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Garden columnist Dan Gill answers readers' questions each week. To send a question, email Gill at dgill@agcenter.lsu.edu. 

I’m looking for a shrub that has silver to gray-green foliage similar to a Russian olive but does not grow larger than about 5 feet. The area where it will be planted is well drained and sunny. — Cindy

I love plants with silver or gray foliage in the landscape. They provide an excellent contrast to green-leaved plants, and almost any flowers look good with them. Unfortunately, many plants and shrubs with silver or gray leaves are not well adapted to our hot, humid and often wet summer weather.

A few silver-foliage shrubs that have done well in south Louisiana include: Powis Castle artemisia (Artemisia "Powis Castle"), Texas sage (Leucophyllum frutescens) Russian sage (Perovskia atriplicifolia). Excellent drainage is very important. 

My holly ferns are about 5 years old and are rather large. They have not been moved or divided in that time. I did not apply fertilizer to them or make any changes in the care of them this year; however, the leaves have begun to turn a tan color. I noticed today the bottom leaves are dying. I have more than 20 large plants and do not want to lose them. Could you please advise me how to treat and what it could be? — Bob

The symptoms indicate your holly ferns (Cyrtomium falcatum) have been attacked by thrips. These tiny insects damage the tissue, making it look faded or tan. Fortunately, the damage is not life-threatening. You can prune off the worst-looking leaves, and the plants should eventually recover and look decent again.

The dead leaves you see are the oldest, and it is typical for a planting to accumulate old, dead fronds over time. These should be cleaned out occasionally anyway. You can control the thrips and prevent additional damage with spinosad (various brands at nurseries and feed stores). Be sure to spray thoroughly under the leaves.

In the future, if you treat at the first sign of symptoms (now that you know what it looks like and what causes it) you can prevent extensive damage from occurring. 

The new growth of my satsuma and lemon trees (both planted two years ago) is all deformed and it looks like silvery trails are running through them. Some of the leaves are curled and I see some webbing. It’s really made a mess of the new growth. What is going on and is there anything I can do? — Bob

This damage is due to citrus leaf miners, a common insect problem that first showed up in May 1994 in Plaquemines Parish. The adult citrus leaf miner is a tiny moth. The female moth lays her eggs on tender, new growth of citrus just as it emerges in mid- to late summer. After the larva hatch, they enter the leaf and feed on the inside, creating a silver sheen, serpentine trails and twisted, deformed leaves.

The larvae eventually emerge from the leaf and make a pupal chamber by folding the edge of the leaf down and securing it with silk.

Spraying may not be particularly effective by the time most home gardeners realize there is a problem and decide to do something. Insecticides will not take away damage that has already occurred. Fortunately, the damage looks a lot worse than it is. Affected trees generally recover very well and little or no reduction in harvest occurs on productive trees. Given that the damage is mostly cosmetic, most people choose not to spray.

If you decide you want to try to fight the citrus leaf miners, begin spraying the insecticide spinosad as soon as you begin to see the new growth emerging. Continue to spray regularly following label directions until the new growth matures and turns dark green. 

Garden tips

CALADIUM CARE: Keep caladiums well-watered during dry spells to keep the foliage in good shape through the summer. Apply fertilizer now to encourage vigorous growth. Break off any flowers that form.

AWAITING THE COOL: If your spring-planted eggplant and bell pepper plants are still in good condition, they can generally be relied on to produce a fall crop even if they are not producing well now. Control pests and keep the plants well-watered and fertilized as needed. They will begin to set more fruit as the temperatures become cooler.

TROPICALS NOW: Despite the heat, now is a good time to add palms and other tropical plants to your landscape. They establish best when the soil is warm, and there is time for them to establish before winter. Hold off on planting hardy trees and shrubs until the weather cools off in November. 

CAREFUL CARE: Avoid using most weed killers on your lawn now. High temperatures increase the chance of discoloring or damaging the grass. Metsulfuron and Celsius may be used now despite the heat to control Virginia buttonweed, lespedeza and other summer weeds.

PEACH TLC: Spray peach-tree trunks with permethrin to prevent the peach tree borer from getting into the trunk and causing damage. Repeat the spray every two weeks through September.

A LITTLE TRIM: Cut back perennials in the garden when they finish flowering and trim away unattractive foliage.