Suterra’s aerosol puffers that dispense pheromones for mating disruption in California tree nut, stone and pome fruit orchards will have a different look starting this season.

Zak Clark, senior manager for engineering and quality at Bend, Ore.-based Suterra, described some of the improvements made in their puffers to improve durability and performance.

“We worked to make these stand up to the orchard environment, so growers could depend that they were working throughout the season,” Clark said.

Suterra has been making aerosol puffers and their own cans for over 10 years. Clark said they have been collecting, diagnosing and refurbishing puffers for almost that long, and in the process determining how to make them better.

“The goal is to get the pheromone out at the right dose at the right time, regardless of environmental conditions,” Clark said. “We want a precision dose for every shot it makes throughout the season.

“We consider it a catastrophe if the can empties early or doesn’t deploy at all due to clogging or mechanical defects. That is not acceptable.”

Clark said the gear train will deliver puffs for an entire season with only 2 AA batteries that can withstand environmental conditions including heat.

The dispersing device is a key component in the puffers and Clark said the aim was to make them lighter in weight, with a sealed compartment and a one-step power on feature. The technology includes a patented cam drive for dispensing, and a thermostat to make sure pheromone is released at the right temperature. The sealed compartment protects the electronics and gear from heavy rain, residues and dust. The sealed head unit prevents jams and friction from contaminants.

In addition to improved durability, there is now a single button to simplify deployment. The device is also lighter and uses 60 percent less plastic. The lighter weight allows for more movement in the tree canopy to reduce drop. Growers will get a new unit every year, with spent devices recycled at the customer’s convenience.

The new design will be applied to all Suterra’s Puffer products in California, including NOW-Ace, CM-O Pro, OFM-O, and CM/OFM Pro. The pheromone formulation and application rates are the same as previous seasons. The product itself has not changed, the performance and ease of the dispersion vehicle has, Clark said.

Resistance to glyphosate, paraquat and ACCase inhibiting herbicides has been confirmed in Italian ryegrass, a major weed in California orchards, vineyards, field crops and fallow fields.

Control of Italian ryegrass had been achieved with several different herbicides until resistance evolved with repeated use. Resistance to multiple post-emergent herbicides with different modes of action has also been confirmed within the same orchard, vineyard or field in some areas.

Dr. Marie Jasieniuk, associate professor in the UC Davis Department of Plant Sciences wrote in a Weed Science blog that glufosinate is an alternative non-selective post-emergence herbicide that can still be used to control herbicide–susceptible and most herbicide-resistant Italian ryegrass in California as only two populations with resistance to glufosinate have been documented.

Glufosinate-ammonium is a contact herbicide that works by inhibiting an enzyme central to plant metabolism. Plants absorb this substance primarily through their leaves and other green parts.

Jasieniuk noted that the higher cost of glufosinate relative to other herbicides may drive lower use rates. The lower rates and other drivers including herbicide applications at non-optimal weed size, inappropriate weather conditions and insufficient spray coverage may result in sublethal rate selection of ryegrass by glufosinate.

Jasieniuk conducted a greenhouse study to evaluate the potential for low glufosinate rates to select for reduced susceptibility to the herbicide and to determine if selected populations are cross-resistant to herbicides with other modes of action.

The study was conducted with an herbicide susceptible parent population collected from a Sonoma County vineyard. Plants were grown in the greenhouse to the 3-4 leaf stage and treated with low glufosinate rates for three generations.

To evaluate the potential for low glufosinate rates to select for reduced susceptibility to the herbicide, and to determine if selected populations are cross-resistant to herbicides with other modes of action as has been observed in a few studies, Jasieniuk conducted a greenhouse study using an herbicide-susceptible parent population originally collected from a vineyard in Sonoma County. Plants were grown in the greenhouse to the 3- to 4-leaf stage and treated with low glufosinate rates for three generations.

In the first round of treatments, the plants were treated with glufosinate at one-eighth, one quarter and one half of the labeled field rate. Surviving plants were grown to reproductive maturity and allowed to cross–pollinate. Seeds were harvested from all plants pooled and germinated. Plants in this second generation were treated at slightly higher rates at one-half, three-fourths and the labeled rate. For the third round the treatments were three quarters, the labeled rate and one and a quarter of the labeled rate.

