The Tropical Fruit Forum

Coming back to this, I'm fairly certain now that it's Alternaria Brown Spot.

Don't have a good mechanism for control yet given how often it rains.

I'm "only" running ~17 true W/sq ft. Two sets of Kingbrite 650W LED light bar fixtures (10x LED light bars of LM301H + deep red/infrared). The mix tests at 3400K and 175 lumen/W (and ~1660 total PPF). The LED drivers are not 100% efficient; each fixture pulls closer to 750W from the wall to generate 650W LED output. Kingbrite was highly recommended by some of the other research forums.

The original Kingbrite mount was 100mm spacing between light bars. This would have created a more pronounced PPFD spike in the center. I remounted at ~300mm spacing to distribute the light over a substantially larger area and make the PPFD coverage more uniform.

Lumens or foot candles aren't a great measure of PPFD because it's spectrum dependent. But it's easier to measure the former. 1700 FC at the plant bases and 2700 FC a little over a foot below the lights. If it's close to sunlight spectrum, that's 350-540 PPFD.

Running 12hrs on/12 hrs off. Tops of plants are getting DLI in excess of 25, the bottoms are closer to 15. I planned for 21 for healthy growth.

VPD is averaging 0.9-1.0 with range of 0.6-1.2. Trying to keep humidity up to sustain beneficial mite populations.

Humidity and airflow - There's an HVAC vent into the room, and a door. The heater is running for the house more frequently now with the lower temperatures, so that's the positive pressure into the room. Between the vent and keeping the door almost all the way closed, the humidity has been in a good range. There are 30 citrus trees transpiring water vapor into the air! (and evaporation from the pots.) I also have a floor fan on a timer to turn on for 30 min every 2-3 hours for more circulation. It's a very relaxing - if bright - space to be in. Lots of blooming now, too.

Agree with all the comments here about the Root Maker pots, especially for up-potting. It's easy to cut the zipties and expand/add panels around the existing root ball. Combined with the 5-1-1 mix (I generally add more perlite to be closer to 5-1-2) it's a forgiving setup. You can get a feel for the watering by the weight of the pots,, and there's a clear relationship between canopy size, growth, and diameter of the pot for how frequently watering is required. Some of the smallest pots get water every day and they're growing like crazy (finger limes in particular). Tricky to think about up-potting again during constant flushes.

Brian, good question and something I stressed over in the months leading up to the transition. I ended up building a wood platform on casters, covered with panda film to catch any water (any sturdy plastic barrier will do). The trees sit on top of this. I also used some existing plastic catch basins on wheels as well for some trees. So, all the water is caught above the floor and I can maneuver around to get into the thick of the trees to sweep/vacuum as needed. Downside is losing 6-8" of allowed height but well worth avoiding water damage. Need to get the greenhouse planned .

Thankfully, have not had to deal with any scale in the region. Lots of caterpillars and earwigs before they came in, and of course the big cicada emergence. The surprise pest was a single Boxwood Psyllid on the pomelo but that was months ago.

Does anyone have suggestions for treatment? New growth continues to be affected.

It does not look like Alternaria Brown Spot.

The mystery continues then.

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?

   

Madison Citrus Nursery ( https://madisoncitrusnursery.com/ )

Brian, how were you able to defeat the scale?

I have found this presentation on citrus pruning techniques to be informative, although I haven't cross-referenced with any academic papers:

https://crfg.org/wp-content/uploads/CITRUS-PRUNING-Presentation.pdf

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?

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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):

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:

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?

Hi Matt, what are the symptoms on your tree? Do you have old leaves falling?

Mtlgirl, see images here with similar symptoms:
 http://tropicalfruitforum.com/index.php?topic=25226.0

I didn't say I agreed . But would love a better diagnosis!