New Growth Tip Curl

[herbswork]

Hey folks! My plants are in soil and when they were first put in they looked like they might have a magnesium defficiency (brown spots and yellowed edges), so I've been giving them cal/mag. As seen below, the new growth is curling. Next watering I plan on giving them pure water in hopes of some turn around since I'm trying to start flowering in the next couple of days. I suspect my pH meter may need to be re-calibrated, as it appears to be coming out of the tap at 8.4... I have been using a ppm meter and keeping the TDS around 300-500 since the curling started...trying not to give them too much food. I'm using liquid karma, thrive alive, and some kelp extract with a 1-1-17 ratio. There are two strains, Platinum Kush and Black Domina. Last flowering, the Domina seemed to be lighter green than the dark green Kush...I think I may have not added enough phosphorous...and possibly micro-nutrients. I also have gnats and am planning to buy some nematodes (unless I hear of a better way to get rid of them).

The Temperature range has been kept between 60-75,
The plants are under cool tubes.

Thanks for any suggestions anyone might have!

 

[billmoe93]

I dont think the pics are coming through.

Without them I dont know which way they are curling. Up or down? Whats your humidity at?

Neem oil is also a good way to kill gnats. I just killed a small gnat infestation by spraying every 3 days, and killing the adult gnats.

 

[herbswork]

Thanks for the reply Billmoe, the range of humidity is from high 40s to low 60s, and now that the picture are up you can see the tips curling downward, thanks for your help!

The leaf at the bottom of the third picture shows some previous signs of what I took to be a magnesium def....does this seem like a correct diagnosis?

 

[billmoe93]

Heres an article from another site. Its hard for me to narrow it down without asking you a bunch of questions, but this should explain a lot.

Leaf curl/cupping & leaf margin rolling-signs of Plant Moisture Stress


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 (in the root medium) compared to the 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 - 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 (most times up) 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 upward/inward with the grass taking 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. 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 in the 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 - for those doing soil, 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 inducing root rot and root decline with the end result showing up as leaf stress, stunted growth, and in severe cases, death. <gasp!> Overwatering creates a perfect environment for damp-off disease, at, or below the soil line. 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.

All of the above issues relate to a plant's internal cell turgor or cell water pressure. If water pressure within the plant's stem and leaf cells are positive, the plant will look strong and stocky with flat leaves that are cool to the touch due to good transpiration from the leaf surface. By the same token, if the water pressure is not up to par, whereby water is being extracted from the plant and not replenished like it should be.... the leaves and/or stems will droop.



As for the the leaves in the third pic. Its hard to tell it kind of looks like a potassium def. You will probably want to test your ph of the run off water and make sure there isn't a lockout before trying to over correct with nutes. Hope this helps

Great looking garden by the way.

 

[PBRMJ]

billmoe93 thank you that was a very helpful post to me anyways I guess I was letting my dry out a little to much. Once again thank you.

 

[herbswork]

Thanks Billmoe! I'll let ya know what happens.

 

[ozric420]

very good info. thanks

Heres an article from another site. Its hard for me to narrow it down without asking you a bunch of questions, but this should explain a lot.

Leaf curl/cupping & leaf margin rolling-signs of Plant Moisture Stress


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 (in the root medium) compared to the 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 - 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 (most times up) 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 upward/inward with the grass taking 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. 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 in the 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 - for those doing soil, 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 inducing root rot and root decline with the end result showing up as leaf stress, stunted growth, and in severe cases, death. <gasp!> Overwatering creates a perfect environment for damp-off disease, at, or below the soil line. 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.

All of the above issues relate to a plant's internal cell turgor or cell water pressure. If water pressure within the plant's stem and leaf cells are positive, the plant will look strong and stocky with flat leaves that are cool to the touch due to good transpiration from the leaf surface. By the same token, if the water pressure is not up to par, whereby water is being extracted from the plant and not replenished like it should be.... the leaves and/or stems will droop.



As for the the leaves in the third pic. Its hard to tell it kind of looks like a potassium def. You will probably want to test your ph of the run off water and make sure there isn't a lockout before trying to over correct with nutes. Hope this helps

Great looking garden by the way.