Laurel Wilt-Ambrosia Beetle Grower's and Advisory Panel meeting to update and discuss research and extension programs supported by the USDA research grant.
Purpose: The Univ. of Florida/IFAS created a panel consisting of local commercial avocado growers and handlers and scientists for the USDA grant on laurel wilt and ambrosia beetles. The purpose of the meeting is for researchers to update avocado growers and the advisory panel on the progress of research on this grant and to discuss future research and extension plans. This meeting is open to anyone to attend.
Date: July 23, 2020
Location: ZOOM, recording available HERE
Dr. Crane, welcome and introduction
Brief updates, plans and discussion:
1. Dr. Schaffer, Environmental Plant Physiology – Laurel wilt susceptibility of avocado scions and rootstocks in relation to physiology and stem anatomy
2. Dr. Gazis, Plant Pathology – Laurel Wilt - Plant Pathology: Research Accomplishments, Current Work, and Future Direction
3. Dr. Carrillo, Entomology – Update laurel wilt ambrosia beetle research
4. Dr. Evans and Mr. Ballen, Ag Economics - current work and work in progress and plans
5. Dr. Crane and Mr. Wasielewski – Current extension program and plans
Bright metallic colors, flitting from flower to flower. Wasps. And they are going after other wasp species and bees. It's hard being a bee.
These wasps are parasites, and like their namesake cuckoo birds, they lay their eggs in the nests of other species (wasps or bees in this case). Since the cuckoo wasps depend on trickery and camouflage to fool their hosts, you might expect them to be drab. Scientists have not figured out whether the bright colors serve any function, and it wasn't known until 2009 that the color is actually produced by light refracting through open spaces between six layers of cuticle in the wasps' exoskeletons.
Cuckoo wasps favor warm Mediterranean climates, and California is a center of cuckoo wasp biodiversity in North America – 166 species in CA and 230 in the US. Maybe because there are so many native bee species in California is the reason there are so many cuckoo wasp species. They are most active in dry, open areas between May and August, with adults foraging on flower nectar as they follow favored routes multiple times a day searching for solitary wasps and bees to parasitize.
Cuckoo wasps are classified in the family Chrysididae, in the order Hymenoptera, and they are sometimes called Gold Wasps, Emerald Wasps or Jewel Wasps. The family name comes from the Greek, chryso, meaning gold. Besides green, they come in red, blue and purple and the thick cuticle of their exoskeleton (they are described as “heavily armored”) is often “pitted.” The common name refers to their habit of depositing their eggs in other insects' nests; a strategy practiced by birds like the Old World Cuckoos and the New World Cowbirds. Some sweat bees look similar, but cuckoo wasps tend to be “chunkier.”
Cuckoo wasps, like the majority of bees and wasps, are solitary. In highly social species like honeybees and paper wasps, there is a caste system. Since the queen is the only female that lays eggs, she is the only one outfitted with an ovipositor. And, since part of their job is defense, the workers' vestigial ovipositors have been modified into stingers. Solitary wasps need ovipositors, and many (but not all) sources say that cuckoo wasps have lost the ability to sting.
Read and see more about cuckoo wasps: The Cuckoo Wasp: A gorgeous parasite by David Lukas
And Lynn Kimsey's blog: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26461
2020 Climate Action and Agriculture Symposium
Information and documents related to the 2020 Climate Action and Agriculture Symposium Webinar featuring information on current climate trends and agricultural impacts, soil health and updates about related projects in San Diego and neighboring counties.
Featured Organizations and Programs:
- San Diego County Farm Bureau
- Spadra Farm, California State Polytechnic University, Pomona
- CDFA-Healthy Soils Program
- Composting Resources, County of San Diego
- Resilient Roots: Climate Smart Agriculture & Food Systems,
Climate Science Alliance
- Carbon Farming, Resource Conservation District of Greater San Diego County
- Solidarity Farm
- San Diego County Food Vision 2030, San Diego Food Systems Alliance
Technical Reports and Resources:
Compost and Mulch Market Study, County of San Diego (PDF Download,2.1 MB)
by the County of San Diego and Hidden Resources
Mulch Resources from Ben Faber, Ph.D., UCCE Farm Advisor (PDF Download,994 KB)
Questions and comments always come up about the use of mulch in orchards. Mulch has its benefits and drawbacks and they need to recognized in order to manage it. It serves to combat erosion and root rot, but it can also burn. Mulch and wood piled up against tree trunks and near trunks can cause damage to those trunks. A Fillmore grower actually goes through the orchard with a blower to move mulch away from trunks when alerted to fire. On the other hand, irrigated orchards have been shown to be effective at suppressing fire encroaching on homes. And mulches can suppress weeds and reduce water use, but it's possible that importing material for mulch can introduce weeds.
So where to read more about fire? Check out some of the blogs from the past.
Mulch and green waste applied to orchards
- Green Waste, Yard Waste, Whatever You Call It- It has Simple Rules for Use
- A Safer Source of Inexpensive Orchard Mulch
- Avocado planting holes
- Cellulase Production by Various Sources of Mulch
- A Caution on Free "Compost/Mulch"
- A Safer Source of Inexpensive Orchard Mulch
- Mulch, Avocados and the Home Garden
- Mature Compost Does NOT Kill Phytophthora
- Use of Mulch in Organic Orchards Called into Question
Mulch and Landscapes
From the Citrus Industry
The new Sugar Belle hybrid rootstock LB8-9xS13#16 has quite a history, according to University of Florida Institute of Food and Agricultural Sciences citrus breeder Jude Grosser.
