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December Questions &Answers Compiled by David Rodriguez County Extension Agent-Horticulture Bexar County

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Special thanks to Forrest W. Appleton and volunteers of the "Master Gardener Hotline" in support of the weekly gardening questions and answers.

Question:
David, I have several citrus trees that I planted in full sunlight in our sandy soils and they have never produced not even a shadow of a flower! They all have these new green, great smelling leaves, but not one piece of fruit. Do I need to fertilize the soil during the summer? While other citrus trees around me are drooping from so much fruit, I'm drooping from discouragement!
Answer:
Gloria, citrus require several years of age before bearing fruit. Be patient. More information on maintenance and fertilizing citrus trees may be found at: http://aggie-horticulture.tamu.edu/patiocitrus/index.html.

Question:
David, how or where can you obtain seed for St Augustinegrass? I'm told that it is not available and I can hardly believe that. It has to originate from something. Please fill me in.
Answer:
Steven, there is no St. Augustinegrass seed available commercially. All St. Augustinegrass sold is grown vegetatively and sold as sod. While this grass does have a few seed heads, it is my understanding that harvesting them is economically unfeasible and most of the seed is sterile.

Question:
David, we have several Burford holly bushes that have developed areas that appear to have spider web-like material. Also, the underside of many of the leaves has a white powdery appearance and the leaves are dying and falling off. Can you tell me what's going on and what the best treatment would be?
Answer:
Henry, the white powdery substance is probably the residue of a white fly infestation. Do you see small white insects flying around when you disturb the foliage? They are hard to control. Spraying with an Acephate or Malathion spray, directing the spray at the underside of the leaves several times at about a seven day interval, will help eradicate them. I don't know what the web might be. A severe infestation of spider mites can result in webs. Tap a branch sharply on a piece of white paper or cardboard. If you see a lot of small specks moving around on the paper, they are mites. A spray containing the miticide Kelthane is the best remedy for them.

Question:
David, my husband trimmed our Red oak tree and wants to use the black pruning sealer. Wouldn't a clear acrylic paint work as well and not look so black?
Answer:
Sharon, any substance that will seal the wound to prevent the sap from being available to attract the sap sucking beetle which spreads the spores of the fungal disease, oak wilt, will work. However, unless the cuts were to large limbs, the black will be almost unnoticeable.

Question:
Mr. Rodriguez, I have a heavy occurrence of black soot on dwarf burford hollies that are lining an AC unit. I have treated for the insect infestation, but have the unsightly soot remaining. Blasts with water do not seem to help. Any suggestions?
Answer:
The black sooty mold will have to wear off with age. The water spray should help and as the leaves naturally fall off to be replaced with new leaves, the problem will correct itself. However, you need to be sure that the insect infestation is, in fact, corrected. First you need to identify the insect which could be aphids, white flies and/or scale. You should treat them when you find them regardless of the season.

Question:
Mr. Rodriguez, is it helpful to treat crape myrtle that is not mildew resistant with a fungicide in the fall to help prevent problems in the spring? Do you have any recommendations?
Answer:
There is no fungicide that, when applied in the fall, will prevent problems in the spring. So long as there are no leaves, there will be no powdery mildew. You should apply the fungicide in the spring or at the first sign of the problem. Since crape myrtles are such fast growers, the better solution might be to replace them with mildew resistant varieties.

Question:
Dave, I was pruning a large oak tree in my backyard and was trimming some dead limbs off the tree. After cutting the branch, I noticed a large number of carpenter ants coming from the wood. How dangerous are these ants in hurting the tree? How do I get rid of them?
Answer: Anthony, carpenter ants do not eat wood; they merely build their nests in it. If they were in a branch that you cut off, they will hunt another place to build. A fire ant insecticide with Acephate should kill them.

Question:
Mr. Rodriguez, I would like to know what plants I can plant in winter to give my garden some color. What plants will flower all winter?
Answer:
Eddie, certainly the pansies are the hardiest of the bloomers being able to survive any freezing temperatures we might have. The ornamental kale and cabbage give foliage color through the winter. Also you should consider petunias, cyclamen and primrose which in most winters do fine but could be killed in a hard freeze.

Question:
Mr. Rodriguez, do you have any suggestions on ways to keep neighborhood cats from using the mulch around my trees as their litter box? I want to do something that is safe for the cats and keep them away. I've heard there are plants that have a scent that keeps them away. I like that option over anything chemical, but I'm willing to try anything. Any suggestions for that?
Answer:
The mulch you are using must be a very finely ground one. They will be discouraged by a larger mulch such as pine bark or one in which it is difficult to dig such as cypress mulch. Spreading chicken wire over the bed will also keep them from digging. I have heard that vinegar or citrus peels (oil) will also act as a deterrent but I do not know the veracity of that. There are also cat repellants that are commercially sold at most nurseries/garden centers.

Question:
David, can I plant and grow lavender in the house, or do I need to start outside during the spring?
Answer:
Lavender will not grow inside and it will be a challenge for you to grow it outside. It must have full sun and extremely well drained soil.

Question:
Mr. Rodriguez, we were given a lemon bush last spring and we have kept it in its 5 gallon pot. We have an area that gets about 7 hours of sun in the summer, is that enough sun? When should we plant the lemon bush and also, what fertilizer is best? This plant's parent is in Garden Ridge and has done well, so we know it will thrive here.
Answer:
Mark, visit the information at: http://aggie-horticulture.tamu.edu/extension/homefruit/citrus/citrus.html. You should hold off on planting it into the ground until next spring. The area you have selected should be okay. Full sun is preferred, but our summer sun is very intense and 7 hours should be sufficient. Even though the parent has thrived, you will still have to give it protection in the event that freezing temperatures are predicted.

Question:
David, when is the best time to plant bougainvillea outdoors? I have some in containers and would like to plant them.
Answer:
In areas where winter freezes are normally expected it is recommended that bougainvilleas be grown in containers. If planted in the ground, the above ground vegetation will be killed and they will spend their time and energy re-growing their vegetation at the expense of blossoms. If you still wish to plant yours in the ground, I recommend that you wait until about mid March to do it. This will allow them a year of establishing a root system to ensure their survival of a light freeze.

Question:
What can be applied to ligustrums and hackberries to be totally and permanently rid of them? I'd prefer an organic solution, but if there's none, is there a chemical that would not harm surrounding plants?
Answer:
There is, to my knowledge, no organic method other than physically removing them. You can cut them off close to the ground and then immediately paint the cut trunk surface with a full strength, concentrated herbicide such as Ortho Brush-B-Gon or Green Light Cut Vine & Stump Killer. This will kill the root system of the plant. There is no danger to any other plants if you only get it on the cut surface.

Special thanks to Forrest W. Appleton and all the Master Gardeners of the "Hotline" in support of the weekly gardening questions and answers.