Scientific evidence for selective DEFOLIATION

[Weezard]

In the 60's growers were using hot ass Halogen lights to grow indoors, and indoor grows were extremely rare. So are you saying that you defoliated an outdoor plant back in the 60's??

Im confused.

Nope, not what I said, and I never used Halogens.

Well actually,I did, once, for about 2 weeks.
Then tried incandescent.
Won't do that again.

Went from 6 foot fluorescent "shop lights", to Growlux fluorescent tubes as soon as they hit the market.
Claimed to be more efficient because they targeted the red and blue chlorophyll peaks.

They actually worked quite well.
Did a side by side under growlux in '72.

Had a friend offer to show me the "right way" to selectively prune.
Was all excited after hearing about it and then having a pro grower show him how.
Went on and on about how it improved his entire crop.

Wanted to do my whole crop too.

I needed to know if it actually worked, so I insisted that we only molest half of 'em.

Turned out to be a good call.
We both learned something.

And by the early '70s metal halides and HPS lights were available, but expensive.
So, when I started growing outdoors, I already knew better than to chop healthy fans.

Now I'm sittin' at my 'pooter waiting for some real science to make me re-think my conclusions.

Aloha, and thanks for asking.

Weezard

 

[Weezard]

I remove the lower branches too, but to be honest I also used triacontanol on the last grow and a lot of my mates are reporting heavier crops of denser flowers using it too so that could have been responsible

I know its off topic but I really recommend triacontanol, I think its brilliant. Someone I know consistently hits 500g per sqm and last grow got 650, only difference was he used tria

You are kind of missing the point here.
A statement like, "This crop is 150gpsm better than my last crop!"
Is worthless as it stands.

If your crops don't get better with each grow it means you didn't learn much from your last grow, yah?

Giving credit to a variable that applies to the whole crop is fuzzy thinking.
It's how all that worthless crap on the Hydroshop's shelves get sold.

Had even one of your mates applied it to only half the crop, he would only have to stand there and point at the happier side to prove, or disprove his belief.

Do you see what I'm saying here?

Anecdotes are fun, and may actually have some truth to them.
But good science, validates your premise upon presentation.
Think on it.

Aloha,
Weeze

 

[SativaBreather]

thats all well and good, but I'm capable of knowing by knowing

if someone maxes out 500g every crop then changes one thing and gets nearly a third more, that works for me

plus another 2 buddies have just significantly broke the 1gpw for the first time - guess what? Only thing different was they used triaconatanol

 

[Weezard]

Ok brah,
I'm happy for you.
Carry on,

Weeze

 

[siftedunity]

I remove the lower branches too, but to be honest I also used triacontanol on the last grow and a lot of my mates are reporting heavier crops of denser flowers using it too so that could have been responsible

I know its off topic but I really recommend triacontanol, I think its brilliant. Someone I know consistently hits 500g per sqm and last grow got 650, only difference was he used tria

I think ive read abit about it. where do you get it?

 

[siftedunity]

tbh yield is more or less strain dependant anyway. ive hit silly numbers before with high yielders but the quality generally isnt there. I like to judge everything by taking everything into consideration. like veg time/flowering time/space/wattage/electricity compared to yield/quality. I mean its like the a popular cut around at the moment is classed as a ''high yielder'' but then they have to veg it for three months in a 12 gallon pot lol its all relative.
the perfect plant for me roots easy, not a fussy feeder, vegs up in 4 weeks, doesn't stretch too much, then yields good at the end with a good quality out come.
another thing about defoliating is that surely you must be allowing for recovery time unless you do it in flower. and if you do it in veg your gonna increase the overall veg time.

im open minded to seeing defoliation work but atm im a non believer.
another thing which ive just thought of is that uptake of water and nutrients are directly affected but how much leaf surface area you have because transpiration from leaves is what pulls water/nutes back into the plant.
it seems like , common sense and scientific fact imply that you will yield less if you defoliate. fans of the method say you yield more.

 

[SativaBreather]

thus far I have only defoliated in flower no earlier than 3rd week in after I have used SWITCH which stops the stretch and puts em into flower within 4/5 days of 12/12

 

[SativaBreather]

I think ive read abit about it. where do you get it?

from a small UK based company called Triaplantanol.
comes in sachets that you add to 5 litres of water and foliar in veg
and/or
a 6ml test tube that you can add either to a big 200l rez/water butt or you can add to a bottle of gro/bloom, shake and then use as normal.

it is the bollocks, seriously

 

[siftedunity]

does it affect the quality?

 

[SativaBreather]

does it affect the quality?

quite the opposite in my experience, assuming you meant negatively
increased resin production, flavours not effected adversely

i got 4-5 mates on it and they'll never stop now they love it

 

[Weezard]

Triacotanol is available on Ebay.
And it does work on many different crops, including MJ.
And there is acceptable scientific proof that it works.
For instance:
http://link.springer.com/article/10.1007%2FBF00388770#page-1
There are also side by side growths of cannabis that prove it's worth.
And it's a plant hormone that is relatively non-toxic.

