California Ag Network

Category: Pest/Disease Management

  • HLB Detected on Residential Property in Riverside

    The California Department of Food and Agriculture (CDFA) and the United States Department of Agriculture (USDA) have confirmed the detection of the citrus disease known as Huanglongbing (HLB), or citrus greening, in Riverside County. The disease was detected in plant material taken from a grapefruit tree in a residential neighborhood in the city of Riverside near I-215.

    The infected tree has been removed and agriculture officials are moving swiftly on mandatory surveying in an 800-meter area. Mandatory treatments will soon follow. CDFA staff will visit all regulated entities in the quarantine area, including retail and production nurseries and packinghouses. Additionally, local, state and federal agriculture authorities are working together to determine potential implications to the University of California, Riverside, which will fall within the 5-mile quarantine area.

    Riverside County Agricultural Commissioner/Sealer Ruben Arroyo plans to take an aggressive stance on any abandoned groves in the area, and the Citrus Pest & Disease Prevention Program outreach team is already working with the City of Riverside to inform residents of the actions needed to stop HLB’s spread.

    Learn more in the press release shared by Riverside County.

  • USDA California Crop/Weather Report

    Sacramento, Calif., (August 1, 2017) – The weather last week was hot and dry across the State. The summer monsoon across the southwest desert helped trigger some showers across the deserts last week, while additional pockets of moisture found their way into the Sierras and managed to produce a few scattered showers throughout the week. Rainfall was limited to Monday through Thursday across the interior deserts and parts of the central and northern Sierras. A few monsoon showers and thunderstorms dropped up to half an inch of rain in places across the desert, with most areas receiving around a tenth of an inch. A stray thunderstorm near Alturas in the northeastern corner of the State dropped nearly half an inch of rain. Snow cover continued to dissipate across the State; however, some areas of the Lassen Volcanic National Park still had nearly ten feet of snow in some areas.

    Temperature highs were in the 60s to 80s along the coast, 70s to 90s in the mountains, 90s to 100s, in the valley, and 90s to 110s in the desert. Temperature lows were in the 30s to 50s in the mountains, 50s to 60s along the coast, 60s to 70s in the valley, and 60s to 80s in the desert.

    Wheat was harvested for grain and shaft baled for straw. Alfalfa fields were being irrigated, cut, and baled. Corn and sorghum for silage were cultivated and irrigated. The corn silage crop was in various stages of development, from already tasseling to developing ears. Cotton continued to be irrigated, cultivated, and was growing well. Cotton was blooming and forming bolls. Black-eyed beans continued to be irrigated and cultivated.

    Mid-season peach, nectarine, pluot, and plum harvest continued.  Some harvested stone fruit orchards were pruned and topped. Table grapes were harvested and vineyards irrigated. Wine grapes were maturing well.  Valencia orange harvest continued but was winding down due to high temperatures and fruit availability.

    Walnut, almond, and pistachio orchards continued to be irrigated. Mechanical and chemical weed control continued in orchards.  Harvest preparation was underway in almond orchards. Almond harvest began in the warmer regions of Kern County. Pistachios were beginning to split. Navel Orange Worm sprays and fertilizers were applied to pistachios. Walnuts were sizing well.

    In Colusa County, triple digit heat impacted the harvest of vegetables, including processing tomatoes and honeydew melons.  The processing tomato harvest was somewhat erratic, interrupting the smooth flow of ripe tomatoes to the canneries.    The melon packing sheds were affected by the inconsistent flow of fruit.  In San Joaquin County, harvest was ongoing for honeydew melons, watermelons, cantaloupes, onions, and fresh vegetable crops.  Farmers’ Market vegetables continued to be harvested and offered for sale.   In Monterey County, mid-year harvest and production slowed for two weeks.  It was expected to pick back up with more harvesting and preparation for the third or last rotation of the year.  All commodities, lettuces, brassicas, and spinach were in production.  Asparagus was finished and artichokes will pick up again in August.  In Fresno County, harvest continued for both organic and conventional tomatoes with lower yields than expected.  Quality was reported as very good.  Onions, carrots, and lettuce seed were harvested.  Soil was prepared for yellow peppers.  In Tulare County, tomatoes, cucumbers, squash, and peppers were picked by certified producers and sold at the local Farmers’ Markets.  Yellow squash, zucchini, eggplant, Bell peppers, green chili peppers, and cucumbers were harvested and shipped domestically.  Sweet corn harvest continued and was sold at roadside stands and local Farmers’ Markets.  Melons were irrigated and prepared for the upcoming harvest.  In Kings County, the tomato harvest continued with a decent harvest reported.  Tomatoes were sprayed with fungicide and pesticide.

