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.
“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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Promising Drought-Resistant Genes Research Underway
By Brian German, Associate Editor
A team of UC researchers headed by Jeff Dahlberg, director of the UC Kearney Agriculture Research and Extension Center (KARE) in Parlier, Fresno County, is conducting critical drought-resistant genes research on plants. “I’m pretty excited,” Dahlberg said, “because California is the perfect place to study drought tolerance and we have never really delved into it too much because our agriculture is mostly irrigated. This is a perfect, perfect, place to do drought tolerance.”
“We are using sorghum because it is inherently drought tolerant, and we are searching for the genes that control how sorghum responds to drought,” explained Dahlberg, who has worked with sorghum during most of his career. “The idea is to identify the sorghum genes for drought tolerance and see if other cereal crops, and even other crops, have those genes but they are just turned off. I don’t believe that genes are just specific to single crops. I think that these genes are throughout most crops; we just don’t know how to turn them on or off,” Dahlberg noted.
“And so, I’m hoping that we can use sorghum as kind of a model for how these drought-resistant genes get turned on,” said Dahlberg, “and then use that model to relate it to other crops. We want to see if we can tweak them and get them to respond to drought in a different way.”
“I really am excited that we are able to develop these field drought nurseries because I think [our research] will have tremendous impact worldwide for helping to feed people,” he said.
As the demand for healthy food items increases, farmers are choosing from among a larger diversity of crops to grow. Dong Wang, research leader with the United States Department of Agriculture Research Service in Parlier, spoke at the 2015 UC Kearney Ag Research and Extension Center (KARE) & USDA-ARS Pomegranate Field Day last week.
Wang said “the International Society of Horticultural Sciencesorganized a conference in 2013 on pomegranates and other minor fruits. Attendees from about 20 countries presented their pomegranate research findings on crop production, yield, quality, and genetic aspects of different species, including cultivars. They also presented findings relating to health benefits and the biochemistry of pomegranate products.”
Researchers and experts in California and around the world continue to explore producing a plant variety with the genetic potential for higher yield. And while increased marketable yield is important, Wang said researching pomegranate health benefits and phenolics—compounds with antioxidant properties—may be more beneficial than the absolute yield, “so people are researching multiple aspects of the topic.”
While the U.S. has a relatively small market for fresh pomegranates, pomegranate juice and secondary products, which are more common in the U.S., help to increase the fruit’s marketable yield. Wang explained some Americans eat fresh arils atop salads and other dishes, but those not-so-perfect on-the-surface pomegranates will still be desirable for the fresh market because they still contain beneficial compounds when processed. This research on phenolics, vitamins, and other compounds found in the fruit has been performed not only on the juice and the arils, but also in high-concentrate peels.
The International Society of Horticultural Sciences organized a conference in 2013 on pomegranates and other minor fruits. Conference attendees from about 20 countries presented their pomegranate research findings on crop production, yield, quality, and genetic aspects of different species, including cultivars. They also presented findings relating to health benefits and the biochemistry of pomegranate products.”
As a result of the 2013 International Society of Horticultural Sciences Conference in 2013 on pomegranates, Wang co-authored a proceedings book published by the International Society of Horticultural Sciences in July 2015. Co-written with Zhaohe Yuan, Nanjing Forestry University and Erik Wilkins, Paramount Farming Company, the volume, “Proceedings of the Third International Symposium on Pomegranate and Minor Mediterranean Fruits,” covers the following major areas of research and state-of-the-art technology: Physiology and Biochemistry, Secondary Metabolism and Human Health, Integrated Pest Management and Disease Control, Marketing and Economics, Genetic Resources and Breeding, Cultivation Techniques, and Post-harvest Technology. According to the USDA, “The book serves as the largest collection of the most current knowledge on pomegranate science and technology in the world.”
UC ANR Research and Extension Centers Strategically Located
By Charmayne Hefly, Assistant Editor, California Ag Today
Bill Frost is the director of the University of California, Division of Agriculture and Natural Resources’ Research and Extension Center System that has nine different research and extension centers located throughout the state.
Describing the strategy in their geographic placement, Frost said, “We have located them in different growing zones, climates and environments. We have chosen everything from the desert region in El Centro, to cropland here in Kearney, to livestock grazing in both our Hopland and Sierra Foothill Research and Extension Centers, all the way up to Intermountain in Tulelake, where we research potatoes, garlic and crops that can be grown in that fairly short growing season.”
The goal, according to Frost, is to solve local issues from a local or regional perspective. “Each one of our centers has different environments, crops and pest issues to address,” he explained. “These diverse locations are critically important to us because we can do localized, applied research and get useful information out to people, whether they are homeowners in their gardens or growers managing a thousand acres of a crop.”
Frost noted the UCANR Research and Extension Center System has been actively seeking new personnel to better meet the needs of growers. “Just in the last four years,” he said, “we’ve hired almost one hundred new cooperative extension advisors and specialists around the state—many of whom are housed here at the Kearney Research and Extension Center. They are also housed on UC campuses and in our county Cooperative Extension offices.”
Frost commented, “We continue to be relevant. We continue to do cutting-edge applied research. Our programs provide information to everyone; from our youth development program in 4-H and our nutrition education, to master gardener programs that help homeowners with pest problems and water management.”
“And of course, we serve the agricultural community. We have a lot of good research going on and we’re generating lot of good information in commodity production, pest management and water management,” Frost said.
