Any idea what this is? Rot on leaves? (outdoor)

[Scrappy-doo]

I noticed this starting on one plant last time I was at this location. It's a swampy area. Went again this morning and it has spread on that plant and starting on a couple others. Didn't have my camera with me so I took a cutting.

Plant is a Bubba Cush from Melting Pot.

If need be I can go back tomorrow and take more pics. Seems to be on the newer more delicate growth.

Any idea what this is and what I can do about it?

 

[br26]

https://www.icmag.com/ic/showthread.php?t=11688

Potassium lockout or lacking. Has it been cold in the mornings?

 

[Granger2]

Are the leaves sticky? -granger

 

[Hash Zeppelin]

Prosperous lock out due to cold temps. In the winter I do this to purp up my shit end of flower.

 

[Scrappy-doo]

OK it does look a lot like the phosphorous deficiency from that guide. My nighttime temps are in the high 60's right now though. That's cold enough to cause this?

The leaves weren't noticeably sticky from what I remember. There was morning dew on them though. What do you mean by sticky?

I'll go back in the morning and take some better pics of the whole plant.

 

[Nes]

Prosperous lock out due to cold temps.

This is an awesome autocorrect. It's true though, cold temps will definitely lock out your prosperous!

 

[Scrappy-doo]

So is there anything that can be done?

 

[Granger2]

Thought maybe they were sticky with honeydew from aphids or white fly, and that it was Sooty Mold growing on the honeydew. Guess not. -granger

 

[Scrappy-doo]

Ah ok. Haven't seen any aphids or whiteflies, but I was thinking it could be mold, fungus, or bacteria related because it started on one plant and only seems to have spread to foliage of other plants that are close to it.

So if it's phosphorous deficiency should I foliar something onto them, or amend with something? They're in an organic mix.

 

[MynameStitch]

Prosperous lock out due to cold temps. In the winter I do this to purp up my shit end of flower.

This is exactly what it is, P lockout from cold temps Nice hash

 

[MynameStitch]

no don't do that, the reason why is the cold temps make P unavailable, so even if it's there it's absorbing a small amount of it and it's having trouble. Anytime it's cold your going to get a slight less yield, because the plant uses up less nutes. Cold slows the plant down. So do not add it, it won't be able to properly take it in. If you want to foliar spray do so when temps are warmer and make sure it's the start of the day, anything over 75 to 80 will be fine as long as the plant is in veg, if it's flowering depending on how far into flowering it's not safe to foliar because of bud development.

 

[Nes]

if its a cold temp thing, how about mulching?

 

[Scrappy-doo]

Is it undoubtedly a cold temp thing? It's just hard to imagine being it's still summer and all. Like I said it's high 60's at night I woulda thought that's plenty warm enough.

The other issue is in my area it's been an extremely dry season. Even though this is in a swampy area it's pretty much all dried up. I've been carrying in water at some locations but this one I haven't been able to get to very much. I went there yesterday morning actually half expecting some plants to have wilted and died. Maybe the soil being so dry has locked up the P?

I really should have laid down some mulch, I just have never had to before this season.

I think next time I go there I'm gonna lay some mulch down and give them a real good watering.

 

[Nes]

You mentioned being in a swampy area, Do you have any idea of your soil ph or ph of your water? below 5.5 can lock out P as well.
(http://www.noble.org/ag/soils/phosphorusbehavior/)

I haven't dealt with this issue personally. I assume when folks say temps can lock out P, its the soil temp that matters more than the ambient air temp. thats why I ask about mulching.

Some folks use a "hot bed" technique for growing vegetables early in the season. It's often coupled with a cold frame, but the idea is you dig out a whole, several feet deap and layer 6-12" fresh manure and compost at the bottom, then backfill with soil. The idea is that as it breaks down it'll warm the soil from below. I wonder if you could somehow incorporate this idea into the tops or sides of your already planted plants? maybe mixing manure with straw so it decomposes on the surface without burning the plants too bad. Horse and rabbit manure burn less than chicken or cow. Other than that, i cant think of a way to warm your soil..

Oh wait, black plastic mulch. Would warm your soil and help retain water. again, I haven't dealt with this, just a thought.

Gotta get that prosperous deficiency in check!

 

[ozza]

15 degrees Celsius or 60 Fahrenheit is cold for a weed plant. Over 18 celsius it will grow. Just wait. Or put it in more sun.

 

[Hash Zeppelin]

This is an awesome autocorrect. It's true though, cold temps will definitely lock out your prosperous!

Lol, didn't even notice.

 

[Granger2]

If it's dried up, that could be the problem. And if you visit the plants in the a.m., they may not wilt till afternoon, then recover overnight, for awhile.

 

[Scrappy-doo]

Thanks Granger! Yeah I've been reading up a bit on dry soil and and nutrient availability, and according to the literature P and K are the first two nutrients to lock up in dry soil conditions.

This makes much more sense to me than temperature since I'm on my 4th year outdoors and I don't ever see any purpling until October when it actually starts to get cold.

I'm gonna pick up some mulch and apply it with a real good watering next time I'm there.

 

[MynameStitch]

from what I am seeing in the pictures I do not see a ph problem. As for dry soil, can you take a pic of the whole plant?

Ya scrappy that is cold temps to cannabis, anything under 70F will trigger a slowdown in some strains as far as I can tell from your pics all I see is a color change from cold weather.
trust me it's definatly a temp thing, look it up one week of cool weather is all it takes to trigger the plant to do that and most strains have different tolerances to heat and cold they are all different when it comes to care. but trust me it's a cold weather thing. That is a huge temp swing which is setting the plant off. better be careful too, with those temps swinging l like that you will get dew and if you use mulch bags its going to lock in water and not get enough fresh air and you got a whole new problem. Take a picture of the whole plant because pH issues would show on the leaves in spotting or tip burn on the leaves. Dry plants will droop. most of the time outdoor plants don't need the pH adjusted unless the soil is not good, or not a good spot for the plant. before you do anything else can you post pictures of the whole plant? Is the plant droopy and the leave tips kinda pointing down? btw that color will stay there. untill the leaf gets dropped by plant or you chop it. Once it changes colors it stays that way.

 

[Scrappy-doo]

Stitch thanks for coming back and sharing your insight. No I have not seen any drooping and if you're sure it's a temp thing then I'm gonna take your word on it. Organics is new for me and I botched up my first batch pretty bad indoors so I'm a little paranoid I guess. Just want these girls to do well and finish proper. So the bottom line is I'm willing to learn from more experienced people and very appreciative for everyone's help.

There is one plant that had some odd kinda lockout or burn damage on a couple leaves but not bad.

OK so I'm gonna hold off on the mulching and get some more pics up. I'll stop by in the morning with a camera and get some up hopefully in the afternoon.