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Azaleas need scouting during summer

Photo by Vicki Harris

Photo by Vicki Harris

Azaleas, one of the more common plants in the southern landscape, need some particular care during the summer. The azalea puts on a spectacular flowering show in the spring and summer. However, a maintenance plan needs to be devised in order to continue that flower show for the next year.

Not pruning azaleas at this time is the most important thing that you can do for them.

However, in the coming weeks, azaleas should be given an application of fertilizer and scouting should continue for insects and caterpillars.

Technically, azaleas are one of those plants that should be pruned just after flowering. A general rule of thumb is that if it blooms before May, then it should be pruned immediately after flowering. Azaleas set flowers from buds in early July; this is why it is important not to prune your azaleas after early July or you risk the reduction of next year's flower production, so do not prune azaleas after July 4th.

July was also the last time of the year that you need to apply fertilizer to your azaleas. This was the topic of another recent question about azaleas. Fertilization application should be made in three split, light, applications, rather than one application a year. Make your first application in March, followed by one in May, and finishing with your last application in July. An all purpose fertilizer such as 8-8-8 or 10-10-10 will yield satisfactory results. Also, a 2:1:1 ratio such as 12-6-6 provides excellent results when a portion of the nitrogen is in slow release form. So if you have not made that final application of fertilizer, please do so now.

Scouting during late spring and summer is a good way to detect pests that feed on foliage, like the azalea caterpillar, or pests residing under the leaf, like aphids and azalea lace bugs.

At this time I am asked about a recommendation for this large caterpillar that is defoliating the leaves of azaleas within a matter of days. This culprit is described as a black and yellow "worm" with a red head. These caterpillars are noticeable this time of year measuring about 1 to 2 inches. They have reddish brown legs, head and "neck" area. The body is black with rows of white or pale yellow stripes. They feed on the foliage from late summer through early fall, however, there is only one generation a year. The pupae overwinter in the soil. The azalea caterpillars feed together when they are young, but disperse as they mature. They have been known to defoliate an entire branch or plant during the summer. They can be hand picked from the plant if only a few are present. If the numbers are larger, Bacillus thuringiensis should be applied only if the caterpillar is less than a half-inch in length. Repeated application may be necessary 10-14 days later. It is very important that these caterpillars are controlled because azaleas are not the only host plants. Other hosts include witch-hazel, sumac, apple, crabapple, red oak and andromeda.

Take some time in the coming days and give your azaleas the attention that they deserve so that you can enjoy the flower show next spring.

For more information on selecting and growing azalea, please feel free to contact me at (229) 436-7216 or morganjl@uag.edu. Our azalea publication can be found at http://pubs.caes.uga.edu/caespub/PDF/B670pdf

James Morgan is the urban horticulture county extension agent who works at the Dougherty County Cooperative Extension Office in Albany. He can be reached at (229) 436-7216 or morganjl@uga.edu. Also, visit the website at www.ugaextension.com/dougherty.