White spots on leaves but healthy plant

[WebGuyTom]

I noticed a couple of weeks ago that 1 of 3 plants I have in a 2x2 growing area (indoors - closet) had quite a few white spots, but only on a few leaves. The same plant now has maybe a couple of dozen leaves with the white spots. I've checked the various bug infestation possibilities and don't find anything that matches. I've watered each plant the same using Botanicare Pure Grow for flowering on all 3 plants. Only the 1 plant has the issue. If you overlook the spots, the plant is otherwise just as healthy as the other 2. When you view the images, understand this is the first grow I've done in nearly 30 years...yeah...old guy. I've checked under the leaves and find nothing. I do have bloody fruit flies which came from the soil (Black Gold). 1 of the 3 plants is ready for harvest. The other 2 are a couple of weeks behind. I have a single 2 foot fluorescent 150W light, keep the area between 38 and 43 percent relative humidity, and the light keeps the area between 73 to 83 (most always between 78 and 83), depending on how cold it is outside. I crack the window to the room daily so there is always fresh air, but I close the window just about the time the light goes off (12 and 12).
For the life of me, I cannot figure out if it's a deficiency (doesn't seem like that nor does it fit any of the symptoms) or bugs. I'm pretty familiar with spider mites and other plant bugs. I've taken close ups of both top and bottom of the leaves and can't find anything that looks like a bug. In fact, the bottom of the leaves looks healthy. The leaves that are spotty are further away from the light than any others, so it's not heat. The closest any part of any plant comes to the light is about 6 inches. And those that are closest are really healthy.
Remember now, these plants are nearing harvest. 1 will be harvested in the next 2 to 3 days. The plant with the "ick" will be ready to harvest in about 2 weeks. The spots didn't start appearing until about 2 weeks ago. I started them flowering the last few days of December. So they are nearing the end of week 6. That means, the plant with the "ick" was in the bloom area for 4 weeks before I saw any spots.
I don't see any signs of bugs because there are no bite marks, and nothing on the underside of the leaves. And the leaves are otherwise normal, as in the first picture, other than the white spots (and the few frickn fruit flies that are stuck to the trichomes). I'm not worried about the bloody, pesky fruit flies. Any thoughts? Who can say without a doubt they know the answer?

[OzBud]

Is it sort of powdery?

http://www.growweedeasy.com/white-powdery-mildew

[ZigZag]

That's the first thing I thought of too_ white powder mildew. take a paper towel, get it wet and squeeze out the extra water. take one of the affected leaves and see if you can gently rub the white stuff off. If it is mildew it should wipe off. If it doesn't wipe off then its likely something else.....some nutrient deficiencies (and toxicities) can show as light colored spots and/or blotches. If it is mildew then you want to get that plant away from the others fast.Then you want to check out the link OzBud provided. I'd go with whatever method is the best for plants already in flower. If your humidity is over 50% get it down to 40% or less, even 35%. That should help. You might also want to take some steps to prevent bud rot too_again low humidity. Hopefully its a nutrient thing. If it is_ flush the plants with 2X as much PH water for the size pot you're using. As long as your grow medium is draining well. Good luck and our prayers are with you. many of us have been there before!

[WebGuyTom]

Thanks for the input, but so you know, I'm the type who won't post something unless I've done my due-diligence. In this case, I spent days pouring over images, "what if's", comparing issues, but I drew a blank, and I'm pretty good at troubleshooting.
No, it's not wet, moist, or mold. I checked that. I checked for bugs, as I mentioned, and the only "varmints" I can find are fruit flies. However, I have a difficult time distinguishing between fruit flies and fungus gnats.
I "think" they may be fungus gnats. Some are brown but most are black. There is NO fruit or any sort of food anywhere close to the plants. So I'm in the midst of letting every plant I have (pot or not) dry out right now - that should take care of either pest. I think the 13th was the last time I watered, but I didn't water the flowering plants. They haven't been watered since the 11th, and I'm not going to water them until that soil is really dry.
It's hard to tell without sticking your fingers in the soil to see if it's damp because the soil is so dark. I checked yesterday and it's still damp, but not wet...like that cold damp but no actual moisture. I'm going to wait a total of 7 days before watering to see if the bloody gnats/flies go away.
But all of that doesn't address the issue with the leaves.
It's not something that can be wiped off either.
I was diligent to the conditions as close to perfection as possible in the way of heat and humidity. I'm in Washington State and we just went through some really cold weather, which brings with it very dry air. The grow is in a closet. I also have a small de-humidifier. If the humidity gets over 45% I turn it on and let it run until the RH returns to under 40%. So I can't imagine that mold, mildew or anything from moisture could be the issue.
It seems to be some sort of infection, but I can't figure out from what.
If it's an infection, why didn't it show before 2 weeks ago? It's like the infection (or whatever) didn't show until that plant started getting trichomes. But, again, it's not everywhere and there is no pattern as to where it appears on the plant.
I harvested the biggest plant today. Luckily it didn't have even 1 leaf with spots. It did, however, have tons of gnats/flies stuck to the plant! &#*! Under the leaves, top of the leaves, in the buds...I spent nearly an hour just using tweezers to gently pluck every bloody gnat off ONE branch....sigh...that was discouraging. But I have 2 branches hanging now and a lot more to go. I cut off a branch from the plant that is still growing in the pot in order to work on it and keep the plant healthy.