Results showed that susceptibility to glufosinate was reduced in offspring in comparison with the susceptible parent population following only three generations of selection.

The study showed that repeated selection with glufosinate at low rates can reduce the susceptibility of Italian ryegrass populations to glufosinate, and points to the importance of incorporating a diversity of approaches, both chemical and non-chemical, in the management of ryegrass in annual and perennial cropping systems of California.

Choosing the right seed to match the site and goals is key to getting desired benefits from a cover crop in nut orchards, according to speakers during a California Alliance for Family Famers webinar that focused on cover cropping in tree nut orchards.

Organic walnut grower Sean McNamara of Winters reported on his challenges and successes with choosing a cover crop seed mix, planting and stand establishment in his orchards.

McNamara said changes were necessary in orchard management to have a successful cover crop, but there were also some cover crop decisions made to match his management system.

As an organic grower, McNamara said nitrogen fixation was an important goal for his cover crops. He also wanted to mitigate soil compaction and add diversity to the seed mix. What he did not want was a lot of biomass in the orchard at the end of the growing season.

“With those parameters in mind, he also noted “if you can’t get it to grow, it is a waste of time and money.”

He advised paying attention to not just ratios of seed in mix, but also seeds by weight. Grass seed can overwhelm the cover crop mix due much higher numbers of seed per pound.

Kamprath Seeds representative Tom Johnson provided his ‘decision tree’ for choosing a cover crop. The ‘right’ one for a specific grower and orchard takes into consideration the orchard age, soil type, depth and infiltration rate. Rainfall amounts for germination, slope of the ground and available equipment are other factors. Grower or manager expertise with cover crops and the time available for management also play a role in cover crop seed selection.

Johnson covered reasons to plant a cover crop in an orchard and choosing a system that fits time and management capabilities.

“My advice is to start slow and simple, you can make it as complicated as you want later,” Johnson said. No one crop mix will deliver all the results desired, he said.

The main issue in the orchard that a grower wants to address with a cover crop will determine the seed mix and system that will work best.

An example is a crop planted to improve water infiltration. Brassicas and small grains grown in a plow down system would achieve that goal. A solution for nutrient management could be a legume mix with annual reseeding.

Wendy Rash with the Natural Resources Conservation Service presented information on the eVeg Guide on the NRCS website. The current map data gives information on suitability for seed mixes at valley locations. The site also includes a model for developing a cover crop seed mix, compatibility information and warnings for seed choices.

Additional resources for growers include CAFF’s Cover Crop Webpage, NRCS EQIP program and Project Apis m.’s Seeds for Bees program.

Development and introduction of new, high quality and disease-resistant cultivars in almonds, apricots, table and raisin grape varieties is the goal of USDA’s Crop Diseases, Pests and Genetics Research team in the Parlier research facility.

In its annual report, the team announced five-year goals to enhance breeding efficiency for table grape fruit quality and other priority traits by identifying associated molecular markers and through trials to determine their commercial use and map fruit traits related to flowering time, rachis structure and berry size. The research includes identifying sources of resistance and to develop molecular markers associated with resistance to Botrytis cinerea, powdery mildew and Pierce’s disease. Advanced table grape selections will be compared for production timing and fruit quality after cold storage with existing table grape cultivars.

Prunus development will focus on high-yielding, self-compatible almond varieties and glabrous-skinned or smooth skin apricot. Hybridizations will be performed to identify and select new almond varieties that are California adapted, early ripening and also have nonpareil-like kernel characteristics. Newly available glabrous skinned apricot accessions from Kyrgyzstan will be propagated when available from plant protective quarantine and used in hybridizations to assist with the breeding effort.

In almonds, hybridizations have been performed among self-fertile selections having nonpareil shaped kernels. A research-sized roller-cracker provides data on kernel durability at harvest. Multivariate kernel analyses are being used to identify new selections with nonpareil-shaped kernels.

Glabrous skin apricot imported to the U.S in the 1990s have been hybridized with California adapted apricots, but the initial crosses had no glabrous skin offspring. When the first generation was crossed amongst themselves, 25 percent of the offspring produced glabrous skin fruit. These crosses are being evaluated for fruit quality characteristics and ranked for use as parents. Fruit size and detrimental skin characteristics were listed as main concerns along with small fruit size. Neutral flavor skins predominate in apricots, but the glabrous skin apricots can exhibit both acidic and astringent skin flavors. Current fruit evaluations of the glabrous skin accessions will identify the largest fruited crosses having neutral skin flavor for use in planned crosses.

