After pruning Japanese maples in late January - February should the cuts be sealed or coated with a paste or was like "Phytech 50"? I have several trees to prune and have seen and heard conflicting advise on whether to seal or not.
If the pruning cuts are of light wood then there is no need to seal the wound. However, if the wood you are cutting away is a heavier branch then it is prudent to seal with arborex or similar. This helps healing and stops infection getting into the sound wood Cut right back to the trunk (or branch) being careful not to damage the 'collar' close to the trunk (or branch)
generally speaking pruning seals or paints are only for cosmetic purpose, the exception would be a medicated treatment which may or may not be available in North America. If you prune in appropriate weather and make proper pruning cuts (location, "clean" tools) you shouldn't need to worry.
It used to be common practice to paint a black tar emulsion on the fresh pruning cuts to help prevent decay. Now however, prevailing scientists, like Alex Shigo, have found that such 'paints' retain moisture, warms in the sun, and shuts out UV rays. Thus creating a perfect environment for fungal and bacterial growth. As a result, the wound becomes a much more hospitable environment for the countless vectors that cause decay! Generally, 'pruning paints' do little good! However, the exceptions are: 1. For aesthetic purposes. In some instances, pruning cuts can be a continuous eye-soar for homeowners or those who pass by the area. In such a case, an extremely diluted latex paint can be applied to camoflauge the bright colored wound-wood. The dilution allows the wound to still exudate spring sap flow and dry out like nature intended. 2. To control certain disease vectors. In some instances, insects and bacteria my be attracted to a pruning wound. Therefore, some 'paints' will be applied to deter their entrance. This is where a product such as Phytech 50 could be used, however, I honestly do not think that you are going to have a problem with you tree. There has also been some research into applying honey to fresh pruning wounds on trees susceptible to bacterial infestations, such as fireblight. The naturally occuring enzymes found within the honey, make for an inhospitable environment for the bacteria. However, placing honey on wounds obviously creates new problems, such as continued follow-up maintenance. 3. When mixed with a growth retardants, such as NAA (Naphthalene Acetic Acid) to reduce watersprouting along the edges of the wound. NAA is a naturally occuring Plant Growth Regulator collectively referred to as Auxin. Studies have shown how the presence of NAA in a paste application will drastically reduce future watersprouting. And if you have ever heavily pruned any maple, you will have seen how the tree will respond in an attempt to survive! Everything in life comes with varying pros and cons. However, in this instance, the cons far outweight the pros! Simply some food-for-thought! T. Shane Freeman
