Biology and Chemistry are irrefutably linked together and we see this partnership every garden season. Following is a good example of what is required to rid yourself of suckers…the plant variety! This is Ethyl 1-naphthaleneacetate or NAA and more commonly marketed as Sucker Stopper©. But before you reach for the chemistry solution, an understanding of the biological reason for a plant to sucker.
A sucker, (the less woody sucker is called a watersprout), is when a plant root sends up a new stem away from the main stem. In trees, it looks like new vertical growth from the base of the trunk. Also, any robust growth below a graft union on a plant are suckers. During the spring season of active growth many plants (mostly noticeable on crabapple, apple, and plum trees in the Denver area; but limited to these species) are responding to a stressed condition or poor pruning practices or both. The stress the trees in the Denver area occurred the fall of 2014 and then again in the spring of 2015. A tree will show signs of stress for several years. Now is an excellent time to take stock of those suckers.
Watersprouts are easier to remove because they are smaller and have more fleshy leaf growth. These can be manually removed by diligent pruning or cutting as the shoots appear. Suckers are a bit tougher to remove. They are usually growing in the wrong place on the plant, rob energy from the main plant, and if they are not removed, as in case of a grafted plant, will overtake the main plant as the suckers are coming from the rootstock part of the graft. If the problem is extensive and manually removing the the suckers will prove to be most difficult, then the application of a little chemistry will be in order.
The main ingredient in NAA is a plant growth regulator. This chemical is used in the green industry to slow the growth of plants so they can be shipped at the proper stage for planting times throughout the country. As a control method for suckers, when applied, performs in the same manner in the plant tissue, when applied during early sprout growth. It may take 2-3 applications over a period of a season to slow and halt the growth of suckers on a tree. If this is the management plan chosen, with any chemical process remember, the Label is the Law, more is not better.
