Neil Sperry's Mailbag

DEAR NEIL: What kind of spray should I use to keep web worms off my pecans? They are so ugly every spring.

Sprays aren't really very efficient. It's difficult to get a sprayer that will reach that high into tall trees. In the meantime you will have used a lot more of the insecticide than you really would like to.

Pruning is probably a better option, at least for those webs that are 25 feet or less from the ground. Long-handled pole pruners will extend to 24 feet.

If you clip off the webs when they start to appear you'll be cutting small twigs and there will be no impact on the trees.

If you wait a week or two too long, however, the webs will have grown to 3 or 4 feet and you'll be cutting larger branches.

At that point you may just want to use the saw attachment that comes with your pole pruner to pull the webs apart and open them up to predatory insects.

However, to have given you an actual answer to your question: use either B.t. biological worm spray or a general-purpose insecticide such as malathion or sevin if you do decide to spray. Include one or two drops of a liquid dishwashing detergent with the spray to help it penetrate into the webs.

DEAR NEIL: There are several large roots from my fruitless mulberry that are aiming directly at my foundation. The tree is about 12 feet from the house. How much threat do they pose?

Very little at all. At that distance they won't be large enough to lift and crack the concrete. They might dry the soil beneath the foundation which wouldn't be a good thing, but you can easily enough replenish that supply with a soaker hose. If you feel there are multitudes of roots under the concrete you could cut a 15-inch-deep trench along the foundation and install a root barrier material. Don't do that now, however, as the tree will need all its roots for the summer. October is the best time to install root barriers.

DEAR NEIL: I have a Carolina jessamine vine growing on my wood fence. It has done very well for many years but now it's only at the top of the fence and all of its ugly stems are showing. It also didn't bloom very well this spring. Can I prune it back to make it look better? Can I still do that now?

You certainly can try cutting it back rather severely, reshaping it as you do. You'll probably also see some new canes coming up from its base. Leave those in place to become the new stalks. Apply a high-nitrogen plant food and water it deeply to promote strong new growth. If that doesn't work as well as you hope you may want to replace it with a new and vigorous plant.

It seems like Caroline jessamine plants sometimes just wear out after 10 or 15 years, particularly when they're grown in soils that are not perfectly to their liking. It's easy enough just to plant another one.

DEAR NEIL: I planted several cleyera shrubs. The nurseryman told me they would do well in the shade, which they have - until now. However, one-by-one they have thinned and died. Today I noticed that the next-to-last one is actually tipping over in the bed, almost as if its root system isn't sufficient to hold it upright. What might I have done wrong?

Cleyeras are very compelling shrubs. Their deep green and extremely glossy foliage is stunning. However, it sounds like yours have had root problems.

Their margin of error in terms of soil moisture is much more narrow than for most shrubs. They can't handle drought and they are very intolerant of waterlogged soils. Expose them to either and their roots will die. The plants thin out next and then they begin to falter. Dwarf burford holly, Italian jasmine and several other plants can fill the same spaces with far fewer issues.

DEAR NEIL: Every time I work around an old privet hedge I get swarms of little white insects in my face. What are they and how can I get rid of them? Also, they seem to cause a black mold on the leaves.

Those are whiteflies. They're factory equipment with privet, gardenias, gerbera daises and even tomatoes. They're even more prevalent on greenhouse plants for gardeners who try to grow plants like tropical hibiscus or poinsettias. Your best bet in controlling them on your privet would be a systemic insecticide called acephate (formerly know as Orthene). It's reasonably effective on white flies on ornamental plants but it does not have label clearance on vegetable crops. And the black sooty mold actually grows in the honeydew left behind by the whiteflies. They're a partnership.

It will wash away after you have killed the insects.

DEAR NEIL: I have a ton of nutgrass in my St. Augustine lawn. What kills it without hurting the St. Augustine?

Use a product called Image. You'll need two applications 30 days apart and both of them must be made between mid-May and mid-September. Image is active through the soil which means that you will put it on, then water it into the ground thoroughly. You will gradually notice the nutsedge (not a true grass) will disappear. Read and follow label directions, most especially if you are going to use it around other types of plants. Image will retard growth of your turfgrass in treated areas. A similar product called Manage is more commonly used by professional turf care people.

Have a question you'd like Neil to consider? Mail it to him in care of this newspaper or e-mail him at mailbag@sperrygardens.com. Neil regrets he cannot reply to questions individually.

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