Rhododendron and Azalea Issues

Recently I have had several people bring in samples from azaleas and rhododendrons. These shrubs where showing loss of leave color, and leave loss. This time of year it is no untypical to see these symptoms. There are a couple of insects that will be attacking the azaleas and rhodos around this time of the year in the mountains. They will cause a discoloration of the leaves, yellowish to light green blotchy spots, which can lead to leaf fall. This is a problem that can cause damage to the plant, and is more typical on evergreen varieties of these two plants. The insects that are most likely the suspect for such damage are the Azalea or Rhododendron Lace Bug. These are small insects that suck the sap from the leafs, particularly the young leaves. They lay eggs on the underside of the leaf on or near the midrib, and over one hundred eggs can be found on a single leaf. Both nymphs and adults will feed on the specific host plant. The discoloration is most visible from the top of the leaf, while the underside will be speckled with a dark brown to black excrement and body castings. Detailed descriptions of these insects can be found, respectivily, here and here. If you are unsure of the diagnosis please bring a sample to your local Extension agent for another opinion.
Happy Gardens.

Photograph by: James. L. Castner, University of Florida

Ever wonder about the bumpy leaves?

I have had several calls and visits from people around the county with several different problems. One of these problems was the nasty bumpy leaves you may be seeing on a whole bunch of different host plants. These are called leave galls, and are caused by several different insects ranging from aphids to sawflies. The good news about galls are that for the most part these are not very harmful to the plant, of course a severe infestation could pose a problem. There are chemical control measures for controlling galls and for information on specific treatments for host plants please contact your local Extension agent or check the NC Ag Chemical Manual for suggestions. The image is of a maple gall, caused by a mite. This image came from a webpage you may find useful, buggide.net. It is a good resource for finding out more on insects. You can also visit the NCSU Entomology Insect Note page. It is a great resource as well, with links to other helpful sites such as the Entomology department web page, the Plant Disease and Insect Clinic, and others. I do hope this is helpful and answers some questions about those nasty bumps.
As always, Happy gardens.