Agriculture Research Service researchers in Parlier have announced the release of a new early season table grape variety that has both exceptional eating quality and reduced cultural input needs. Solbrio has a large berry size, a crisp texture and full color. Many of the standard cultural practices used to enhance these characteristics in other table grape varieties are not necessary with Solbrio, ARS researchers report.

Discovery of the first substance capable of controlling citrus greening disease or Huanglongbing was recently announced by UC Riverside.

According to UC Riverside, a naturally occurring molecule found in Australian finger limes, an antimicrobial peptide, is more effective in treating the disease than the antibiotics currently in use in Florida.

UCR geneticist Dr. Hailing Jin said that, unlike the antibiotic sprays, this peptide is stable even in high temperatures. Florida citrus growers have been using antibiotic sprays in an attempt to save their trees from the CLas bacterium that causes citrus greening.

Dr. Jin isolated the genes from the finger lime that contribute to the bacterial immunity. One of the genes produces the peptide which was tested over a two-year time span.  She said the peptide is applied to the trees a few times per year to control citrus greening. The material can be applied by injection or foliar spray and it moves systemically through plants and remains stable, making the effect of the treatment stronger.

The California citrus industry has been focused on suppression of the Asian citrus psyllid, a vector of citrus greening, as the infection has not been found in commercial citrus production in the San Joaquin Valley.

Some of Dr. Jin’s research was funded in 2018-19 by the Citrus Research Board. The study was conducted within the UC Davis Contained Research Facility on year-old Madam Vinous, Washington Navel and Lisbon lemon plants that were treated through either foliar sprays or pneumatic injections.

CRB’s initial $100,000 investment in this research was supplemented by a nearly $4 million grant from the USDA National Institute of Food and Agriculture. USDA-NIFA funding for this phase went into effect in February of last year and is scheduled to continue through January 2023.

The long-term effectiveness of this treatment has not been confirmed or published in a scientific journal and the project is still in its early stages. Dr. Jin’s promising findings have resulted in a commercial licensing agreement between UCR and Invaio Sciences. In this case, more work still needs to be done to confirm the robustness and viability of this treatment. Additional greenhouse trials are being initiated by Dr. Jin and her team at the citrus-specific Bio-Safety Level-3 Laboratory in Riverside, California. It also is expected that field trials will be conducted to show the effectiveness of the treatment under commercial grove conditions.

The need for a citrus greening disease cure is a global problem, but hits especially close to home as California produces 80 percent of all fresh citrus in the United States, said Brian Suh, director of technology commercialization in UCR’s Office of Technology Partnerships, which helps bring university technology to market for the benefit of society through licenses, partnerships, and startup companies.

“This license to Invaio opens up the opportunity for a product to get to market faster,” Suh said. “Cutting edge research from UCR, like the peptide identified by Dr. Jin, has a tremendous amount of commercial potential and can transform the trajectory of real-world problems with these innovative solutions.”

Pests are out in full force. Protect your crops this summer with the addition of an adjuvant that can double the potential of your insecticide. Using technology that reduces evaporation and keeps tank mix droplets on the target in a liquid state twice as long as a typical surfactant, OMRI listed Ampersand® adjuvant gets more of your tank mix to the leaf and keeps it there longer, giving your insecticide time to perform its function. Learn more at www.attuneag.com

Weekly ET rates are available online on the Sac Valley Orchards website along with information on how to use the reports. UCCE irrigation resources Farm Advisor Allan Fulton explained that the weekly tables provide real-time estimates of crop ET for crops with approximately 70 percent or more midday canopy shading. The weekly reports provide both crop ET estimates not adjusted for irrigation system efficiency and adjusted for 70-, 80- and 90-percent irrigation efficiency.

Measurement of applied water and understanding of the irrigation system performance are necessary to use these weekly reports. Knowing how closely the amount of irrigation water plus rainfall matches estimates of real-time orchard ET can help make irrigation scheduling decisions, especially if this information is teamed with measurements of tree water status with a pressure chamber or with soil moisture monitoring.

