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Topics - matt_citrus

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Citrus General Discussion / Winter, indoor citrus, mites, and UV
« on: March 03, 2024, 10:12:07 PM »
I've always noticed that in the summer, when the trees are outside, I never have issues with mites. I considered that the rain kept the population low but I noticed I would still have mite issues inside (or this year, in a greenhouse) that would start in Jan/Feb even when I would spray the trees with water, soap, or oils.

The timing was puzzling. Mite populations can reproduce quickly (one search says 8.5x in 10 days) yet it took 3-4 inside months before suddenly requiring back-to-back-to-back-to-back endless spraying regimens.

So why absolutely no issues outside with no regimen, but a delayed issue inside?

Two interesting papers that highlight the effect of UV both as a) a direct suppressor of mite populations and, more interestingly, as b) a catalyst for defensive citrus resistance to mites.

This is slightly problematic for greenhouses with UV-blocking polycarbonate! But perhaps there is a time lag after UV is reduced (for example, when plants are moved inside) where the mite-preventing volatiles are still produced within the plant.

Deleterious Effects of Uv-B Radiation on Herbivorous Spider Mites: They Can Avoid It by Remaining on Lower Leaf Surfaces

UV-induced citrus resistance to spider mites (Tetranychus urticae)
  • "Abundances of Tetranychus urticae on Citrus exposed to solar UV decrease compared to seedlings under UV filtered radiation."
  • "Mite induced plant mediated resistance is dependent on exposure to UV radiation."

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Citrus General Discussion / Topsoil recommendations inside greenhouse?
« on: September 10, 2023, 03:49:50 PM »
I'm in the last stages of greenhouse construction, and my base soil is a fine, but light, clay/silt. Are there any recommendations for topsoil ("normal"? amended with mushroom compost? other?), and if there are citrus-specific adjustments (for example, make more acidic) to mix in to any standard topsoil.

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Citrus General Discussion / Indoor winter growroom
« on: October 30, 2021, 06:42:36 PM »
Brought the trees in about two weeks ago, just before the fall storms. Almost every tree is flushing now.


The lights are creating a 10°F temperature delta.


A few of the trees require almost daily watering. They may overtake the space within a couple months.

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Citrus General Discussion / Fungal disease on new flushes?
« on: August 24, 2021, 07:23:05 PM »
30 or so trees in very close proximity and the only one experiencing this is a Shiranui. New growth flushes are browning and dying off. Is this one of the common fungal infections?

   

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Citrus General Discussion / Scion or rootstock? (Baboon lemon)
« on: June 22, 2021, 05:28:19 PM »
Trying to determine if this low growth is scion (Baboon lemon) or rootstock (allegedly US-897).

US-897 should be easy to identify (trifoliate), so I am wondering if there's an interstock. The petiole wing of the low growth is much larger than the top growth.

Any ideas?



Low growth


Scion growth


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tl;dr: Reported suspected HLB in a stranger's front yard lemon tree in August. CDFA (a state agency) replies ask me (a private citizen) to arrange for samples with the unknown homeowner. How can we slow ACP/HLB if it takes half a year for a CDFA inspection?

Four months ago, I reported a lemon tree in Westchester, CA to the Asian Citrus Psylid / Huanglongbing (Citrus Greening) branch of the California Department of Food and Agriculture. The tree is infested with ACP and showing potential signs of citrus greening, but it's not in my yard -- it's in the non-fenced and non-gated front yard of a stranger's property, and I only see it when I walk our dog down a particular street (not on our usual route).

I recorded the address, and sent a note to the CDFA's Report A Pest email. I indicated the date, the suspected HLB, the address of the property (and that it was in the front yard), and that I did not know the landowner. To their credit, a response: "please send photos." It seemed that despite the report, no action would be taken without imagery. Nonetheless, a few weeks later I was again on that street, took a photo, and sent it in.

The response from CDFA (bolded emphasis is mine):
Quote
Our State Entomologist in Sacramento sent me the following information in response to the picture you submitted:

“It appears that the resident is correct—this does appear to be an infestation of Asian citrus psyllid.  It appears there is some asymmetrical yellow mottling of the leaves.  This is characteristic of what we are asking residents to look for HLB.  I recommend that we have someone collect a sample of symptomatic tissue and psyllids for testing the next time we are working in the area”.

Your information will be provided to the CDFA office that is in charge of your area. Once the office receives your information your call will be handled in the order it was received and an inspector will contact you to make arrangements to pick up samples. Can you please email your name, and contact phone number.

I gave them the benefit of the doubt and sent a response reminding them that the tree wasn't at my house, that I didn't know the homeowner, and that it was accessible in the front yard of the address provided. I asked why I would be responsible to make arrangements for samples as a private citizen, instead of their organization (given that their organization is chartered to handle exactly that kind of thing)?

The response:
Quote
I received your email in regards to the property not being in your home. In order for an inspector to survey the property we would need permission from the homeowner. If it is possible to have the homeowner call CDFA to have an inspector survey the citrus tree located in the front yard that would be great.

Every indication is that they're expecting me to facilitate this exchange. Is it incorrect of me to think that CDFA should apply their "government agency" card here to contact the homeowner and continue this process?

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To be honest, I tried another forum a month or so ago but am looking for more opinions. There was a long-ago post where another user (in Florida) had the same issue but never indicated if it was resolved (not sure if we can link there, but if you web search for "Problem With Meyer Lemon Leaves" and "charles27gardener" his post will show up).

My improved Meyer lemon (on a standard non-dwarfing rootstock) has been growing like gangbusters since planting a year ago. Recently, the underside of many of the leaves have started to become covered with rough brown spots. A number of the leaves fall off.

This is the only tree experiencing the issue of five trees that are about the same size and on the same watering schedule (two blood orange, one minneola tangelo, one page mandarin, and this meyer lemon).

The suggestion was fungal and that fungicide could control - I've begun that regimen but it continues to get worse (more leaves falling off, at the same time the tree is flushing with newer growth). Could it be mites? Edema? Fungal but takes longer to control? Other ideas?

I'm in the coastal Los Angeles area. Theoretically greasy spot is rare here?

Top of leaves, backlit (no noticeable issues with tops of leaves, but you can see where whatever is happening is affecting the tissue to make it lighter yellow) (Click for full-size)


Underside of leaves, note (necrotic?) brown spots (Click for full-size)


Fallen leaf top and bottom (click for full-size)


The tree itself, in lighting that doesn't reveal the issue, except for the defoliation near the top:

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