- Author: Ben Faber
WESTMINSTER, Colorado - November 23, 2018 - Herbicides have been instrumental in managing Italian ryegrass, a weed that frequently competes with perennial crops in California. Herbicide-resistant populations have become increasingly commonplace, though, including paraquat-resistant Italian ryegrass found recently in a California prune orchard.
A team of scientists set out to determine if the paraquat-resistant population might also be resistant to other postemergence herbicides. Seven other herbicides commonly used in fruit tree and nut tree crops were included in the study, including clethodim, fluazifop-P-butyl, glufosinate, glyphosate, pyroxsulam, rimsulfuron and sethoxydim.
Researchers found the paraquat-resistant population was also resistant to both clethodim and glyphosate. Among the remaining herbicides, glufosinate, rimsulfuron and sethoxydim were found to deliver the best postemergence control. Unfortunately, though, other populations of Italian ryegrass have developed resistance to the three herbicides, indicating their effectiveness may be short-lived.
"Overreliance on postemergence herbicides from a variety of chemical classes can result in weed populations that exhibit multiple resistances," says Caio Augusto Brunharo, a postdoctoral research fellow at the University of California, Davis. "Effective herbicide-resistance management programs are necessary for sustainable weed control."
The researchers recommended a number of preemergence herbicides as control options for Italian ryegrass in fruit and nut tree crops, including tank mixes containing indaziflam and flumioxazin.
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Full text of the article, "Multiple Herbicide-Resistant Italian Ryegrass (Lolium multiflorum) in California Perennial Crops: Characterization, Mechanism of Resistance and Chemical Management" is now available in Weed Science Volume 66, Issue 6.
About Weed Science
Weed Science is a journal of the Weed Science Society of America, a nonprofit scientific society focused on weeds and their impact on the environment. The publication presents peer-reviewed original research related to all aspects of weed science, including the biology, ecology, physiology, management and control of weeds. To learn more, visit http://www.
- Author: Ben Faber
UC Ag Expert talks about
Fuller rose
beetle (weevil)
Date: January 23, 2019
Time: 3:00 PM - 4:00 PM
Contact: Petr Kosina pkosina@ucanr.edu
Sponsor: UC Ag Experts Talk
Location: Webinar
Event Details
Register in advance for webinar at:
https://ucanr.zoom.us/webinar/register/WN_RIYGPBgkTo6o_hPooWlfmg
Participants of this webinar will receive 1 hour of 'Other' CE units
Note: This webinar has no fee.
Dr. Beth Grafton-Cardwell, citrus IPM specialist and research entomologist, will discuss the lifecycle, damage to citrus, monitoring, methods of control and export issues associated with Fuller rose beetle. Participants can use the chat function of the webinar to ask questions.
http://ipm.ucanr.edu/PMG/r107300311.html
http://entnemdept.ufl.edu/creatures/orn/beetles/fuller_rose_beetle.htm
Event Reminder
- Author: Ben Faber
Ground squirrels eat a variety of fresh greens as well as seeds and dried nuts. In spring, ground squirrels prefer greens over seeds and nuts. Once the natural grasses begin to dry and wither, squirrels will actively forage for seeds.
As foragers, squirrels are well-adapted to find sparsely dispersed food, one seed at a time. Once squirrels have had their fill, they will
collect food in their cheek pouches and take it back to the nest to form a cache for later use. Squirrels tend to forage close to their burrow, although they will travel for desirable foods.
How Biology relates to control:
The California ground squirrel prefers to forage for food in the early morning or late afternoon/early evening to avoid the day's heat. In some crop situations, especially nut crops, squirrels may prefer the crop to the point where they will not eat any bait. If the squirrel won't eat the bait, the poison bait method will not work. In this case, an alternative control approach may be necessary (trapping or fumigation).
Understanding these feeding preferences is extremely important when using baits since they are seed based. Also, in irrigated crops or landscape areas, squirrel feeding preferences are influenced by what food is available. For example, the natural vegetation may be dry in early summer and squirrels are actively foraging for seed. If newly sprouted crops are available however, the squirrels may take them with great delight.
The calendar of ground squirrel diet, activity and control measures is adapted from the Best Management Practices for Ground Squirrel Control website http://ipm.ucanr.edu/PMG/PESTNOTES/pn7438.html. Calendar dates are merely an estimation of time; actual time frames may vary according to the weather and location.
