Navel Orangeworm Pressure Could Be Increasing in Almonds

Lack of Good Sanitation Leads to High Navel Orangeworm Numbers

By Jessica Theisman, Associate Editor

It could be another heavy year for Navel Orangeworm (NOW). David Haviland, UC Cooperative Extension farm advisor for Kern County and entomologist told California Ag Today that sanitation in almond orchards over the winter was not as good as it could have been.

“Everything right now is about trying to prevent a repeat from last year, and it is a little tricky so we know that sanitation wasn’t as good this winter as it generally should be,” he said. “The best time to shake NOW mummy nuts from an almond tree is after a rain when the nuts are heavier.”

David Haviland on Pyrethroid Review
David Haviland

However, rains came late this season, and by the time the rains left, there was only a few weeks before spring.

“This left a very short window to get any shaking done, and some people did an excellent job during that window to sanitize and other people just couldn’t get around all their acreage,” Haviland said. “On average across the whole industry, sanitation was not up to where it should have been, and it gave growers a difficult start to the season.”

NOW could be early this year, but the crop is on time.

“With all of this prolonged hot temperatures, particularly high night-time temperatures, the trees are shutting down a little bit at night compared to what they would do if the nighttime temperatures were cooler,” Haviland explained.

As a result, harvest is not coming as quickly as people would like.

“The problem is that the longer the nuts are in the orchard, the greater chance there will be NOW damage,” he said.

Timely crop protection sprays are recommended.

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Navel Orangeworm Prevention Critical

High Navel Orangeworm Numbers Statewide

By Jessica Theisman, Associate Editor
mycotoxins
Bob Klein

Almonds are deep into hull split, and it is absolutely critical to control any damage from navel orangeworm (NOW), the number one pest in almonds and pistachios. California Ag Today spoke with Bob Klein, manager of the California Pistachio Research Board, about the issue.

“One of the big control strategies for NOW should have happened many months ago during the winter, such as cold sanitation,” he said.

Pest programs start with orchard sanitation. Many growers are lax on sanitation or spend low amounts.

“Those who do stringent jobs are spending $200-$250 an acre on sanitation. And so growers need to be prepared to pay that as far as insecticide applications,” Klein said.

Critical questions that need to be addressed are what you are going to choose to apply and how you are going to time it. When growers are gearing up to put on protective sprays, there are things to remember to increase efficacy. There are always ways in which application can be improved.

If you have a ground rig with fan sprayers, you can get a high kill rate on the lower canopy. You may have to make multiple applications to be able to penetrate the higher portions of the trees.

“You need to look at where your NOW is and maybe make multiple applications. So you can cover both the lower two-thirds of the tree and the top third,” Klein said.

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Orchard Sanitation is Critical This Season

Orchard Sanitation to Push Back on NOW Underscored

By Mike Stevens, Associate Editor

We are completing our coverage of the importance of orchard sanitation to push back on Navel Orangeworm (NOW) pressure for 2018.

We recently spoke with David Haviland, UC Cooperative Extension entomologist and farm advisor for Kern County. He spoke about how sanitation is the most important practice that needs to be implemented.

David Haviland on Pyrethroid Review
David Haviland

“Yes, 2017 was a really interesting year on NOW. It was a bad year overall. Several things led up to that. The first one was sanitation was an issue,” Haviland explained. “There is not much of an excuse in the southern half of the almond industry, but with all the rain up north and the flooded orchards, yes, it was very difficult to get in and do sanitation, and we know that that is the absolute backbone of navel orange worm programs.”

Pistachios were also a concern when it comes to NOW.

NOW was right on schedule in pistachios. The pistachio crop was a little behind and so it was common to do a normal monitoring, normal spray program, and set up for a normal harvest. But then the crops sat out there for another 10 days or two weeks, which, of course, makes it very vulnerable to NOW worm damage.

