OK Folks,

This is going to sound like a strange question, but here we go. Does anyone know of a method to defoliate trees that only damages the foliage? We are working on a research project to measure tree vigor or the trees' ability to leaf out after defoliation. Leaves can be hand picked from small trees, but we need to find a way to economically remove leaves from mature trees with out causing other damage.

We are currently considering using high concentrations of backing soda since we know that this will burn back leaves in hot weather. We have considered using hormones like ethylene, but we are afraid that this might disrupt other normal functions in the tree resulting in bad research data.

Any suggestions would be appreciated.

W. Todd Watson

Reply to post by W Todd Watson, on December 03, 2001 at 15:06:32:

Hi Todd. How important is the location of the test plots? Either for convenience or for environmental conditions or constants?

What occurs to me is that we have outbreaks of insect defloiators (free little leaf pickers) going on someplace just about all the time. Maybe find out where there is a gypsy moth outbreak and go to the trees. Or a late frost somewhere. You'd have to factor out underlying stress like a prior defoliation or drought and factor for how mature the foliage is at the time of defoliation... you'd probably hae a different effect defoliating in mid or late season than from defoliating realtively new foliage which has used energy to develop but not put much back yet (the typical gypsy moth pattern). I also recall talking to Shigo in the early 80's about the potential effects of admitting high overhead, Summer sun to the forest floor for several weeks after a gypsy moth defloiation. Walk through the same bare forest in July and it feels and looks different than in January. And now that I think of it, there may be some decent literature on such insect defloiations.

Where is that baking soda going to wind up and will it alter soil Ph? There must be scads of things that are phyto-toxic if you up the concentraions or even the linger time with an airblast sprayer (mist blower), maybe horticulural oil or soap.

Scott Cullen

Reply to post by Scott Cullen, on December 03, 2001 at 15:06:32:

Are these specimens container grown and young still? Are they indoors? Is the experiment taking place now or in Spring? What species?

Auxin mimicing compounds artifically induce production of the stem base constrictors that detach structures - this cellular "collar" grows beyond normal hormone induced reactions and the leaf dies, sans loss of chlorophil, and falls off...like inducing cotton to open it's bolls prior to picking or turning apples red before harvest.

Unfortunately, what is a good auxin replacement therapy is 2,4-Dichlorophenoxy acetic acid, or 2,4-D, one of the deadliest compounds in use today. Application for your needs is difficult because you want locational or specific targeting and plants absorbe this salt systemically, no matter how an application is made and it goes onto kill roots and any symbiant organism associated with the host. @,4-D was developed at Ft. Detrick Maryland as a warfare agent to be used against the Japanese in WW2, but the war ended and it became the most readily used herbicide today. It's design is to promote uncontrolled cell growth (cancer in short) and it's effective as any carcinogen known. You may attempt to (if the specimens are small) apply through transdermic injection at the leaf stem bases minute amounts but I can't assure it won't go beyond it's intents. Isolating into a pressure chamber and exhausting all Co2 replacing with pure 02 will defoliate, I've had success with that. Also, temp reductions and light deprevation work well, but again, test host size will determine what you can do.
Releafing is an adaptable phenomena, a "learned" response but it can only occur at certain windows of opportunity. What exactly is it your attempting to illustrate? It sounds interesting and I would like to keep tabs on your work.

Sincerely,
Reed Holt