Defoliation: Myth vs Science

It may surprise you to hear, that there is a small but very dedicated group of cannabis farmers who are convinced they can increasing their crops by removing ALL the big leaves in the flower cycle. Believers in this myth call the technique Schwazzing.

If you're a Scientist, the same thing is called "Abscission Stress" and the data produced by this group generally shows that any stress in the flower cycle results in lost profits.

You might think that any technique claimed to make a significant difference in the production of Cannabis flowers would be important enough that it would be tested and proven with some real data. Hopefully this would be a University study with no financial gain from the data, but even a private study could be fine if it were done well and not just to promote some product.

So far.... NOTHING!

Real data on this issue - with cannabis - simply does not exist.

Both sides are absolutely adamant in their conviction about how correct they are, but no matter what either side "thinks" they know... neither one can prove it.

To a scientist, the first law of thermodynamics states, "you can't get something from nothing" and this is one of the single most foundational observations of the universe. According to this concept, the leaves capture light and convert it into sugar which is used as the chemical power source to build the body of the plant, so removing the leaves will remove the power to grow, and thus have a negative effect on plant growth.

Believers in the myth say this treatment will somehow magically make the plant bounce back and produce even larger flowers than it would have if left alone under the same conditions.

Call me crazy but this just seems to defy physics.

However, I've been wrong before, and physics has been wrong before.... so I'm willing to hear this out.

Believers typically say things like,

Removing the leaves gets more light on the buds and that makes them grow bigger.

As a non-believer with a little science training and a lot of skepticism, I ask, "Why do you believe that?" To which they reply, "Because I've done it and it works!"

If you're a non-scientist, you might hear another grower say something like that and you simply take that word as gospel, without any supporting evidence, and that's all you need to create a FACT in your mind. This is a huge problem for our industry. The willingness of to believe something a friend says without any proof, is the very reason for the existence of the scientific method in the first place.

When I asked one grower to show me why he believes in this, here's what he said,

It's not bro-science, it's generations of growers passing down their knowledge of the plant. If you really are a cultivator you would know that pruning makes bigger final flowers

That statement is the "poster child" for the scientific method.

Right here is the point where non-science and real science split off on two different paths. Non-scientist types are accustomed to simply taking the word of a good friend, or an obviously successful grower. Especially when the information "seems" like it might be plausible. But they have not yet learned the value of the need to see some supporting evidence. A person with a little scientific training knows to be skeptical and ask some basic questions.

Oh, you've done tests.... so tell me...

• How many plants were in each test group?
• How many plants were in the control group?
• What variables did you limit?
• How many strains did you test?
• How many times did you repeat the test and get the same results?
• What steps did you take to equalize the environment among the groups?
• Did you perform the test at different weeks in the flower cycle?
• How did you standardize the harvest time between the control and the test groups?
• How did you define the difference between "A" bud, larfy bud and trim?
• Did you define defoliation so all plants got exactly the same treatment?

All that questioning typically results in either; an angry tongue lashing (how dare you not believe me), or a stunned silent pause because a non-scientist will not have done any of those things.

Occasionally I talk with someone that swears they did all that, so I drop the bomb...

That's awesome... can you show me your data?

NOT ONE PERSON, has ever produced a single scrap of actual data showing that they (or anyone) performed any kind of even moderately scientific trial - on Cannabis - that produced data that actually supports this weird Bro-Science myth. I've seen a little data on studies of defoliating other plants, but Cannabis is different, because once you enter the flower cycle, Cannabis is on a countdown that can't be stopped. Sure your plants would recover if you had a month to wait, but with Cannabis, you can't just pause the timer.

But guess what!

I can't show them my data either because this study has never been done!

Here's what I think I know because it "seems" plausible to me... When you flip the lights to 12/12, the race is on! Creating a stress event in the flower cycle is the equivalent of tripping a runner in the middle of a race. That runner can still get up and continue on to the finish, but it will either be later, or your flowers will be smaller. Longer time, or smaller flowers both equal money lost to a commercial farmer.

Yes, I realize that what "seems" to be right to me, is the same as what "seems" to be wrong to them - which perfectly illustrates the need for some data. Somebody has to do this test!

The simplest fact that I think we can all agree on, is that leaves are the solar panels that gather energy from light and convert that energy into food, which is then used to grow the body of the plant.

If you take the leaves off, you reduce the energy gathering capacity of the plant, and since you are on a limited time schedule, you don't have time to pause to recover, so you've limited the final size of the end product.

This defoliation myth requires us to believe that a SEVERELY defoliated, super stressed plant, can not only recover, but then come back and EXCEED what it would have done naturally without that stress. This is the part that defies physics.

You simply can't get something from nothing. If you manage to prove you've done it, I'll happily attend the awards ceremony where you get your Nobel Peace prize for disproving one of the most fundamental laws of the universe.

This issue perfectly represents the quandary of the current state of the Cannabis industry where the people that know the most about growing Cannabis and truly have the passion to stick with it, generally don't come from scientific backgrounds. They're great people, and many are brilliant at growing cannabis, but they never got that background education that makes a scientist agnostic about everything.

A scientist learns that you never believe - or disbelieve - until some logical information presents itself and provides a clear reason for leaning one way or the other.

Most cannabis farmers will certainly have spent some time studying their favorite plant, but how many actually sit down and truly study basic Biology, Chemistry or Physics textbooks? Missing out on that foundation creates big holes in the picture when you're trying to be a horticultural scientist - which you are if you're serious about grow pot.

