzle size and nozzle pressure (which the applicator can control).

Weather can also affect drift including air movement, direction, velocity, temperature, humidity, air stability/inversions (not an advisable time to spray) and topography (low and high spots).

McGiffen also spoke about the importance of adjuvants. He said growers and PCAs should always follow the label suggestions on the type of adjuvant to use with a spray material.

Barry Tickes, with the University of Arizona Yuma Ag Center, spoke about the lack of good herbicides for lettuce crops in Arizona and California.

Barry Tickes
Of the new pesticides registered for leaf lettuce in the last 10 years, 15 were insecticides, four were fungicides and -1 was an herbicide (negative since Kerb was pulled off market).

Tickes noted that the registrant for Kerb has been working hard to complete necessary studies to get it reregistered, and hopefully it will be available in about three years.

Tickes said the EPA is allowing a Section 18 Emergency Exemption, “but we will have a tough time getting approval because one of the first questions they has is if there is an alternative.”

“We can always use hand labor to get the weeds out, but that would not be cost effective for growers,” Tickes said. “But there are exemptions in the area that—without the material—could result in an economic loss, which may qualify.”

Alternative lettuce herbicides may come from new uses of old products registered on other crops, such as Pursuit; however, its low rate will most likely not be enough for adequate efficacy.

“We are also looking at new application techniques and genetics,” noted Tickes. “Herbicide-resistant lettuce has been developed, but genetically-modified lettuce will most likely never be approved by consumers.”

Tickes surmised that mechanization might be the way to go. “This new machine does a remarkable job in large scale weed control as well as lettuce thinning."

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