Question. One of the trunks of my ligustrum and some additional limbs are dead. I prune them off when noted and apply a fungicide. What else can I do?

Answer. Some young but mainly older ligustrums develop dead areas in the trunks and stems called cankers. These result from wounds, insect damage and similar injuries that become infected with fungal organisms. What you are doing is the best control.

Do make sure you prune the dead portions back to healthy normal looking wood. Then apply a copper fungicide or similar product to provide some protection from additional infections. Also sterilize the pruners between cuts so not to spread the disease organisms. Often weak or poorly maintained ligustrums are the most susceptible to this decline. Make sure the shrubs or tree forms remain moist during dry times and are fertilized with a slow-release product in March, May and early October.

Q. I have an older bird of paradise plant I want to keep healthy. What type of fertilizer should I use and how often?

A. Mature bird of paradise plants are not heavy feeders. In fact, too frequent feeding may lead to growth without the blooms. Normally after a plant reaches three or more years of age fertilization is reduced to two or three times a year. A good schedule would be to apply a slow release landscape shrub or perennial product once in March, May and early October. Also, promote blooms by only watering during dry times. Bird of paradise need minimal care to remain healthy and produce attractive flower clusters.

Q. Our mango tree has grown to about 20 feet tall and wide. When do we perform needed pruning and how much should we remove?

A. Delay the pruning until after the summer crop of mangos ripen and then decide how large a tree you want to maintain. Mango trees can grow more than fifty feet tall and wide but most gardeners like to keep them in the fifteen to twenty-five foot range.

Wait to prune Mango trees until the current crop of fruit is finished ripening. (Sun Sentinel file photo)

Trim the limbs back to remove overgrowths and reduce the tree height and width. Also, thin out the smaller crisscrossing limbs and your pruning job is done. Central Florida mango trees are pruned by cold during the winter so much of your trimming may be to remove dead or declining portions and allow the rest to regrow your tree.

Q. A container-grown peace lily has filled its container. Can we divide and repot the plant at this time of the year?

A. Tropical-like conditions of summer make an ideal time to divide peace lily plants, also known as spathiphyllum, and similar foliage plants. These make great growth during hot, moist weather. Dividing the plants may not be all that easy. Some may be pulled apart but don’t be shy to take a sharp knife or pruners to cut the plants into sections. Large plants may be halved or cut into even smaller portions. Give each a container of fresh potting soil a few inches larger than each section. Or, arrange several separated portions in a large container. Keep the new plants moist and in the filtered sun. Apply a slow-release or houseplant fertilizer to encourage new growth.

Q. Orchids we received as gift plants have been moved outdoors to a shady location. What type of fertilizer should we use and how often?

A. Locate your orchids suspended under tree limbs with filtered sun so they receive good air movement. A spot on the shaded patio will work too and probably be the next best location. Fertilize every other week during the warmer months with a liquid fertilizer solution made for container plantings or use one of the special orchid products as instructed on the label. Many gardeners are switching to slow-release fertilizers made for house plants or container plants. Usually, a small handful is placed in a fine mesh bag and set among the orchids. These normally fertilize for several months or as noted on the label.

Q. We don’t want our St. Augustine lawn to get insects. Should we be applying regular treatments with insecticides?

A. Many gardeners are skipping the regular or scheduled insecticide treatments and apply pesticides only when the insects are noted or expected in home lawns. This gives the beneficial insects living in the lawn a chance to control the pests without the use of insecticide. Even some insect damage can be tolerated by lawns such as the chewing from lawn caterpillars. If chinch bugs are noted or regular occurrence then the application of an insecticide might be needed. Don’t forget when the pests are present some natural or low-toxicity pesticides may be available.

Q. My roebelinii palm has green and black on the trunks. Is this from too much rain or a disease?

A. Trunk blemishes often look damaging but they are normally harmless Florida flora. Moss, algae and lichens are commonly found growing on the trunks of roebelinii palms also known as pigmy date palms.

Plants in shady sites and receiving frequent watering can be expected to have more moss, algae and similar growths. The green, gray and black blotches may make the trunks look less attractive but they are not going to cause their decline. If needed, a natural copper fungicide can help reduce the growths following label instructions for the plants you are treating.

Q. I planted three raised bed gardens and one has filled with clumps of roots. What is causing these clumps?

A. Roots grow where they want even upwards into a bed of soil and sometimes containers. Nearby trees or shrubs have found your raised beds of soil a moist and nutrient-rich site to grow. This is a normal occurrence but the roots compete with what you want to plant.

Before replanting, loosen the soil in each bed to locate and remove the clumps of roots. You may also want to use a square pointed shovel to make downward slices into the soil about six inches deep along the edge of the beds to sever invading roots. Other beds may eventually be affected as tree and shrub roots grow some distance from their planting site.

Tom MacCubbin is an urban horticulturist emeritus with the University of Florida Cooperative Extension Service. Write him: Orlando Sentinel, P.O. Box 2833, Orlando FL 32802. Email: TomMac1996@aol.com. Blog with Tom at OrlandoSentinel.com/tomdigs.