October "In The Grow" - Indiana Yard and Garden - Purdue Consumer Horticulture

October “In The Grow”

Q: HELP!! The bagworms are killing my trees. How can I stop them? What importance are bagworms to the environment? Do they do any good? If stripping the tree of all its nutrients is their only purpose, I’m for trying to get rid of them! Besides killing my trees, they form a strong web that allows them to cling to the side of my house, my lawn furniture, the outside grill, etc. Hope you can help me! – Sherril Criswell, Worthington, Ind.

A: You’re being irritated by fall webworms. They’re capable of covering entire trees with their webs and eating all the leaves. Usually, they form webs on the ends of deciduous tree branches, eat the leaves and leave black droppings underneath their web site.

In the future, look for early signs of webbing in June. They’re likely to show up in the same places next year. Kill the caterpillars before they lay eggs for a second generation. Small webs can be pruned off and destroyed. When webs cover too much of the tree to allow pruning, you can spray with Bacillus thuringiensis (e.g. Dipel or Thuricide). This will kill the feeding caterpillars without harming beneficial insects.

If the population is already out of control, you’ll need to take a different approach and use a more powerful sprayer. Sevin (carbaryl) or orthene will kill the caterpillars without completely coating all the leaves.

Webworms don’t benefit people directly, but the next time you enjoy a songbird, be grateful to the webworms it dined on!

Q: To the north of my house and on either side of the front of my house, I have beautiful maple trees. I noticed in the spring of 1996, and also this spring, that they were not as full and lush as they should be. The bark on all three trees is all cracked and can be peeled off. You can see the cracking creeping up to the outer limbs. The leaves are not as big, and they have a brown/black growth on the leaves. I sure don’t want to lose these trees, as they shade my home. I thought after the spring of ’96 it would correct itself. Can you advise me on how to treat this problem? – Bonnie Sanow, DeMotte, Ind.

A: Maples have thin bark that can split and crack as it expands and shrinks when winter temperatures fluctuate. If the cracks are on the south and west sides, you have frost cracks. Often, the cracks close during the following growing season, but they may remain open or reopen the following winter.

Many maple owners protect the trunk from winter sun by wrapping it with tree wrap during the first few years of the tree’s life. Professional arborists can bolt large trees back together with a rod.

The black growths are probably bladder and spindle gall, caused by tiny mites. The galls are bumpy growths on the tops of the leaves. Early in the season, they are yellow-green, then become pink, red and finally black. Galls don’t cause serious harm to the trees and are not related to the splitting problem you have.

Q: I have at least 100 feet of daylilies that grow along the side of my driveway. My problem is that the weeds are as tall as the blooms, especially where they get more sun. The weeds are the type that resemble wheat with the seeds on the top. Is there a weed killer I can put on in the early spring when the lily shoots first appear to kill the weeds while not harming the daylilies? Any help would be appreciated. One hundred feet of daylilies standing 3 to 4 feet tall make a beautiful sight, but in one area the weeds are crowding them out. I read your column every month and learn a lot from it. Keep up the good work. – Paul F. Roembke, Pierceton, Ind.

A: A thick layer of mulch is the first line of defense. A preemergent herbicide will prevent annual weed seeds from germinating. Finally, post-emergent herbicides (like Fusilade) are available to remove grasses from broadleaved plants. Make sure any herbicides you use are labeled for daylilies, and read and follow all directions.

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