David Doll0 commentsApril 23, 2018General

Got voles? Perhaps anthraquinone is the answer.

Article written by: Roger A. Baldwin and Ryan Meinerz Department of Wildlife, Fish, and Conservation Biology, University of California-Davis, Davis, California Gary W. Witmer and Scott J. Werner USDA/APHIA/Wildlife Services-National Wildlife Research Center, Fort Collins, Colorado Recent research has shown we may have a new tool to protect trees and vines from vole damage. However, this product is not currently registered for such a use.  We need your response to know whether there’s enough interest in a new way to control vole damage to warrant seeking registration. Voles are short, stocky rodents that often cause extensive girdling damage to a variety of tree and vine crops throughout California.  Effective management has often relied on some combination of vegetation removal, exclusion using trunk protectors, and rodenticide application. However, all these management solutions have shortcomings. Vegetation removal doesn’t always eliminate all problems in an area.  Trunk protectors should be buried at least 6 inches below ground, increasing the labor required to protect trees and vines.  Rodenticide applications are generally not allowable within an orchard or vineyard during the growing season, when it is most needed.  See the following link for more details on voles and vole management:  http://vpcrac.org/files/4314/7612/1259/Meadow_vole_chapter.pdf. Clearly there is room for a new tool to be added to the proverbial IPM toolbox when it comes to managing voles in orchard and vine crops.  In recent experiments with a chemical repellent, anthraquinone, on citrus trees, we found that anthraquinone was highly repellent following trunk application (sprayed or painted on), with a >90% reduction in girdling damage observed following application regardless of the season when it was applied.  Anthraquinone exhibited substantial longevity, with no increase in girdling damage observed for the entire summer (5 weeks) and spring (6 weeks) sampling periods.  This clearly indicates substantial repellency for anthraquinone applications, with repellency to

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David Doll2 CommentsMarch 30, 2018General, Horticulture

2018 Spring Update

Spring conditions over the past week have finally turned favorable for growth. After a very warm winter, a long bloom with periods of cold weather, followed by a few weeks of wet weather, trees are starting to grow and nuts are beginning to size. These weather conditions have led to a few interesting observations and considerations for the spring. Leaf lesions caused by bacteria. Observations from several fields have yielded the occurrence of bacterial leaf spots. These spots are thought to be caused by Pseudomonas syringae, the same bacteria that causes blossom blast. Lesions are often varied in shape and have a distinctive yellow halo. Generally, the tree recovers after shedding a few leaves. Conditions can worsen if rains persist. Copper treatments to prevent may do more harm than good due to tree sensitivity. Lesions can be easily confused with herbicide drift or shot-hole; review application history to determine if these could be potential causes. Vegetative bud failure. Just as we observed in 2015, we have been observing vegetative buds within last year’s growth failing to push. This “bud failure” is not the same as non-infectious bud failure (crazy top) as future generations of buds will be healthy. Although we are unsure of exactly why this type of bud failure occurs, we believe it to be due to a reduction of localized carbohydrates from the December and January temperature ranges. Explained simply, warm winter days and nights below freezing increase the rate of respiration, leading to reduced carbohydrates to assist with bud break. If levels drop too low, buds can die. Often, healthy buds below the affected area will grow and hide the damage that occurred. Sometimes, buds will break later than normal. More rain. Mid-range forecasts are predicting rain for the end of the first week of April. These

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David Doll2 CommentsNovember 28, 2017General

