Two Plants, Two Problems (Maybe just 1); Please Help

[RobbyCN]

First time grower here. I'm growing two plants. One is great, it is nearly seven feet tall, but it MAY have a problem. Some of the leaves have white spots on them, they have been there for some time and don't seem to be getting worse. But I'm worried maybe this is White Powdery Mildew (WPM). Although it is fairly windy in my location and I thought it was hard for WPM to take hold if there is a strong breeze. Please take a look at the first three pictures and let me know if you think that is WPM, or not. If you do think it is WPM, do you have any thoughts on how to attack it. Thx.

The second plant I know I have a problem. Many of the leaves are yellow. This happened during vegetative stage and I added Nitrogen and the problem went away. But two weeks ago when flowering started I went to a lower nitrogen fertilizer (2,8,4--Tiger Bloom) and now the leaves have started to turn yellow. I thought Nitrogen wasn't an issue during flowering stage, but yesterday I went back to a high nitrogen fertilizer. Do you think high nitrogen fertilizer is the way to go, even though the plant is now in (early) flowering stage.

 

[Ninjadogma]

The first plant where you are suspecting WPM, that looks more like insect predation to me.

The other picture with fluorescent yellow fans popping up in different spots is classic symptom of nute lock. If I had to take a guess, there's a civil war going on between N and K with there being lingering N from the extra you previously added canceling out the K in the bloom nutes you later added. If you don't fix it, pH will drop and then it'll start looking calcium deficient on top of everything else. I've been there, many others too. Easy way to fix is catch it early, stop all your feeding and add more volume of water to your next couple waterings. Monitoring with an EC pen as you're pouring is a big help. And small increments! It can drop and go from ideal to too low with a pretty small amount of additional water.

 

[LoveGrowingIt]

The first plant has insect damage. It could be spider mites or thrips.

It's unusual for yellowing leaves up the main stem like that. It may have needed nitrogen and that started the yellowing. Then when you gave it some, the rest of the plant recovered, but some leaves couldn't. Most yellowed leaves don't go back to being green again.

Do you think high nitrogen fertilizer is the way to go, even though the plant is now in (early) flowering stage.

For this plant, I'd continue with the nitrogen for a few more weeks. Nutrient timing is important, especially with those synthetic nutrients. Nitrogen is important at least until budding begins when it can be reduced. Then phosphorus and potassium become more important.

 

[Ninjadogma]

The first plant has insect damage. It could be spider mites or thrips.

It's unusual for yellowing leaves up the main stem like that. It may have needed nitrogen and that started the yellowing. Then when you gave it some, the rest of the plant recovered, but some leaves couldn't. Most yellowed leaves don't go back to being green again.


For this plant, I'd continue with the nitrogen for a few more weeks. Nutrient timing is important, especially with those synthetic nutrients. Nitrogen is important at least until budding begins when it can be reduced. Then phosphorus and potassium become more important.

We can probably presume that there's liquid ("synthetic") nutes going in some soil that has its own nutrients. Nitrogen and potassium start canceling each other out at some point. That fluorescent shows up, then gets worse after a fresh watering after they took a drink of toxic amounts of nutes.

 

[LoveGrowingIt]

We can probably presume that there's liquid ("synthetic") nutes going in some soil that has its own nutrients. Nitrogen and potassium start canceling each other out at some point. That fluorescent shows up, then gets worse after a fresh watering after they took a drink of toxic amounts of nutes.

Could be, even though presumptions can be troublesome. The OP is using Fox Farm Tiger Bloom, which I believe is synthetic, but didn't say the N source or the soil type. What started me down the path I followed was the addition of more N after the yellowing began. That would've or could've greened up most of the plant while the chlorosis became necrotic. That is an unusual pattern for chlorotic leaves, though. I figured the worst of them might also be the oldest.

 

[Ninjadogma]

Could be, even though presumptions can be troublesome. The OP is using Fox Farm Tiger Bloom, which I believe is synthetic, but didn't say the N source or the soil type. What started me down the path I followed was the addition of more N after the yellowing began. That would've or could've greened up most of the plant while the chlorosis became necrotic. That is an unusual pattern for chlorotic leaves, though. I figured the worst of them might also be the oldest.

That fluorescent yellow isn't the deficiency fade I see with either typical nitrogen or potassium. I just leaned in for a closer look. Looks like N and K packed up and left those affected leaves together. It was given both nutes so there's no way it should still trigger a deficiency that drastic unless they've become completely unavailable.

 

[RobbyCN]

Thanks for all the great advice. I hope I can recover the second plant, but I'm more interested with preserving the first. I don't smoke a lot of week and if I can get the tall plant to harvest, I will have more weed than I know what to do with. I'm pretty sure I don't have spider mites. I have checked very carefully with a magnifying glass and I just don't see them. But yeah, I'm pretty sure I have thrips. For the thrips, I plan to treat with Spinosad and Diatomaceous Earth. If anyone has any other ideas for treating thrips, please let me know.

There doesn't seem to be a consensus here for treating the yellowing plant. But I will say there has been quite a bit of rain lately, and it seemed to get worse with the rain, when I wasn't adding nutrients. When it was low in nitrogen in the vegetative stage, 3 or 4 days after feeding the yellowing started to clear up. I gave it nitrogen yesterday and will keep my fingers crossed and if it doesn't start to get better, it's back to the drawing board.

Thanks again for the great comments.