Ask Wendy
Weekly Home Horticulture Column
Fall 2005
- Agapanthus or Lily of the Nile
- African Violets (mealy bugs)
- Chamberbitter weed
- Clover in Lawn
- Confederate Jasmine
- kumquat (citrus leafminer)
- Ligustrum Tree
- Peace Lily
- Walnut Caterpillar
- Fall Webworm
September 2005
Every year when my confederate jasmine has finished blooming, it starts growing like crazy. When I prune it back there is a sap that comes out of the stems, should I keep pruning it back and is the sap poisonous?
Confederate jasmine ( Trachelospermum jasminoides ) is a favorite evergreen vine in Alachua County . It is well know for its beautiful white flowers that have an intoxicating fragrance. The vine does best in full sun and it is easily trained on a fence, trellis, or over a mailbox. The jasmine usually finishes blooming in June which coincides with the beginning of the summer rains. The warm weather and the water really make the plant grow. Even without fertilization it is considered to be a vigorous grower. In order to keep it in bounds, have the pruning shears handy. The plant is not considered poisonous, but the milky sap may be irritating to you. If you are likely to have a reaction to the sap, wear gloves and a long sleeved shirt when working with this plant.
We bought a ligustrum tree from a local nursery and planted it in our front yard in April. It had a few problem leaves at that time. Now, however, more are affected. The leaf develops a round brown spot that is encircled by a yellow ring. The leaf turns yellow eventually and then drops off. What do I do about this problem? We have many other ligustrum shrubs and they do not have this problem.
It sounds like you have a leaf fungus, possibly Cercospora leaf spot. This fungus attacks the leaves and can cause premature leaf drop. The disease spots are dark brown with a yellow border. You will need to destroy the infected leaves and spray a fungicide like Immunox, or Dithane, or Fung-away. You must rake up the leaves and spray in order to get control of the problem and prevent it from spreading to your other ligustrum plants. Not to sound like your mother but, let me take this opportunity to gently remind you that a savvy plant shopper does not bring plants to the home landscape that look diseased. When you are purchasing plants you want to select plant material that is insect, disease, and weed free. It also should have healthy leaves and strong stems and it should not be root bound. Plants on the bargain bench are not bargain if you have to spray them when you get them home. Use a nursery that has a staff that you feel comfortable talking to about the general health of the plants.
There are fuzzy caterpillars all over my hickory tree and it sounds like it is raining with all the stuff falling down from the leaves. It is making a mess of the driveway and pool deck. What are these things and are they going to kill the tree?
The Master Gardener phone lines have been swamped with calls about this caterpillar. It is called the Walnut caterpillar, and it is being seen in hickory, pecan and oak trees. They started showing up around Labor Day and will probably be with us until the end of the month. Walnut caterpillars do not make web nests in the trees like the fall webworm does, but we do see them on the same species of trees during the late summer and early fall. The larva or caterpillars are nearly black and covered with long white fluffy hairs. There also appears to be 2 or more long stripes that run the length of the body. The eggs are laid by moths high in the leaves of the tree canopy. The eggs hatch and the caterpillars feed voraciously on the leaves of the tree. The material falling from the trees is called frass, which is another way to say caterpillar droppings. When they are ready to molt they gather in a mass on the trunk. After molting, they go back to feeding on the leaves up in the tree, and leave a clump of cast skins and heads. When the caterpillars are mature they move back down the tree to find a place to pupate or form a cocoon, they usually do this in the soil. A single defoliation will not harm the health of the tree this year, so there is not much you should or could do to control the walnut caterpillars this September. If we were to have repeated infestations of this caterpillar on a high value tree, you might need to contact a professional pest control company with the specialized equipment that could treat the canopy of the tree. In the meantime just try to stay ahead of the frass and sweep the fallen caterpillars and frass off of the driveway and pool decks.
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I recently moved into a new home that is a subdivision built on an old cow pasture or sod farm. It is in Meadows on the Prairie between Archer and the "Haile Plantation light" on Archer road. Clover is over running the yard and choking out the Bahia grass. What can I do?
Yes, I am pretty sure that the land that you live on was once grazing pasture. In a pasture, the clover is seen as a bonus, because it has high forage value for the cows, but in a lawn it is a weed. The best way to discourage weeds is to maintain a healthy lawn; this is pretty easy to do with Bahia because it is considered a low maintenance grass. Bahiagrass only needs to be fertilized twice a year in the spring and fall. It is exceptionally drought tolerant so it doesn't need to be irrigated beyond normal rainfall. Mowing bahia at the proper height of 3-4 inches also will help keep weeds down. To begin to get control of the clover problem that you are having now, you can use a selective herbicide that contains 2,4-D + dicamba + MCPP. Be careful with weed and feed products that contain atrazine because they are harmful to bahiagrass.
I have had very good luck with African Violets but a couple of my plants seem to have tiny white "critters”. I'm spraying but it seems impossible to be rid of them completely.
