- Author: Ben Faber
If you're sticking close to home these days and looking for something to do (or looking for something for kids to do) the Xerces Society has several bee monitoring guides and tools worth checking out.
Developed for conservationists, farmers, land managers, restoration professionals, and community scientists, the Bee Monitoring Protocol and Community Science Guides are useful for documenting how native bee communities change through time in pollinator habitats. The publications include an introduction to bee identification, a detailed monitoring protocol, and data sheets for different habitat types.
- Author: Ben Faber
Efficient and precise irrigation management is critical if California producers are to maximize crop quality, conserve water, and protect the environment. The use of evapotranspiration (ET) estimates is a significant component of irrigation management. ET refers to the sum of water lost from the soil (evaporation) as well as that used by the crop (transpiration). While the California Irrigation Management Information System (CIMIS) network of weather stations derive daily ET values, there is a perception that CIMIS does not produce accurate ET estimates for all locations. This view is particularly prevalent in the canyons of Ventura County where weather conditions differ substantially compared to CIMIS locations. Since avocado and citrus thrive in these areas, it was concerning when it was determined that ET scheduling is not widely used.
That is, a Ventura County Resource Conservation District (RCD) review of California Department of Food and Agricultural State Water Efficiency and Enhancement Program (CDFA SWEEP) projects concluded that Ventura County growers substantially lagged their state-wide peers with respect to implementing ET-based irrigation scheduling (14% versus 44%).
RCD seeks to reverse the low implementation of ET-based irrigation scheduling within Ventura County by using simple, rugged on-site ET devices (atmometers) to determine on-site ET values. These on-site values will be compared to CIMIS values to determine local correction factors and develop refined ET maps for the canyon and valley areas. RCD will present these results at outreach events and provide workshops demonstrating how ET data, whether from CIMIS or on-site atmometers, can be used for irrigation management.
PHOTO: Atmometer Test/Calibration Site @ UC Hansen
- Author: Ben Faber
April, 2020 CAS/CAC/UC
Avocado Grower Meetings
The original field meeting for avocado growers was canceled this year. This was to be an opportunity for growers to get out and see, touch and interact with other growers and people experienced in the various topics that were to be covered. The meetings were to be in real groves at Cal Poly San Luis Obispo, Pine Tree Ranch in Santa Paula and Rancho Aqua Tibia in Pauma Valley. The discussion and viewing topics ranged from 1) Planting Density, 2) Pruning, 3) Root Rot Management, 4) Pest Monitoring, 5) New Scions/Rootstock and 6) the Healthy Soils Program. We had a range of speakers arranged for the different sites to show, demonstrate and spark discussion. The actual sessions were designed so that every topic got covered and everyone got to hear the highlights of the topic in a 15 minute period, before moving on to the next topic. For the Scion/Rootstock session, this would have been just a brief introduction before the more elaborate workshop of that topic which will be held in June. The enclosed outlines and references cover the topics that would have been covered at these field meetings. They are not a substitute for actually being out in the field, but hopefully they will keep you thinking about how to improve your avocado production.
Planting Density: Tim Spann of CAC
Pruning: Gary Bender, Sonia Rios of UCCE and Gabe Felipe of Mission Produce
Root Rot Management: Ben Faber of UCCE
Pest Monitoring: Enrico Ferro, Tom Roberts, Jane Delahoyde, Jim Davis
New Scions/Rootstocks: Mary Lu Arpaia, Patricia Manosalva of UC Riverside
Healthy Soils Program, Alli Fish, Esther Mosase of UCCE; Lance Andersen of Mission RCD; Jamie Whiteford of Ventura RCD; Claire Balint of Cal Poly; Mary Matava of El Corazon Compost
/span>- Author: Ben Faber
Lemons Hit Hard by Covid-19 Losses
Lemon growers are seeing good production this year, but the market for choice lemons has been ruined by COVID-19 food-service industry losses.
“We've seen 20 to 25 percent decrease in fruit movement, and that's mainly attributable to the decline in the food-service industry,” according to Ventura County lemon grower Will Pidduck.
Ironically, it is otherwise a good year for lemons in Ventura County. “We're growing great quality fruit. The quantity is great,” said Pidduck.
However, with the coronavirus pandemic forcing the closure of restaurants, schools, cruise lines and other commercial food-service operations, the market for an entire class and size of lemon has all but vanished.
“That's a big hit,” Pidduck said. As a fourth-generation citrus grower in the Ventura area, Pidduck also grows mandarins, oranges and avocados, but is primarily a lemon grower.
“A large portion of the choice fruit goes to the food-service industry. And without that industry, it's bad. The movement has slowed dramatically on the choice fruit,” Pidduck said. “We're still moving the fancy, the higher quality fruit. But for the choice and some smaller-sized fruit, it definitely slowed way down.”
And what is happening in the global lemon market? from Fresh Plaza
- Author: Ben Faber
An Automated Delivery System for Therapeutic Materials to Treat HLB Infected Citrus
Ozgur Batuman1 and Louise Ferguson2
¹Southwest Florida Research and Education Center, University of Florida, Immokalee, FL; 2UC Davis, Department of Plant Sciences, University of California Davis, Davis CA
Why is this research needed?
