Question: Something is boring into the trunk of my crape myrtle, and webs are covering two of the trunks. What's the cause and treatment?
Answer: Most likely, you can take this weekend off because these problems don't sound as if they are threatening your crape myrtle. If the boring marks are in a row and not shallow, they are likely produced by a sapsucker, a type of bird. Such injuries have to be tolerated.
Webbing on trunks can seem scary, too, but in this case, it normally belongs to psocids, often called tree cattle. They live on bits of old bark and lichens found on the trunks and cause no harm. During the warmer months, they spin the webs to conceal their young. If they become a nuisance, the webs and insects can be washed away with a strong stream of water.
Lichens on ligustrums
Q: We have a 30-year-old ligustrum with trunks and limbs that are covered with a grayish substance. Some of the leaves have a few brown spots, too; otherwise, the tree appears healthy. A neighbor said to water and fertilize the tree and sandpaper the gray off. Can you advise us?
A: Old ligustrums and most other plants get spots and blotches from time to time; it's normal. Your tree likely has lichens on the trunk and some cercospora leaf spot on the foliage. The advice to water and fertilize a bit more was a good one.
Often when these plants slow down, the lichens become more prolific. The extra care can increase growth which helps to make conditions less favorable for lichens which are a combination of algae and fungus. If they grow too well, they can compete for foliage sites. Where needed, a natural copper fungicide can be used to reduce their growth; there is no need to resort to sandpaper, which is not good for the bark.
Almost all local ligustrums also have some cercospora leaf spot. This is a common fungus that affects the foliage, producing yellow, then brown spots. Healthy vigorous plantings outgrow this pest, and it can usually be ignored. If needed, the copper fungicide can help here, too.
Was purchaser sold a bill of goods?
Q: I recently purchased a white bird of paradise that the salesperson said had been grown in low light and would do well in my dining room. The room faces east and gets light through a shuttered bay window. It is about 18 feet from the window in a corner. The leaves are starting to yellow. What should I do?
A: Get this plant outdoors quickly. Your salesperson was optimistic to think a white bird of paradise could grow at such a reduced light level. At best, these plants can grow in filtered sun outdoors, but this spot in your room is too far from a window; the light level is way too low.
A move outside should save the plant, and you might use it as a patio or landscape specimen where it has plenty of room to grow. Did the salesperson also tell you this plant can grow clumps at least 20 feet tall and wide? Just thought you should know.
Pineapples are great communicators
Q: Two years ago, we purchased a pineapple plant with fruit which we set in the ground and then started a plant from the top. This year we have two pineapple plants with fruits. How do we know when they are ripe?
Also there is a new plant near the base of one plant. Will it produce fruit, too?
A: Ripening pineapple fruits make it quite clear they are ready to harvest. First, they turn a yellow to orange color, and then they give off the familiar fragrance. If your plants flowered in March, as many do after a cool winter, the fruits should be ready in August. And yes, the shoot from the base is going to produce another plant that could be in bloom and fruiting by next year.
Leaves turning brown? Sounds like mites
Q: Our Formosa azalea leaves are turning brown and dying. What is the cause and cure?
A: Normally, uniformly browning leaves at this time of the year on azaleas are caused by mite infestations. Using a hand lens, look for these pinpoint-size arachnids plus their shed skins and eggs on the undersides of the leaves. If you cannot find them, take some of the leaves to your local University of Florida Extension office to have them checked.
If present, either an insecticidal soap or a horticultural oil spray does a good job of controlling mites. Make sure you hit the undersides of the leaves and follow label instructions.