Because my citrus and I live in a humid semi-forest, dealing with all the black sooty mold is a challenge. Besides growing on metal fence posts, roofing shingles, and auto paint (etc.), it also grows on citrus leaves, new green shoots, and older 'barked' branches. When grafting to the moldy branches, I use 91% alcohol to sanitize everything involved. I try to wipe off visible mold on the branches with facial tissue soaked in the alcohol. Many bark grafts have succeeded, but many more have not. After doing an autopsy on the dead ones, they almost always have a huge amount of new mold under the tape.I have clipped off many dead grafts and regrafted a few inches below. Sometimes, the second try is "the charm".Most of the citrus that I am still grafting on is quite mature and tall. Only the very newest triangulated shoots at the top are still clean and green.......Is there a better chemical warfare plan that has worked in such a mold kingdom? I will next try hydrogen peroxide, since the "alcohol drench/evaporate away/then graft" plan is only partially successfull after more than 50 bark grafts using clean satsuma and orange scions.

Take care of the insects that cause the sooty mold & you will fix your problem.

This mold kingdom is different from the insect-enabled variety. For a clearer description, imagine your white Toyota Tacoma that is always parked on the concrete driveway in full Sun.....has a living, growing crop of black sooty mold growing on the roof, hood, and campershell top. After the once-in-a-while soapy brushing and rinsing that removes most of the 'crop', it grows back in a couple humid months. Same for galvanized fence posts, wooden decking, etc., etc., and most importantly, citrus leaves/twigs/branches. For whatever reason(s), it does not grow on some fruit leaves/twigs/branches...like mulberries and muscadines. It will even grow on curry leaves that are 2 humid months old. Rather than a mold that feeds on insect contributions, this stuff seems to live on airborne nutrients and high humidity, like the Spanish Moss here that grows while hanging on a utility pole or wire fence.

OK, maybe I'm missing something... What are you talking about ? Sooty mold is mostly caused by an infestation of whiteflies and/or aphids.

After risking being too wordy twice.......bottom line question: Other than using multiple coats of 91% alcohol sprayed on 'everything' in contact with r/s branch graft area, as well as the clean prepared scion, is there a better chemical or strategy to neutralize the black mold than habitually contaminates more than half of my citrus bark grafts? ? Either some mold is alcohol resistant, or a spore may float by after the alcohol has evaporated away and lands on the fresh wound before it gets wrapped up. Ideas? ?

copingwithclay,

Sounds like your area is hardly infested and you have to live with that. If so, knowing more about 'enemy' should help.

Lets start with:
"Sooty molds are dark fungi that grow on honeydew excreted by sucking insects or on exudates from leaves of certain plants. Typically, sooty mold growths are composed of fungal complexes made up of ascomycetes and fungi imperfecti. Some of the common genera of fungi found in sooty mold complexes are Cladosporium, Aureobasidium, Antennariella, Limacinula, Scorias, and Capnodium."
taken from "Recognize and Control Sooty Molds"
http://na.fs.fed.us/spfo/pubs/howtos/ht_sooty/ht_sooty.htm

From above one could built two approaches:
A)
A1. identify the insect(s) that is causing the problem
A2. identify plants with exudates
and deal with A1/2 separately.
B)
B1. identify genera of fungi and act based on that

I don't have specific answer directly applicable to your problem, some testing/experimenting needed:

"For most plants, adding a mild soap or detergent solution (at one teaspoon per gallon) will aid in cleaning them. Use caution, since some plants may be damaged by soaps. You should test for damage if you are not sure. Prepare your wash suspension, spray a small area of the plant, then wait a week or so to see if any damage will appear."
more in "Sooty Molds on Trees and Shrubs"
http://ohioline.osu.edu/hyg-fact/3000/3046.html

There are hundreds of types of mold. My guess is that copingwithcla's mold is not the common sooty mold associated with citrus, but a native type of mold in his area.- Millet (331 ABo-)

Sounds like you have large numbers of mould spores coming in from the environment. Alcohol might knock out the living mould, may or may not kill spores etc, but it has no residual effect, so new spores floating in are going to reinfect. Even if you spray fungicides, I dought if you can spray your whole forest to stop spores drifting in.
You may be better to try to control a smaller area, such as inside a plastic house, or large plastic bags, such as from mattress shops.
When you graft, maybe whitewash/paint the trunk under the graft to further inhibit the spores. Treat your grafting with alcohol, then maybe cover your grafts with sterile plastic bags to stop spores re entering.
Oil of Cloves may help some of your situations?? 1 tsp per litre water
Not sure if it is toxic to plants, I guess it would be undiluted.
http://www.lifestyle.com.au/diy/cleaning-benefits-of-oil-of-cloves.aspx

A highly diluted solution of chloride bleach would work.
But I prefer YOU test first.

I've never been to Texas, but my geography teacher never mentioned any wet tropical forests in that part of the world. Where exactly are they?

citrange,

they are wet subtropical forests. Anyway, I've never seen such a mold problem down here... guess his place is different from ours.

Just a thought, what if instead of liquid fungicides, a fungicidal powder would be used to treat the bud union? Could it help?

Well, if nothing else, this thread has taught me about the Texas climate.
I always had the impression that Texas was hot and arid. Some of it is, but eastern areas have high rainfall and high humidity. Port Arthur, Texas, is apparently the third most humid city in the USA.