Problem with leaves on White Widow - Any suggestions?

[thehiker]

I have three WW plants in FFOF. I'm using 2 x 300W LED arrays plus 3 x 100W CFLs. They were started from feminized seeds in July and I flipped them in early Sept. I don't over water and use very small amounts of MG general fertilizer. About 4-5 weeks into the grow, I started to see some abnormal leaves, mostly on one plant. The plants appear to be growing ok and I have plenty of flowers. White "dust" is beginning to show up on many of the flowers, and the nugs are swelling. Can anyone tell me what the cause of this problem is?

Thanks everyone!

The Hiker

 

[Sorenna]

Hello, Hiker. Check out this link that shows pictures and gives descriptions of many plant issues.

Some plant deficiencies - Blogs - 420 Magazine ®

Good luck!

 

[Weaselcracker]

I think it is calcium deficiency, sometimes called 'calmag' deficiency. The usual solution is to get cal-mag supplement and feed it to the plants every time you water, at the rate of about 5 ml/gallon.

 

[Sorenna]

I think it could be a phosphorus deficiency caused by the MG general fertilizer. I think a food that is bloom specific is needed.

Disclaimer: I have only been growing myself for less than a year and have not personally had a phosphorus deficiency, but I think it makes sense. I could be wrong, however.

 

[Weaselcracker]

It appeared 5 weeks into veg? Or into flowering? That time in veg is when I'd normally see the calmag issue. If it was 5 Weeks into flower would be a different story then -more what Sorrena said

 

[thehiker]

Thanks everyone!

This occurred about 3-5 weeks into vegetative growth. I'm leaning towards calmag deficiency. Later leaves didn't appear to have the problem.

At this time, I'm 4+ weeks into flower. Lots of buds forming and trichomes developing on all plants. I'm contemplating doing a flush with distilled water, but since buds seem to be developing nicely, I hesitate to "rock the boat" so to speak. The plants don't seem to be developing many new leaves at this stage of growth. I estimate I have another 4-5 weeks of flowering before chop. Would a flush slow down or inhibit the plants' growth? Comments?

Hiker

 

[iwltfum]

Hi there thehiker,

She definitely has a deficiency that you should take care of, but the white dust peaks my curiosity (even though I couldn't find any in the pictures). There are two options that cross my mind when considering what it could be. It makes me think of either pollen or mildew. If it's either of these, it is an important issue! Check for preflowers and if you find any, try to identify them as either male or female. I think visible amounts of pollen only get released when white flowers (with pedals) are visible, but I'm not positive. As for the mildew possibility, maybe you could take some pictures of this white dust? It would help alot with identification. Cheers!

 

[Weaselcracker]

T.Hiker could you post some more pics? And some more info about what they're/it's growing in and feeding routine, etc? I'm not saying I could answer your question for sure- but if not- others can. If the issue isn't spreading and it was just an issue with the older leaves during veg then I wouldn't flush. They don't need as much calmag later in flowering as far as I know. Flushing wouldn't help if it's a calmag issue, (barring some sort of lockout from high levels of other nutes, which may be possible I suppose) I'm not an expert on the subject- and it's super complicated.
But generally - if a plant has buildup of nutrients in the medium that you want to get rid of, then flushing is the way to go.

 

[thehiker]

I may have confused you with my choice of the term "dust". It's actually the thick trichomes that are covering the buds. There's no mildew or mold (I'm a microbiologist and would recognize those). Thanks for you comments.

 

[thehiker]

T.Hiker could you post some more pics? And some more info about what they're/it's growing in and feeding routine, etc? I'm not saying I could answer your question for sure- but if not- others can. If the issue isn't spreading and it was just an issue with the older leaves during veg then I wouldn't flush. They don't need as much calmag later in flowering as far as I know. Flushing wouldn't help if it's a calmag issue, (barring some sort of lockout from high levels of other nutes, which may be possible I suppose) I'm not an expert on the subject- and it's super complicated.
But generally - if a plant has buildup of nutrients in the medium that you want to get rid of, then flushing is the way to go.

Hi again.
This grow is 3 WW from seed. I'm growing in FFOF. I'm using 2-100x3W LED arrays and 3-100W CFLs for side light. After about 4 or so weeks of vegetative growth, a number of larger fan leaves on two plants developed the brown spots visible on the photos. I flipped to flower on Sept 9. The spots spread to other leaves in the last 3-4 weeks. Smaller fan leaves near the tops of the plants curled up, in addition to the spreading brown spots. Many of those leaves have died and I trimmed them off. I'm sure this has reduced the photosynthetic potential of the plants by 30-40%. The plants also did not stretch very much when I flipped. I was using a very rich MG multipurpose fertilizer, but not every watering, and only about 1/10 to 1/5 strength. When the brown spotting appeared, it was very quick...like over a weekend from no leaves affected to 20% of major leaves affected. Right now, the plants are growing and buds are getting larger...just a few of the white hairs have turned golden brown, so I estimate another 4 weeks of flower until chop. The leaf loss is going to cost me quantity...hopefully not quality. I decided to flush one of the plants to see what happens...I figured it couldn't hurt. I'll post some pics in a few days.

