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Editor’s Note: The following are bonus photos from a profile of Bob Labadie’s garden featured in the April 2018 issue of Michigan Gardener. To read the full story, pick up a copy of Michigan Gardener in stores or read it in our digital edition, which can be accessed for free on our website home page.
I have a purple smoke tree that is about 9 years old. It is a large, healthy tree, but it has never “smoked.” Every spring it is full of blossoms, then when other smoke trees are beginning to smoke, the blossoms on this tree shrivel and die. I have tried watering it more, I have tried watering it less. Any ideas? J.W., Ann Arbor
Although smoke tree or smoke bush (Cotinus coggygria) requires well-drained soil and full sun, it is quite adaptable to different soil conditions. A large shrub or small multi-stemmed tree that can grow to 15 feet tall, it can work as a background plant for the mixed border or as a single specimen plant. Its claim to fame is the cloud of pinkish gray “smoke” that covers the plant in the summer. The effect is the result not of flowers, but of tiny pinkish hairs on the small fruits that occur in large clusters. There are some popular cultivars with purple leaves and darker flower clusters, such as ‘Royal Purple,’ ‘Velvet Cloak,’ and ‘Nordine Red.’
While smoke bush is relatively easy to grow, it can use some help in the early stages of development. For a new plant, avoid planting in waterlogged or poorly draining soil. For an existing plant, dig a dozen holes with a crowbar at the drip line that are a foot deep. Fill these holes with 5-10-10 fertilizer. This should be a one-time application. Early spring is best but it can be any time. It isn’t necessary to repeat this unless the smoke bush is not thriving in later years. Woody plants are going to be happier if you don’t overdo it. Annuals, tropicals and turf are heavy feeders, but over-fertilizing perennials and woody plants can force them to produce more stems and leaves than they want to, which can lead to unnecessary stress. Once established in the landscape, shrubs and trees adjust to the nutrients in the soil and often don’t want too much extra pampering. Avoid fertilizing (directly or indirectly) with high nitrogen (lawn) fertilizer; nitrogen promotes stem and leaf growth at the expense of flower production.
If your tree is planted in the lawn, remove the grass in at least a 6-foot diameter area around your tree. Mulch the area (do not pile mulch up against the trunk) and water infrequently: a good soaking once per week is much better than multiple small waterings. Smoke bush is drought-resistant and overwatering can result in few or no blooms, and makes it more susceptible to disease. Woody plants need watering less frequently than tender annuals, lawn, or herbaceous plants. Most established trees and shrubs can go weeks without supplemental watering except in very hot or windy weather.
What are the causes of apples dropping from trees prematurely while still very small? Is malathion a safe, readily available treatment for apple trees after the petals fall? Can you recommend a book for growing apples in Michigan? D.E.
Premature fruit drop can be natural, environmental, or pest-related and it takes some careful observation to determine which category yours falls into. An early apple drop before the fruit has matured may be the result of an overproduction of fruit by the tree. The plant simply cannot support the continued nourishment for such a vast number. Profuse flowering and extensive pollination can cause this overproduction beyond what the tree can sustain. Subsequently, it “sheds” a few pounds of excess fruit to conserve energy in a natural thinning process. Some fruit tree growers will even manually thin a tree to increase the quality and size of the final product, beating the tree to the punch.
Premature fruit drop can be environmentally stimulated by unfavorable conditions like frost, excessive heat or cold, or drastic changes in humidity. Living in Michigan, any of those conditions are quite possible in the flower to fruit cycle. Since symptoms can also be soil-related, it is important to check your regularity of watering and that the proper nutrition is offered the tree at the root zone. A soil test geared toward fruit tree production would zero in on those nutrients and their correct proportions. You can obtain a soil test kit from your county’s MSU Extension.
Another environmental occurrence is herbicide drift. Never apply herbicides in windy or dead calm conditions. Dead calm is often associated with a phenomenon known as temperature inversion. Contrary to popular belief, spraying under such conditions can actually increase drift distance. The culprit spray may be several yards away, making it difficult to pinpoint the source.
Pest-related fruit drop occurs much later in the season, when the fruit is very near maturity. So insect pests are probably not the reason for your premature drop.
As for the application of malathion, a readily available insecticide for homeowner use, proceed with caution. Make certain you correctly identify the pest, that the insect pest exists on your apple trees and that it is doing damage before arbitrarily applying any insecticide. Malathion is particularly effective against leafrollers and codling moths, which can damage apples, and must be applied at specific intervals. All label instructions and cautions should be followed to the letter if applying it yourself. A better choice would be to contact a certified arborist for an accurate diagnosis and treatment. Oftentimes beneficial insects can be eliminated from nature’s cycle in the homeowner’s fury to protect their plants.
For Michigan apple growing information, contact the your county’s MSU Extension and obtain how-to bulletins on tree fruit. For a nominal cost, you will get targeted, science-based information on Michigan climate, the best apple varieties, and proper techniques to successfully grow apples in Michigan.