Ground squirrels - Spenrophilus sp. of which there are 17 species may cause damage to avocado orchards by eating fruit, branches, and making burrows near or under trees which expose roots and redirect irrigation water. The most common ground squirrel is the California or Beechey ground squirrel Spermophilus beecheyi.
*An adult will weigh from 1 to 2 ½ pounds and is tan in color with flecked or mottled fur.
*Females produce one litter each year, averaging six to eight offspring.
*They are active in the daytime.
*Their diet may consist of green herbage in winter and spring and seeds during the summer and fall.
*They hibernate during cold winters, but are active year-round in avocado growing areas
*Ground squirrels are not repelled by any chemical or physical means. Thus, control through the use of toxic fumigants, poison baits, traps, or shooting is the only effective control measures available
*They are also preyed on by eagles, raccoons, foxes, badgers, weasels, rattlesnakes and clever dogs
more on those cute animals:
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7438.html
- Author: Cameron Zuber
While conducting surveys across Merced County, I have noticed diverse ways growers secure the ends of irrigation tubing. Many are attached using some type of stake made of wood or PVC in which the tubing is tied. Other orchards have the lines wrapped around a tree and used as an anchor for the line. Finally, some of them are staked directly into the ground.
Irrigation tubing moves because of expansion and contraction of the plastic caused by temperature changes, as well as, from the water and air moving through the irrigation system. Securing the tubing creates tension that helps prevent the tubing from moving. These keeps the emitters and microsprinkers in place which helps maintain good irrigation efficiency.
There are a few problems with securing the tubes. The first is the added cost and time to first secure the tubing and then maintain how the tubing was secured. Secondly, the lines may contract after fixing, which can pull them off the riser. Finally, the lines, if wrapped too tight, can cut into and girdle the tree. All of these are preventable.
If you do choose to secure the end of your irrigation tubing, below are some considerations to take into account:
- Leave some slack in the tubing: Due to changes in temperature, plastic tubing expands and contracts. When tightly secured tubing contracts, coupling points may become undone (e.g., at the riser) or may cause the plastic in the tubing to stretch, creating weak points that may eventually break.
- Be wary of using trees to secure tubing: While this may cut down on supply costs, make sure it does not begin to girdle the tree.
- Do it right: Since you are taking the time (and money) to secure your tubing, be sure to do it right. There is a lot of power in the contraction and expansion of irrigation tubing, and a poorly installed system will eventually fail.
- Secure irrigation tubing in the winter: Securing tubing on colder days prevents problems related to contraction. Cold tubing that does not have enough slack will just expand and create the slack that was needed. Hot tubing that does not have enough slack will contract and cause problems, as described above
- .
Whether or not you decide to secure your irrigation tubing is up to you. Ultimately, the end goal is a well-irrigated field. Securing irrigation tubing, if done right, is just one thing to help accomplish that goal.
From the Almond Doctor: https://ucanr.edu/sites/sayalmond/The_Almond_Doctor/
- Author: Ben Faber
The best way to delay arrival of HLB in our area and minimize its impact is to keep ACP suppressed down to the lowest level possible. By treating in coordination with neighbors in an areawide approach, grower ACP treatments can have a greater impact on ACP populations than treating independently and out of sync with neighbors. Best Management Practices, such as making sure all equipment arriving and leaving your grove is free of citrus stems and leaves, can also greatly reduce the risk of HLB-positive psyllids entering your grove.
CITRUS REMOVAL PROGRAM: Citrus trees that are neglected or abandoned may harbor ACP and HLB, increasing risk to other citrus in the area. Abandoned and neglected trees may be reported to Cressida Silvers at 805-284-3310, or the county Ag Commissioner's office. The Citrus Matters ACT NOW program may be able to assist in citrus removal. For more information contact Joel Reyes at jreyes@cacitrusmutual.com or (559) 592-3790.
Asian Citrus Psyllid / ACP
There have been no ACP detections in San Luis Obispo County since our last update.
