Garden Help Desk: Why do my Sycamore trees look bad? 01

A leaf affected by Sycamore scale.

Question: I have two big sycamore trees and they look terrible this year. The leaves are drying out and already dropping. When I looked at some of the leaves, they had lots of little dark spots on them. Is this some kind of disease? Will it kill my trees? What should I do?

Answer: From your description, it sounds like your trees have been hosting an infestation of sycamore scale, a very tiny insect that causes problems because they show up in such large numbers. Even though they are too small to be seen without a good hand lens, their feeding causes visible damage to the leaves — small yellow spots that eventually turn brown. That damage causes the early leaf drop that you’re seeing. Unfortunately, these insects also feed on the sap of branches and cause twigs to die back.

The most important part of controlling sycamore scale is to maintain the health of your trees. Deep, infrequent watering is important. If your trees are in the lawn, or watered along with the lawn, it is important to water your lawn deeply, but as infrequently as it will tolerate. Maintain a grass-free area around your trees to prevent damage from mowers and string trimmers.

This winter, these insects will be overwintering as eggs under the bark scales on your tree. The eggs will hatch in the early spring and the young nymphs will begin to move back onto the leaves of your trees. At that time, you can use an insecticidal spray to help protect the leaves. Your Sycamores are large trees and you may need to hire a professional to spray your trees. As an alternative to spraying, you can use a once-a-year soil drench with a systemic neonicotinoid product when you see that almost all of the leaves have fully opened. It’s simple and easy to do yourself and puts the chemical only where it is needed. You’ll mix the insecticide with one or two gallons of water, according to the instructions on the label, and pour it slowly right at the base of your trees. Read the label carefully for all the directions you’ll need and follow them carefully.

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Question: A big branch on my peach tree is partly broken off. The peaches have ripened anyway and I’m ready to pick them. Once I’m done, can I prop the branch up and fasten it back together with bolts?

Answer: It sounds like you may have forgotten to thin your peaches this year. Apple and peach trees normally produce more fruit than they can carry. If you leave all the fruit on your trees, the branches will bend as the fruit gets larger. Before the end of the season, the fruit can become so heavy that the branches break. Thinning your apples, peaches and pears next year so that they are all spaced about 6 inches apart can prevent this from happening.

There are other reasons why you’ll want to thin your fruit each year, and we’ll go into more detail in this column next spring.

Whether or not a branch can be successfully bolted back together depends on several things, such as the size and age of the branch, how much weight the branch will have to support in the future and how long it has been since the break happened.

For your tree, the branch is a major branch, was badly broken at the trunk, and most importantly, the break is old enough that it’s very unlikely you’d be successful even if there was a good way to reattach it. It’s best to go ahead and remove the branch, leaving the cleanest cut possible so that the tree can close over the wound.

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