I should also mention that my last grow was AK-47 from seed, and a similar problem happened to that grow. I'm thinking the MG notes may have had something to do with the problem. Next grow is going to be strictly organic.

 

[Emilya Green]

I find it curious that no one has asked you about pH. Do you adjust to any particular pH when you apply fluids to your plant?

 

[fanleaf]

i find it curious that no one has asked you about ph. Do you adjust to any particular ph when you apply fluids to your plant?

bingo! Yahtzee!

 

[thehiker]

bingo! Yahtzee!

pH has consistently been 6.5 - 7.0

 

[fanleaf]

pH has consistently been 6.5 - 7.0

MG ferts are never recommended. There are plenty of easy to get and inexpensive nutes that are made for cannabis. Has the pH of the water/ nutes or pH of soil been 6.5-7?
What soil?

 

[Emilya Green]

pH has consistently been 6.5 - 7.0

if you have been adjusting on the high side, or at 7, I can see where you could easily be having trace mineral deficiencies due to pH. If you would have said that you are lock tight on 6.5 every time you add fluids, I would still be perplexed. You giving a range like that tells me that you probably don't pay much attention to pH and are using test strips at best to measure it and it is my opinion that if you want to get rid of this deficiency you are going to have to take pH more seriously, and adjust it down just a bit. Keep in mind too that this is a logarithmic scale, and that 7.0 is 5x more base than 6.5... it really is a huge difference between those range limits.

 

[thehiker]

if you have been adjusting on the high side, or at 7, I can see where you could easily be having trace mineral deficiencies due to pH. If you would have said that you are lock tight on 6.5 every time you add fluids, I would still be perplexed. You giving a range like that tells me that you probably don't pay much attention to pH and are using test strips at best to measure it and it is my opinion that if you want to get rid of this deficiency you are going to have to take pH more seriously, and adjust it down just a bit. Keep in mind too that this is a logarithmic scale, and that 7.0 is 5x more base than 6.5... it really is a huge difference between those range limits.

Thanks for the advice. I'm growing in FFOF. I have a small Rapidtest pH meter. It's a cheapy, but I periodically test it against dilute lemon juice or a ground up antacid tablet (sort of poor man's pH standards). It does work adequately. It seems the soil is very good at buffering pH. I've never had readings above 7 or below about 6.6. It stays pretty close to neutral. I have a couple of years of general, organic, and biochemistry...I do understand what pH is about. I've never had to adjust pH of the soil....it just always measures in the range.

At this point, I've flushed all plants and they seem to be hanging in there. I'm about 6 weeks into flower and even though I've lost lots of leaves, the buds are looking nice...swelling slowly and I'm seeing lots of trichomes on the buds and surrounding leaves. It looks like a covering of "snow" or "white dust"....call it what you will. About 20-30% of the pistils have changed from white to a dark orange color. So, the yield may have been greatly affected by the lost leaves, but I'm hoping I'll still get a couple of dry ounces of bud from the 3 plants. I hope it's potent and tastes OK. After the flush, I gave them some Big Bud and Epsom salts. That's all I'm giving them until chop in another 3 weeks.

 

[Emilya Green]

Sorry thehiker, but your soil pH reading is mostly meaningless. From the moment you water a container of soil, that water starts reacting to what is in the soil, and your pH starts to drift upward. At best a measure of soil pH is just a moment in time, and tells you very little about what is going on.

Furthermore, if you have never had a reading below 6.6, then of course you are having micronutrient deficiencies, because they are not picked up very well above 6.5. Neutral or 7.0 pH is NOT good... stop thinking that it is... it is way out of the usable range.

When you saturate your soil, for that moment the pH inside of that container has to take on the pH of the water that you just applied... it has no choice, about 2/3 of the volume of that container will be water at that point. If you insist on keeping your pH high, you will continue to have these deficiencies... there is no magic here that makes that not happen. Adjust your pH to 6.5 every time, and your soil WILL take care of itself.