For the most part, healthy, well cared for African violets are trouble free. Occasionally, they will have an insect problem like the leaf mealy bugs that you are describing. The leaf mealy bugs are small waxy insects that are found on the undersides of the leaves and leaf stems. An easy method to control them is to touch each insect with a cotton swab dipped in alcohol, (70% isopropyl). With the swab try to remove each insect, and then rinse the plant with warm water in the sink do not allow the leaves to stay wet. You will need to repeat the swab treatment, until the insects are gone. If the infestation is really severe you might have to use a systemic insecticide that is labeled for African violets. There is a granular product available that you can spread on the soil of the pot. It will take a little longer to work, but maybe better than a spray since the leaves of the African violets are sensitive to chemicals. Also think about how these insects were brought into your collection and carefully inspect new plants before you bring them home.
I have had a peace plant for three years and it has never bloomed. I've tried everyone's suggestions (and their plants are blooming) but to no avail. Any suggestions?
The peace lily or Spathiphyllum is a great house plant because it does so well inside under low light levels. They come in dwarf varieties that stay around 12 inches tall and a full sized type that can grow up to 3 feet tall. From this tropical green plant will come a pure white flower that is very long lasting. Even if they do not bloom, the dark green foliage makes for a handsome indoor plant. Spaths, as they are sometimes called, prefer a well drained potting mix, and they flourish when their soil is kept moist but not soggy. If the plant wilts down and the leaf margins yellow you know that you need to increase your watering frequency, but they are quick to bounce back from brief neglect. The main reason that these plants do not flower is because of insufficient lighting. Try to move the plant to a brighter environment that is not in direct sun. I have had good luck with moving the plant to a bright porch or window. It takes a month or so for flowers to begin, but it will happen. Also these tropical plants require little fertilizer, so if you have been using a high nitrogen fertilizer more than every 3 months you might be encouraging leaf growth instead of blooming.
August 2005
My landscape beds are full of this weed that looks like little mimosa trees. What is it and how do I get rid of it?
This weed has a few common names, my favorite of which is “Gripe weed” but most of the gardeners in Florida refer to it as “Chamberbitter”. Chamberbitter ( Phyllanthus urinaria ) is a summer weed that is usually introduced into our landscapes and lawns from weedy nursery stock. It is native to Asia but is seen as a weed throughout the Gulf States . The weed ranges from 2 inches to 18 inches in size and it can grow in shady or full sun conditions. The leaves are thin and have round warty like seeds under them. It is an annual that spreads aggressively and will quickly take over a landscape bed and then move into the turfgrass. Luckily it is easy to pull and you can get control of it in your landscape beds. Be sure to collect the pulled weeds and put them in a lawn trash bag; you don't want the seeds of Chamberbitter spreading around your yard. If the problem cannot be managed by pulling you could use a non-selective herbicide like Roundup or Finale. Be careful to follow the label instructions and to avoid having the weed killer drift onto your landscape plants. If the chamber bitter has spread into the lawn grass you will either attempt to hand pull it or use a selective herbicide that is appropriate for the type of grass at the correct time of year. To prevent this weed from taking over your landscape beds in the future consider laying down a layer of weed cloth then apply 2-3 inches of organic mulch on top of the cloth.
The leaves of my young kumquat tree get weird little trails through them and then the curl up and turn yellow, what can I do about this?
It sounds like you are seeing leaf miner damage. The citrus leafminer is a moth larva that feeds on leaf tissue of citrus trees. This small larva creates serpentine mines as it feeds on the inside of the leaf. The result is curling leaves that have a silvery film over them. The problem seems to be worse on young trees because the frequent new flushes of growth are the most susceptible to this citrus pest. As the tree gets older there is less damage and it will not affect the amount of fruit that you get from the kumquat. To try to control them now you can use an fine horticultural oil spray, and with in a few years you will not even notice the leafminer damage. There has been a parasitoid wasp (biological control) released that seems to be making differenence in suppressing the problem.
My pecan tree has two big web nests over the branches. What are these webs and how do I get rid of them?
The nests that you describe are made from a caterpillar called the fall webworm. Even though it is still summer, groups of fall webworm get started making their nests in pecan trees in July and August. They will make their silky webs in Sweetgum, hickory and other hardwood trees that grow in Gainesville as well. The fall web worm is not considered a major pest, but the webs that the caterpillars make, and defoliation are considered unattractive by many gardeners. These moth larvae will not cause serious damage and insecticidal control is not practical in the home landscape. It is best to physically remove the nest by pruning. Often this is not possible; because the webs are high in the trees, so just try to tolerate them for the next few months.
I have planting of agapanthus that will not bloom. I think that they are getting too much sun. What can I do to get flowers?
Agapanthus or Lily of the Nile, perform well in full sun so I don't think that the exposure is the problem. Fertilization and irrigation are the keys for these bulbs. Some guides recommend fertilizing monthly during the growing season. Regular watering will also help since they thrive in slightly moist soil. Also, agapanthus will bloom best when they are crowded. So if you have been dividing the bulbs to fill out the bed; stop and let the bulbs grow in closely, this should help you get the large blue or white clusters of flowers, blooming in the late spring. If you have grown these plants from seeds, they can take up to 4 years before they begin blooming.
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