    The decline in nutritional quality of rangeland grasses and forbs continued. Range and dryland pasture conditions across the state were reported as fair to very poor. Wildland fires burned some north state pastures and ranges.  Elevated temperatures continued to impact milk production. Bees were active in melon and sunflower fields.

  • UCR Research Showing How Nematodes Use Smell To Select New Insect Hosts Could Improve Biological Control Of Crop Pests

    Riverside, Calif., (July 26, 2017) – Tiny eel-like creatures called nematodes are surrounding us. While they can be free-living (a cup of soil or seawater contains thousands), the most well-known nematodes are the parasitic kind that wreak havoc in people, animals and plants.

    Despite their reputation, scientists at the University of California, Riverside are studying nematodes as a force for good: to kill insects that infect crops and trees.

    In a paper published today in Scientific Reports, a team led by Adler Dillman, assistant professor of parasitology in UCR’s College of Natural and Agricultural Sciences, has shown how nematodes use smell to seek out uninfected insects, which they then enter and kill. The findings support the group’s long-term goal of improving how gardeners and the agricultural industry use nematodes in biological pest management.

    Nematodes, which are transparent or milky white unsegmented worms between 0.1 and 2.5 millimeters long, represent a whopping 80 percent of all animal life on earth. The varieties that infect insects, such as the Steinernema carpocapsae species studied at UCR, enter their hosts through natural body openings, replicate, and secrete a deadly cocktail of proteins. These nematodes show promise as biological insecticides for more than 250 pests that attack plants such as corn, oranges, tomatoes, peaches, and pine trees.

    Insects (like the larva shown in this figure) that have been infested with nematodes emit an odor called prenol that repels other nematodes seeking a host.

    Insects (like the larva shown in this figure) that have been infested with nematodes emit an odor called prenol that repels other nematodes seeking a host.

    While previous research has shown that nematodes can differentiate between insects that have already been infected and those that have not, the mechanism by which this occurs has remained a mystery. In the current study, the researchers discovered that infected insects emit an odor called prenol that is repulsive to nematodes looking for a new host.

    “The nematodes are using odors like prenol to identify insects that are already infested and therefore not worth infecting because they have depleted resources. Instead the parasites are more likely to choose insects that are not emitting prenol, since those represent untapped resources,” said Tiffany Baiocchi, a graduate student in Dillman’s lab and the lead author on the paper.

    An unexpected plot twist was the team’s finding that some insect larvae are attracted to prenol, suggesting the same odor that signals nematodes to steer clear of an infected insect may also attract uninfected insects to that area.

    “This is a cunning way of attracting new hosts for the generation of nematodes that will emerge from the infected insect cadaver. The way that nematodes can essentially engineer the recruitment of new insects toward them is certainly something we can exploit in our efforts to improve nematode-based biological control,” said Dillman, who is a a member of UC Riverside’s Institute for Integrative Genome Biology and the Center for Disease Vector Research.

    The title of the paper is “Host Seeking Parasitic Nematodes Use Specific Odors to Assess Host Resources.” In addition to Dillman and Baiocchi, contributors include: Grant Lee, an undergraduate researcher, and Dong-Hwan Choe, an assistant professor in entomology, who used mass spectrometry to help identify the odors. The work as supported by the National Institutes of Health.

    Below is a short video showing the life cycle of insect-killing parasites known as entomopathogenic nematodes (EPNs).

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  • Citrus Growers Reaffirm Support For State’s Citrus Pest & Disease Prevention Program

    Sacramento, Calif., (July 25, 2017) – California growers have affirmed the extension of a cooperative effort in response to the most serious threat to the state’s citrus crops.  Years before the discovery of the citrus pest the Asian citrus psyllid (ACP) in California in 2008 and the subsequent detection in 2012 of Huanglongbing (HLB), the disease spread by the ACP, California’s citrus growers had begun preparations for the arrival of this dual threat. Research and education efforts began well before the pest and disease were detected in Southern California, and since then a governing committee of citrus industry representatives has guided the state’s comprehensive response and advised the California Department of Food and Agriculture (CDFA).