 

[thehiker]

This is confusing. i've read a lot and seen that hydro grows seem to require a lower pH than soil grows...at least that's what I've taken away from my readings. (Seems every question has several answers, depending on who is answering.) I've seen recommendations that state any pH from 6.0 - 7.5 should be fine in a soil grow. I don't agree with the upper end of that range, but felt my actual readings (mostly 6.7 - 6.8) would be acceptable. Next grow I'll aim to reduce pH down to a 6.3-6.5 range and see what happens. I may be over-thinking this, but I was wondering if the MG fertilizer that I used with high P might tie up the calcium/magnesium ions at the more neutral pH. Those phosphates have relatively low solubilities. Maybe a bit more acid will prevent the precipitation or dissolve any phosphates that may have formed. Oh well...just thinking there.

I am really appreciative of all the comments I've received.

Even though I've had a lot of leaf loss, this grow seems like it will still be good. I have lots of large and swelling buds, covered with trichomes.

 

[Emilya Green]

These plants are extremely resilient, and I too am convinced that you will have a wonderful harvest. It could have been better though, we generally these days are dealing with some highly superior genetic lines and most of us fail to meet the full potential of these hybrids.

You are also exactly right about the MG soil... I found my best pH response using that soil was by watering at the low end, and I always adjusted to 6.3. Now in a well constructed soil, I shoot right for the middle, or 6.5, every time.

The growing world is a very confusing place. I have been writing about growing for several years now on various boards, and I am even appalled at some of the early things that I have written in the past and the misconceptions that I had at the time. I am just as sure that given another 5 years, I may have changed some of today's opinions and beliefs about growing, but I like to think that over time I have gotten pretty good at this stuff and that my writing is becoming more consistent.

As you are seeing however from this discussion, it is not only possible, but necessary, to take what we know from our own educations and our own set of expertise, and apply it to the grow room using logic and common sense. I am an economist by trade, and look at all interactions as a counterplay between opportunity costs and diminishing returns. You are able to look at the chemical reactions with expertise, and that can definitely be applied to what you are doing here in this hobby. Hopefully I helped form a connection in your mind to the role of the acid to break down the nutrients and organics into their component elements, and with this epiphany you now can logically apply what you know to the grow room.

Live and learn they say... we all get better at this over time.

 

[thehiker]

if you have been adjusting on the high side, or at 7, I can see where you could easily be having trace mineral deficiencies due to pH. If you would have said that you are lock tight on 6.5 every time you add fluids, I would still be perplexed. You giving a range like that tells me that you probably don't pay much attention to pH and are using test strips at best to measure it and it is my opinion that if you want to get rid of this deficiency you are going to have to take pH more seriously, and adjust it down just a bit. Keep in mind too that this is a logarithmic scale, and that 7.0 is 5x more base than 6.5... it really is a huge difference between those range limits.

Thanks for all the suggestions! I just wanted to sort of summarize/end this thread and not leave it hanging. I've learned a great deal. From the 3 "less than great" plants I harvested, I got a total of about 2.5 ounces (dried) of reasonably decent product. (I think I was lucky)

Now I have a chance to put all the suggestions to work. I took 2 cuttings from one plant about a week after I flipped them to 12/12. I just wanted some experience cutting and rooting clones...never did it before. I used a rooting hormone, got good roots after about two weeks under 24 hour light. I put them in FFOF under 24 hour light for about 3-4 more weeks. I couldn't just toss 'em, so I decided to grow them out with some of the things I'd learned from this last grow. I transferred them to 2 gal Smart Pots and 18/6 lighting. Instead of just adding water/nutes like I did with the last grow, I prepared the water with a bit of fish emulsion, adjusted to pH to about 5.5 -5.9 with a meter, and added about 3 quarts until I got about 1 quart to drain out the bottom. The water that drained tested at about pH 6.0. I stopped using a soil pH meter...I had 2 but they seldom gave me readings below pH 6.8, no mater how low the pH of the feed water was set to. I didn't think the soil meters were very helpful.

The clones are doing very well right now. I flipped the lighting at about 5 weeks into vegetative growth. I'm two weeks into "flower" and the plants look healthy. I've not seen the leaf loss that I experienced with the mother plant and her mates...in fact, there have been no dropped leaves! Now I have plenty of nice looking flowers forming. I'm keeping up the watering/draining regimen with fish emulsion and a little "Big Bud" fertilizer. I use some phosphoric acid pH down and some baking soda for pH adjustment when necessary. I also add about a quarter tsp of epsom salts and a gram of sugar per liter to the water/fertilizer.

As I said earlier the plants look great...the best I've grown so far! I'll never go back to hard plastic pots. The Smart Pots are far superior, IMHO.

Thanks everyone again for all the suggestions!

Hiker