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/

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

Date: December 15, 2018

Time: 9:00 AM - 12:00 PM

Contact: Jasmin Del Toro: 559-592-2408 ext 1151

Sponsor: Lindcove Research and Extension Center

Location: Lindcove Research and Extension Center

Event Details

The general public is invited to join us for a family friendly Citrus Tasting Event. You can see and taste more than 100 citrus varieties that are grown at Lindcove Research and Extension Center. Take a bag of fruit home for $10. Choose from Cara Caras, Navels, Mandarins, or assorted citrus from 4 bins located in front of the Conference Center. The Master Gardeners as well as UC Cooperative Extension Advisors will be happy to answer questions from home gardeners and citrus connoisseurs.

Directions: Take Highway198 east to Mehrten Drive (approximately 15 miles) and follow the signs to our Event. The University of Lindcove Research and Extension Center is located at 22963 Carson Avenue Exeter, CA. The Conference Center is located at the end of Carson Avenue. If you have any questions please contact Jasmin Del Toro at 559-592-2408 Ext 1151 or jzdeltoro@ucanr.edu

 Lindcove Fruit Display Tasting-home owners 2018

It has been a struggle to get through these hot times and now it's getting cooler, it's even rained, and suddenly that beautiful citrus that has just broken color and is an orange globe splits.  It's most common in navels, but all citrus that ripen in the fall – tight-skinned satsuma mandarins, early clementines, tangelos and blood oranges.  With the hot summer, it seems that a lot of citrus fruit have accelerated their maturity and are ready, ripe and sweet right now, and maybe ready to split.

And that's the problem. Drought stress.  Salt stress due to drought.  Water stress due to miserly watering. A heat wave in July.  And a weird fall with maybe rain and maybe no rain and is ¼ inch considered rain or just a dedusting? Irregular watering is the key to splitting this time of year.  The sugar builds, the pressure to suck in water builds and the fruit has been held back by a constrained water pattern and suddenly some water comes and it goes straight to the fruit and Boom, it splits.

Years of drought, and a stressed tree are a perfect set up for a citrus splitting in fall varieties like navel and satsuma.  The days have turned cooler and there's less sense on the part of the irrigator to give the tree water and suddenly out of nowhere, there is rain.  That wonderful stuff comes down and all seems right with the world, but then you notice that the mandarin fruit are splitting.  Rats? Nope, a dehydrated fruit that has taken on more water than its skin can take in and the fruit splits.  This is called an abiotic disorder or disease.  However, it's not really a disease, but a problem brought on by environmental conditions. Or poor watering practices.  

Fruit that is not yet ripe, like ‘Valencias' and later maturing mandarins are fine because they haven't developed the sugar content and have a firmer skin.  They then develop during the rainy season when soil moisture is more regular.  Or used to be more regular. With dry, warm winters this may become more or a problem in these later varieties, as well.

Several factors contribute to fruit splitting.  Studies indicate that changes in weather, including temperature, relative humidity and wind may exaggerate splitting.  The amount of water in the tree changes due to the weather condition, which causes the fruit to shrink.  Then with rewetting, the fruit swells and bursts.  In the navel orange, it usually occurs at the weakest spot, which is the navel.  In other fruit, like blood orange, it can occur as a side split, as seen in the photo below.

Proper irrigation and other cultural practices can help reduce fruit spitting.  Maintaining adequate but not excessive soil moisture is very important.  A large area of soil around a tree should be watered since roots normally grow somewhat beyond the edge of the canopy.  Wet the soil to a depth of at least 2 feet, then allow it to become somewhat dry in the top few inches before irrigating again.  Applying a layer of coarse organic mulch under the canopy beginning at least a foot from the trunk can help moderate soil moisture and soil temperature variation.

Once split, the fruit is not going to recover.  It's best to get it off the tree so that it doesn't rot and encourage rodents.