Subsurface drip irrigation is growing more and more common in field crops, but what about in the orchard? The UC Cooperative Extension has been experimenting on this for a few years now in a stone fruit orchard at the Kearney Ag Center, and the results are very positive. Watch California Ag Network’s interview with Becky Phene as she explores the benefits of converting to subsurface drip, and read more about it in California Fresh Fruit Magazine.
When is the best time to prune/top stone fruit in-season to keep from shading next year’s fruitwood? For conventional orchards? For pedestrian orchards? Watch this brief video interview with UC Farm Advisor Kevin Day as he answers these important questions.
Parlier, Calif., (July 26, 2017) – For centuries, farmers have used all the colors of the rainbow to assess their orchards: The bright pink of blossoms in springtime, the vibrant green of heathy leaves, the red blush on fruit ready to harvest.
However, there are wavelengths beyond what a typical human eye can see that also provide valuable information about the crop – including tree vigor, plant stress, water use and fertilizer needs.
UC Cooperative Extension agricultural engineering advisor Ali Pourreza is peering into these previously invisible colorations to create a virtual orchard that will quickly, easily and inexpensively allow farmers and scientists to manage orchards for optimum production.
To develop his first virtual orchards, Pourreza launched a camera-equipped drone over an orchard at the UC Kearney Agricultural Research and Extension Center in Parlier. As the drone flies over the trees, it snaps thousands of photos and, using photogrammetry and software that stiches the images together, makes a three-dimensional point cloud model of the orchard.
A computer program can make colors that are invisible to the human eye – such as near infrared, red edge and ultraviolet – into imagery that illuminates key crop health indicators. Near infrared indicates the amount of healthy foliage, plant vigor and crop type. If the trees have low near infrared values, it means the plants are under stress. Red edge indicates plant stress and nitrogen content. High red edge values indicate nitrogen stress and low water content in plant tissues.
“We are currently working on developing models to help growers determine their fertilization demands and have been contrasting the results from real orchards with the virtual orchard,” Brown said. “We have already utilized the approach to contrast the estimates of tree growth and yield with whole tree excavations and harvests to help validate the virtual approach and provide a more accurate estimate of tree nitrogen demand.”
Ultimately, Brown hopes to develop a way for growers to rapidly and cheaply estimate the nitrogen demand of their orchards, monitor the status of their orchards and manage nitrogen fertilizer applications.
In addition to the color variations brought to light by the virtual orchard, the system provides detailed data on other aspects of the crop development.
“We can learn canopy height and width, the spacing between the trees, total leaf area, canopy density and the amount of shaded area in the orchard,” Poureza said.
This data is of interest to scientists studying plant development, soil health and irrigation.
For example, UCCE agricultural water management specialist Daniele Zaccaria is researching the impact of soil-water salinity on water use by pistachio trees in the San Joaquin Valley.
“In our on-going research study we are characterizing the functional relationships between soil-water salinity, canopy size and density and evapotranspiration of pistachio trees through the light interception by the canopy,” Zaccaria said. “We plan to work with Ali to see how the virtual orchard approach can represent that and simulate the physical process of soil evaporation and tree transpiration as a result of different canopy sizes and densities intercepting different amounts of solar radiation.”
Zaccaria said he also plans to deploy a similar approach to understand how different canopy sizes, planting densities and row orientations found in commercial citrus orchards in the San Joaquin Valley – from navel oranges, to mandarins and lemons – can affect the citrus water demand and use.
In addition to the rich data that scientists can glean from the virtual technology, Pourreza envisions many applications of this technology for farmers, including yield forecasting, blossom mapping, variable pesticide application and robotic harvesting.
View a video on YouTube produced by the scientist, Ali Pourreza. The video shows images of the virtual orchard.
Sacramento, Calif., (June 28, 2017) – The impacts of such an unusually wet winter and prolonged spring rain events on insect and mite activity are still developing. This article summarizes some notable observations thus far and specific pest management considerations as we move into summer.
The first codling moth biofix generally ranged from early- to mid-April in 2017 in the Sacramento Valley (many of the same orchards observed first biofix in late March the previous two years). As this goes to print, we are nearing 1060 degree days (DD) in most blocks and are on the lookout for the second biofix. The first codling moth flight this year (1A and 1B peaks) were reported to be quite high in many orchards throughout the region, and applications targeting one or both of these flight peaks were common. Keep in mind that a good codling moth program can help minimize early-season infestation by navel orangeworm, so keep a close eye on your trap counts and the numbers of codling moth-infested dropped nuts in your orchards.
Although wet winters can cause increased overwintering mortality of navel orangeworm, significant survival was apparent in walnut mummies examined this spring (March 2017). Bear in mind that your neighbors may not have been able to execute their normal NOW sanitation programs last winter either, and these may be a source of populations moving into your orchard as the season progresses (in addition to any carry-over populations you may have in your orchard). Prior to husk split, NOW will go back into mummies and into this-season’s damaged nuts (codling moth-infested and blighted nuts).
