What is the average humidity in the greenhouse and how is air circulated?
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Of course it varies some, but now humidity ranges from 10-60% Usually higher in that range at night, and fairly low on our typical sunny dry days.
Air is vented by a 16" exhaust fan located at the peak on an end wall. That fan is controlled by a thermostat set to 90F. Air intake is thru two 3âx7â doors which are left open during the day. Currently I have not setup air circulation fans, but perhaps this is a sign that I should.
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The humidity seems fine, moving more air around might help. It could be a lot more humid right down in the zukes, near watered soil and cramped spaces.
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Good point LarryGene.
I visited my friend who has a Concord grape growing in her GH and compared notes. She is at the same altitude as my place but there are some significant differences between our setups. She has E and W doors which are kept open for venting during the days, and since the prevailing winds here are from the W, this keeps her GH considerably cooler and less humid than mine. Her grape vine is doing beautifully, and has never suffered from any diseases (I know this started as BER on a zuke, but my grapevine in the GH also has some rust like problem).
So I decided to keep the vent fan on all night for a night. It made quite a difference in temps and humidity (our nightime air is ~60F and 5-10% humid). The cooling also carried over to the next day, with humidity and temps significantly lower than before.
I think that running the vent fan only when the temp is >90F is inadequate. I am going to continue this experiment with the thermostat set to 55F (essentially run all night unless it gets really cold like 50F or below). Iâll keep monitoring and see if the increased airflow and lower temps and humidity have the desired effect on these diseases.
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I run a 36 inch exhaust fan 24/7 during the freeze free season, half the yr. This keeps the humidity down at night and helps to keep out some insects like leaf rollers and peach twig borer, adults are moths. The moths canât find there way in against the fan. With no fan running the attractive scents at night draw them inside.
I havenât had any significant fruit or tree diseases doing it this way.
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Good to know. Should have asked you about this firstâŚ
BTW, have you had to replace/repair any fan parts yet with this much use?
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None so far in 12 yrs. One fan has 8-9 yrs run time. Itâs run ~75% of the time for 12 yrs with no issues. Just replace the belt a few times. The original recommendation was to run 1/2 to 3/4 horse motors on the fans. I looked at it and found that a 3/4 hp motor did 12,000 cfm vs 8,000 cfm with a 1/4 hp motor. So I run the fan slower to save energy. That may also increase fan bearing lifespan.
The greenhouse has three 36 inch fans. Running two is enough. Three only drops temperature a couple degrees more than two. Two is still around one air exchange per minute, thatâs the recommended rate. At night I just run one. #2 comes on at 84F. The wet wall comes on at 86F. Recent highs inside have been 90-94F with outside about the same.
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Can anyone tell me what is going with this pear? Maybe @clarkinks can help?
The leaves are drying pretty fast. We are dry and hot right now, so is it the lack of water?
Or more probably a disease?
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My Korean Giant scorches something like that on the west side when it hits 100F+. Yours looks to be lower on the plant and probably something else. The damaged leaves on mine are those most exposed to the sun at the hottest time of day.
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Thank you fruitnut. The tree is young on the dwarf rootstock and it gets hot afternoon sun, so might be it. It also looks like a psylla damage, but I do not see any honeydew on the leaves. Tomorrow I will check for the insects on the leaves.
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Thank you Clark, I will keep an eye on this tree to see what is going on.
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Can anyone help identify whatâs happening to my pathetic looking little peach tree. I have 2 others that are healthy in the same are, Iâm in zone 8b. Our rain levels have been near perfect and itâs in its first year so Iâve done no treating anything whatsoever.
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Some very strange looking stuff on my fig? Also, a very odd happening with a fig. These could both be absolutely normal but it doesnât look good to me. Perhaps someone can say good, bad or indifferent? Thnx
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I have been spotting these guys around they orchard this year. I just identified them Green June Beetle. They look like Japanese Beetles on steroids measuring up to 7/8"! apparently, they can be a considerable agricultural pest.
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I have recently seen psyllids on my grape Vines. They are brown (not tan), about 3/8" to 1/2" long, and have red dots on the rear portions of their wings. Any idea which psyllid this might be?
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What do I have here? Type of leaf hopper maybe? 
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Tree hopper rather than leaf hopperâthese are in different insect families. Yours is likely in the genus Ceresa, Buffalo Treehoppers.
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Thanks Larry! He looked like trouble to me and now I know for sure!
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