Are you considering fumigating your soil soon? California regulations are changing and there are some things growers should know about, and consider getting involved in the conversation. Watch this brief interview with Gabriele Ludwig from the Almond Board of California for more information.
Please thank this video’s sponsor Suterra for their industry support.
Although almond trees are at rest and dormant for the winter, growers were reminded at the recent Tree & Vine Expo that their work isn’t finished regarding the fight against Navel Orangeworm. Watch this brief interview with David Haviland from the UC Cooperative Extension, as he shares year-round tools and practices to stay on top of managing the number one insect pest in the tree nut industry. Read more about it in Pacific Nut Producer Magazine.
Please thank this video’s sponsor Suterra for their industry support.
A foul-smelling, voracious, wide-spread pest of fresh fruits and tree nuts could become even more ubiquitous with climate change.
A recent modelling study found that changing weather could increase suitable habitat for the brown marmorated stink bug in the United States by 70%. The study, published in Pest Management Science, draws on data from a three-year stink bug monitoring effort in 17 states as well as several potential climate scenarios. However, whether the insects will thrive in new places depends on the conditions of each area and potential mitigation measures.
“Every system will change with climate change, so the fact that you can grow garbanzo beans, lentils or wheat without these pests now, doesn’t mean that you will not have them in a few years,” said study lead author Javier Gutierrez Illan, a Washington State University entomologist. “There are mitigating things that we can do, but it is wise to prepare for change.”
The study found that overall, there is likely to be a northward shift in stink bug-friendly conditions. Regions that may be particularly affected include the Mid-Atlantic, areas surrounding the Great Lakes, and the valleys of the West Coast, such as the Sacramento Valley in California and the Treasure Valley in Idaho.
The brown marmorated stink bug is a generalist herbivore — it is known to feast on nearly 170 different plants including crops and ornamental plants. Originating in Asia, this type of stink bug first appeared in the U.S. about 20 years ago and has since spread coast to coast. It’s been detected in 46 states and considered a pest in 15 of them.
Homeowners may recognize brown marmorated stink bugs because they like to overwinter indoors. In fact, the study found that proximity to populated areas appeared to help the insects get established in new places, but once there, they did not need to be near people to proliferate. Other factors like availability of water mattered more for their abundance.
People are likely inadvertently transporting stink bugs in vehicles or farm equipment to areas that would otherwise be hard for them to reach by flying alone, said Gutierrez Illan.
Stink bugs dislike cold winters, but the rising temperatures brought by climate change are not necessarily a good thing if the land becomes too dry. They need water, so the researchers said that changing patterns of precipitation will likely influence where the stink bugs will thrive.
In some states including Washington, officials and researchers are employing a parasitoid insect, called the samurai wasp, to control stink bugs. The wasps lay their own eggs inside stink bug eggs. This not only destroys the affected eggs, but when the wasp larvae hatch, they eat other developing stink bugs. Measures like these might help prevent or minimize stink bug spread into new areas, Gutierrez Illan said.
For Washington growers, the researcher recommended using WSU’s DAS, or Decision Aid System, a web-based tool which provides information to help prepare for changes to their agricultural systems, including the possible appearance of these pests.
Gutierrez Illan also advised growers to familiarize themselves with the brown marmorated stink bug through sites like stopbsmb.org, even if they have never had the pest in their fields.
“Most growers learn from their parents or from the previous generation, but the information that they had is probably no longer as useful because the climate is changing, so they need these types of tools,” Gutierrez Illan said. —
It’s that time of the year when orchards are being pulled and growers begin preparing their soil for future plans. For growers looking to replant their orchards, watch this brief interview with UC Riverside Nematologist Andreas Westphal as he shares some considerations to take for fumigation when it comes to nematode pressure.
Please thank this video’s sponsor Suterra for their industry support.
Watch this brief interview with UCCE Farm Advisor Brent Holtz as he talks about a new tool to fight the tree-killing phytophthora crown and root rot in almond, and be sure to read his monthly Almond Tasks column in Pacific Nut Producer Magazine.
Please thank this video’s sponsor Suterra for their industry support.
Considering converting your hazelnut farm to organic production but not sure how to keep pest and disease pressure at bay? Watch this brief video with the organic grower Taylor Larson from the Oregon Organic Hazelnut Collective as he offers his personal insights and read more about it in Pacific Nut Producer Magazine. Don’t currently receive the monthly publication? Subscribe for free at: https://malcolmmedia.com/subscribe/
Please thank this video’s sponsor George Packing Company for their industry support.
