A Challenge Regarding NOW Monitoring

NOW Monitoring Challenged This Season

By Patrick Cavanaugh, Farm News Director

Navel orangeworm (NOW) is the number one pest in almonds and pistachios. There are many tools to monitor and control it, and ironically, one tool is making it difficult for researchers to understand the pressure in the orchards. Joel Siegel, a research entomologist with USDA ARS in Parlier in Fresno County, spoke with California Ag Today about the issues in NOW monitoring.

Joel Siegel, research entomologist with USDA ARS in the Parlier office in Fresno County.

“One of the problems now is so many people are using mating disruption that it’s shutting down the pheromone traps, so I don’t have reliable trap data anymore. I have my own traps. Most of them are at zero,” Siegel said. “That could mean no caught navel orangeworm adults.”

“I have some traps that are catching, so I would tell people that the population is on the upswing now. We’re coming up to 2700 degree-days in a lot of locations,” he said.

That degree-day number represents the amount of accumulated heat units, or higher temperatures to push the pest to a new generation. NOW mating disruption is a strategy where the female pheromone is spread through the orchard through special aerosol emitters, and the widespread pheromone confuses the males because of the high pheromone concentration and thus, no mating.

“When you have mating disruption nearby, it interferes with the NOW traps,” he said.

The pheromone trap attracts males to it and gives researchers an idea of the concentration of the males in the orchard. No trapping of males? Then you really don’t know the numbers in the orchard.

“The PCAs are going back to a lot of their traditional methods, such as egg traps instead,” Siegel said. “Time will tell if navel orangeworm pressure is great this year.”

California Ag Today2021-05-12T11:01:58-07:00August 16th, 2017|

Almond and Pistachio NOW Sanitation Critical This Winter

Joel Siegel on NOW Sanitation

By Patrick Cavanaugh, Farm News Director

Last year was a bad year for navel orangeworm (NOW) mainly in pistachios, but also in almonds. If left in the trees, infested nuts become a great reservoir for more NOW to inhabit them.

Joel Siegel, NOW research entomologist, USDA Agricultural Research Service

Joel Siegel, research entomologist, USDA Agricultural Research Service

Joel Siegel, a research entomologist for the USDA Agricultural Research Service based in Parlier, stresses the importance of having a good sanitation plan in place to remove those NOW mummy nuts. “When we talk about sanitation, it should be the foundation for everyone’s nut program. That’s something that you control.”

“In almonds, it’s absolutely essential. Where we’ve taken a look at it in the south, every infected mummy per tree is good for 1 percent damage. So going from one mummy to two mummies, your damage on average increases another 1 percent.”

“It’s also important to destroy the mummies on the ground. You figure, for every eight or nine mummies on the ground, that’s good for about a half a percent increase in damage. Get them off the tree and shred the almonds.”

Siegel noted that while pistachio growers can clear mummy nuts off the tree, the industry has not been able to shred the fallen pistachios effectively. The hard, rounded pistachio shells just bounce around in the shredder machine.

Almond Mummies

“What you can do is shake them off the tree as soon as possible so they’re on the ground where they can start rotting. You get those weeds growing around them. It has been shown that they break down faster in the weeds,” said Siegel.

“Growers disc them in. But if you’re going to disc them in, you have to disc them twice. Again, you’re not destroying the nuts, you are burying them so that NOW cannot lay eggs in the spring,” he said.

The risk of poor sanitation is high. Considerable NOW damage can prevent pistachio and almond growers from earning the premium paid for nuts that are pest-free.

California Ag Today2021-05-12T11:05:44-07:00November 22nd, 2016|

Jamming Leafhopper Signals

Jamming Leafhopper Signals to Reduce Insect Populations that Vector Plant Disease

By Patrick Cavanaugh, Farm News Director

An innovative team of researchers at the San Joaquin Valley Agricultural Sciences Center, USDA Agricultural Research Services (ARS) in Parlier Calif., are trying to confuse leafhopper communication in hopes of reducing certain devastating plant diseases. Of particular interest is the glassy-winged sharpshooter, a large leafhopper that can vector or spread the bacteria Xylella fastidiosa from one plant to another which causes devastating plant diseases such as Pierce’s disease in grapes and almond leaf scorch.

Dr. Rodrigo Krugner, a research entomologist on the USDA-ARS Parlier team since 2007, explained, “We started on this glassy-winged sharpshooter communication project about two years ago. These insects use substrate-borne vibrations, or sounds, to talk to, identify and locate each other; actually do courtship; and then mate,” Krugner said.

Click here to hear LEAFHOPPER SOUNDS!

Glassywinged Sharp Shooter

“This area of research started probably 40, or 50 years ago with development of a commercially-available laser doppler vibrometer (LDV), a scientific instrument used to make non-contact vibration measurements of a surface,” Krugner said. “Commonly used in the automotive and aerospace engineering industries, the LDV enabled an entomologist to listen to and amplify leafhoppers communicating,” Krugner said. “We’ve been doing recordings in the laboratory, learning about their communication with the idea of breaking, or disrupting, that communication. Once we disrupt that, we can disrupt mating and thereby reduce their numbers in vineyards and among other crops.”

Krugner noted the research team is evaluating two different approaches: one is to discover signals that disrupt their communication, and the other is lure them away from crops or towards a trap. “We may be looking at female calls, for example. An analogous system would be the pheromones, or long-range attraction volatile chemicals released by female lepidoptera, to attract males.” However, since leafhoppers use only sound, Krugner said, “We’re trying to come up with signals to disrupt their mating communication. We’re also looking at signals to jam their frequency range, 4000-6000 Hz, so they cannot hear each other,” Kruger said. “We’re also looking at signals that can be used to aggregate them, or lure them, into one section of a crop, or maybe repel them from the crop. These are all different approaches that we’re investigating right now.”

Krugner explained, “Researchers are attempting to perfect the disruptive sounds in order to do the things we need—to actually implement a management strategy for disrupting not only glassy-winged sharpshooter, but anything in a vineyard that actually communicates using vibrational communication. We know what they are saying to each other, which is very important. In the laboratory, the signals that we have look promising in disrupting the communication of these insects, so we’re taking them into the field.

Current mating disruption trials are underway in Fresno State vineyards. “We’re going to finish that research, hopefully, next year,” said Krugner, adding, “usually, fieldwork takes two to three years to show something.”

(Featured photo: Rodrigo Krugner, research entomologist, USDA-ARS, Parlier)

California Ag Today2021-05-12T11:05:49-07:00August 15th, 2016|