Is it Salt Damage or Almond Leaf Scorch

Salt Damage and Almond Leaf Scorch Look Similar

By Patrick Cavanaugh

Franz Niederholzer is a UCANR Cooperative Extension Orchard System Advisor based in Colusa County. In his area some growers are seeing symptoms on their almond leaves and they don’t know if it’s leaf scorch or chloride damage.

“Could it be salt damaged, take a sample for chloride and sodium. Just to check that box,” Niederholzer said.

He said to send those leaf samples to an agricultural lab. “If that comes back negative, there are labs that do test for the bacteria Xylella fastidios that causes almond leaf scorch. Answer that question,” he said. “The symptoms are similar, but not exactly the same. The chloride test is easier to do, but if it comes back that the chloride levels are low, then that leaves you with the option of testing for the almond leaf scorch bacteria, to be absolutely certain that that’s what’s going on,” Niederholzer explained.

And Niederholzer said, depending on where you’re growing your almonds in the Northern Sacramento Valley harvest could be starting about two weeks from now.

“I bet that’d be some people going in the next 10 days at the very earliest site. Maybe I’m getting ahead of myself, but on the farthest West side where there are some gravelly soil, things happen early. So those are the earliest sites in the Sacramento Valley,” Niederholzer said. “I know the weather between now and then could alter things, but I wouldn’t be surprised that somebody was shaking first week of August.”

2020-08-03T08:55:45-07:00August 3rd, 2020|

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

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)


 

2021-05-12T11:05:49-07:00August 15th, 2016|
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