Using weather-based evapotranspiration rates as a guide for irrigating young orchards can be a helpful water management tool, but adjustments will be needed as most published rates of water demands are for mature trees (about five years and older.)

In a video tutorial, Fulton explained that ET rates should be adjusted for tree size and irrigation efficiency. Soil variability and irrigation system performance should also be taken into account when making irrigation management decisions for young trees.

Irrigation management in young orchards can be challenging due to the expanding tree canopies and root systems from planting up to production. Young orchards, while not yet yielding much crop, are using water and nutrients to grow. Expanding leaf area means more leaves with stomata to transpire water and take in carbon. As roots grow, they may also access additional soil moisture other than from irrigation.

Smaller trees have lower ET rates, Fulton said. The question is how much lower and how does it change as the trees grow? Older research has shown that once first leaf trees are established and growing well, almonds may require on average about 40 percent of the ET rate for a mature tree over the course of the first season. More recent research in almonds with lysimeters suggests these older research based estimates may even be conservative (a bit low.) First leaf walnut tree water demand is on average 30 percent of the ET rate for a mature walnut tree. By the fourth year, demand by an almond tree is 90 percent of the ET rate for a mature tree. In walnuts, fourth year trees are on par with a mature tree especially if vegetation in the orchard middles is growing.

Many factors can influence how a young orchard develops ranging from previous crop if it is an orchard replant situation, soils and site preparation, planting date, the source of the new trees, nutrition, and weed competition. As a result, a more advanced and site-specific approach to adjusting ET based on field measurement of canopy shading may interest growers.

Examples of how to specifically adjust the weekly reported estimates of crop ET for mature almond, walnut and other tree crops for younger developing orchards will be provided in an upcoming video series that should be posted in July or August 2020 at the Sacramento Valley Orchard Source website. It is also covered in the Almond Board’s Irrigation Continuum https://www.almonds.com/almond-industry/orchard-management/water-and-irrigation

Five Romaine lettuce varieties that brown less quickly and are slower to deteriorate postharvest have been identified by Agricultural Research Service scientists.

In determining the genetic basis for deterioration, the researchers have identified the location of genes associated with postharvest deterioration of fresh cut lettuce and are in the process of identifying genes associated with browning—two economically important traits. This work will accelerate development of new Romaine varieties with better shelf life as lettuce breeders will be able to check that offspring carry these genes without needing to grow out and test for browning and deterioration resistance.

Lettuces are the most popular commercially produced leafy vegetable in the world and one of the top 10 most valuable crops in the United States. One of the main challenges with this crop is that it is highly perishable.

Having the molecular markers means that slow deterioration and eventually less browning can be more easily integrated into lettuce breeding. The inability to evaluate for deterioration has been an impediment to breeding advances, said study leader Ivan Simko, ARS Crop Improvement and Protection Research Unit in Salinas.

When you consider browning and deterioration ratings together, the best breeding lines for commercial production and also for use as parents to develop new varieties are (in alphabetic order): Darkland, Green Towers, Hearts Delight, Parris Island Cos, and SM13-R2, which is a breeding line developed at the ARS lab in Salinas.

In addition, the researchers found the chromosome region that contains the genes for slow deterioration also contains four genes (Dm4, Dm7, Dm11, and Dm44) and one DNA region (qDm4.2) that codes for resistance to downy mildew—one of the costliest lettuce diseases.

This colocation indicates a strong linkage between one or more of the four genes and the rate of deterioration. DNA-based markers can be used to develop new breeding lines with slow rate of deterioration and desirable combinations of resistance genes. Deterioration is the rupture of cells within lettuce leaves, leading to waterlogging and the lettuce turning to mush. Browning is the discoloration of the edges of lettuce after cutting or tearing. Either development can spoil the leafy vegetable’s value by decreasing shelf life.

In an effort to control browning and prolong shelf life, lettuce processors have been turning to modified atmosphere packaging and flushing bags of cut lettuce with nitrogen gas to reduce oxygen levels in the bags.

These practices are expensive and can lead to other problems such as off-odors and, when coupled with high storage temperatures, anaerobic bacteria growth on the bagged lettuce.