In the Garden:
Coastal and Tropical South
April, 2012
Regional Report

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Signs of spider mite damage on lantana include burnished and stippled leaves like these.

Face Your Pests

From the tiniest mites to browsing deer, a gardener can remain vigilant for pests and still occasionally be blindsided by the sight of damage to his or her plants. There can be no better reason for my number one garden rule: walk the garden daily. When you see the early signs of pest issues, getting a grip on them is much simpler.

Seeking Small
Here are the signs often seen when mites and insects are damaging your plants and some prevention and control strategies. Spider mites are tiny, often red, specks of dust that move when disturbed. They are most active in dry, hot weather and attracted to many plants. Watch for dehydration despite watering, leaves that are pale, stippled, or bronzed in stages, poor growth and flower production. You can almost always hold spider mites to a manageable level with weekly sprays of water under the leaf canopy of plants like lantana. Sprays containing Neem can effect some control.

Neem can sometimes be effective against azalea lace bugs, too, especially when combined with annual pruning and good garden sanitation. These insects cause many azaleas to develop ugly leaves covered in tiny white pin pricks with corresponding little black droppings on the undersides.

Stunted growth such as rose buds that do not open are the hallmark of aphids. These sucking insects no bigger than a pinhead that gather on flower buds and new leaves can sometimes be deterred by a strong stream of water. Larger infestations may require pyrethrin sprays at eight day intervals.

White flies may stir when you pass your gardenia or hibiscus, but they probably live in the privet or ligustrum nearby. They also dehydrate the plant and cause leaf drop when they feed in great numbers. Since all of these pests multiply several times each month, their numbers can get very large, very fast. White flies are least active in the evening and most likely to be in their nest plant, the privet or another leafy shrub such as abelia. Take advantage of that by timing sprays late in the day to best disrupt their habits.

Look for Leaf Chewers
Caterpillars are the larvae of butterflies and moths. (Larvae are the immature form of any insect.) They have segmented bodies and three real sets of legs, although they do have other appendages that may look like legs. They also have big mouths and voracious appetites. While we may rejoice when monarch butterfly babies strip the leaves from their milkweed hosts, we're not as happy when it is the corn earworm or tomato hornworm devastating our food crops. Caterpillars grow quickly and can cause a great amount of damage by the time control products take effect. You may notice leaves chewed or gone entirely and black frass or excrement left by the caterpillars on stems and remaining leaves. When the bad boys appear, pick off the offenders and stomp them or drop them into a kill jar of bleach and water. The microbial insecticide BT is also effective against caterpillars, especially when they are small, but they need to ingest it, along with the leaf it coats, in order get inside the caterpillar and do its deadly work, so don't expect immediate results.

Got Worms?
Lots of gardeners say they have worms when they see caterpillars and other larvae. Some pests like cabbageworms and cutworms even bear that name, although they are truly caterpillars. Cutworms spend their days in the ground, coming out at night to feast on plans. You'll know they have been around when you discover that young plants are simply gone. Cutworms wrap their bodies around little stems, so can be deterred with a cardboard collar installed at planting time. If they cannot grab it, they cannot cut the stem.

Moles in the garden are searching for food, often the white grubs living underground. These grubs are the larvae of beetles such as June bugs that emerge as adults from the ground in late spring. You may find grubs in a shovelful of soil when you poke around to see why grass simply will not grow properly near sidewalks and driveways. When their numbers are great enough to bring in the moles, you will want to treat the lawn. Combine the short term control of granular pesticides applied to the lawn and the long term approach of using milky spore sprays to effect good control of grubs.

Like so much of gardening, our job is to strike a balance between growing plants and controlling the threats to them. When it comes to mites and insects, good information and a hand lens are often our best control tools.

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