Observations from a Trip Down Under – The Australian Almond Industry

During the first two weeks of November, I was able to attend the once-every-four-years International Research Congress on Pistachios and Almonds. This meeting was held in Adelaide, Australia in which almond and pistachio researchers (as well as some growers) attended to discuss recent research within these crops. Prior to the conference, I toured some orchard operations in the Mildura area. These orchards had the look and “feel” of California orchards and  yields in the 2700-3000 lbs/acre. Through the visits and discussions with my various hosts, issues that many of the operations were trying to manage were similar but different to what we experience within California. Below are a selection that I found interesting and thought I would share. Good water management can compensate for limiting soils. Across all of the properties I visited, the soil profile was very shallow with  18-24″ of sand before hitting a limiting layer of clay. To make matters worse, the layer of clay often had a very high pH (>9) and boron (>3.0 ppm) – which would kill almond trees. These conditions reduced the rootzone to the sand profile which has limited water and nutrient holding capacity. To compensate for these “shallow soils,” most orchards are planted on a raised bed and irrigated daily with double drip systems to match the tree’s water demand for that day. The water applied does not exceed the holding capacity of the 24″ of soil to prevent root movement into the deeper toxic soil. This practice also prevents excess water from running off or creating a perched water table. This was an “eye-opening” experience for me. We generally have the luxury of deep soils within California in which we can irrigate deeply, less frequently. These irrigation practices, however, produced tree growth and yields which were comparable to California orchards.

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Franz Niederholzer0 commentsJune 6, 2017General

Varietal trends in acres planted to almond, 1988-2016

The almond acreage report for 2016 was released by California Department of Food and Ag (CDFA) on April 26, 2017. Click HERE to link to the report.  This report is developed from voluntary grower survey responses, pesticide use reports and the annual nursery sales report. Along with total almond acreage for 2016, [940,000 bearing acres and 3000,000 non-bearing acres], the report gives values for the acreage in individual counties, Nonpareil planting by county, and trees by variety.  While not perfect, the report gives a sense of how much is being planted and what varieties are being planted. Curious about what varieties are being planted in the state and in what proportion, I calculated the percentage of total plantings for each reported variety over time from the raw numbers in the report. I selected the top eight varieties and made the graph of percentage acres planted over time that appears below.  Growers can see for themselves the patterns of acres planted by variety as the industry has grown.      

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David Doll3 CommentsMay 30, 2017General, Technology

Small Drones and Monitoring Orchards: Project Update and Field Day

Aerial imaging can provide real-time information to growers regarding water usage and crop health. Within agriculture, these tools provide a valuable service for identifying problematic areas within fields, thereby increasing efficiencies for both small and large scale producers. Currently, most aerial imaging is conducted by flights with mid-elevation aircraft or satellites. These flights and corresponding images are usually conducted by a service company and provided on a weekly or monthly basis. Autonomous or Unmanned Aerial Vehicles (UAVs) may provide a format in which more regular flight data can be obtained. Most discussions within agricultural settings have been focused around large fixed wing drones. However, smaller, less sophisticated and less autonomous UAVs could provide a useful platform for California farmers. These smaller UAVs would be less expensive to construct, may require less regulatory permitting, and provide a mobile platform that can be quickly deployed within a field setting. In these settings, small UAVs would have the ability to quickly monitor crops for water stress, nutrient management, and pest and disease epidemics. A major barrier for small UAVs is camera/imager selection and processing. Currently, most work within crop stress management has focused on the use of thermal cameras that operate in the far-infrared spectrum (Maes and Steppe, 2012). These cameras are expensive, which inhibits the adoption of UAV technology. More commonly used spectral wavelengths, such as visible and near-infrared wavelengths can be used for other vegetation indices need to be researched to determine if they provide comparable results as thermal imaging. These imagers and indices are attractive to the end-user due to the lower cost to implement. With these challenges in mind, a research project sponsored by the University of California Agricultural and Natural Resource Competitive Grants Program was awarded to determine the feasibility of using small UAVs for perennial crop water

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Emily Symmes2 CommentsJanuary 24, 2017Diseases, General, Insects

