Guarding plants against winter

By George McVey, Ph.D.
Contributing Writer
Union County Post

Q. When should I apply a winterizer fertilizer to my lawn?
A. The winterizer fertilizer should be applied to the lawn in the late fall, not winter. The application is usually applied in late October or early November, but only if fertilizer was also applied in early September. The September application prepares the lawn physiologically to receive the full benefit of the late fall application, mainly for increased root growth. Also, if you plan to make only one fertilizer application in the fall period, do so in late September or early October.
Q. What does Powdery Mildew look like? What are the signs? What can be done to help infected plants?
A. Powdery mildews are with us much of the growing season. This fungal disease often appears as a white or gray powdery growth on the surface of leaves, stems, flowers, and fruit of affected plants, which may eventually cover the leaf surface. Less familiar are the symptoms of reddening and/or bronzing of leaves on dogwood, magnolia, and roses. Young foliage and shoots may be especially susceptible and leaf curling and twisting may be seen before the fungus is actually noticed. Severe powdery mildew infection can result in yellowed or dried and brown leaves, and disfigured shoots and flowers. In most cases, powdery mildew does little real harm to plant health, though it may hasten defoliation and fall dormancy.
Powdery mildew fungi infect many ornamental plants including some deciduous azaleas, cherries, some flowering crabapples, flowering dogwood, English oaks, euonymus, honeysuckle, lilacs, roses, serviceberry, and some viburnums, as well as other plants. Powdery mildews also infect some plants in the herbaceous border including chrysanthemums, dahlias, delphiniums, monarda, phlox, snapdragons, and zinnias. Each species of powdery mildew has a limited host range, for example, the powdery mildew fungus that infects roses does not spread to monarda.
Infection occurs via airborne spores under moderate temperatures of 60-80 degrees F. Powdery mildews do not necessarily require free water on the plant surface in order to infect it. Some mildews are also favored by high humidity.
Attempt cultural management of this disease before treating with fungicides. Start by selecting disease-resistant plants and cultivars when possible, and maintain plants in good vigor. Plant in well-prepared and well-drained soil in full sun exposure - especially highly-susceptible plants such as roses and zinnias. Space plants properly for good air circulation to facilitate lower humidity. A labeled fungicide can be applied to protect uninfected foliage, but is not useful in “curing” the disease.
Q. This season I planted a few small trees and shrubs in containers. They are too large and numerous to move into the garage for winter. What should I be doing to ensure their survival through winter?
A. There are a few options for “over wintering” large, hardy plants in containers, which are usually left outside. The challenge is that roots are above ground where they are subject to cold temperatures. Use a soil thermometer to monitor winter temperatures, making sure soil temperatures do not fall below freezing. If they do, move containers to a garage or shed temporarily for added protection. Other plants, such as perennials, ornamental grasses, roses, bulbs, etc. in smaller pots can be placed in a trench in the ground and covered with mulch or soil to protect the root systems. Water it well into late fall before covering. If plants are in clay pots that could crack over winter, remove the plant from the pot and place the rootball into the trench. If trenching is not an option, group pots together, water well, then cover with a thick layer of straw, compost, mulch or leaves to protect the root systems against freezing.

This article was taken from The Ohio State University Plants Facts Web site. The Master Gardener offers horticulture advice and tips, focusing on current issues, by volunteers who are with The Ohio State University Extension, Union County Master Gardener Program. For answers to gardening questions, call 937-644-8117 or e-mail mcvey.22@cfaes.osu.edu.