Prevention and Control: If possible, select resistant varieties. Keep nitrogen-heavy fertilizers to a minimum as well as over-irrigating as they encourage lush growth. Practice crop rotation and prune out or better yet remove infected plants.

Pest : Mealybugs

Small, wingless, dull-white, soft-bodied insects that produce a waxy powdery covering. They have piercing/sucking mouth parts that suck the sap out of plant tissue. Mealybugs often look like small pieces of cotton and they tend to congregate where leaves and stems branch. They attack a wide range of plants. The young tend to move around until they find a suitable feeding spot, then they hang out in colonies and feed. Mealybugs can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.

Prevention and Control: Isolate infested plants from those that are not. Consult your local garden center professional or the Cooperative Extension office in your county for a legal insecticide/chemical recommendation. Encourage natural enemies such as lady beetles in the garden to help reduce population levels of mealybugs.

Pest : Caterpillars

Caterpillars are the immature form of moths and butterflies. They are voracious feeders attacking a wide variety of plants. They can be highly destructive and are characterized as leaf feeders, stem borers, leaf rollers, cutworms and tent-formers.

Prevention and Control: keep weeds down, scout individual plants and remove caterpillars, apply labeled insecticides such as soaps and oils, take advantage of natural enemies such as parasitic wasps in the garden and use Bacillus thuringiensis (biological warfare) for some caterpillar species.

Pest : Scale Insects

Scales are insects, related to mealybugs, that can be a problem on a wide variety of plants - indoor and outdoor. Young scales crawl until they find a good feeding site. The adult females then lose their legs and remain on a spot protected by its hard shell layer. They appear as bumps, often on the lower sides of leaves. They have piercing mouth parts that suck the sap out of plant tissue. Scales can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.

Prevention and Control: Once established they are hard to control. Isolate infested plants away from those that are not infested. Cosnult your local garden center professional or Cooperative Extension office in your county for a legal recommendation regarding their control. Encourage natural enemies such as parasitic wasps in the garden.

Diseases : Dutch Elm Disease

Dutch Elm Disease is caused by a fungus that is spread by elm bark beetles infected with Ophiostoma ulmi. The disease was originally brought to the United States via elm burl logs to be used for furniture veneer. Beetles begin by feeding in the upper portions of a tree. As the fungus spreads, toxins are produced which inhibits the water conduction in the tree.

Acute Dutch Elm Disease is rapid, leaves often wilting, curling and dropping while still green. Death often occurs in just a few weeks. Chronic Dutch Elm Disease is much slower. Though infected trees leaf-out in late summer, leaves towards the top of the tree yellow and often drop. Closer inspection of limbs reveals that wood beneath the bark is ringed with brown dots, or clogged water-conducting tubes. Though trees may struggle for several years, they will eventually die.

Prevention and Control - Unfortunately, very little can be done to prevent the disease except to plant resistant varieties. Most will agree, early detection is a must. Elms should be inspected each spring and again in late summer. Infected trees must be destroyed immediately as elm bark beetles feed on healthy wood and breed in dead or dying wood. Do not try to salvage any of the wood.