Taco leaves ???

[nomoreschwag]

I've got an AK that is 2-3 weeks into flower and the leaves are curling up like a little taco. I did a search and it seems its either a Mg def, or heat stress. Neither of these really make sense to me.

This started about 3 days ago. The day before I fed her a 2/3 strength shot of PBP bloom, full LK, accelerated cal-mag, and some blackstrap. My temps have been in the mid 80's b/c the ac is broke in my house right now and I have a couple days until all my hanging plants are in jars so odor issues go away. She should have plenty of Mg and temps are not all that bad. I also have a couple NL clones in their that aren't showing any signs of stress at all...

 

[Blackvelvet]

16.67 ml pbp bloom for soil + 5.8 ml cal mag plus per gallon of water. If you have fresh dolomite lime, you would reduce the cal mag plus. You didn't mention testing ph...

How to test soil ph: (Virginia tech method) After watering well, wait 30 minutes. Then apply a small amount of distilled water to the pot. Catch this runoff. You only need 1 or 2 ounces. Test ph. 5.6 to 6.2 is good. If you can tilt the pot after 30 minutes and get some runoff, you can use that.

You might adjust your fert water to about 6 after mixing to prevent surprises.

Apply your fert water till quite a bit flows from the bottom of the pots. Really soak it well then let it dry out. No wimpy watering.

Your plant looks quite good. Worry more about the bottom yellow margins/edges and tip burn. Potassium problems from too much cal mag?

 

[Breezy420]

why would you tell a guy in soil to go with a ph of 5.6 to 6.2

 

[Brian1975]

Because he's a 6.5 is the ideal number to shoot for in soil, unless we are re-writing the "book" on growing. "How to kill a plant in 10 days", by Black Velvet.

Found this in a search. Old sticky from OG."Quite often I hear groans from folks having leaf problems - “Help, my leaves are cupping and the leaf edges are turning brown!”, or, “My plant's leaf tips are curling down and turning black ....what's wrong?” Unless insect damage has occurred or the plant is suffering from a severe case of calcium deficiency, the plant is trying to tell you that it is water stressed. It's hard to tell *exactly* what the culprit is, and unfortunately the “solution” the grower chooses many times is not the right one. A mis-diagnosis only serves to make matters worse by promoting further decline. I’ll try to cover some of the more common causes that can induce these common symptoms and try to offer a few simple solutions. The ultimate and correct solution is in the hands of the grower.

1. Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf. When you have a high concentration of salts in solution (or in the root medium) compared to lower salinity levels found in the plant’s tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance. IOW, this is a natural, osmotic response that serves to equalize salinity levels on both sides of the root’s epidermal gradient. Back off on the amount and/or frequency of plant food. Too much plant food can also burn the roots, especially the sensitive root tips, which then creates another set of problems. Note for the bio folks - as soil dries, the concentration of the remaining salts rises further exacerbating the problem.

2. High Heat - the plant is losing water via it’s leaves faster than what can be replaced by the root system. The leaf responds by leaf margin cupping or rolling (up or down) in order to conserve moisture. A good example is reflected by the appearance of broad-bladed turf grass on a hot summer day, high noon, with low soil moisture levels - the leaf blade will roll in and the grass will take on a dull, greyish-green appearance. Upon sunrise when moisture levels have returned to normal, the leaf blade will be flat. Lower the heat and concentrate on developing a large, robust root system by practicing sound plant culture. An efficient and effective root system will go a long way to prevent heat induced leaf dessication and leaf margin curling. One short episode of high heat is enough to permanently disable or destroy leaf tissue and cause a general decline in the leaves affected, which often occurs to leaves found at the top of the plant located near HID lamps. The damaged leaf (usually) does not fully recover, no matter what you do. Bummer in the summer. One can only look to new growth for indications that the problem has been corrected.

3. High Light - yes, it’s true, you can give our faves too much light. Cannabis does not receive full sun from sunrise to sunset in its natural state. It is shaded or given reduced light levels because of adjacent plant material, cloudy conditions, rain, dust, twilight periods of early morning and late afternoon, and light intensity changes caused by a change in the seasons. Too much light mainly serves to bleach out and destroy chlorophyll as opposed to causing leaf cupping, but it often goes hand-in-hand with high heat for indoor growers. Again, back off on the light and concentrate on developing/maintaining an efficient and robust root system.

