Learn about vertebrates in the orchard.
And all those other animals
that are attracted to avocado orchards
The California Avocado Society,
California Avocado Commission
and University of California Cooperative
Extension have their bimonthly meeting:
June Seminar Topic
(2 hours of DPR CE Approved)
Speakers: Niamh Quinn: Human-Wildlife Interactions Advisor
Tuesday, June 11, 2019, 1:00 p.m. to 3:00 p.m.
UC Cooperative Extension Office Auditorium, 2156 Sierra Way, San Luis Obispo, CA 93401
Wednesday, June 12, 2019, 9:00 a.m. to 11:00 p.m.
UC Cooperative Extension Office Auditorium, 669 County Square Dr., Ventura, CA 93003
Thursday, June 13, 2019, 12:30 p.m. to 2:30 p.m.
Fallbrook Public Utility District Board Rm., 990 East Mission Rd., Fallbrook, CA 92028
No registration is required.
We are creatures of habit and when we see the effects of a treatment, we can often persist in seeing the same or similar symptoms and assuming the cause is the same. In a recent case, a newly planted ‘Pixie' orchard, planted in August had gone into an old ‘Valencia' ground. The trees went through an adjustment period, but still didn't look sprightly in the fall. The grower applied a hand application of urea on the rootball that within 10 days had caused the trees to go into a salt swoon. Meaning, they got too much fertilizer that burned them. The grower seeing the effect, immediately started the sprinklers, but the damage was done. Several months later the trees had either died or were still lingering, but hanging in there. The trees were still coming out of winter, but the trees hadn't perked up. It was a dry winter and some of the yellowing was due to underirrigation, that overall yellowing from lack of nitrogen and the leaves were curled. But the assumption was still that the trees were recovering from the salt burn from the urea.
Looking more closely at the trees, something else was odd about some of the trees that were continuing to die. The leaves suddenly wilted. Getting down on hands and knees and digging around the roots, there were few roots and ………………………….a tunnel. A gopher had been at this tree and the lack of roots were probably due to Phytophthora root rot. Looking around there were some old ‘Valencias' that had been hit by gophers and there were gophers mounds and runs all over the place.
So, young trees planted in the heat of the summer into root rot ground with gophers waiting in anticipation that had been salt burned in a year with little rainfall. A lot of causes for trees that generally weren't happy – triste, as they say in French.
So what are the lessons here? Avoid old citrus ground when planting with citrus, and if you can't make sure, don't plant in a stressful period. Phytophthora loves stressed trees and adding lack of rainfall an gophers and salt, just heightens the stress. Make sure to get the irrigation right. Don't irrigate them to the schedule of the older trees and start them off on one of the phosphite materials.
Wilted, yellow leaves from lack of water and Phytophthora
Gopher chewing on stem
Gopher run and lack of roots from Phytopthora and gopher
Gopher mounds in planting area
Older Valencias dead and dying from Phytophthora and gophers
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/