    Huanglongbing is fatal for citrus trees and has no cure. The disease has been detected in more than 70 citrus trees in California, which have all been in urban areas of Los Angeles and Orange counties and have been removed. The Citrus Pest & Disease Prevention Program (CPDPP) — funded through industry assessments and state and federal funds — guides efforts to limit spread of the disease and the ACP, which can spread HLB from tree to tree as it feeds.

    The program was created in 2009 by legislation that included requirements for periodic hearings to review progress and give the industry and the public an opportunity to weigh in. Following a recent series of such hearings, the California Department of Food and Agriculture has determined it will continue the Citrus Pest & Disease Prevention Program.

    “It has never been more important to protect California’s citrus farmers, which represent a $3 billion economic driver for our state and 20,000 jobs,” said CDFA Secretary Karen Ross. “The feedback CDFA received from the industry was overwhelmingly supportive of this program.”

    Five hearings were held in June in citrus production areas to determine whether the program and its governing committee, both established in 2009, should continue for four more years. All comments received at the public hearings and in written submissions to the Department were supportive. No question of opposition was raised. Therefore, the Department determined a referendum is not warranted.

    “This program has evolved as the threat of the Asian citrus psyllid and Huanglongbing has progressed in the state, which is one of the reasons we’ve been successful at keeping the disease out of commercial groves,” said Nick Hill, chairman of the Citrus Pest & Disease Prevention Committee. “Having learned from our partners in Florida, outreach has occurred throughout the state and to urban areas, treatment coordinators have been engaged to make sure growers are working together for maximum effectiveness against the pest, and scientific research has been supported.”

    Continuation of the program reinforces the collaboration of the citrus industry, agriculture officials, researchers and the general public as they work together to save California citrus from HLB. Florida’s citrus industry has been decimated by the disease. An estimated 68.7 million boxes of citrus were harvested during Florida’s 2016-2017 harvest season compared to a record high of 244 million in 1997-1998

    Citrus Pest & Disease Prevention Committee meetings are open to the public. For a calendar of upcoming meetings, visit cdfa.ca.gov/citruscommittee/. For regional and statewide news related to citrus pests and diseases, sign up for emails at citrusinsider.org/.

  • USDA California Crop/Weather Report

    Sacramento, Calif., (July 6, 2017) – A ridge of high pressure sat over the western United States, which resulted in another hot and dry week across the State. The only rain for the week was along the northern coast, where Eureka reported four hundredths of an inch for the week. A broken band of snow approximately 40 miles wide between Lake Tahoe and Sequoia National Forest still existed above 9,000 feet. Snow depths in this band were two to four feet at most. The peaks of Mt. Whitney, Mt. Lassen, and Mt. Shasta remained snow-capped.

    Temperature highs were in the 50s to 80s along the coast, 70s to 90s in the mountains, 80s to 100s in the valley, and 90s to 110s in the desert. The temperature lows were in the 30s to 50s in the mountains, 50s to 60s along the coast and the valley, and 60s to 80s in the desert.

    Alfalfa fields were making excellent progress and being irrigated. Corn and sorghum planting for silage were almost complete, but still being cultivated and irrigated. The corn silage crop was in various stages, from newly planted to already producing tassels, and the earliest planted corn was developing ears. Cotton continued to be irrigated, cultivated, and was growing well. Black-eyed beans continued to be irrigated and cultivated.

    Peach, nectarine, apricot, and plum harvests continued. Fruit orchards and vineyards were irrigated. Some apple orchards used overhead cooling systems to mitigate the impact of the heat. Late Navel orange harvest was complete for the season.  Valencia orange harvest continued.  With high temperatures, regreening in citrus has become more common, and packers were color sorting to compensate.  Ruby Red grapefruit were harvested.

    Walnut, almond, and pistachio orchards were irrigated. Mechanical and chemical weed control continued in nut orchards. Pistachios were fertilized. In some locations walnut growers applied sunburn preventive materials.

