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Possible culprits of dogwood problems

Branch injury or disease could be to blame for this reader's pagoda dogwood problem. Special to Forum News Service

Q: The leaves of our 4-year-old pagoda dogwood tree started curling in July, although it was well-watered during dry periods. The curling started on the south side and now the majority of the leaves look this way. Is it a disease or insect affecting it?—Lori Keller, Barney, N.D.

A: Pagoda dogwood has an interesting branch structure giving it an Oriental, miniature tree appearance. Several possibilities could cause the symptoms you're seeing. The lower parts of certain branches could have been injured by rabbits, voles or sunscald last winter. Shrubs sometimes have enough energy to leaf out, but then injured branches wilt by mid-summer when they can no longer function normally. Injured tops can often be pruned back severely in early spring and the shrub will regrow better than ever.

Another possibility is a disease called pagoda dogwood golden canker. The fungus disease turns parts of branches golden yellow, contrasting with the normal reddish-brown color. Prune affected parts during winter and sterilizer pruning shears between cuts to prevent fungal spread.

Q: I'm not successful in mulching perennials for extra protection during winter. Everything I've used blows away, and I can't keep the plants covered. Of course, the worst part is when the snow cover doesn't remain. How can I be more successful? - Teri Smith, Reile's Acres, N.D.

A: Protective winter mulch should be between 12 and 24 inches thick, using straw, leaves, peatmoss, compost or shredded wood products. Mulch should be applied after plants have "hardened" from freezing temperatures, with some frost in the soil, usually in late October or early November. Applying too early can cause problems. The goal is to keep the perennials gently frozen, protected from extremely low temperature exposure and from fluctuating freeze/thaw cycles.

Wetting the surface of the mulch greatly reduces the wind problem as the moist mulch freezes in place. Some gardeners use chicken wire cages. Leaving perennial tops intact also helps hold mulch. Loosen mulch in early spring, around late March or early April, by pulling it away from the perennials, but leave close by so you can quickly recover if frigid weather returns. Always uncover before new growth begins.

Q: I have a hanging basket of New Guinea impatiens, and also a geranium hanging basket, and both are still blooming. I'm wondering how to bring them indoors for the winter.—Marian Sorum, Breckenridge, Minn.

A: Geraniums are the easier of the two and winter quite successfully indoors in a sunny window, where they'll continue to bloom if light is sufficient. Feed monthly with a water-soluble fertilizer, and don't keep overly moist, as geraniums like to dry out well between waterings. Next spring, about March 1, cut it back severely to four inches above soil level to encourage robust new regrowth. Repot into fresh soil, and your geranium will be ready to return outdoors in mid-May.

New Guinea impatiens are more temperamental, but can be successful if given sunshine indoors and kept on the dry side to prevent root rot troubles. Avoid dim interiors, too-moist soil and watch for insects. I always enjoy hearing results, so please stay in touch.

If you have a gardening or lawn care question, email Don Kinzler at All questions will be answered, and those with broad appeal may be published, so please include your name, city and state for appropriate advice.