Hullsplit is a time when growers’ various orchard practices – proper irrigation, nutrient management, pest control and orchard monitoring – come together in an effort to maximize almond quality and yield. To assist during this busy season, we’ve pulled together a list of the top five things you should consider before hullsplit.
1. Measuring Hullsplit Progress
Proper detection is the first step in effectively managing the potential for myriad pest and rot issues that may occur following hullsplit.
Hullsplit typically begins in early July, starting in the early growing regions and spreading to later growing regions accordingly. The splitting of blank nuts (as much as 3–5% of the almonds) will occur about a week ahead of hullsplit and serve as a “heads up” that split will soon occur.
Tip: A key to identifying hullsplit is to look for an initial split in the upper and outer portions of the canopy, particularly the southwest quadrant. Once the fruit splits, hullsplit has begun.
The most effective time to spray for NOW is during its second flight, which often coincides with the initiation of hullsplit. As a confirmation that flight activity is coincident with the beginning of hullsplit, check to see that eggs are being laid on egg or pheromone traps (note: mating disruption may affect trapping). Then, when spraying, make your application no later than at 1% hullsplit. Find out more about mating disruption for NOW.
If your orchard experiences high NOW populations, a second insecticide application may be needed two-to-three weeks after the initiation of hullsplit, and a rotating of chemistries is advised to reduce resistance development pressure. As noted in the University of California (UC) Integrated Pest Management (IPM) guidelines, be sure to consider the following before conducting a second application:
varieties in the orchard, particularly late harvested varieties
anticipated harvest dates
pest pressure noted from egg and pheromone traps
overwintering mummy load
proximity to an external NOW source, such as neighboring pistachio or almond orchards managed by a different entity
As indicated in the UC IPM guidelines, Intrepid (methoxyfenozide) and Altacor (chlorantraniliprole), are preferred materials for hullsplit sprays. Pyrethriods have been used in the past, but their use should be considered with caution as NOW resistance to these materials has emerged, and pyrethriods are toxic to beneficials. If pyrethroids are used, they should be applied only be once per season. It’s imperative that you also make sure your sprayer(s) are well calibrated to improve spray efficacy and minimize drift.
Almond hulls are susceptible to several hull rot fungi from the beginning of hullsplit until the hulls dry, typically a month-long period of time. This period may vary, however, depending on fertilization and irrigation. Successful hull rot control is based upon effective strategic deficit irrigation and nitrogen management.
Strategic Deficit Irrigation (SDI)
SDI, also known as regulated deficit irrigation or RDI, is the practice of mildly drought-stressing almond trees at hullsplit. By managing SDI, growers can reduce hull rot by 60–90% and experience a more uniform hullsplit and timely harvest. These factors may contribute to less crop damage from weather and late-season NOW flights, leading to less aflatoxin contamination, as well. What’s more, SDI reduces water use for 2-3 weeks without impacting crop productivity.
The target period of when growers should stress trees is from the start of hullsplit through 90% hullsplit, a period of about three weeks. The most accurate way to practice SDI is to use a pressure chamber to track and maintain slight tree water stress levels, between -14 bars and -18 bars, depending on the weather. Information about the pressure chamber is available on the UC Davis Fruit and Nut Research and Information webpage.
Growers who do not rely on pressure chambers, particularly those with a history of hull rot and a visual baseline from which plant stress can be observed, may achieve similar results by irrigating at 50% of normal tree demand, using crop evapotranspiration (ETc) calculations during hullsplit.
The onset of hullsplit will vary according to orchard conditions; stress levels vary with soil type and other factors. In shallow soils where trees may dry quickly, growers should initiate stress when blanks start to split, usually about a week before the onset of hullsplit. On deeper, well-drained soils, it can take up to 20-to-30 days to reach mild-to-moderate stress levels. In this case, growers may want to reference UC Agriculture and Natural Resources Publication 8515 to determine when to initiate water stress.
Nitrogen Management
Almond Board-funded research has found that excessive nitrogen increases incidences of hull rot. It is critical that a proper nitrogen budgeting plan, which is a function of crop load, is in place for the growing season to ensure that only the necessary amount of nitrogen is applied. Growers should also follow their nitrogen budgeting plans throughout the whole season and update their plans as actual yields become more evident. Regular updating will also allow growers to focus their nitrogen applications to the key times of nitrogen demand in almonds: For instance, application(s) during kernel fill should typically occur the during end of May through early June.
You can find more information on nitrogen budgeting and management at Almonds.com/Nutrients.
Recently approved for use in almond orchards, the Aspergillus flavus biocontrol agent AF36 Prevail offers a supplementary approach to reducing aflatoxin contamination in the orchard.
