Integrated Pest Management: Tips for March

Now is a good time to check your ground cover junipers for off-color or brown foliage. These dead or dying branches may be infected with juniper tip blight and should be pruned out completely. This will remove some of the spores, improve the appearance of the plant, and increase air circulation. Junipers growing in the shade are more susceptible to this fungal disease and can be replaced with Siberian cypress, Microbiota decussata, a shade-tolerant evergreen ground cover that looks like juniper.

When the first temperate days of late winter arrive it’s time to check your hemlocks for eriophyid rust mites. These tiny, yellow mites are wedge shaped and cause needles to turn bronze and drop prematurely. The easiest way to check for these mites is a beat test. Place a piece of white paper under a branch and tap the branch vigorously. Use a magnifying glass to check the paper for the tiny pests that are no larger than pollen grains. Also check for the larger, fast-moving predatory mites that may be feeding on the eriophyid mites. If there are more than fifty eriophyid mites per beat test and you don’t see any predatory mites, you may want to treat the tree with insecticidal soap or horticultural oil.

Carefully examine the small branches of your apple, crabapple, and cherry trees for shiny, black masses that look like styrofoam. These are the egg masses of the Eastern tent caterpillar. Prune them out or scrape them off now. This will prevent the eggs from hatching into caterpillars in the spring and defoliating your trees.

Although some experts recommend the widespread use of dormant horticultural oil in late winter to control pests like scales, mites, and aphids, it is not considered a sound IPM practice. The best time to treat for these pests is in early spring when they have just hatched. Check plants regularly for pests and only treat those plants that are seriously infested. If you apply a dormant oil now, you will destroy any beneficial insects that may also be overwintering in your landscape.

This winter’s ice storm did serious damage to many trees. Take the time to evaluate the trees in your yard. If any of your trees lost more than half of their main branches, and especially if they lost their tops, you should consider removal. When a tree has many large wounds it is very difficult for it to heal, and it will probably never fully recover. The same can be said for trees that have started to lean due to storm damage. Young trees can regrow their root system if braced properly, but adult trees can’t and should be removed before they topple.

Wood ashes from your fireplace are high in potassium, a major plant nutrient that is easily leached from the soil by rain. Work your ashes into the soil around plants like peonies and roses that use a lot of potassium. Wood ashes can also serve as a lime substitute and will raise the soil pH to make other nutrients more available to plants. Wood ashes generally are a good soil additive, but be sure to spread them thinly and do not use them on acid-loving plants like azaleas and blueberries.

Winter annuals like chickweed, annual bluegrass, and wintercress produce large quantities of seeds in the first warm days of spring. Take the time to remove these weeds now.

What you have in your mind?