There are differences. First, let me let you know that our company manufactures Treekote Tree Wound dressing. There are three basic types of aspahltic tree wound dressings as well as a couple of other types which I am not very familiar with. Of the aspahltic types there are the aerosol asphalt, asphalt emulsions (modified asphalt so that it is water soluable), and liquid asphalt.
The aerosol types are an asphalt cutback which results in a fast drying easy application. I would like to point out that our product, Treekote, contains more asphalt (35%) than any of the other brands that we have compared it to (16%). Aerosol Tree wound dressing provide good coverage and protection from disease but due to the solvents the can not be used to seal grafts.
The asphalt emulsion wound dressings, have been shown to reduce dieback, offer good protection, are safe for use in grafing, but take longer to dry and to apply. It is VERY important when using this type especially to apply the wound dressing in as thin a coating as possible while getting complet coverage. care should be taken to get the material on the edges of the wound to control dieback, but NOT thickly! If it is applied to thickly it can lift off and create a "pocket", this is where the problems that have been related to use can develope.
The liquid asphalt type sealers (non-emulsion), in my opionion are the last choice. They offer no additional benefit than the asphalt emulsion pastes, but the solvents used make them unuseable for grafting because they can (minimal) damage the cambian layer., and they are not as convinient or fast drying as the aerosols.
No matter which product you choose, remember that it should be applied as soon as possible after wounding or pruning, and in a thin yet complete, coating - More is Not Better!
Here is a partial list of studies and/or guides that support the use of Tree Wound Dressings.
Diseases of Apples and other Pome Fruits, N.D.S.U, H.Arthur Lamey, Robert W. Stack
Diseases of Apples and Other Pome Fruits
Silver Leaf Disease of Trees and Shrubs, Agiculture and Agri-Food Canada
www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1198274535415&lang=eng
Overland Spread of the Oak Wilt Fungus in Minnesota, Journal of Arboriculture 11(11):November 1985, Jennifer Juzwik,D.W. French, Jon Jeresek
Studies on Pruning Cuts and Wound Dressings for Oak Wilt Control, Kim Camilli, david N. Appel, Todd Watson, Arboriculture and Urban Forestry 2007 33(2):132-139
Tree Susceptability, Inoculum Availibity and Potential Vectors in a Texas Oak Wilt Center, D.N. Appel, R.Peters, R. Lewis, July 1987,Vol.13, No.7 - Journal of Arboriculture
Healinf of Wounds on Trees, Dan Neely, Journal of American Society of Horticukltural Science (95(5):536-540
How To Prune
www.na.fs.fed.us/spfo.pubs/howtos/ht_prune/addinfo.htm
Pruning to Prevent Silver Leaf
HortFACT - Pruning to prevent silverleaf
Silver Leaf Disease in Fruit Trees
P.Larkin Hedges.ie
Silver Leaf
www.sardi.sa.gov.au/pestsdiseases/horticulture/horticultural_crops/apricot_pests_a
Sapstreak Disease of Sugar maples
treehelp.com/trees/maple/maple-diseases-maple-sapstreak.asp
Diseases of Sugar maple
Diseases of Sugar Maple | eHow.com
Disease Control in Cheries, Plums and Other Stone Fruits, NDSU
www.ag.nsdu.edu/pubs/plantsci/hortcrop/pp689w.htm
Black Knot of Plums and Cherries, Department of Crop Sciences, University of Illinois At Urbana-Champaign,RPD No. 809, September 2000
Black Knot of Plum and Cherry, Agriculture and Agri-Food Canada
www4.agr.ca/AAFC-AAC/display-afficher.do?id=1198101468695&lang=eng
Black Knot Diseases of Plums and Chokecherries, NDSU Extension Service
Ask Extension Database, NDSU Extension Service
Oak Wilt, The Gardening Lauch Pad
http://gardeninglaunchpad.com/oWilt.html
The Dutch Elm Disease,David French, Mark Ascerno, Ward Stienstra, Minnesota Extension Service, University of Minnesota, AG-BU-0518, Revised 198-0
Cankers on Locust Trees
Diseases of Tree Bark | eHow.co.uk
How To - Identify, Prevent and Control Oak Wilt, USDA, Forest Service, NA-FR-01-11
How to Prune
www.na.fs.fed.us/spof/pubs/howtos/ht_prune/addinfo.htm
Our company has also conducted a study on wound closure which is available on our web site :waltereclark.com