Proper care can ensure azalea health

How are the azaleas?

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This is a question I get numerous times in the weeks leading up to the Masters Tournament. We want the azaleas to be at their peak when the crowds come to town.

The azaleas were at their peak last week; some varieties are still just coming into their bloom stage and some have finished blooming.

For those that have finished blooming, it is time to get them ready for next year's bloom. What you do now will affect how well the plant blooms next year. This includes fertilization, pruning and insect control.

There are a number of factors to look at when considering fertilizing azaleas. The first is knowing the nutrient levels in the soil. This can be accomplished with a soil test. The soil sample will provide a recommended fertilizer analysis to apply. Without a soil sample, it is best to use an azalea special fertilizer.

The timing of the fertilizer application is very important. Fertilize after the plants have flowered. If you fertilize before they flower, the new growth can cover the flowers and the bloom will not be as spectacular. Do a second fertilizer application in June at half the rate applied in April. Don't apply any fertilizer after July 1. This can interfere with flower bud formation and can make the plant more susceptible to cold damage in the winter.

In older beds, the organic matter could be high and this could supply all the nutrients that the plants need. To properly fertilize, apply the amount called for on the soil test results, or put one tablespoon of fertilizer per foot of plant height. Applying too much fertilizer can burn the plants.

When applying fertilizers, remember that azaleas are shallow-rooted plants. The root system easily can be damaged by excessive fertilizer application. This is especially true when the fertilizer is placed in piles around the plant.

The proper way to fertilize is to evenly spread it around the root system of the plant. Start broadcasting 4 to 6 inches away from the center of the plant. It's OK to broadcast over the top of the plant, but when you are finished, use a broom or rake to knock the fertilizer off the leaves. The plant needs to be dry before applying the fertilizer or it can burn the leaves. Water the plants afterward to get the fertilizer to work.

There is no need to remove the mulch around plants. As the fertilizer dissolves, it will move through the mulch.

Just like fertilizing, the best time to prune azaleas is after they bloom. Always prune with a purpose in mind, not just because it is time to prune. You might prune some plants to remove tall, lanky growth or vigorous suckers that detract from the overall form and shape of the plant. It might be desirable to prune to maintain a more compact form.

Sometimes it is necessary to prune old, overgrown plants to rejuvenate them or to reduce their size. Like many other broadleaf plants, healthy azaleas can be pruned to within 6 to 12 inches of ground level and will respond with an abundance of new shoots growing from the old wood.

Also, never prune azaleas after July 1, because this is when they set the flower buds for next spring's blooms.

If your azaleas have white or yellow mottling on the top of the leaf and black specks on the bottom of the leaf, you have azalea lace bugs. These insects live on the bottom of the leaf and suck the juices out. The lace bugs over-winter as eggs, and will start emerging near the end of March through April. There are two generations during the year. The second generation will emerge in August.

The key to controlling the lace bug is to control the first generation. Two insecticides that are effective for controlling lace bugs are acephate and imidacloprid. Acephate is considered a local systemic. When sprayed on a leaf, it moves throughout that leaf. Imidacloprid is a systemic that is applied to the root system and moves throughout the plant. With either of these products, there is no need to spray the bottom of the leaf. When using pesticides, remember to always read the label and follow the directions on the label.

Another insect that causes problems for azaleas is the red-headed azalea caterpillar. This is an insect that attacks the azalea in late August or early September. These caterpillars can defoliate the plant in a short time. Acephate, Sevin, or Bt can be used to control them.

We look forward every spring to the sight of azaleas in full bloom. Start now to prepare for next year's bloom by properly fertilizing, pruning and controlling insects.

Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at charlesp@uga.edu. The extension Web address is www.ugaextension.com/columbia.