“This is one of several projects I did with Orie Lee toward the end of his Florida Citrus Hall of Fame career/life,” recalls Grosser. “We did a lot of brainstorming together, and he was full of ideas and the energy to make them become a reality!”
Before HLB became the dominant scourge of Florida citrus, Grosser was heavily invested in trying to solve blight. Lee had a great interest in blight, because in several of his most productive blocks the annual tree loss to blight was about 12 percent.
“Evidence was showing that pummelo x mandarin hybrids had superior blight tolerance as compared to other rootstock categories, so I made a lot of pummelo x mandarin hybrids,” says Grosser. “Orie was in a hurry to plant rootstock hybrids to test for blight tolerance, and he had just planted a large block at the Alligator Grove. He suggested we plant trees in between each of the planted trees. We made cuttings from about 125 new rootstock hybrids and we tried to get at least seven liners for each rootstock. We grafted them all with Valencia and planted them one year after the original grove was planted — about 12 years ago.”
According to Grosser, the Alligator Grove has never had psyllid control, and about four years after planting, it was evident that nearly all the trees were infected with HLB. “For the past six years, I have been scoring the individual trees for HLB. There were only two of the trees on the S13 parent (salt tolerant HB pummelo x Cleo). During the 2020 scoring, this hybrid had the highest tree health rating (4.25 out of 5), indicating very good ability to transmit HLB tolerance from the rootstock to the Valencia scion,” he explains.
Grosser says it has become evident from multiple trials that Sugar Belle has exceptional HLB tolerance no matter what rootstock it is grown on. “I thought that maybe we could flip this equation and develop a rootstock that any scion could grow on in the presence of HLB,” he says. “Sugar Belle is not used as a rootstock because it does not come back true-to-type from seed and is purported to be susceptible to phytophthora.”
So, Grosser decided to use Sugar Belle as a rootstock breeding parent to test his hypothesis. He made the first crosses with Sugar Belle in 2015, using a salt-tolerant HB pummelo x Cleo hybrid (S13) and a salt-tolerant HB pummelo x Shekwasha (S10) as the pollen parents.
Since then, Grosser has made other crosses using Sugar Belle. As the rootstocks progressed through the screening process, he says one hybrid jumped ahead of the others. So, he planted two trees at the Citrus Research and Education Center (CREC).
“I planted the hybrid #16 tree on the corner of Block 8, just behind our barn, so I could watch it every time I drove up the road to my greenhouses or field plots. I noticed that psyllids were feeding on the tree during every new flush (despite the CREC spray program), and there was visible psyllid damage on leaves from all flushes,” says Grosser. “Despite starting infected and continuous psyllid re-inoculation, this tree has grown off like a normal pre-HLB tree and looks beautiful today, two years after planting. It has set some fruit, so I will begin to get an idea of fruit quality this coming fall.”
Grosser says the second tree, on a different hybrid, is doing okay, but nothing like #16.
“After what I saw the first year, I grafted an infected Murcott (the most HLB-susceptible variety) onto the rootstock and planted it, and it is also growing incredibly well,” he says. “The Murcott tree is now one year old. We tested the original Valencia tree by PCR in December, and the scion had a ct value of 24, indicating a high titer of CLas (the causal agent of HLB); whereas the roots had a ct value of 32, indicating no active infection. We tested this tree again in April, and the ct value went up to 36, indicating no active infection. So, even starting out infected and under heavy psyllid pressure, the rootstock seems to have suppressed the infection, allowing the tree to thrive.”
Although it has only been two years from planting, Grosser is hopeful that the “HLB tolerance, maybe resistance, holds up over time (like it seems to be doing with its parents). I have pathogen-free material of this rootstock, and we are now making cuttings as needed for large-scale evaluations. We have also started this rootstock in tissue culture for micropropagation.”
The University of Florida Institute of Food and Agricultural Sciences and Southeast AgNet are partnering to provide the latest news on citrus-related research in a monthly podcast.
The podcast, “All in for Citrus,” features short interviews with scientists working to find solutions to citrus greening and other devastating citrus diseases.
“This is the latest tactic in a comprehensive communications effort launched this past summer by the UF/IFAS Citrus Team,” said Michael Rogers, statewide citrus research coordinator and director of the UF/IFAS Citrus Research and Education Center in Lake Alfred, Florida.
The podcast complements the new website, citrusresearch.ifas.ufl.edu, and a new monthly newsletter, both launched at the August Citrus Expo held in Fort Myers, Florida.
“We are working hard to get the latest research findings directly to growers in a timelier manner,” said Rogers. “We are also streamlining the research results to focus on what growers could use immediately in their groves or what might be a longer-term strategy.”
LISTEN IN: http://citrusindustry.net/allinforcitrus/
The latest podcast is on protection practices to reduce infection of young trees.
Five UF/IFAS scientists are comparing several insect-management tools. This includes evaluation of individual protective covers (IPCs), which are essentially bag-like covers placed over newly planted trees to keep pests away.
In addition, researchers are also studying reflective mulch, kaolin clay and chemical-based insect pest management. Kaolin clay is a powdery white compound that is sprayed over the trees. Kaolin provides trees with a rough surface, making it harder for HLB-spreading psyllids to grasp. The clay may reduce the transmission of HLB and provide some shade to the plant, allowing better growth.
Through this U.S. Department of Agriculture funded project, the research team hopes to develop new recommendations and provide a comprehensive overview of existing tools that growers can use to combat HLB.
The research project has secured two years of funding. Diepenbrock hopes to receive additional funding in order to study the impacts of these tools on harvest.
This interview with Diepenbrock is part of the June All In For Citrus podcast, a joint venture of UF/IFAS and AgNet Media. Listen to the full podcast.