    In Tulare County certified producers were picking tomatoes, cucumbers, squash, and peppers for sale at the local Farmers’ Markets.  Italian squash, eggplant, and cucumbers continued to be harvested.  Blueberry and strawberry harvests slowed down and were expected to come to a close with hot weather.  Sweet corn harvest began with a few roadside stands opening and sales at the local Farmers’ markets.  Carrot harvest had slowed down.  In Fresno County, carrots harvest was reaching its end.  Pepper harvest was completed with good yields. Dehydrated onion left to dry.  Fresh onions harvest was half completed. Roughly one-third of the onion harvest had been completed. Onion seed drying out. In Monterey County, celery harvest began and was picking up.  In Imperial County, spring melons and sweet corn were harvested.  Some growers reported exceptional yields.  Many farmers were finished with melon harvest and were plowing fields.   In Colusa, Sacramento, Solano, and Yolo Counties, tomato crops were progressing, even though the recent heat wave slowed crop development.

    Non-irrigated grasses and forbs continued to dry out as the dry days of summer continued. Rangeland was reported to be in good to very poor condition depending on elevation, aspect and soil moisture. Foothill watering holes were drying up. Cattle continued to be moved to higher elevation range. Milk production was impacted by the high heat.  Livestock deaths increased due to the extended elevated temperatures. Sheep grazed on retired pasture and dormant alfalfa. Bees were active in melon and vegetable fields.

  • Insect and Mite Updates – 2017

    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).

  • “Don’t Pack A Pest” Traveler Education Outreach Program Expands To California At San Francisco Airport

    Sacramento, Calif., (June 27, 2017) – San Francisco, California, June 27, 2017 – People traveling to and from San Francisco International Airport are now advised, “Don’t Pack a Pest,” on signs placed at various locations in the terminal.  A news conference today announced the expansion of this successful awareness campaign into California.

    “Don’t Pack a Pest” helps protect against invasive species introduction in the U.S. and the Caribbean with a simple message:  When You Travel, Declare Agricultural Items, Don’t Pack a Pest.

    The program was launched at Miami International Airport several years ago. The ongoing outreach program is a cooperative effort between CDFA, the USDA, United States Customs and Border Protection, the Florida Department of Agriculture and Consumer Services, several Caribbean countries, California’s county agricultural commissioners, and San Francisco International Airport.

    “Invasive species have the potential to devastate California’s agricultural industry and its natural resources,” said California Secretary of Agricultural Karen Ross. “Keeping these invasive species outside of our borders is the most effective way to protect our state,  and the Don’t Pack a Pest campaign aims to help us do just that.”

    Key components of the program are a video that currently runs in the 20 busiest U.S. airports, including San Francisco, and signage that has been placed in over 50 major ports of entry in the U.S. and Caribbean.  The “Don’t Pack a Pest” website www.dontpackapest.com assists travelers to determine what agricultural products are allowed or prohibited entry into
    the U.S.

    Although all of the United States is at risk of invasive species introduction, California is particularly vulnerable because of its climate, geography, crop diversity, and high number of international air, marine and land ports.  On average, at least one invasive species is introduced into California every month, including invasive species that are new to California. As the state produces 50 percent of the fruits, nuts and vegetables for the USA, it is imperative to protect against invasive species.

    San Francisco is one of the most popular destination cities for overseas travels with approximately 3,632,000 visitors in 2015.  The number of visitors is expected to increase in the years ahead, which would also increase the possibility that an unsuspecting traveler could bring an invasive plant pest or animal disease into California.

    For more information about the “Don’t Pack a Pest” campaign, please visit www.dontpackapest.com.

  • Managing Vole Populations in Alfalfa with Roger Baldwin

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    Do you have voles present in the field? If so they can cause an average of 11% damage in alfalfa, a percentage that can’t be ignored. But how do you manage these pests. Watch this brief video interview with UC Wildlife specialist Roger Baldwin as he answers the question, and read more in California Dairy Magazine.

  • How Rodent Populations have been Impacted by Early Season Floods

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    With the early season rains and floods, many growers have wondered what kind of impact that might have had on rodent populations on the farm, and want to know how to manage them moving forward. Check out California Ag Network’s video interview with Wildlife Specialist Roger Baldwin from UC Davis to find the answers.

  • Managing Seedcorn Maggot in Tulelake Processing Onions

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    Seedcorn maggot has been a significant problem for processing onion growers in the Tulelake area. Watch this brief video interview with Rob Wilson, UC Farm Advisor & IREC Director, as he shares the latest chemical and cultural practices to minimize this pest in the field. Read more in Vegetables West Magazine.