“The longer you get away from your insecticide sprays, the more damage that’s going to occur, and a lot of the crop was harvested after the fourth flight occurred,” Haviland said. “When you put in the concerns with sanitation this year, and with the increased degree day accumulation, there were plenty of moths and then the crop got delayed. The overall effect was that this was a worse than normal year.”

At the same time, the industry is full of examples of growers that had very acceptable damage.

“Growers that did follow in greater pest management practices … did get their sanitation done. They documented that those things are really important, they are very effective, and the growers that weren’t able to get that sanitation done hopefully got a case study, personal experience in the value of sanitation,” Haviland said.

Every grower needs to do their part by incorporating sanitation, noted Haviland. “Obviously, if you’re the only one sanitizing amidst a bunch of growers that aren’t, that’s a concern,” he said.

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Navel Orangeworm Control Critical

Orchard Sanitation is Critical This Season To Lower NOW Numbers

By Patrick Cavanaugh, Farm News Director

Emily Symmes is the area Integrated Pest Management farm advisor for the Sacramento Valley in the statewide IPM program. She recently spoke to California Ag Today about the high level of Navel Orangeworm (NOW) damage in nut orchards throughout California this past season.

“We had a lot of unique circumstances. The amount of rainfall we got in late 2016 into 2017 was pretty unprecedented and really led us into a really bad navel orangeworm year because we couldn’t get out and sanitize our nut crops,” she said.

Emily Symmes

“NOW is ubiquitous, and there is an increased nut crop footprint in California, with more than one million acres of almonds, plus pistachios and walnuts,” Symmes explained. “All play host to NOW, as well as a host of natural plants. This thing isn’t going anywhere. And it was pretty bad in 2017 in terms of harvest damage.”

One of the key factors for higher navel orangeworm damage was not being able to get into the fields because of the standing water.

“There were a couple of other factors as well. Typically, rainfall and moist conditions can help NOW mortality in the winter. We tend to think that it can help rot the nuts and do us some favors, but we have to be able to get out and get the nuts shaken or get pulling crews in and get those things on the ground. And then them being on the ground is not always a sure thing. Sanitation was huge in terms of NOW problems this year,” Symmes said.

Heat units also played a part in the development of more NOW pressure. There were a lot of moths flying around longer and laying eggs.

“It got hot in mid to late June, and it seemed to just not let up. What that meant was, in terms of our degree-day models or the heat unit that drive insect development, it ended up getting pretty far out ahead of what is typical, if there is anything such as typical. But certainly ahead of the last couple of years,” Symmes explained.

By September, we were about two weeks ahead in degree-days and that means that the moths were out earlier. They’re flying around. They’re laying eggs on the nuts when they’re still on the trees.

Symmes stressed that the importance of sanitation is to minimize the site where the NOWs mature.

“It’s really important to remember that sanitation efforts aren’t just directly killing any worms that are over-wintering in your orchard. Yes, it does that. But it also minimizes those sites where your first and second generations are going to develop next year,” she said.

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Push Back NOW with Orchard Sanitation

Part One of a Series

Orchard Sanitation Critical This Season

By Patrick Cavanaugh, Farm News Director

We recently spoke with Emily Symmes, the UC Area Integrated Pest Management farm advisor for the Sacramento Valley in statewide IPM program. She told California Ag Today about few reasons as to why Navel Orangeworm damage was so devastating this year, costing tree nut growers at least $137 million.

UC Cooperative Extension Integrated Pest Management Advisor, Butte County
Emily Symmes, UC Cooperative Extension Integrated Pest Management Advisor, based Butte County.

NOW is ubiquitous. And the nut crop footprint in California is larger, with one million acres of almonds, along with pistachios and walnuts up and down the San Joaquin valley.

“The pest is not going anywhere,” Symmes said.

“We had a lot of unique circumstances. The amount of rainfall we got in late 2016 into 2017 was unprecedented and led us into a bad navel orange worm year because growers couldn’t get out and sanitize their orchards”

“Growers were not able to get into their orchards because of standing water,” Symmes explained.