In 2005, a disease called Huanglongbing (HLB, citrus greening, was identified in Florida's commercial citrus groves. The disease is caused by a bacterium that affects all citrus cultivars by disrupting the flow of nutrients from the source of production, to the site of use, causing tree decline. HLB weakens the root system, increases early fruit and leaf drop, lowers tree productivity and fruit quality and ultimately kills the tree. The disease has spread to all the major production regions in Florida. Economic losses have exceeded more than $4 billion dollars. Currently, more than 95% of Florida's trees are infected. There is currently no cure for the disease.
Efforts to control HLB have been unsuccessful as the bacterium cannot be cultured, literally grown, in a petri dish, and once in the plant it proliferates within the citrus phloem. Phloem is the system that transports sugars from their site of production, the leaves, to plant parts that use sugars, the roots or flowers.Phloem transport is generally downward but can be upward as well.
Once the HLB bacterium is in a tree's phloem it has the potential to infect the entire tree. It is exceedingly difficult to introduce any control agent into the phloem with the conventional control methods of foliar spraying or soil drenching.
Thus far, no treatment preventing HLB infection, or controlling the bacterium once within the tree, has been developed. Potential chemicals are being investigated, but in order to test them, direct or indirect phloem delivery, where the bacterium proliferates, is needed. Therefore, an effective method of delivering an effective volume of theraputics into the phloem is needed to evaluate potential treatments.
What is the focus of this project?
Our project focuses on developing a method of delivering therapeutic liquid materials, bactericides, microbial metabolites, RNAi, or biologicals, into the citrus vascular tissues, both the xylem which conducts water and nutrients upward from the roots and the phloem, which conducts sugars and other metabolic products downward from the leaves. We are investigating diffusion, trunk punctures with a surrounding liquid reservoir for passive uptake and infusion, low pressure active injections. We are focusing on these methods as foliar sprays and root drenches have not been successful phloem delivery methods.
Who will be doing the research?
The project is led by plant pathologist Dr. Ozgur Batuman with colleagues at the Southwest Florida Research and Education Center (SWFREC) at University of Florida in Immokalee. This four-year project will also study the citrus vascular system with a multidisciplinary research team including UF Plant Pathologists Drs. Nabil Killiny and Amit Levy at Lake Alfred, SWFREC UF Plant Physiologist Ute Albrecht, Citrus Horticulturist Fernando Alferez, Precision Ag. Engineer Yiannis Ampatzidis, Agricultural and Natural Resources Economist Tara Wade, University of California-Davis Extension Specialist Louise Ferguson and Texas A&M-Kingsville Citrus Center Plant Pathologist Veronica Ancona as well as number of graduate students, postdocs, and Florida, Texas and California citrus industry members.
How will this research be done?
Our earlier research involving comparisons of delivery methods including foliar sprays, soil drenching and trunk injection determined Needle-Assisted Trunk Infusion (NATI) was the best potential delivery method (Figure.1). In initial experiments, using NATI, 1 ml of rhodamine (1%) dye was injected into the trunks of one-year-old citrus seedlings. A visible red color, indicative of rhodamine uptake and movement, was detected in the upper-most leaves within 30-60 min and an increase in color intensity was observed within 24 hours. Similar results were observed in two-year-old grafted Valencia plants within 48 hours. If the NATI delivery method can be automated, large numbers of trees could be treated quickly. Once the delivery method has been developed, implementation will be tested with potential treatments developed within other research projects.
Our proposed automated delivery would consist of a robotic arm with several modules at the end of the arm, installed on an ATV or tractor. One module with needles would grip and puncture the trunk, a second module would wrap a reservoir around the trunk below the punctures and third module would fill the reservoir. (Figure 2). Hopefully, a robotic arm plus automated system will be inexpensive enough for growers to purchase and simple enough to use.
Another approach is disease prevention; application pf prophylactic chemicals that prevent infection. In this scenario our system would be used treat healthy young trees with bactericides or boost their immune system. When infected by the ACP the bacterium would either be killed or suppressed, perhaps below the level that harms tree growth and productivity. This option is analogous to the vaccinations that prevent diseases in humans and animals.
What are the greatest challenges and opportunities.
The greatest challenge is successful phloem delivery. The greatest opportunity is that, if successful, we will have developed a method that will allow much more precise deliver of theraputics to citrus trees. For example, if an effective phloem delivery method is developed, it could be used to control insects that feed on citrus plant parts. Or, it could be used to deliver growth regulators, perhaps nutrients and carbohydrates, to roots and fruits to increase growth, development and fruit quality; much like an intravenous injection functions in an animal.
Among the questions we hope to investigate are:
- When, what kind of, and what amount of therapeutics can be applied by NATI?
- At what frequency?
- What type of citrus tree: cultivar, age, infected, healthy is the best for treatment by NATI?
- Can we kill the bacterium? How and when to assess a change in bacteria titer after treatment?
- When will become available and be economically feasible for growers?
Figure 1. Distribution of rhodamine (red dye; 1%) applied by NATI in various tissues (left) of grafted and non-grafted young citrus plants grown in the greenhouse (right). Photos taken 2 weeks after the treatments. Treatments and tissues observed are indicated. Yo = year-old.
Figure 2. Projected automated delivery system (ADS); an ATV with extendable arm with NATI and the cover placement systems on the arm guided onto the tree trunk (upper panel), and closeup of NATI and cover placement system (panel below).
Acknowledgement
The United States Department of Agriculture National Institute of Food and Agriculture (USDA-NIFA) Grant # 2019-70016-29096.
For more information, please visit this project's dedicated website:
https://swfrec.ifas.ufl.edu/programs/citrus-path/automated-delivery/