Plant Moisture Stress - Symptoms and Solutions

SRT_designs

Member
PLANT MOISTURE STRESS - symptoms and solutions (revised Jan. 12, 2009)

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 size, 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. Sometimes copper colored necrotic spots show in the leaf also. 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 and hairs, which then creates another set of problems such as nutrient deficiencies. A note for the bio folks - as soil dries, the concentration of the remaining salts rises further exacerbating the problem. Leach (flush) your pots once in a while to get rid of excess salts.

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 by supplying sufficient moisture for good plant health. One short episode of high heat is enough to permanently 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 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, debris and dust collection on the leaf surface, 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. Keep in mind that all but equatorial material receive less light during flowering than during the vegetative stage.

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. <gasp!> 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 soak the pot from the bottom up until moisture levels reach an even consistency throughout the medium especially with mixes that are heavy in peat. If severe, a little surfactant (liquid Ivory dish soap) added to the drench will help return the organics back to a normal moisture retentive state. If the pot feels light to the lift - it&#8217;s time to water. Don&#8217;t wait until the soil pulls away from the sides of the pot or leaves droop before you water.

Happy gardening,
Uncle Ben
That was a good read and definitely a lot of useful info!! Thanks
 

Árboles verdes

Well-Known Member
PLANT MOISTURE STRESS - symptoms and solutions (revised Jan. 12, 2009)

Quite often I hear groans from folks having leaf problems -> &#8220;Help, my leaves are cupping and the leaf edges are turning brown!&#8221;, or, &#8220;My plant's leaf tips are curling down and turning black ....what's wrong?&#8221; 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 &#8220;solution&#8221; the grower chooses many times is not the right one. A mis-diagnosis only serves to make matters worse by promoting further decline. I&#8217;ll try to cover some of the more common causes that can induce these coflowering than during the vegetative stage.

4. Overwatering - this practice only serves to weaken the root 27B257F4-ED51-4793-ABCA-C29F29FE827B.jpegCC6D9243-57AC-4D27-90F3-565F81E862C7.jpegcan anyone help me out please, not sure if salt buildup or too much light. I was thinking of flushing with light nutes
 

raggyb

Well-Known Member
if you suspect salts I say flush in a sink with 2-3x the pot size amount of water. go as slow as you need to so it all goes through. it won't recover right away and it probably will not need to be watered again for a long time. then start up easy again with flower nutes and make sure you have some K and Ca. just a suggestion. not sure about the too much light problem.
 

Solo0420

Well-Known Member
ok so these are around 12 days old it's got good drainage the soil is a organic potting soil mixed with mushroom compost and chucky wood chips I jumped the gun and used old nutes to early one I think it was to much to early even tho I only used what was recommended ph was 6.5 I make the mix in 1 gal jug then fill a solo cup up and split between the two plants watering when it's dry the nutes are from about 5 yrs ago I think they are the problem that and way to early what do yall think
 

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raggyb

Well-Known Member
ok so these are around 12 days old it's got good drainage the soil is a organic potting soil mixed with mushroom compost and chucky wood chips I jumped the gun and used old nutes to early one I think it was to much to early even tho I only used what was recommended ph was 6.5 I make the mix in 1 gal jug then fill a solo cup up and split between the two plants watering when it's dry the nutes are from about 5 yrs ago I think they are the problem that and way to early what do yall think
funny I reply a lot in this thread and I'm not that great at this. But I know wood chips are no good and it looks like you have no perlite. Is there enough holes in the bottom of your solo? Are you saying you give 1/2 gallon per plant? Holy crap? You don't need any nutes when this small. Your avatar looks like you have done better so what's the story there?
 

Solo0420

Well-Known Member
yes I've done better this is my second indoor grow my avatar is from my out door grow my first Indoor went off with out a hitch lol I never really used perlite and I thought what I bought for potting soil already had that in there and it does not I have a bag coming in the mail I have to get everything onine nobody sells shit around here unless I drive 2hrs away so it's definitely not a draniage issue it is the nutes way to early but what I was doing was just mixing up a gallon at a time but only splitting a solo cup of water between the two girls but now that I'm pretty sure it's the nutes shocking them I flushed with just 6.5 hydro and it's been two day since I'll post pics later thanks for getting back tho very appreciative to you guys on here we brought eachother long ways keep growing big dawg
 

Solo0420

Well-Known Member
you guys think it's ok to pot up then mix in some perlite and sprinkle in a slow burn top coat or should I hold out and flush with 6.5 for another week roots are showing threw one or two bottom holes theres definitely plenty of hols I got 8 in each solo cup 4 in the bottom and 4 around the bottom sides but there's no way it's crowded
 

raggyb

Well-Known Member
if it were me I'd say there can't be much roots they are so small so you risk shocking them if you uppot right now so i think you have to accept they are going to go slow for a while in this setup. just water plain for now. when they start growing up pot but i think it's more than a week away.
 

iceman3000

Well-Known Member
Need a little help Fams! 20+ and seams to come across things I don’t have the answers for.. so we are seeing this problem usually about 1 to 2 plants for a room some 230 to 250 plants per room.. symptoms are like the plant didn’t get watered even though it still has plenty away to the pot.. it’s like it just crashes once the first signs are exhibited usually within 24 to 36 hours the full plant will crash but not die.. I have kind of ruled out all subterranean pest but I could be wrong.. it’s not strain specific like I said very random here are some pictures of a Mac that’s showing early signs it starts usually with 1 arm and moves on like I said it seems like the plant went completely dry is the only thing I Can say it reminds me of.. obviously everything is in balance because none of the other plants are showing signs so not a pH, nuit or environment Any help would be great 4991FFFD-3A36-4002-BEAA-970B803F6C40.jpegEA5A001D-6D7C-4C3F-AE6B-EBBDF831F334.jpeg4B88DBA1-37A8-4387-8546-A78E8F5E2FE2.jpeg1E58E0D9-5DEB-465B-8B7A-346C405FC618.jpeg
 

Kushash

Well-Known Member
Need a little help Fams! 20+ and seams to come across things I don’t have the answers for.. so we are seeing this problem usually about 1 to 2 plants for a room some 230 to 250 plants per room.. symptoms are like the plant didn’t get watered even though it still has plenty away to the pot.. it’s like it just crashes once the first signs are exhibited usually within 24 to 36 hours the full plant will crash but not die.. I have kind of ruled out all subterranean pest but I could be wrong.. it’s not strain specific like I said very random here are some pictures of a Mac that’s showing early signs it starts usually with 1 arm and moves on like I said it seems like the plant went completely dry is the only thing I Can say it reminds me of.. obviously everything is in balance because none of the other plants are showing signs so not a pH, nuit or environment Any help would be great View attachment 5034461View attachment 5034462View attachment 5034463View attachment 5034464
Looks like more than one problem. All pics especially the third pic leaf in the lower left corner looks like it might be bug damage.
Possibly spider mites.
Might want to start a new thread.
 

Sif1

Well-Known Member
What signs to plant exhibit if they are in a low humidity environment? My plants RH is 16-20% And I read thats way too low
Your RH is way too low. Minimum RH coming to the end of flowering is 30%, And that's pushing it.
 
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