- Author: CA Dept Food
Two additional trees in San Gabriel have tested positive for Huanglongbing. The two trees, an orange and a kumquat, are on separate properties but are both within the core area in San Gabriel where 10 diseased trees were confirmed last summer. Given the close proximity, there will not be a quarantine expansion.
One of the HLB-positive trees has already been removed and California Department of Food and Agriculture officials are in the process of contacting the other homeowner to schedule tree removal. Agriculture officials are working quickly in the area.
Citrus trees in San Gabriel had already been treated for the Asian citrus psyllid within the last few weeks as part of CDFA's routine HLB response. Asian citrus psyllid populations are closely monitored in areas where HLB has been detected and treatments occur if there is a noted increase in population size. Since trees have been recently protected, no additional treatments will take place at this time. Instead, CDFA will focus on sampling extensively in the area. Much of the area has already been sampled and CDFA's lab has identified all samples from San Gabriel as high priority.
The Citrus Pest & Disease Prevention Program is working with the Los Angeles County Agricultural Commissioner's office and CDFA to develop a multi-lingual informational flier to notify residents of the significance of these finds and potential implications to other citrus trees in the area. CDFA staff will distribute this information as they go door-to-door sampling and surveying.
More information will be shared as it is available. In the meantime, the citrus industry is encouraged to keep a critical eye on all plant material moving into or out of your groves. Remove all leaves and stems, shake out picking bags, inspect harvesting equipment and educate fieldworkers. Additionally, get on board with area-wide treatments. Collectively, as a team, we can all save our citrus trees.
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 your local agricultural commissioner's office.
These official UC-approved guidelines for pest monitoring techniques, pesticide use, and nonpesticide alternatives for agricultural crops are essential tools for anyone making pest management decisions in the field. This 124-page guideline covers citrus fruit.
A hard copy version of these guidelines can be purchased as Publication 3441P.
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You come on a leaf with the margins munched on. It's got to be a beetle or a looper or some insect doing the damage, right? Not necessarily. It's not time to drag out the Raid. Look at the damage closely. In the photos below you can see the dead leaf margins caused by either salt damage or more likely leaf blight. Leaf blight is a disease that shows up with water stress and is caused by a fungus, one of the Botryoshpaerias. It causes an uneven marginal necrosis that goes along the margin in a somewhat irregular pattern and often not at the leaf tip. In this case it does affect the leaf tip, and since salt burn and leaf blight are caused by the same conditions of water stress, it's probably a bit of both.
Lepidopteran larvae will more commonly feed in a smooth pattern, not the rough pattern seen here. Now with this dead tissue, the wind blows it out, and what's left is the uneven margin. No it's not time to spray an insecticide. It's time to reflect on irrigation. There's a lot of this damage out there now. On avocados, citrus, landscape plants. It's going away until the leaves drop and are replaced with new ones, that will hopefully be well hydrated by rain and proper irrigation.
Top photo is salt/leaf blight damage
Bottom is necrotic tissue that the wind has blown out
It ain't over yet, and this last week we had a wonderful 2 day meeting with folks who have dealt with drought in many different ways. Here are presentations made by people from Israel, Australia and California. Soon the actual videos will be available, but now see the powerpoints.
The grower panels are wonderful, but are not uploaded at this point
DAY I: UNDERSTANDING IRRIGATION WATER MANAGEMENT
Session I: California Response to Drought
9:15am // Overview of California Drought Response
Session II: Technology of Water Management
9:45am // Soil Water Sensing
11:00am // Salinity Measurement
12:00pm // Precision Water and Fertility Management During Deficit Irrigation
Session III: Alternative Water Supplies
2:00pm // Effects of Irrigation With Poor Quality Water on the Soil - California Experience
3:00pm // The Challenge of Sustainable Irrigation with Water High in Salts: Lessons from Dates, Olives and Grapevines
Session IV: Water Management Strategies During Drought
Day II: WATER MANAGEMENT FOR INDIVIDUAL CROPS & GROWER EXPERIENCES
Session V: Technology Demonstrations
8:30am // Using the Pressure Chamber for Drought Mangagement Decisions
9:00am // Irrigation System Evaluation
9:30am // Salinity Mapping for Water Management
Session VI: Conncurrent Breakout Groups
10:30am // Citrus - Israeli Experience: Long Term Effects of Deficit Irrigation, Salinity, and Rootstocks on Orchard Productivity
10:30// Almond Irrigation, the Israeli Experience
11:15am // Grapes - Wine Grapes Irrigation - Coastal Vineyards
11:15am // Deciduous Nut Crops - Almond Irrigation - Israeli Experience
1:00pm // Avocado - Israeli Experience
1:00pm // Grapes - Wine Grapes Irrigation: San Joaqin Valley
1:45 // Subtropical Crops - California Experience
2:00pm // Deciduous Nut Crops - Walnut Irrigation
2:30pm // Grower Panels
3:15pm // Concluding Remarks
I get a call.
He: My trees not doing well.
Me: What's the problem?
He: It's yellow?
Me: Have you looked at the roots? Are there roots?
Me: I'll be out next week, but in the meantime, look at the root system.
This is a pretty common exchange and when I got out, you find out that the emitter is clogged, the ground is soggy, there's weed whack damage, there's gopher damage, there's…………………. All kinds of things that pop up and until you see the context that the poor tree is in, it's hard to diagnose the problem. Too much fertilizer, black drip tubing that had water heated in the sun and burned the roots, the trunk buried in mulch, it's hard to imagine all the possibilities. But start with the roots and then go where that leads you.
So, here's the scenario.
You get a call/email.
He: What's wrong with my young tree? It snapped off in the wind. Here's a picture of what's left. Corroded, bulbous graft union. Incompatibility? Extensive decay that indicates a problem of long standing. The leaves are green though, so it means it was hanging in there until the wind blew. Was the trunk buried at planting leading to asphyxiation and crown rot? Is it some sort of wound that started it off? Oh, and about 1% of the planting is like that.
Me: OK, I better take a look at it. I'll get some samples and send them into Akif Eskalen at UC Riverside and bring our plant pathologist Jim Downer out to look at it with me.
So tune in to find out what we diagnose as the problem. In the meantime, if you have an unknown avocado or citrus problem that looks of root origin. You can contact Akif and send him a sample after following the “Sample Submission Form” at: http://eskalenlab.ucr.edu/