Claiming the title "Master Grower" perfectly illustrates this issue. In the rest of the agricultural world, you can't just randomly bestow upon yourself the title "Master." Agronomy and Horticulture students spend years of dedicated study before a Masters Degree is bestowed upon them - by others. You can't just walk out from your first garage grow and claim that title for yourself. To be a Master actually means something. You get trained in Chemistry and Physics and Biology, and along the way you learn critical thinking, and the scientific method, and you understand the importance of performing studies that can be repeated and are published openly in Scientific Journals. In the cannabis world, that broad range of training is often missing.

We have a generation of highly skilled Cultivators with a lot of very real knowledge and experience, but without the science training they need to help them see through the mythology we get from other growers, and the outright deception we frequently get from product manufacturers.

We have to acknowledge where we come from. In the not-so-distant past, writing an article about growing was like printing your own ticket to prison, so it was hard to find information about growing cannabis. Someday those times may come to be called, "the dark ages of pot." If we want to really learn about our girls, we have to let go of those ways and rely on the scientific process enough to begin questioning all these myths that began in those times and are still being taught today as if they are fact. We have to learn to apply that scientific agnosticism and question everything that we think we know. Otherwise we'll just be stuck there in the dark.

Now that we can actually talk, and write openly... We have to learn to think like a scientist to get some real answers to the questions we've only guessed about in the past.

This issue of Defoliation, or Abscission Stress when it's done in flower, is only one of the many questions we have to answer. But as scientific experiments go, this is a super easy test to perform. It doesn't require a big budget or any technical tools to answer the question. All it takes is a little careful preparation to design a test.

Let's Do It!

I'm proposing that we (commercial growers), devise and perform, a real scientific test that can put this baby to bed once and for all, and make the results openly available to all growers.

I'm hoping that by openly designing and performing this test as a group, maybe a few Bro-Scientists will join in and begin to see the beauty of working and thinking about farming in a more scientific manner.

CAN YOU DO THIS TEST - AT YOUR FARM?

HERE'S THE QUESTION:

Does removing the leaves from a Cannabis plant, at different times in the flower cycle, have any impact on:   

1. Dry usable "A" grade bud weight
2. The ratio of "A Bud" to "larfy bud"
3. THC, CBD and Terpene levels

TEST METHODS:

• Using a single strain of plants at a time, in good health, started from evenly sized clones, grown under uniform feed/water/temp/humidity conditions, and NOT using the outside rows of the garden where light will be uneven.
• All plants undergo the same topping schedule to create an even and flat canopy.
• All groups undergo the same preventive IPM spray schedule.
• Plant clones into final pots or beds and begin defoliating 3 weeks later.
• Do NOT remove any leaf or bud due to discoloration, aging, Powdery mildew, Budrot, or other issues. (These conditions may be caused by defoliation)
• During each week of the entire veg and flower cycle, take one test group of plants and remove ALL leaves that measure greater than 2" across.
• Keep one bed untouched to act as the Control group.
• The total number of defoliated beds will depend on the ripening schedule of that particular strain, so if it is an 8 week strain you will have 7 test beds. A 12 week strain will have 11 test beds.
• ONLY the Control Bed will be used to determine maturity, measured as roughly 25% amber Trichomes. The actual harvest date is not critical as long as all beds are harvested on the same day, and ONLY the maturity of the control bed is used to determine harvest date.
• In order to properly account for the possibility of delayed onset of maturity caused by early defoliation, all beds must be harvested at the same time as the control bed - even if they are not fully matured at the same time.
• Test each group, for THC, CBD and Terpene content.
• After trimming all buds, the finished material is passed over a screen with openings of roughly 5/8" to 3/4" to searate the Top grade buds from the B grade and trim.
• Dry buds with visible Powdery Mildew or Budrot are weighed and separated. This group is listed as "discarded" to account for the possibility of defoliation causing an increase in the occurrence of fungal pathogens.
• This list is just a start. There are FAR more variables that need to be defined and controlled before you actually run the test - let's talk.

If you are the lead cultivator in a large farm with tightly controlled environmental conditions, perhaps you can volunteer to perform the test???

We need multiple farms to run the test with different strains each time.

We need to get results from at least two strains in each group of Sativa, Indica and Autoflower.

Any thoughts on how to design the test? I would be happy to work with you to create an outline for how the test is to be performed.

After a couple test runs are complete, I will put the results in a spreadsheet and make it available for everyone.

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My own predictions...

I'm not trying to promote more myth here but I do have a side prediction that I'll throw out because I think it might entice some of the more serious farmers into helping with this project. In a different study I found recently, cannabis plants were severely wilted (drought stressed) but only in week 7 and the results were STUNNING!

This study performed by Deron Caplan at the University of Guelph...

Upon harvest, drought-stressed plants had increased concentrations of major cannabinoids by 12% compared with the control.

Further, yield per unit growing area of THCA was 43% higher than the control, CBDA yield was 47% higher, THC yield was 50% higher, and CBD yield was 67% higher.

What would happen if you combined drought stress, with abscission stress in week 7?

We have Soooo many exciting questions to answer...

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Other articles by Glen Johnson:

Defoliation vs Science / Cloning Studies / Do You Defoliate / Flushing Debunked

Copyright Glen Johnson 2020 [email protected]