South Park "Tree Dripping Problem"

Updated: August 2, 2013

As many of you are aware, South Park has, what appears to be a "tree dripping problem". This article is written to give you some history and describe the action that the Board is taking..

To begin with, the trees that are affected are the tulip, tulip-magnolia and hackberry trees. The dripping is not sap, it is from two different insects, aphids and scale, and is called 'honeydew'. These insects fly into and nest in the tree. The tulip trees in particular became popular in the Valley about 30 years ago. Many HOAs and cities planted them around that time. There is no universally accepted reason, but beginning almost ten years ago, aphids and scale began infesting the tulip trees and causing this problem of dripping.

Tree experts of all types have been fighting this problem since it began. Companies have developed chemicals to specifically address this problem. None of the chemicals developed have been the hoped for panacea. While there has been some success with aphids, scale is still a problem.

Today there are two preferred methods of control. Each method has advantages and disadvantages. The first method is to spray the tree with an insecticide. The advantage to this is that it is immediate - it basically kills the aphids on contact. The disadvantages are numerous. Only about 10 - 20% of what is sprayed actually gets on the tree, the rest is carried off by wind. The affect is short-lived; the aphids not killed just fly to a nearby tree and will return to the sprayed trees in a week or two. Tall trees require special equipment to reach the upper leaves, increasing cost.

The second method is to inject the tree with a compound that gets carried up to the leaves. The aphids don't like this and tend to leave the tree alone. The advantages to this method are that it is more direct, nothing gets wasted and no chemicals are floating around in the air. Because it is injected near the base of the tree, the chemical gets carried up to every leaf of the tree. It is longer lasting. A single injection is typically all that is needed for the entire "aphid and scale season" which lasts a few months. It is easier to do, taking a few minutes per tree, as opposed to setting up equipment to spray an entire tree. The disadvantage is that the compound itself is very expensive. One thing that greatly helps the effectiveness of the injection method is to give the tree additional water. The additional water is absorbed by the root system and as this water gets transported up the tree to all the leaves, the compound is transported up as well.

Neither method is 100% effective and we've tried both over the last few years. Over the last few years, we've treated each of the affected trees twice in the season. In consultation with several arborists we've tried different chemicals. The treatments being used seem to have more affect on aphids, but scale is still a problem. Also, hackberry trees seem to respond better than the tulip trees. Unfortunately, the original developer planted many tulips and we have about 60 in the complex still today.

While we believe we've seen some improvement over the last couple of years, this continues to be the biggest landscape problem in our community.

As an aside, we will no longer plant these trees in the complex.

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