Also, rainfall and moist conditions can help NOW mortality in the winter. “

We tend to think that it can help rot the nuts and do us some favors, but we have to be able to get the nuts shaken or get pulling crews in and get the mummies on the ground and destroyed,” Symmes said.

Heat units also played a part in the development of more NOW.

“It got hot. And it seemed to just not let up. Our degree-day models, or the heat unit that drive insect development, ended up getting pretty far out ahead of what is typical,” Symmes explained.

“By September, we were about two weeks ahead in degree-days, and that which meant moths were out earlier. They’re flying around. They’re laying eggs on the nuts when they’re still on the trees, and we are talking almonds, pistachios and to a lesser extent, walnuts.”

Symmes said the importance of sanitation is to minimize the site where the NOWs mature.

“It’s really important to remember that sanitation efforts aren’t just directly killing any worms that are over-wintering in your orchard. But the other thing that it does is it minimizes those sites where the first and second generations are going to develop next year,” she said.

Despite all these circumstances as to why NOW was serious this this year, it is critically important to start orchard sanitation as soon as possible. It may not be a good idea to wait for rain and fog to help loosen the nuts this season.

 

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Pistachios Suffer Navel Orangeworm Damage

Overwintering NOW Population Must Be Reduced

By Robert H. Beede, UCCE Farm Advisor, Emeritus

The following is a special report by Robert H. Beede, UCCE Farm Advisor, Emeritus, on the state of the pistachio harvest and the fight against navel orangeworm damage.

Season Wrap Up: It looks like we wound up with about 600 million pounds. Only God knows how many million navel orangeworm got, but you all know it was a bunch! Processors have their hands full delivering the quality nut California is known for. Many growers I speak to ask, “What happened?” From my discussions with many crop consultants, what DIDN’T happen was sanitation! This was not only true for the pistachio growers, but almond producers as well.

Growers barked at me about the wet weather making orchard access difficult to impossible, the size of the trees making sanitation cost prohibitive, and the difficulty in getting the nuts out of the trees. These issues are all true. So, if you decide that you cannot sanitize, then you had best figure out how you are going to run the ranch on pistachios that are 30 to 40 cents less valuable than those with low worm damage.

I know I sound like the donkey’s behind with all the answers, but the pistachio industry needs to join forces with the almond guys to determine what we can collectively do to reduce the overwintering NOW population.

There has been millions spent studying NOW, and I have NEVER waivered on the fact that sanitation is the cornerstone to controlling this beast! I also still think that once we get the kinks out of mating disruption, that everyone should use it as a means to SUPPRESS the population. Note that I did NOT say, “Control it as a stand-alone program,” just in case someone out there wants to stuff words in my pie hole!

We are in DESPERATE need of an effective adult monitoring tool for NOW mating disruption. I hope this comes soon, in order to give pest managers a method of knowing when the pheromone is not reducing mating sufficiently. We also need more research on the cultural and environmental factors affecting the number of early split nuts, which become the NOW link to the new crop at harvest.

Sanitation: Now is the time to begin winter sanitation by removing the nuts that did not come off during harvest. Many of these nuts are blank, but do not assume that all of them are. Research by many good scientists has proven that winter sanitation is the key to breaking the overwintering NOW population cycle, which looms ever greater when the winter is warm and dry. Beginning the season with a large overwintering population simply reduces the effectiveness of your in-season sprays. Although the research has not been done, to my knowledge, the TIMING of sanitation may be a factor in its efficacy.

Nut removal and destruction early in the fall may be more effective, because the percentage of NOW larva in the early instar stages should be greater. This is due to the large peak in egg laying that occurs during hull degradation. Thus, they may be more susceptible to desiccation or fungal attack because of their smaller size. Disturbing their overwintering site from the tree onto the ground early also places more environmental pressure on their survival. This is just my opinion; it may be worthy of investigation.

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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 on 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.”

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