Now, If I could find that sort of proof for selective defoliation, I'd happily reverse my position and grab my pruning shears.

That's all I'm asking.

Aloha,
Weezard

 

[Elite Nugz]

thats all well and good, but I'm capable of knowing by knowing

if someone maxes out 500g every crop then changes one thing and gets nearly a third more, that works for me

plus another 2 buddies have just significantly broke the 1gpw for the first time - guess what? Only thing different was they used triaconatanol

1 gram per watt is only 2.25 pounds per 1,000 watt light.

I pulled 27 pounds off of 10 lights. The only crazy chemical that I used was Phosphoload. LoL. So thats 1.2 grams per watt, without mutilating my plants. I just pumped em up with some steroids. lol.

 

[SativaBreather]

are you broken ?

I'd rather defoliate than pump my plants full of carcinogenic shit. That crap you use contains 17,800ppm Daminozide and 20.6ppm Paclobutrazol.

so well done you and ya 27 lbs lol you must be proud of ya cancerbis

any monkey can get big yields using that shit but the quality is wank and your conscience absent

and I've hit 1.5gpw with no defoliating, c02, triacontanol or pac
just good afghan genetics

 

[Weezard]

Well, on this, I'm going to have to agree with SB.
(Not on defoliating, yet. )
But this shite is not arguable!

"These two dangerous chemicals are not approved for crops intended for human consumption, and should never be used for growing medicine."

And that is why I grow my own medicine.

You can not trust meds that are grown for profit!

We have patients with severely compromised immune systems.
I used to say that no one should ever do a day in jail for growing Cannabis.
I look at crap like this, and think it's time to start making exceptions to that rule.
Using banned chemicals on meds to increase return on investment is a criminal act.

Where's the love?

Weeze

 

[Sativied]

yes we all leaned about photosynthesis.

The most knowledgeable people in the field still learn about photosynthesis, you cannot dismiss the photosynthesis factor that easily.

Although it has been mentioned in the quote in the first post (the part that doesn't really suggest defoliation), the words source and sink rarely come up in these discussion while that's what it's all about. Max yields are achieved by an optimal balance between sources (leaves) and sinks (fruits, flowers, roots, stems). While it's possible to improve the balance by removing some sources, you can't measure it and the results will differ per species, strain, phenos and even clones. Perhaps that explains why some are so sure they see improved results (I doubt most actually used a scale to make that determination though), it 'can' work. Just like you 'can' win the lottery.

For example:
http://link.springer.com/article/10.1007/s11099-012-0029-3#page-1

Note it specifically mentions lower and senescing (deteriorating) leaves and not removing healthy leaves near that supposedly cause shade.

Google for defoliation sink source and you can find a large amount of relevant resources with an even larger amount of more conflicting results and hypotheses. I could make a strong case for and against defoliation based on nothing else than articles as the ones in the first post. Point is, one more or less about apples or pines or grapes or soybeans isn't going to make a difference.

 

[mojave green]

balance is good

 

[FRIENDinDEED]

It sure would be nice to see this type of testing done on actual marijuana plants.

so you need to go check out the defoliation thread that's been created and gets updated damn near weekly with ppl still trying to quell the nay sayers

as for me, yeah, proper defoliation is a way of life

 

[EclipseFour20]

Some points to ponder about partial defoliation (25% or so).

1. Increased photosynthetic rates are observed in most plants. An increase in chlorophyll concentration leads to an increase in the amount of photosynthetic enzymes.
2. Increased leaf Nitrogen, Phosphorous, and Silica are observed after partial defoliation.
3. Decrease in carbohydrate levels due to altered source-sink relationships.
4. Increase in Brix and Light-saturated CO2 uptake.
5. Decrease in stem size, but application of Nitrogen before defoliation will increase stem diameter
6. Timing is everything. Carbohydrate supply at flowering is a primary determinant of fruit set, and early leaf removal (grapes--four weeks after flowering) reduced yield, but when performed later, yield was not be impacted.
7. Reduction in leaf canopy increases light penetration, air movement, and can reduce the occurrence of PM (less fungicide sprays).
8. Defoliation rates for these plants had NO effect on yield: 25% oranges, 20% apple, 20% sour cherry, 25% tomato, 40% hybrid clone tomatoes, and 25% grapes.

The attached pdf files are the sources for my above observations and contain good references to more science--and yes, they discuss non-cannabis plants; could not find a single cannabis defoliation study.

So...it seems that defoliation around flowering time is where many will "succeed" or "fail"--so "when to defoliate" is the real question...as opposed to "should I". After all, pruning, training, bending, topping, fimming, lollipopping, etc....are popular tricks of the trade that most cannabis cultivators do regularly. IMHO, defoliation can be a good thing--or a bad thing, depending on severity (percent leaves removed) and timing (when and frequency).