If you plan to apply AF36 Prevail this season, plan to do so around early July and make the application on or close to the berms so that following irrigations can wet the Aspergillus-carrying seed. Learn more about AF36 Prevail and how it should be applied in this article from the Almond Board: “AF36, Biocontrol Agent for Aflatoxins, Now Approved for Almonds.”
Growers should keep in mind that a third-generation NOW flight poses one of the greatest threats to the orchard around harvest time, so almonds should be harvested as soon as possible. Timely harvest is when there is 95–100% hullsplit at eye level in the canopy and will avoid NOW infestations and subsequent aflatoxin contamination. Early-harvested varieties, such as Nonpareil, are much less likely to attract egg laying once they’re on the ground, reducing the risk to later harvest varieties remaining in the trees.
Click here to learn more about NOW control and management strategies. More details on SDI and other irrigation best practices may be found in the Almond Board’s Almond Irrigation Improvement Continuum. You can download a free copy of the Continuum at Almonds.com/Irrigation. — By the Almond Board of California
Almond Board of California — With the rise of leaffooted bug damage showing up in almond kernels at the handler, the bottom line of growers is at stake. Research funded by the Almond Board of California and conducted at UC Riverside, is expanding much needed tools for effective IPM monitoring protocol to combat the pest.
Across the industry, handlers have seen higher rates of brown spot damage caused by leaffooted bug – and true bugs, such as stink bug – which has led to increased rejection rates.
Growers are limited to the best monitoring protocols available today, but they can be time and labor intensive, often pointing out damage after it’s too late to act.
A multiyear effort led be UC Riverside Entomology Professor Jocelyn Millar – and funded by the Almond Board of California – has worked to improve the monitoring options for the pest.
“You can take beat samples of the crop canopy to look for adults or nymphs, but we’ve never established any kind of treatment threshold for that practice,” said Houston Wilson, assistant cooperative extension specialist in the Department of Entomology at UC Riverside and collaborator on the project. “You can look for signs of feeding damage, which manifests in gummosis, which can also be caused by a number of things.”
Wilson said growers can cut gummy nuts open to look for evidence of leaffooted bug penetration of the kernel.
“Identifying gummosis is easier because you can look for the signs, but it’s an artifact – by the time you see it, the leaffooted bug has already damaged the nuts,” Wilson said. “We don’t have a passive sampling system for leaffooted bug, like for navel orangeworm, where a pheromone attracts the insect to a trap,” Wilson said. “What we’re trying to develop is a lure – a pheromone – and a better trap.”
Over the past five years, Millar and his team have been isolating and identifying compounds that make up the leafooted bug pheromone. Nine compounds were identified, and the team began work to synthesize each one. Wilson said that some of the compounds were relatively easy to identify, but others were not, “the last pheromone compound we identified was entirely new to science.”
In the latest project update, Millar noted that this new compound was a relatively small part of the overall pheromone composition but it packed the biggest punch, triggering the strongest responses from the bugs. Over the last two years, Millar’s team has been able to collect enough material to identify the compound and effectively synthesize it.
At the same time as the pheromone work, the team at UC Riverside – and other collaborators such as Cooperative Extension Specialist Kent Daane – began looking at the best trap for the application. They tested multiple styles of traps and colors, ultimately identifying that a hanging cross-vane panel trap coated with a sticky substance – yellow or blue in color – performed the best for trapping leaffooted bug.
With a fully recreated pheromone and an effective trap, the team ran trap trials in commercial almond, pistachio and pomegranate orchards in the Central Valley. Based on in-field trials, the team concluded that the trap and pheromone were both very effective and will look to the private sector to commercialize the new monitoring system.
“We demonstrated in field trials last summer and this spring that the synthetic pheromone blend is highly attractive to females,” Wilson said. “Now we’re looking at what minimal blend of compounds are needed to attract the pest. If we want this to be a commercially viable lure, we have to find the most cost-effective composition. In many cases, it’s not necessarily required to have the full bouquet of compounds in a pheromone blend to have a functional lure.”
Once the right balance is determined for a synthetic blend that lures leaffooted bugs to a trap the next step is understanding what trap catch means on population density in an orchard. This will define treatment thresholds, giving growers guidance on timing to combat leaffooted bug before damage occurs on kernels. Private industry will likely takeover at this point to develop the traps for the industry. For Wilson, this prospect has him cautiously optimistic.
“We’re very fired up with this pheromone blend, but I’m also trying not to get ahead of myself before we know what the cost will be for a commercial and scalable lure.”
More information about best management practices of leaffooted bug is available at the UC Statewide IPM website.