Michigan Gardener - Your guide Great Lakes gardening: Garden Event Calendar / Expert Advice / Plant Profiles / Tree Care

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Preferred growing conditions for redbuds

February 24, 2020 • Leave a Comment

I bought a 4-foot tall redbud and it has not grown at all. It leafs out, blooms for spring, then it looks dead by mid-August. Maybe it has verticillium wilt? Does this come back every year? If so, how do I prevent it?

Eastern redbud (Cercis canadensis) is highly valued in the urban landscape for its pink spring flowers and its smaller, manageable size. As an understory tree, it prefers moist, well-drained, deep soils. It tolerates various soil types, except those that are permanently wet, and adapts to full sun or light shade. Regular watering and fertilizing are keys to keeping it vigorous. Unfortunately, it suffers dramatically from lack of water, too much water, or mechanical injury.

Since your redbud does bloom and leaf out in spring, but looks dead by mid-August, your tree may be responding to inconsistent water patterns. There is plenty of moisture available in spring, from snowmelt and rain. By the apex of summer heat, the redbud may be packing all its energy into saving moisture for survival by dropping leaves and going dormant. This is not the typical pattern of a tree suffering from the soil-borne fungus verticillium wilt, which is incurable and progresses over time until the tree is dead.

Before assuming your redbud has this disease, consider the soil conditions where you planted it and your maintenance practices. Is the tree in the middle of lawn, competing with turf up to its trunk for moisture and nutrients? Is it subject to potential mowing damage? Has it ever received a slow-release granular fertilizer beyond its nursery container? Does it get regular deep watering during periods of no rain? With conscientious adjustments to maintenance and amendments, you strengthen your redbud’s ability to withstand such diseases as verticillium wilt, canker, and even insect pests.

With the new growing season upon us, re-examine your plant maintenance routine and strategize a consistent watering program as well as a spring and fall granular fertilizer application. If your tree is sited in lawn, remove the turf away from the trunk out to the tree’s drip line so the root zone has an equal chance for water. The redbud likes moist (not soggy) soil that is well-drained and rich, medium sunlight, and fertilizer to replenish what was used from its original container. Be observant about the tree’s progress through the season, and you may get to enjoy your redbud’s lovely yellow fall display.

Diagnosing and preventing brown spots in lawn

January 25, 2020 • Leave a Comment

In my lawn, there are random brown spots about the size of a tennis ball or slightly larger. This condition only seems to happen during mid to late summer, nothing earlier. I fertilize about every six weeks and mow weekly, never cutting more than 1/3 of the grass blade. I don’t have pets, though there are plenty of squirrels and birds. I have a lawn irrigation system that I operate on designated days with about 20 minutes in each zone. What is causing the brown spots and how do I eliminate them?

What a great analysis of your lawn problem; it shows you pay attention to details in the management of your turf. It appears you have a fungal disease called “dollar spot,” so named because the sunken dead spots are about the size of a silver dollar. The spots are about 2 to 3 inches wide, and several spots may grow together, killing a larger area. The fungus can survive in an unseen dormant state in infected turf. When the daytime temperatures reach 60 to 80 degrees, it resumes growth and infects healthy grass blades. Dollar spot occurs when a combination of warm days and cool nights produce dew on the lawn in the morning, which was our mid to late summer pattern this year.

You are mowing exactly the right way. The fact you need to mow once a week says your lawn is actively growing and is probably receiving sufficient fertilizer to maintain nitrogen levels. Kentucky bluegrass, a cool-season grass, grows most vigorously in the cooler months of fall and spring. So, the most important time to feed it is in spring and fall. Feeding every six weeks as you are doing may be unnecessary.

For the best lawn appearance, Ron Calhoun at Michigan State University’s Turf Management Center recommends the “holiday program.” Make one full application about Memorial Day, a half-strength application around the 4th of July, a half-strength application around Labor Day, and one full application around Thanksgiving. Include the pre-emergents for crabgrass with the last one.

The key adjustment for you may be in the amount of water. Your irrigation system may be set to compensate for drought conditions. Try reducing the irrigation frequency and duration, and avoid watering in late afternoon and evening. The rate should be 1/10 inch per ten minutes. Water in mid-morning so that the grass has time to dry out before nightfall. Check the amount of thatch in your lawn. It could benefit from core aeration, a mechanical process that methodically punches holes in the turf and pulls tiny plugs of soil to the surface. Aerating does exactly what it sounds like: it increases air spaces for healthy root growth. If you want to reseed areas, look for resistant bluegrass varieties such as Adelphi, Eclipse, or Vantage. With minor changes and adjustments, you should see those dollar spots disappear from your lawn.

Deterring sparrows from the birdfeeder

January 20, 2020 • Leave a Comment

The sparrows seem to be overtaking our birdfeeder for the finches even though it’s one of those that requires the birds to eat “upside down.” How can I deter the sparrows from throwing thistle all around, wasting it, and interfering with the finches? Would it help to wrap the feeder with a kind of chicken wire that might only allow the smaller finches inside to eat?

The sparrows overtaking your finch feeder are most likely English sparrows, commonly referred to as the house sparrow. They are hard to control around many backyard birdfeeders. They have a tendency to overpower feeders that have a variety of feeds intended for our more desirable native birds. Goldfinches and other small native birds will steer clear of feeders that are occupied by the English sparrows.

Here are two homemade control measures that have been deemed worth a try. The first is an inexpensive method developed by Weir Nelson of Cedar Rapids, Iowa, and used on open port tube feeders with perches. Bend a 10-inch piece of flexible wire in half. Feed the wire through the port and loop it over one perch, then pull it tight and tie off around the other perch. When completed, you’ll have two parallel strands of wire stretched through the center of the port between the opposite perches. The two strands of wire discourage the sparrow from easily extracting seeds from the feed port. It has no effect on finches, chickadees, nuthatches, or other songbirds.

The second method is to shorten the length of perches on thistle tube feeders so they only extend 5/8 of an inch. The shortened perches will not disrupt the ability of goldfinch, house finch, and other members of the finch family from feeding, but should deter the sparrows.

Commercially there is a product available called “The Magic Halo” that seems to be effective. When used in conjunction with either a post-mounted or hanging feeder, it is said to deter up to 86 percent of the English sparrows. With monofilament lines added to the “Halo” at four corners extending below the perches, the elimination of English sparrows from the feeder is said to exceed 99 percent.

There are also several feeders available that have a screen or cage around the actual feeder. It will let the small birds feed while keeping bigger species from getting to the seeds. In general, to discourage unwanted visitors from your feeders, don’t use cracked corn or millet, and don’t use feed mixes, unless they are free of the aforementioned ingredients. Try seeds that are species specific. Many songbirds love black oil sunflower seeds, for example, and will not miss the mixes.

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