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Ask Dr. Hort: An organic solution for treating rust fungus on plumeria

Treat rust fungus on plumeria organically

Q: I have a plumeria in the front yard that in the winter gets black under the leaves. Then the leaves fall off, leaving the stalks and flowers bare. What can I safely spray the leaves with? And, when should I spray? Jake Jacoby

A: You and just about everybody else get rust fungus on their plumerias, also known as frangipani. It starts as bright orange pustules on the undersides of the leaves, followed by black splotches all over the leaf, then leaf drop. Some species seem to have more tolerance than others. Of course, that may be hard to determine if you got a cutting from your next-door neighbor and don't know the species.

There are some great organic treatments for the problem. First, pick off all of the leaves that are heavily infected and the leaves that have already fallen and discard in the trash. Then mix 1 heaping tablespoon of baking soda and 1 tablespoon of horticultural oil (or perhaps better yet, 1 tablespoon of neem oil), adding 1 squirt of dish soap in 1 gallon of water.

Spray your entire plant, even after rain or irrigation, once per week, especially during new growth. This should help to keep your leaves on the plant.

Raised bed best place to grow veggies

Q: I am trying to grow my own vegetables to help with food costs. I have a plot that once contained azaleas that I now want to use to grow vegetables. It is my understanding that azaleas are poisonous. Some azalea roots may still remain in that area. Is it safe to grow vegetables in that plot? If not, how long would I have to wait until it is safe to plant food crops? Cass Laping

A: Azaleas are not poisonous. The bigger problem is our soil in general, which is commonly loaded with nematodes — microscopic roundworms that destroy root systems, especially vegetables. You are better off to set up a raised bed garden. Take 2 by 8s or 2 by 10s and arrange according to your preferred size. Buy a quality potting mix from your nursery and plant according to James M. Stephens' Vegetable Gardening in Florida, available in some local bookstore. For most vegetable gardening, the fall planting season has just passed; you may want to wait until late January to get started for the spring season.

Leaf-losing wisterias probably need water

Q: In the spring I planted wisterias to grow up my pergola and for months they grew like crazy. Then mysteriously the wisterias began to lose all their leaves and stopped growing. One is in full sun for half the day and one is in mostly shade but they both have the same problem. Any help you can provide would be greatly appreciated. Thank you. Scott Meckley

A: I hope that you planted our native American wisteria (Wisteria frutescens), and not Chinese (Wisteria sinensis) or Japanese (Wisteria floribunda), because the Asian types can be very invasive, even though their flower clusters are much larger and fragrant, and their seedpods are fuzzy.

Now, to your question. I think that your leaf loss is associated with a moisture problem. Wisterias love plenty of water through their establishment period, at least 1 inch per week. The larger the plant, say 3-gallon or 7-gallon at installation, the more water is needed for a longer period of time. A 6-inch-tall soil saucer around each plant, filled with water every day for a month, then every other day for two months, then twice per week until it loses its leaves in winter, would be a good regimen. We also had a very hot summer for a plant that is in the southern limit of our growing zone (9). That may have added to the problem during the establishment period. Cut it back a bit, form your saucer, keep it watered, and if you're lucky, new growth will appear.

Squirrels persistently after potted plants

Q: I am having a problem this year with squirrels eating my potted plants. I have contacted several nurseries and have been told to use mothballs or red pepper flakes to keep them away. I have replanted my plants four times and used the pepper flakes, but the squirrels just keep eating the plants. Do you have any solution? Hilda Counts

A: Unfortunately, barriers are about the only answer. Perhaps you could try feeding the squirrels away from your potted plants — or consider adopting a cat to stand guard.

Need help? Greg "Dr. Hort" Charles answers questions about landscape and garden pests. E-mail your questions to drhort@tampabay.rr.com or to features@sptimes.com (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.

Need help? Greg "Dr. Hort" Charles answers questions about landscape and garden pests. E-mail your questions to drhort@tampabay.rr.com or to features@sptimes.com (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: An organic solution for treating rust fungus on plumeria 11/12/10 [Last modified: Friday, November 12, 2010 3:30am]

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