My $0.02....cheers!

 

[Cat Jockey]

So are you saying that you defoliated an outdoor plant back in the 60's??

I certainly cannot speak for Weezard, but these two did:



And concerning the thread, IMO, there is only one lady in that pic that should be naked.

Put me in the selective defoiliation camp. I don't do it in vertically RDWC systems and only selectively, mostly due to light penetration issues, on horizontally lit Ebb & Flow systems or dirt.

I have not read that paper, though I am going to today, but plant species differ, in many areas. Hell, there are species of plants that eat meat - carnivorous.

You can find species that like a pH range in the high 4's, for example. Take a cactus to the rain forest and see if it survives. I always keep my mind open to change, but seed production and protection is the number one goal of our girls. If bigass fan leaves hindered and competed with the plants ability to survive and pass on its genes, Sweet Lady Jane would be gettin' nekid faster than a $10 hooker - dropping big fan leaves left and right during final maturation of the flowers.

But she doesn't. And the farmers, like me, that enjoy a good flush and yellowing of some of those fan leaves in the last week or so of flower have seen a different side of those leaves. Namely, bud factories. They supply the flowers with nutrients, when the root zone is not supplying enough. Another knock against major defoiliation of large fan leaves - you remove your margin for error.

I am open to fan leaves competing for growing energy, but at this point, I ain't there with defoiliation being good for yer ladies and providing you with more, higher quality bud.

 

[Cat Jockey]

That's an interesting sig you have:

... regarding "advance topics", why help those that refuse to help themselves?-

I think differently. That seems to imply 'you're right, they're wrong and won't listen to me on advanced topics'. You are not going to include me in that sentiment if I disagree on your take on an advanced topic, are ya?

Some points to ponder about partial defoliation (25% or so).

1. Increased photosynthetic rates are observed in most plants. An increase in chlorophyll concentration leads to an increase in the amount of photosynthetic enzymes.

Me no likey weed that tastes like hay.

2. Increased leaf Nitrogen, Phosphorous, and Silica are observed after partial defoliation.

Me no likey weed that tastes like hay.

3. Decrease in carbohydrate levels due to altered source-sink relationships.

Me no likey weed that lacks cured aromas and flavors, due to decreased carbohydrate levels.

4. Increase in Brix and Light-saturated CO2 uptake.

That's pretty sweet. But it obviously comes at more than one opportunity cost ...

5. Decrease in stem size, but application of Nitrogen before defoliation will increase stem diameter

Me no likey the lesser of two evils: Do I risk broken stems half way through flowering in a vertically lit RDWC 'cause the nugs are that heavy, or to I undo the stem growth retardation by adding more N during flower?

Me still no likey weed that tastes like hay, and I really hate billy club colas falling over and breaking the stem, 'cause it's weaker, and has less surface area for internal plant processes.

6. Timing is everything. Carbohydrate supply at flowering is a primary determinant of fruit set, and early leaf removal (grapes--four weeks after flowering) reduced yield, but when performed later, yield was not be impacted.

So, defoliation part way into flower, reduces yield in grapes? And after defoliation later in the flowering stage, yield was not affected. Meaning it didn't go UP. So why do it?

7. Reduction in leaf canopy increases light penetration, air movement, and can reduce the occurrence of PM (less fungicide sprays).

I do recommend selective defoliation for that with horizontally lit indoor grows.

8. Defoliation rates for these plants had NO effect on yield: 25% oranges, 20% apple, 20% sour cherry, 25% tomato, 40% hybrid clone tomatoes, and 25% grapes.

No effect, than why do it? And what other negative effects did they test for? Taste? On 'potency', however one would measure the potency of a tomato? On what particular strain eased one's medical condition the most effectively? They performed limited testing for limited things. And they didn't test for many of the things we weed farmers concern ourselves with.

So...it seems that defoliation around flowering time is where many will "succeed" or "fail"

Succeed at what? Apparently, yield isn't increased. On the contrary, even if yield remains constant, looks to me like a risk for a reduction in aromas, tastes and effects.

--so "when to defoliate" is the real question...as opposed to "should I".

Says you ... But I read the quoted findings differently regarding that decision. I do like natural defoliation - a flush, yellowing and dropping of larger fan leaves in the last 1-2 week of flower, but that's it.

After all, pruning, training, bending, topping, fimming, lollipopping, etc....are popular tricks of the trade that most cannabis cultivators do regularly.

And all of those mentioned techniques do not produce the exact same results. Some of those tricks, well, people need to discard them from their bags. Further, some of those tricks, like LST, are not fully understood, nor properly demonstrated in many, many stickies and threads on all of the weed forums.

IMHO, defoliation can be a good thing--or a bad thing, depending on severity (percent leaves removed) and timing (when and frequency).

With the objective of achieving what goals? Yield? Potency? Taste? Satisfying idle hands?

All my opinion, of course.