To Defoliate Or Not To Defoliate

[Dutchman1]

OK OK, I want to hear what you feel is the best way to defoliate or not defoliate from what you have learned. You surely have an opinion at this point. I feel like your still skirting the issue even though you have provided a lot of information at this point. even though you did say that most of the defoliation done by people is incorrect ( in so many words) .

[DrPhoton]

I have reconfigured the explanation for defoliation and omitted, changed and moved the second paragraph mentioning the process.

"There are various methods on how it is recommended to be performed, but typically it will involve the selective or non selective removal of leaves, of a varing amount at varying times during a plants grow. This is dependent on the method provided by the grower and their reasons or beleifs which define the process."

"Removal of lower or older leaves or braches, with less exposure to light, could impact a plants performance, however i would not consider this part of the typical use of defoliation for improved yield but the more practical form through pruning practices.
To some extent plants do this themselves, like how leaves are abscent inside a bushy tree. We do this also by methods such as lollipopping. However this is a proven method and is practiced throughout horticulture."

[DrPhoton]

Good question and i can see your confusion. The problem may be down to what i define the difference between selective and non selective. The selective and non selective terms i associate with location of removal. For example, using non selective herbicide does not differentiate between different weeds, so it is not subjected to a selective process.
I chose that wording to differentiate between defoliation for improved yield and defoliation where leaves are removed for improved health. Such as lollipopping or dead leaf removal etc.

Defoliation describes the process of removal or loss of leaves. It does not describe the methods or purposes it may be used for. That requires extended terminology wether that is current or new.

The other problem is that the different methods of defoliation out there, are based on different things. If one develops their method from their beleif on plant stress response. Then the matter of defoliation is a non selective process as the location of removal is irrelevant. However other methods may be selective.

It may be that i need to redefine the terms as they can mostly be viewed as selective processes as well.

What you think ?

[Obi-Wan]

This is a great article, Thank you for taking the time to research and summarize the information. As a grower that practices controlled and selective leaf removal I have a few follow up questions for you regarding sections that left me somewhat confused as well as pondering what might be a greater reality.

As you close out your introduction you state:

“ There are various methods on how it is recommended to be performed, but typically it will involve the non selective removal of leaves of a varying amount at varying times”

Then under the section titled Air & Light on Leaf Photosynthesis, you state:

”The traditional method of defoliation is a non selective process that removes specific amounts of leaves at specific times. What is usually practiced and is learned through experience is how much is too much, when & how often such a process should be used during a plants life.”

So my confusion is centered around the idea of selective leaf removal. When specifying how many leaves, from what location,at what times, and how frequently. Did we not just create a specific process for selecting leaves for removal?

If so, is a good portion of the controversy surrounding the issue of defoliation simply a misrepresentation of terminology, with some using the text book definition of the word while others practice a more selective approach?

[DrPhoton]

Yes, although i make the comment about leaf transmittance, not all light makes it down. Eventually the light that passes through leaves gets absorbed, by the time you get to the bottom there is not much left. Removing branches that develop flowers is beneficial here as they will only create smaller larfy flowers. So instead that energy is directed to the main flower sites.

[Dutchman1]

Great stuff. Thanks for your time and effort.

[alltatup]

I just read it twice and took notes from it; thanks a lot for all your effort! I had read Clarke on "leafing" before, and I am glad to find that particular passage again.

We watch lower buds mature all the time--buds that clearly aren't getting as much light as the upper buds. I understand why now.

Shade vs. Sun Leaves: Very useful information. Stress and sex change: ditto.

[DrPhoton]

Yes i have followed your work since i was first a member here, i too grow outdoors and indoors. I like to at least top my outdoor plants once because i believe the main cola of a untopped plant acts more like a sink compared to the rest of the plant. Making the main cola larger while the rest of the plant is neglected.

[DingusKhan]

Holy cow. What a great series of reads. Thank you, very thought provoking. I'm definitely going to try to go au naturel on one of my current grows. I might try to get 2 clones to go together in 1 bucket or bin.

[DrPhoton]

Omitted with new information and improved readability. I would really recommended reading again if you have already done so. There has been some good information from people that i decided to add. I am much happier with it now and feel it contructs the message more clearly. There will likely only be minor improvements from here on out.

[DrPhoton]

Ohnestly, so could the larger fan leaves. The smaller "sugar leaves" are just younger leaves that develop between the calyx from the same branch as the surrounding larger fan leaves.

[Campesino]

The sugar leaves may send important signals if not the flowers per se.

[DrPhoton]

Totally understand campesino, but again that would imply that flowers have photoreceptors. Which i argue they do not, at least to the extent of my reading and understanding of the discoveries of how plants have been studied over the last century. For example, taken from long memory. Phytochromes were only found in leaves as plants that were presented with light cues never responded unless the light was presented to leaves. Other parts of a plant such as stems and flowers never responded.

A quote from a quick search on the subject

Hans Mohr · 2012 · Science

"The characteristics of the flowers (including stamens, pistils, corolla and calyx) are hardly modified by light. A potato plant will form very similar flowers under all circumstances which allow flower formation at all."

[Campesino]

I understand, but seems like a rather simple experiment. Two colas, same plant (same node), shade one - and compare to unshaded. At least would show something of whether flowers respond to light.
I am not really arguing the larger point, just the one conclusion that I quoted. I prune my plants rather aggressively at the end of the stretch, but certainly understand the need for leaves to do photosynthesis.

[DrPhoton]

Yes as fingerleafs points out nicely, we may not fully understand the physiology of photorecepters such as phytochrones. But we understand the fundamentals. Much effort before the 21st century has gone into the understanding of plant behaviour to light. Which based on what i have read in my books on plant biology is quite satisfactory, i personally do not think we are missing much. The way i have always invisioned photomorphology is that photosynthesis manufactures the energy, plant processes such as photorecepters direct where and how the energy is used.