The plant with the "ick" has only about 15% of the plant affected, and there is no pattern. There are some leaves on one area of one branch affected, but then nothing on any of the other leaves on the same branch. And, the leaves that have the "ick" are not at the top or bottom exclusively. The "ick" is in various places - no pattern as to where it appears.
If it were a deficiency it should have a pattern, like top leaves, bottom leaves or something.
As mentioned, my humidity remains really constant at about 41%. Sometimes as low as 35%. But never over 45%.
The pots are 5 gallon buckets with 20 to 30 or so holes drilled into the bottom (only enough to retain the rigidity of the plastic) to allow adequate drainage. And they were all scrubbed before use.
I knew when I posted that this wasn't something easy to determine.
Thanks guys. Anybody else?

[WebGuyTom]

I GOT IT!
First, it's not "white" spots. They are called "silver" spots.
I found them by doing some research on "white spots" which led to "silver spots".
I found the exact same spots on leaves at 420Magazine.com (https://www.420magazine.com/forums/p...elp-photo.html - see attached image), but first in another grow site - even though I searched everything and not just 420 sites.
That first site had someone determine from a picture of a leaf that it was infested with thrips.

When I found the first site they said it was definitely "thrips". I'd never heard of the suckers, nor did I see anything they described in the way of how the pests appear. But after reviewing the image in that site coupled with the image in 420Magazine, the conclusion was thrips are the cause. I haven't seen them flying, but they could look just like fungus gnats for the most part. And not seeing them on the leaves is because they don't sit there - they move pretty fast from what I read. Only if you are lucky to figure out "where" you can find larvae would you be able to determine it's thrips from seeing them. But the images from both sites, in addition to others that described the spots, proved to me that it's thrips.
And the cure the person used in that forum was soapy water. I continued the research to find that soapy water will only keep them at bay for a few days, and then they come back. That person didn't post after they used the soapy water solution. I'm guessing they were unhappy that didn't work and didn't return to post the results.

Thrips are like cockroaches. They are either immune to whatever deadly poison you use on them, or, they "become" immune after just a generation or 2.

Then I went to work to find a "natural" cure. WOW! Who would have thought purposely infesting plants with more bugs would kill what you have - fast?
Every time I hear or see this name I think of Sponge Bob.
The cure is.... Nematodes

Specifically, "Double-Death" Predator Nematodes.
They can be purchased for less than $20. That's the smallest purchase I found (so far - I'm going to check some local nursery shops), but that will cover...2,500 square feet of soil. I have just 2 - 5 gallon buckets for my 2 plants. Talk about overkill....
Here's a link to purchase and get all the information about them - http://growhome.com/pest-and-disease...on-live/85701/

OH! Here you go! Amazon has them too - https://www.amazon.com/million-Benef...atodes%22&th=1

I'm hoping that I can get this post to be "sticky" because the "Double-Death" Predator Nematodes feeds on more than 250 different insects. Including: fungus gnats; fleas; thrips; cutworms (which are pretty big I understand).
So instead of risking your grow with spray or adding something to the soil, or anything that may be harmful to the plant, or especially harmful if ingested, use nature - Nematodes. Let the suckers get in and eat all the little jerks that are driving you crazy in your soil crops.

It takes 7 - 10 days to rid the pests, but it will work naturally. Nematodes are microscopic. So you won't "see" anything.
For me, I'm within 2 weeks of harvesting the plants, so I may just not mess with anything and, hopefully, the plant with the thrips will not be horrible at harvest.

On the other side, this is a HUGE reason to go Hydroponic. Screw dirt! Except that it's pretty expensive to go Hydroponics as opposed to soil - especially for the first-time grower.

I hope this helps a lot of people with whatever "bugs" they may have.
It's nearly 420...gotta go.