Lettuce Aphids Showing Up on Late Produce

Lettuce Aphid Pressure Has Been Steady

By John Palumbo, University of Arizona Professor/Extension Specialist, Department of Entomology

This season has been a banner year for aphids in the desert.  Aphid pressure has been steady on most crops throughout the spring.  Consistent with the warm weather we have been experiencing lately, Lettuce aphids, Nasonovia ribisnigri, (aka., Red aphid) have shown up in desert lettuce again.

The last time lettuce aphid was this abundant on desert produce was the spring of 2012.  However, in the past couple of weeks, I’ve identified lettuce aphid appearing on both head lettuce and romaine in Roll and Wellton. I’ve also had reports of the aphid showing up in the Imperial Valley.

At the Yuma Ag Center, we began seeing lettuce aphid a couple of weeks ago on untreated lettuce, and they have recently built up to high numbers. Previous experience has taught us that daytime high temperatures in the 80’s are ideal for population growth.  A few things to remember about lettuce aphids relative to the other aphids we commonly see.

First, the immature nymphs are small and have a red appearance, whereas the apterous adults are typically a large brown colored aphid with dark bands running across the abdomen.  Second, among the crops we grow locally, lettuce aphids are only found on the lettuce types(Lactuca spp.)

Lettuce aphids prefer to colonize the terminal growth, and can often be found in heads or hearts, whereas green peach aphids are often found on the frame leaves in high numbers before moving into the heads. Sampling should be focused on the terminal growth of young plants and in the heads and hearts of older plants. Third, they can reproduce prolifically, producing many more winged alates than other species, which can quickly lead to widespread abundance throughout a field or a growing area.  Finally, as the saying goes “he who hesitates is lost”.

If lettuce aphids are found on your lettuce, it is recommended that you respond quickly with an insecticide treatment. The product of choice is Movento at 5 oz/ac. Because of its systemic activity, Movento will reach aphids in the protected terminal growth.

Be sure to include a penetrating adjuvant for best results at a rate of at least 0.25% v/v. It normally requires 7-10 days of activity before a significant reduction in the infestation is observed. For more information on lettuce aphid please refer to Lettuce Aphid on Late Season Produce.   If you’re finding lettuce aphid on organic lettuce, you’re out of luck; none of the registered biopesticides will control this aphid.

2018 Cotton Crop Proceeding Well

Late Season Pests Can Be a Challenge

By Patrick Cavanaugh, Editor

The 2018 cotton harvest will be starting in the southern part of the Central Valley later this month, and some growers will be facing pressure from pests.

California Ag Today recently spoke about the topic with Dan Munk, a UC Cooperative Extension Farm Advisor in Fresno County specializing in irrigation crop nutrient management and cotton production systems.

“The crop looks very good and loaded with cotton bolls. We don’t have a lot of boll losses, and that’s a real positive thing, so very excited about the potential for fairly high yields in the 2018 season. The biggest concern right now is pest management, press pressures as we approach the latter part of the season,” Munk explained.

The main issue this time of year is the honeydew that pest leave on the cotton. Honeydew is the exudate extracted by the insect as it feeds on the leaves.

“Because we have the bolls on the plant that have opened, we now have exposed lint and need to protect that lint from stickiness that’s created from whitefly and the aphid honeydew, which is basically the added sugars that those insects that feed on the leaves of the plant, and they excrete them and deposit them on the lint,” Munk said.

Munk explained that the big concern right now is dealing with pest pressures in terms of whitefly and aphid—both sucking insects. “The problem right now [is] where we’re seeing pest pressures—particularly from whitefly as we get later in the season—will build in many fields.

There are several approaches to controlling whitefly and aphids. One is to deal with the eggs that they produced. And then there’s a certain class of materials to deal with the eggs.

“There’s another class of materials that deal with the juveniles—that early form of the insect—and then there are ways to control the adults,” Munk said.

“A number of insecticides have been applied to deal with those various levels of insect populations based on the individual field situation,” he explained.

Aza-Direct Stops Insect Feeding

Aza-Direct Targets Critical Pests

By Patrick Cavanaugh, Editor

Aza-Direct, with the active ingredient Azadirachtin, is one of the most potent, reduced risk insect pest controls among all the natural pesticides.

With four modes of action, Aza-Direct targets critical pests such as spider mites, thrips, whitefly, aphids, and lygus. It’s very safe with beneficial insects, especially bees, to help maintain the natural balance within the crop.

The product has a lot of excellent benefits regarding those four modes of action, explained Patrick Holverson, Director of Ag Business with Parry America Inc., which manufactures the active ingredients for Aza-Direct.

“Because of the four modes of action, you will not get a resistance buildup like you can with standard chemicals,” Holverson said. “What I like about it, many growers in California will apply Aza-Direct in anticipation before the target pest hits because it is not a contact killer; it takes two or three days to get into the pest’s system to reduce the population.”

Furthermore, the material is an excellent repellent and as well as an anti-feeding agent.

“Those pests who stay in the treated field will experience severe feeding cessation due to a locked jaw and digestive system,” Holverson said. “So, the pests that do feed on the plant, the material acts as an insect growth regulator that affects both the eggs and the larva, preventing them from reaching maturity.”

Holverson said that in strawberries, Aza-Direct controls two significant pests—including two-spotted spider mite and lygus—that come in after losing their host crop.

“The product prevents puckered strawberries and increases the value of the crop,” he said. “It can be used on both organic and conventional crops.”

It has a zero-day pre-harvest interval, and four-hour re-entry, which is essential in a crop such as strawberries.

BioSafe Systems Offers Biological Control Products

BioCeres Beneficial Fungi Kills Important Pests

By Patrick Cavanaugh, Farm News Director

California Ag Today recently interviewed Jay Sughroue, Ph.D. with BioSafe Systems about the new BioCeres WP Biological Pesticide.

BioCeres is new strain of the fungi Beauveria basiana discovered in Italy in 1815. There was a sharp decline in silkworm production and the entomologist back then, Antonio Basiana, discovered  the fungi  that was responsible for white muscarsdine disease causing the decline of silkworm production.

“The new strain, ANT-03, is different from commercially available strains is that it’s more aggressive and more resilient, so it lasts longer in the environment. And it’s more pathogenic when it comes in contact with insects that you want to control,” Sughroue said.

“Fast forward several decades, and now, we have commercially available products that are controlling very important agronomic pests, such as thrips, aphids and white flies,” Sughroue said.

Sughroue noted that it’s important to follow important application strategies.

“You want to apply this prior to high population development. It’s not a knockdown, so you want to be out there scouting fields. As soon as you start to see numbers that are indicative of causing damage, you want to start a spray program that contains BioCeres, and then after about 5 to 7 days, you’ll start to see the pests decline in population.”

The fungi spore germination is the key to the effectiveness.

“The spore lands onto an insect. It doesn’t matter if it’s an egg, a nymph, a larva or an adult. It starts to germinate, and through enzymatic activity and mechanical pressure, it grows inside the insect, and it will start to sporulate so the insects come down with a severe case of the flu. They stop feeding immediately.

Sughroue said while it takes about 3 to 5 days for the pest to die, it stops feeding very soon after the spore germinates inside them.

Sugroue said the list of the pests will only become larger as time goes by

“We’re going to expanding that list to include other important insects, but this is the first generation of this product,” he said.