4. Overwatering - this practice only serves to weaken the root system by depriving the roots of proper gas exchange. IOW, the roots are not getting enough oxygen which creates an anerobic condition causing root decline and root rot with the end result showing up as leaf stress, stunted growth, and in severe cases, death. Alot of times folks think the plant is not getting enough plant food (which it can't under such adverse conditions), they add more nutes for a "curative", and just add insult to injury.

5. Underwatering - not only is the plant now stressed due to a low supply of adequate moisture, but carbohydrate production has been greatly compromised (screwed up). Step up the watering frequency, and if need be, organic growers may need to water from the bottom up until moisture levels reach a norm throughout the medium. If the pot feels light to the lift - it’s time to water. Don’t wait until the soil pulls away from the sides of the pot or leaves droop before you water. And of course, leach once in a while to get rid of excess salts."

 

[richyrich]

I've got an AK that is 2-3 weeks into flower and the leaves are curling up like a little taco. I did a search and it seems its either a Mg def, or heat stress. Neither of these really make sense to me.

This started about 3 days ago. The day before I fed her a 2/3 strength shot of PBP bloom, full LK, accelerated cal-mag, and some blackstrap. My temps have been in the mid 80's b/c the ac is broke in my house right now and I have a couple days until all my hanging plants are in jars so odor issues go away. She should have plenty of Mg and temps are not all that bad. I also have a couple NL clones in their that aren't showing any signs of stress at all...

I have been growin AK for some time now. It will appear to be too much heat, but the plant actually doesnt like a lot of light. Strange for a sativa. I got one doing it right now and all the other strains are just fine. Always happens. Its not trying to hide from the heat, its hiding from the intense light. I dont know what your using. I have a 1000w cool tube 2 feet away. No heat at all.

 

[Growdoc]

1. Over-fertilizing - the most common cause of leaf cupping aka leaf margin rolling, leaf margin burn, and leaf tip curl/burn is the overzealous use of too much plant food in relationship to factors such as plant vigor and rate of growth. The first unit of a plant to show moisture stress is the leaf at its margins and/or tips, reflected by margin rolling (cupping) or burning. A hard, crispy feel to the leaf frequently occurs as well, as opposed to a soft and cool feel of a happy leaf.

I have to agree with overfertilization, to much K and to small container.

GrowDoc

 

[richyrich]

Got any hot sauce for this AK47 taco. Too much light. Only one doing it with six other strains. Not a fert problem.

 

[Blackvelvet]

why would you tell a guy in soil to go with a ph of 5.6 to 6.2

Looks more like a soilless mix in the picture. There is a bag of peatmoss in the back of the first picture. I guess the thread starter can fill us in.

 

[Core]

.....

 

[Breezy420]

Nice sig Core

 

[MTF-Sandman]

Brian1975 has you covered...and it doesn't look like nute burn to me, so that pretty much leaves low RH, temps or too much airflow - or a combination of them. I've also seen it when doing 125w sq/ft (MH) like RR is referring to with a sativa dom clone (didn't affect indy dom strains)...but i doubt that's the problem with only a 400w.

 

[richyrich]

Yeah, I didnt notice you were only using a 400 watter. Most likely the heat especially in a closet set up.

 

[nomoreschwag]

Thanks for all the replies everyone!
Here's a little more info. I'm using a basic soiless mix of Peat, perlite, worm castings, and dol lime @ 1 cup/sq ft (LC's #1). When the pics where taken the ambient temps in my cab were right around 85. I've gotten the house cooler and now the temps are in the upper 70's. I learned basic organics from Burn1 back in the OG days. Testing ph was never something that was really emphasized in organics. I do have a digital Hanna that I pull out from time to time. My ferts always read in the low 6's with the runoff 6.5-6.75

The problem has pretty much gone away, and I haven't done anything to it. Kinda weird, none of my other plants (save the Hawaiin sativa...) have shown any signs of stress at all. I'm happy that things balanced themselves out, but it would be nice to know what caused it in the first place

 

[Brian1975]

"When the pics where taken the ambient temps in my cab were right around 85. I've gotten the house cooler and now the temps are in the upper 70's."

 

[nomoreschwag]

Ya, I'd say that has something to do with it. I don't think 85 is all that bad, I prefer the 70's but as long as I don't get into the 90's I'm not too worried. I have the same strain outside now, its been in the 80's this week and the leaves haven't done that...