The nine UC ANR Research and Extension Stations are:
Cotton Growers: Beware of Whitefly and Aphid Pressure Early this Season
By Laurie Greene, Editor
Pete Goodell, an IPM Advisor with UC Cooperative Extension based at the Kearney Agricultural Research & Extension Center in Parlier, Calif., noted that cotton growers should be treating for whitefly and aphid pressure earlier—instead of later—this season.
“On cotton, we are continually working with the whitefly and the green peach aphid. They have been a problem for the last 3-4 years, so we are continuously working with educational outreach to catch these pests early and manage their populations,” Goodell said.
Goodell explained, “I think with cotton acreage down significantly this year, we can really focus and ensure that everybody is aware of the pressure and how to handle the problem beginning in July. In some incidences, folks have misunderstood and treated whiteflys like aphids; folks started looking for the pests around the open cotton boll stage of growth. But that’s too late to treat for whitefly; growers must treat earlier to maintain a quality cotton crop.”
“That’s why we’re going to get ‘on the stick’ this year,” Goodell said. “We are going to hold a series of gin meetings and get the word out that growers need to start earlier to prevent damage from these insects.”
Joel Siegel: Beware of Navel Orangeworm Over Next Few Weeks
By Patrick Cavanaugh, Associate Editor
Joel Siegel, research entomologist with USDA Agricultural Research Service (ARS) in the Parlier office in Fresno County, is worried about Navel Orangeworm (NOW) pressure on almonds, pistachios and walnuts this season, “because we have this pattern of hotter winters, warmer springs. And, there is more than enough degree-day accumulation for an extra generation of NOW, compared to what people were dealing with four years ago. And with that, there’s the potential—if you are not on top of things—for it get out of hand.”
Those higher temperatures, he says, are what the worms desire, “Temperature—you can think of it as fuel—fuel for the fire. So the faster the generation time, the more they can start overlapping and possibly resulting in an extra generation, prolonged pressure, and at the tail-end, more NOW going into the next season as well. So you have this cycle that keeps on increasing,” says Siegel.
In describing the different monitoring and spray strategies for the each nut crop, Siegel says, “Well, with pistachios, hull split is not as predictable, so if you have hull integrity maintained, there is less NOW pressure because the nuts are not vulnerable. Navel Orangeworm seems to find pistachios once that hull begins to split. If hull break-down occurs earlier, you are dealing with more pressure.”
“On walnuts,” he explains, “people have been harvesting them later, going into September and October. So, if sun damage or anything else has damaged the hull in these late varieties, NOW will find these nuts as well. So, growers are experiencing higher pressure with late harvest walnuts.”
“NOW management timing is a bit more obvious for almonds,” Siegel explains. “That hull split spray is probably the most critical spray application, plus the new crop nuts are increasingly becoming more vulnerable to NOW. When that hull begins to open seems to be when this moth really notices the almonds.”
Siegel states, “One problem with almonds in particular, is that drought stress may cause prolonged hull-split that is not synchronous within an orchard. You’ll see NOW on the edges and the middle of the orchard, for example, just out of sync. So growers are having to apply an extra spray to treat all of their nuts the first time, and that is a relatively new phenomenon.”
“Second,” he says, “some people get burned in almonds, as they are used to the NOW pressure they encountered two to three years ago when they were not dealing with that extra generation. So they’ve only been applying this single spray; whereas, currently, many people need to do a hull-split spray followed by a post-hull-split spray.” And the way this season is progressing, growers may need to do this second spray over the next ten days.
“With pistachios,” Siegel notes, “these NOW generations are building. And because of the high economic value of pistachios, people are doing a second, or even a third shake. So if you have a scenario in which your crop is not synchronous in development, a lot of nuts become available late in the season, just when the NOW population is high as well. So that last 20% of the pistachio crop is where a great deal of damage is occurring.”
Navel Orangeworm does so much damage to the kernels that many processors are offering price premiums to growers for pistachios with less than 1% damage. Siegel clarifies, “I’m assuming that is the goal of increased subsidies; to help offset either the cost of increased insecticide applications or to offset the cost of puffers for mating disruption.”
Siegel notes some unique NOW attributes, “They are very good at eating a lot of different things. People don’t realize that although these different nut commodities—almonds, pistachios, and walnuts—have chemicals that help protect them from insects, this worm is very good at detoxifying or eliminating these protective chemicals. So, NOW is able to pressure many different crops and moldy fruit, so that any moldy mummies on the ground can serve as food for Navel Orangeworms. This is why sanitation is so critically important.”
Siegel says California tree nut growers are well-known for their high quality product, and this excellent reputation must be maintained. “Pistachios are a valuable crop,” Siegel says. “Growers must balance these advantages, talk with their processors, and look at how aggressive their pest management practices need to be.”
“The reality,” he continues, “is that a lot of people did quite well last year, and their damage was quite acceptable. So again, my advice is to stay the course; if you are happy with your results, continue to do the things that made you happy. If you got stung a little bit, consider adding sanitation or an additional spray.”
Finally, Siegel summarizes, “The California advantage is a quality nut crop that is high in demand. I assume that quality is never static; it always has to improve and respond to the market. As processors continue to pay premiums, they will expect nuts of a certain quality, and that will be the challenge for growers’ management strategies.”
(Featured Photo: Almond damaged by navel orangeworm larvae, UC ANR)