Protecting Honey Bees During Bloom

Written by Emily J. Symmes, UCCE Sacramento Valley IPM Advisor With almond bloom on the horizon, it is time to revisit best management practices for protecting pollinators (e.g. honey bees) during this critical time. Remember that communication is key during the bloom period. All parties should be kept informed so that beekeepers are aware of impending applications and applicators are aware of the requirements related to notification, materials, timing, location, and method of application. This includes growers, beekeepers, land owners-lessees, PCAs/CCAs, pesticide applicators, and county Agricultural Commissioners. General guidelines: Employ sound IPM practices: Apply pesticides only when absolutely necessary based on monitoring and treatment thresholds. Know all of the available materials and application timings. For insect pests, there are effective alternative timings for insecticide applications aside from the bloom period. If the weather remains dry and clear throughout bloom, there should be minimal need to apply bloom fungicides. One solid application just ahead of full bloom should be adequate for good disease control under these conditions. Earlier spray timings (e.g. pink bud) if wanted, may be applied every-other-row. Be aware of the impacts of any treatments on pollinators and other non-target organisms. Always provide adequate clean water for bees: Cover or remove water sources prior to any application. Keep water clean and fresh ensuring bees spend more time pollinating the crop than searching for water. Bees can forage up to 5 miles away seeking food and water if not available in the orchard, increasing their risk of contact with harmful pesticides. Do not spray hives directly with any pesticide. Ensure the spray-rig driver turns off nozzles when near hives. Do not spray flying bees with any applications. Aside from toxicity concerns, bees will not be able to fly because of the weight of spray droplets on their wings. Even water

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David Doll0 commentsJanuary 12, 2017General, Horticulture, Weeds

Dormant Practices and Wet Weather

Over the past week, a lot of rain has fallen across California. Orchard access should be limited during periods of wet soil to reduce soil compaction as well as stuck equipment. Limiting access, however, creates challenges in performing a variety of orchard operations, including the list below.   Winter Sanitation. Removal of almond mummies from trees is critical for Navel Orangeworm management (NOW). Many operations usually wait for the first rains to help with leaf drop and to help “loosen” the mummies. In wet years, however, it becomes difficult to winter shake the trees as orchard conditions remain too wet for access of shakers. Furthermore, the “window” to winter shake is limited on the late end as fruit bud loss increases as trees enter delayed dormancy and buds swell (Mid to late January, depending on location). To manage this limited access, operations should consider poling crews. If these aren’t available, and sanitation is not performed, a spring timed (usually late April through early May) insecticide can reduce overwintering NOW. This strategy is not as effective as winter sanitation, but is better than doing nothing. Insecticide sprays targeting NOW in the dormant period are NOT effective due to NOW pupae being inside of the almond mummies. Planting bare root trees. Hand planting crews have an easier time than machine planting due to limited field access. If planting delays occur, trees should be placed into cold storage at the nursery as soon as possible to reduce the risk of leaf out and weakened trees. Keep trees in cold storage until ready to plant. Unless there is no other option, do not take delivery of trees in bins or plant them in a temporary location at the farm. On delivery, check tree roots to make sure they are healthy and living (should be

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David Doll0 commentsDecember 31, 2016General

2016 Top Ten Articles

With 2016 coming to a close, here is a quick review of the top ten articles read this past year from “The Almond Doctor.” 10. Verticillium wilt of almond (and pistachio). An overview of the disease, symptoms, and management for almond trees. This disease has become more common with increased plantings on land previously cropped to tomatoes and cotton. 9. Bacterial spot vs anthracnose vs plant bug. A series of pictures and a table to help identify the symptoms of these diseases or insect damage. 8. Postharvest is a good time for boron foliar sprays. A review of some research and considerations when making fall boron applications.  7. Independence almond – some observations. A 2010 article that highlighted some early observations of Independence. This variety is becoming more widely planted with an estimated 200,000 acres in the ground.  6. Almond set and nut drop. Summarizing recent research as well as field observations, this article discusses spur dynamics and the various “drops” of almond fruit. 5. 2016 almond bloom considerations. An annual contribution highlighting considerations for the upcoming bloom. 4. Proper almond tree planting. An article written by Brent Holtz back in 2010.  3. Fertilizing young almond trees – a few tips. With all of the newer orchards planted the past few years, this article has been read with increased frequency. 2. The seasonal patterns of almond production. An article about tree physiology and almond production. One of the first articles written for “The Almond Doctor” back in 2009. 1. Nitrogen content in a gallon of UN-32. A short article written in 2010 that provided an answer to a question commonly received. This one was number one last year as well! I would like to thank you all for your support through 2016. We develop many of the ideas for these articles through your requests for visits, phone calls, emails, and