Significant populations of frosted scale were evident in a number of orchards throughout the Sacramento Valley this year. It is not entirely clear why this pest, which it typically present only at low levels, has increased so dramatically in recent years. Research is underway examining this phenomenon, as well as best practices and timings for effective population reduction. Frosted scale produces honeydew when feeding (walnut scale does not). This favors growth of
sooty mold, which increases the chances for sunburn damage, so keep an eye on this if your orchard was heavily impacted by frosted scale this spring. Frequent rains throughout winter and early spring limited the ability for many growers to get into the orchards to apply dormant/delayed-dormant scale treatments, necessitating applications targeting the spring crawler stage. Crawler emergence was observed late in the second week of May 2017 (compared to the first week of May 2015 and last week of April 2016), with peak crawler activity noted approximately two weeks later. This highlights the importance of monitoring the populations, rather than applying treatments based on “typical” calendar timing (which would have been too early this year to target peak crawler activity). Our research trials this year are examining efficacy of different treatment materials and timings specifically for frosted scale (walnut scale has been the focus of research in recent years). If treatments were applied for frosted scale (either dormant/delayed-dormant or crawler), monitor the populations next dormant period looking for the overwintering nymphs (photos and more information at ipm.ucanr.edu/PMG/r881300111.html). Frosted scale has only one generation per year, so the effects of this season’s spray program will be best observed at this time, and as next spring’s populations begin to develop.
Conversely, walnut scale populations have dropped off in many orchards, likely due to effective management programs over the past few years. We observed walnut scale crawler emergence during the last week of May 2017 (compared to first and second weeks of May in 2015 and 2016, respectively). Another reminder the importance that treatment timings should be supported by field observations of pest activity each year.
Walnut husk fly traps just beginning to hit the week of June 5 in Butte and Sutter counties. No activity noted as of that time in our trapping locations in Tehama county. Remember that WHF treatment decisions should be made on a site-specific basis and take the time to hang traps high in the tree canopy – this will provide better accuracy in detecting activity. If trapping indicates the presence of treatable WHF populations, all insecticides should be applied with a bait (i.e., molasses, Nu-Lure®, Monterey Insect Bait®). The exception is GF-120 which contains its own bait. For low- to moderate-populations, coverage is not critical and low-volume and/or partial coverage applications (e.g., alternate row) of bait with insecticide can be effective. However, in high population orchards with extensive previous damage, high-volume, full coverage, and/or multiple applications of bait with insecticide may be necessary to achieve adequate control. If you miss a timing and are observing fresh stings, full cover neonicotinoids that have some ovicidal (egg-killing) activity mixed with an adulticide will provide partial control of eggs if applied immediately after stings are observed. Generally, a short-residual insecticide-plus-attractant will kill walnut husk fly for 10 days. With the egg development period added to this time, there is about 3 weeks of protection after an application (GF-120 treatments often must be applied more frequently).
Spider mite activity remains low at press time, but will likely begin to pick up with sustained warmer temperatures. Prophylactic May applications of abamectin, while still favored by many almond producers, have shown to be less effective and economically-viable in most walnut orchard situations. Treatments should be based on thresholds of spider mites and their natural enemies (particularly predator mites and sixspotted thrips). In general, the goal is to manage the ratio of predators-to-spider mites (not just spider mite numbers alone) to achieve a balance in which predators can provide free control services. Also consider the impacts of other pesticides on spider mite and predator populations (organophosphates and pyrethroids are highly detrimental to spider mite natural enemies and often result in spider mite flare-ups). More information on treatment thresholds for mites and predators in walnuts is available at: ipm.ucanr.edu/PMG/r881400111.html. Best practices for getting the most out of your miticide in walnuts include choosing the right material for the job (i.e., those softer on predators if they are present, desired residual activity and pre-harvest intervals, quick and effective knock-down if needed, etc.) and obtaining optimal coverage (high volume, slow speed).
Orchard Calibration Field Day
April 18, Calif., (April 18, 2017) – Come join us at the Orchard Calibration Field Day on Tuesday April 25th, 2017 from 8:00am to 1:00pm at the Nickels Soil Lab in Arbuckle, CA
The agenda is as follows:
UC Farm Advisor, Franz Niederholzer available for questions
Questions: Franz Niederholzer (530) 458-0570 Peter Bjorklund (707) 322-3729 Dawn Brunmeier (209) 323-9081
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Spring is in the air, the birds are singing, and orchards are beginning to bloom in the warmer areas of California. To ensure successful almond pollination, Bee sure to follow a few safety tips with Billy Synk in dealing with honeybees in the orchard. Watch this video and read more in Pacific Nut Producer Magazine.
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At the annual Tree & Vine Expo in Turlock, nearly a thousand growers & PCAs gathered to network with industry friends and enjoy a great line-up of grower seminars. One seminar featured UC IPM Advisor Kris Tollerup who discussed monitoring and controlling leaf footed bug in the orchard as shared in this video.