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Ask Dr. Hort: Possible reasons for oranges' unsightliness

m Possible reasons for oranges' color

Q: Being a newcomer to Florida, I am frustrated with the lack of information regarding orange trees. My orange tree provided large fruit and plenty of juice a few years ago but since then the fruit has ripened with a rusty rough surface on it. The juice is still good, but the fruit looks lousy. I cannot find anyone or anything to try to remedy this disease on the fruit. Please help.

Tom Mathews, Largo

A: This rusty roughness could be caused by several critters, depending on what variety of orange you have.

I will start with the most common probability. Various mites attack fruit and leaves, leaving both with a rusty appearance, but rather smooth compared with fungus problems. Mites reproduce very quickly during warm, dry weather starting right after fruit set. Mites will reduce fruit size a bit and make it unsightly, but cause little harm to the tree. Mites can be managed by spraying with a horticultural oil after fruit set, in early summer, late summer and fall.

If the rustiness is more corky and bumpy, it is a disease that can appear just on the fruit or on both fruit and leaves. Temple oranges are very susceptible, but all sweet oranges are good candidates. Once again, it causes ugly fruit but little harm to the tree. Scab can be managed by spraying the tree with copper right at fruit set in the summer and again in the fall.

Finally, trees that are in slow decline with rough, corky projections on the fruit and leaves have citrus canker, a bacterium. The only control is to call a reputable pest control company for correct identification and control throughout the year or destroy the tree.

. Artichokes, capers don't like our climate

Q: Is it possible to grow artichokes and capers (caper berries) in St. Petersburg? I have successfully germinated seeds for both only to have them die upon transplanting. Any help would be greatly appreciated.

Peggy MacLeod, St. Petersburg

A: You have chosen two plants that don't care for Florida's climate. They are both native to southern Europe and prefer cool, foggy summers, a good candidate for California. Sorry.

. Sooty mold causes crape myrtle blackness

Q: We enjoy your column and would like to know about disease of crape myrtle. Our trees have black branches and leaves. They still make flowers, but why do the branches and leaves turn black. Can we prevent it or is it okay to ignore it?

Francesco Mannino, Port St. Lucie

A: Usually if you have black on plants, it is sooty mold. This is a fungus that lives off of honeydew, the excrement given off by sucking insects, most notably aphids, whitefly and some other scales. It is not harmful nor parasitic, but it does cut down on photosynthesis and is unsightly. You need to control the pest to control the problem. A strong spray with the garden hose will usually do the trick. Watch closely this spring on the new growth and "nip it in the bud"!

Need help?

Enter Greg "Dr. Hort" Charles, who for more than 30 years educated gardeners through the Pinellas Technical Education Centers. He answers questions about landscape and garden pests. E-mail

your questions to or to (put Dr. Hort in the subject line). Mail questions to HomeLink, Features Department, St. Petersburg Times, P.O. Box 1121, St. Petersburg, FL 33731. Describe your problem in full, and include your name and contact information. If possible, include a photo. We will print his advice on Saturdays in HomeLink.

Ask Dr. Hort: Possible reasons for oranges' unsightliness 01/29/10 [Last modified: Thursday, February 4, 2010 3:39pm]
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