Avoid spraying pesticides on roses unless you have identified the pests and are using the best method of control for those pests. Many problems on roses are caused by misuse of pesticides.
Spider mites are a serious problem on roses and many other plants. They become particularly egregious with the onset of hot, dry weather. The easiest way to determine if you have a mite infestation is to take a piece of plain white paper and put it under the leaves. Shake the leaves sharply and watch the dust that falls on the paper. If that dust starts to crawl, your plants have spider mites. Most people need a magnifying glass to actually see the pests.
Iron chlorosis is a serious problem for roses as it prevents the plant from forming chlorophyll. This means the leaves are yellow and will likely scorch and turn brown in the heat. Avoid overwatering and treat with an iron chelate to prevent this problem.
Pesticide recommendations for rose pests are available on my Web site: www.larrysagers.com.
Friday, July 13, 4-8 p.m.; Saturday, July 14, 9 a.m. to 2 p.m.: Centerville City Garden Walk will feature some of the best residential gardens in the town. Pick up a map at Founders Park visitors information booth north of City Hall, (300 N. Main). Free. Call 295-3477.