Metro-East Living

What causes pine tree needles to turn yellow-brown?

Q: The needles on several limbs on a pine tree in my yard have started to turn yellow-brown. I planted the tree (a variety of white pine) about 15 years ago, and it is about 30 feet tall. The discoloration appears on limbs at different places on the tree. I can see no pattern. I wonder what is happening and how to stop it, if that is possible.

M. R. of Millstadt

A: White pine (Pinus strobus) can be bothered by several conditions — air pollution (ozone and sulfur dioxide) and white pine blister rust (Cronartium ribicola), which is a disease infecting gooseberry plants that spreads the next year to the white pines causing needle destruction. A white pine weevil kills the terminal buds, causing dead branches to form.

Since your symptoms are occurring sporadically and showing up randomly, it suggests the white pine weevil is probably the cause. Check the branches that are affected to find any residue (dung) left on branches or chewed tips off the needles would indicate the weevils. With pollution, there should be a pattern, or all the tips should show some symptoms.

Q: We recently noticed that our tulip tree is emitting a terrible sap that is coating our deck and patio. After a little research, we found out it is called tulip scale. Our daughter noticed her tulip tree is also affected. We did see that there is a chemical we could apply (not sure if it is pet friendly). Is there anything else we can do? The information also stated it could take up to four weeks to penetrate the tree.

L. S. of O’Fallon

A: There could be two different insects emitting honeydew from your tuliptree. One is scale, as you have stated, and the other is aphids. To identify scale, you would notice brown turtlelike bumps on the stems, and over time, the branches should die back. A single female can lay as many as 3,000 eggs a year, so the population builds up fast. There is a pet-friendly remedy — dormant oil, which can be applied in early spring before the buds begin to break form leaves. This light oil will suffocate the developing scales before they begin to crawl on the branches. This light oil will also kill the aphids. Make sure to apply this spray before the leaves develop.

There is also another insecticide — Sevin — which could be applied to your Tulip tree in early August to kill the scale insects. But do not allow the pet in the sprayed area for a week or more.

Q: My wife and I recently found a number of creamy blobs in the mulch around our house. There is black underneath them that looks like mold. Any idea what these are? Where they came from? Treatment?

A.C. of O’Fallon

A: The creamy blobs are slime mold, and the black underneath are spores that can spread this condition by wind, water, mowers or foot traffic. They become most common after heavy rains. This can at times spread to turf plants on the leaves. With dry conditions, they will dry up. This problem usually indicates that the slime mold is living on dead debris, such as the mulch or dead grass clippings. You can control them by hitting them with a hard stream of water, which usually breaks them apart. Be careful not to direct the water in a way that small pieces will land on a building structure.

Charles Giedeman is a local contributing writer. Send your gardening questions to Lifestyle Department, Belleville News-Democrat, P.O. Box 427, 120 S. Illinois St., Belleville, IL 62222-0427, or email them to lifestyle@bnd.com.

Things to do this week

  • Check on the number of Japanese beetles, as they are appearing in large numbers in most of our area. They especially love roses, grapes, all types of flowering annuals and even vegetable flowers. (Note: Do not use Japanese beetle traps, as they attract every Japanese beetle in your neighborhood to the trap.)
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