Posts Tagged: diagnosis
What's Wrong with My Citrus?????????????
Hats Off.
The Orange County Master Gardeners have lived up to their name with their website information on citrus. It's a truly impressive information site for not only homeowners, but also growers:
http://mgorange.ucanr.edu/Edible_Plants/?uid=108&ds=530
The “Citrus Problem Diagnosis Chart” is especially work perusing:
http://ucce.ucdavis.edu/files/datastore/530-15.pdf
Orange County logo
citrus and mountains
Broken Trunk, Dead and Decaying Roots, but Green Canopy? What's the Problem?
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?
He: NO
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/
avocado root rot 4
Disorders and Defects in Head Lettuce
The rainy and cold spring weather in 2010 is apparently having an effect on head lettuce quality in Salinas Valley fields. Symptoms appear as very small, brown flecks and spots along the margins of young leaves (photo 1). Affected leaves are usually found deep within the head. It appears that these defects are occurring in multiple iceberg cultivars in various parts of the valley. Clearly this is a physiological disorder and superficially looks similar to russet spot; however, most of the flecks do not occur on the leaf midribs (photo 2) as would be typical for russet spot. Russet spot is caused by ethylene production and can occur in mature to over mature lettuce, especially following anaerobic conditions in the field. However, in this instance, the location of the flecking along the margin of the leaf more closely indicates tipburn.
The extensive nature of the problem (from Salinas to San Ardo) and the occurrence across varieties indicates that a large-scale factor like weather could be the cause. The heavy rain on April 5 followed by cloudy, cool weather may account for the currently wide distribution of the problem. We are conducting further investigations to more closely determine the cause of this problem.
These defects are not caused by any plant pathogen. Extensive testing has shown that bacterial leaf spot, anthracnose, or other lettuce disease is not associated with these brown flecks. Bacterial leaf spot (caused by Xanthomonas campestris pv. vitians), however, is common this year and should not be confused with this physiological disorder. Bacterial leaf spot occurs on the outer leaves and results in large, black, angular lesions (photo 3).
Photo 1: Lettuce defects in 2010 |
![photo 1 photo 1](http://ucanr.org/blogs/SalinasValleyAgriculture/blogfiles/3569.jpg)
Photo 2: Typical russet spotting of lettuce |
![Photo 2 Photo 2](http://ucanr.org/blogs/SalinasValleyAgriculture/blogfiles/3564.jpg)
Photo 3: Bacterial leaf spot of lettuce |
![Photo 3 Photo 3](http://ucanr.org/blogs/SalinasValleyAgriculture/blogfiles/3570.jpg)