Huanglongbing / HLB
The most recent map and totals for HLB detections are posted at the website https://citrusinsider.org/maps/. As of November 16, the total number of trees that have tested positive for the HLB bacterium is 948, still all in LA, Orange, and Riverside Counties. All HLB detections have been on residential properties and the infected trees have been or are being removed. No HLB has been found in commercial groves to date.
Clarification on Field Cleaning Requirements for Movement of Bulk Citrus
To clarify the approved mitigation measures for bulk citrus fruit movement, the California Department of Food and Agriculture (CDFA) has updated the Asian Citrus Psyllid (ACP)-Free Declaration form. The current options that allow growers to meet the ACP-free standard when shipping fruit to a different ACP regional quarantine zone are the “spray and harvest,” “field cleaning with machine” and “wet wash” methods. Field cleaning must be done by machine, not by hand.
To read the full article, click here: https://citrusinsider.org/2018/11/clarification-on-field-cleaning-requirements-for-movement-of-bulk-citrus/
Upcoming CPDPC Meetings
- Joint Science and Technology Subcommittee and Regulatory Task Force meeting Thur., December 6 at 1:30 pm in Sacramento. Agenda attached, including link to join by webinar/phone.
- CPDPC Operations Subcommittee meets Wed., December 12 at 9 am in Visalia. Agenda attached with link to join by webinar/phone.
- The next meeting of the CPDPC Full Committee will be January 9 in Visalia. Agenda is pending.
- All meeting agendas and eventually the minutes are posted at https://www.cdfa.ca.gov/citruscommittee/ . All meetings are free and open to the public, and accessible via webinar.
Additional Resources
- General information on the ACP/HLB program, including quarantine information: https://citrusinsider.org/
- Biology of ACP and HLB, detection maps and recommendations for monitoring, eradication and management : http://ucanr.edu/sites/acp/
- Summaries of the latest research to combat HLB: http://ucanr.edu/sites/scienceforcitrushealth/
And Now it's in Marin County
SACRAMENTO — Marin County has been placed under quarantine for the Asian citrus psyllid (ACP) following the detection of one ACP in the City of Novato. The entire county is included in the quarantine zone.
The ACP is an invasive species of concern because it can carry the disease huanglongbing (HLB), also known as citrus greening. All citrus and closely related species, such as curry leaf trees, are susceptible hosts for both the insect and disease. There is no cure once the tree becomes infected. A diseased tree will decline in health and produce bitter, misshaped fruit until it dies. In California, HLB has been detected at residential properties in Los Angeles, Orange and Riverside counties. This plant disease does not affect human health.
Residents with backyard citrus trees in the quarantine area are asked not to transport or send citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area. For commercial citrus, the quarantine prohibits the movement of citrus and curry leaf tree nursery stock, including all plant parts except fruit, out of the quarantine area. The quarantine also requires that all commercial citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area. An exception may be made for nursery stock and budwood grown in USDA-approved structures that are designed to keep ACP and other insects out.
ACP quarantines are in place in Alameda, Contra Costa, Fresno, Kern, Kings, Madera, Merced, Monterey, Placer, San Benito, San Joaquin, San Luis Obispo, San Mateo, Santa Clara, Solano, Stanislaus, Tulare, Yolo, Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, and Ventura counties, as well as Marin.
Residents in the area who think they may have seen ACP or symptoms of HLB on their trees are urged to call CDFA's Pest Hotline at 1-800-491-1899 or a local agricultural commissioner's office For more information on the ACP and HLB, please visit: www.cdfa.ca.gov/go/acp. Residents are also asked to follow these steps:
- Inspect trees for the Asian citrus psyllid and Huanglongbing monthly, and whenever watering, spraying, pruning or tending trees. Psyllids are most noticeable when new leaves are growing on the tips of the branches.
- As part of your tree care, visit your local nursery or garden center to get advice on products that can help protect your citrus tree.
- Do not move citrus plants, foliage or fruit into or out of your area, and especially across state or international borders. This could unknowingly contribute to spread of the pest and disease.
- When planting a new citrus tree, be sure to get your tree from a reputable, licensed nursery in your local area.
- When grafting citrus trees, only use registered budwood that comes with source documentation, such as the budwood offered through the Citrus Clonal Protection Program.
- Be sure to dry out citrus tree clippings or double bag them before removing the plant material from the property.
–California Department of Food and Agriculture