Q: My azaleas have been blooming for a few weeks, but there are lots of black spots on the leaves. What are they and how can we control them in the future?
A: I have mold spots on my azalea leaves. Unfortunately, they are fairly common and often cause significant leaf decline by the time of flowering. Fungal infections on azalea leaves often occur during the rainy season. Spraying a fungicide labeled for leaf spot can help control it, but you should start early. It usually begins during the rainy season and continues until autumn. Rhododendrons develop spots, which make their leaves look bad, and they lose many leaves, but they seem to recover if they are cared for carefully. Planting azaleas in open, shady areas also helps prevent leaf spot.
Q: I have a lot of plants that have been frozen and turned brown. Is it safe to cut back?
Plant Doctor: Further advice for plants damaged by the recent freeze
A: My wife Joani said that winter doesn’t end until mid-March with the freeze. Previously, I took every opportunity to do the necessary pruning from mid-February to late February. Several times, she was right, and although we did experience a cold snap in early March, it wasn’t bad enough to cause any major damage. Still, now, in mid-March, should be a very safe time to prune frozen areas from plants. Most plants can be damaged if another severe cold spell occurs. But if you wait too long, pruning can damage new growth and waste a lot of your plant’s energy. Therefore, it is better to take the plunge and prune it. This is also the time to replant warm-season vegetables and flowers.
Q: Since the winter freeze, our lawn has been a mix of brown and a little green. How can I change it back to normal green?
A: With warmer temperatures, fertilizer and water, most lawns will return to green. If there are green runners or leaves between the brown areas, your lawn should recover fairly quickly once the stable spring weather returns. You don’t need to specifically mow your lawn to remove the brown color, but you can lightly rake some areas where there is a lot of dead leaves. Now is the time to apply spring fertilization to lawns other than Shiba and Centipede. Wait until green growth begins to feed. If it rains and doesn’t provide enough moisture, allow weekly watering to keep all lawns moist. Mow all lawns to normal height and also suppress any weeds that may grow. If desired, a combination weed and feed product can be used in place of standard lawn fertilizer.
Q: There are a lot of leaves in the garden this year. Can I till them into the garden soil as a source of organic matter before planting?
A: Fallen tree leaves can be used in landscaping, but should not be mixed into the garden site in large quantities unless you plan to plant for several months. Fresh leaves combine while decomposing plant nutrients necessary for plant growth. I think you could add fertilizer to supplement the nutrients, but that would be an additional cost. It is better to add the leaves to the compost pile until they decompose, and then add organic matter to the garden site. You can also use leaves to form pathways throughout your landscape. It can also be used as a light mulch of less than 1 inch in vegetable gardens or as 1 to 2 inches of mulch around established trees and shrubs.
Q: My once sweet viburnum shrub has grown to the size of a tree. Can I cut off about 2-3 feet from the top without damaging the plant?
A: Topping these shrubs won’t do much harm and may make your viburnum healthier. Be aware that removing the top leaves of a shrub can cause leaf scorch on the lower shrubs. But don’t worry. New bright green leaves will soon follow. This is also a good time to reduce the width of the shrub and remove dead or declining areas. After pruning, keep the soil moist, supplement the root system with mulch, and apply a slow-release landscape fertilizer.
Botany: Recent winter freeze has reduced pests on peach trees
Q: I have a container of mint that has stopped growing. Do these plants die after a certain period of time?
A: Mint plants are usually vigorous until the container is full. Remove the plant from the container and notice the tightly coiled shoots forming a root ball. Frankly, there is no more room in the factory. Cut the plant into quarters using a knife. Next, give each cluster a container with fresh potting soil. Keep the plant moist and fertilize monthly to harvest four times as much mint as before. You may also want to share a plant or two with a friend.
Q: This is the first time the pineapple field has frozen. I hope they grow again. What do you think?
A: Sorry, but many of the pineapple patches look about as bad as yours, or even worse. The photo I received via email showed a lot of yellow and brown among the leaves, but there was also some green. If the buds in the center of the leaf mass are alive, they can regrow and form a plant. Otherwise, the plant should be able to produce new shoots from the base. If you have pineapple plants that have turned completely brown, you may need to remove them and replace them with new plants.
Tom McCubbin is an emeritus urban horticulturist for the University of Florida Cooperative Extension Service. Write to Orlando Sentinel, PO Box 2833, Orlando, FL. 32802. Email: TomMac1996@aol.com.