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David Doll5 CommentsAugust 29, 2016Diseases, General

Considerations for Replanting Almond Orchards

It is the time of the year when many operations begin the process of replanting almond orchards. Orchard removal and eventual replacement is one of the more critical times of farm operations. The decision to remove a block varies by farmer. Some remove blocks based on a cycle of redevelopment, meaning that blocks are removed on a schedule based on age to assist with cash-flow. Some are removed due to expensive or inadequate resources (e.g. water). Many are removed when production drops below a certain profitability level. Removing a block on profitability can be tricky. Blocks tend to alternate bear. An off year may trigger removal, but it could be coming into an on year. Prices also fluctuate. Therefore, this may not be the best way to decide on removing a block. Another consideration should be determining the the stand of trees remaining in the orchard and the rate of tree loss over the past few years. Commonly, in old orchards, trees are lost to heart rot decay fungi and corresponding wind throw. These losses tend to increase as the orchard ages. If this rate is increasing and the orchard stand is below 75%, removal and replanting should be considered. This is a conservative estimate, and should be evaluated with production records and tree stand for your own operations (This estimate is based on an 80% canopy coverage at maturity with minimal tree losses). Once the decision to remove is made, the work begins. Consider harvesting the later varieties earlier to allow more time in the process.  Nematode sampling should occur prior to removal to determine which species are present and assist in rootstock selection. This can be done one to two years prior to removal. Line up the resources for orchard removal, which can be done by tub grinders, whole orchard incorporation, or removal

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David Doll0 commentsJuly 28, 2016General, Horticulture

Stockpiling Almonds During Harvest

With the increase in almond plantings over the past few years, processing delays will become more common. While waiting to be processed, almonds are usually stockpiled. Stockpiling has a number of advantages,  including getting the almonds out of the orchard sooner to allow the ability to perform  post-harvest practices, reduce in-field insect infestations, and allowing greater flexibility in scheduling transport to the processor. When stockpiling, make sure that the total moisture content (In-hull almond) is less than 9%  (Hulls should snap when bent). Choose a location which is suitable for drainage in rainy weather and that is not near equipment or fuel storage.   Stockpiles should be oriented in a north-south direction to aid in drying and covered with white-on-black tarps. These practices reduce humidity and day-to-night heat fluctuations, leading to a reduction in condensation. Monitor humidity and open the tarp when appropriate to reduce condensation and mold formation. Also monitor  and treat for  insect, bird, and rodent pests. If rain threatens, ensure piles are covered . Finally, be aware that stockpiles are a potential fire hazard. Stockpiles should be fumigated to reduce insect infestation. NOW is an excellent storage pest and can survive in stockpile conditions. Furthermore, this pest can continue to feed and reproduce within stockpiles, increasing damage as well as aflatoxin risk. Although time consuming, fumigation is critical in killing larvae and eggs, reducing damage. Finally, be wary of too much moisture in stockpiles. Studies have shown that hull moisture above 14% and a holding temperature greater than 120°F will increase the risk for concealed damage, mold, and aflatoxin. With an earlier harvest, stockpiles will be exposed to higher temperatures. If needed, delay harvest until nuts can dry. This will be increasingly necessary as orchard canopy coverage increases as cooler temperatures and more shade increases dry times. Avoid

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