XIII. Ornamental, Lawn and Turf Insects

W. G. Hudson, S. K. Braman, R. D. Oetting, and B. L. Sparks

There was a change in the severity of some pests on greenhouse crops in 1995. In previous years whiteflies and aphids were the most common pests encountered and they were very difficult to manage with traditional chemicals. In 1994 the insecticide imidacloprid was introduced to the greenhouse market as Marathon 1% granules and became the standard product used for aphid and whitefly infestations. Aphids have been controlled easily on crops which were treated with imidacloprid. Silverleaf whiteflies have been controlled, but there were indications that imidacloprid was not as effective on the greenhouse whitefly. In 1995, the western flower thrips was the most frequently reported pest and the most difficult to manage with insecticides. The problems with thrips were more noticeable because of the association with virus diseases, where the disease was often more damaging than the thrips. The occurrence of virus (tomato spotted wilt or impatiens necrotic spot) was about the same in 1995 as in 1994 and continued tbe more troublesome than in previous years. The biggest change in pest status on greenhouse crops was an increase in difficulty in controlling two-spotted spider mite. Mites have always been very frequent pests but the two-spotted spider mites have not responded to acaricide treatments and repeated applications are required to control them. Fungus gnats were among the more difficult pests to control, but recent registrations of insect growth regulators for fungus gnats have reduced the problems with these pests. Leafminers were reported as pests more frequently in 1995. This is a sign that leafminers are increasing in significance for the greenhouse industry.

There has been an increase in the costs of pesticides used to control pests on ornamentals in the greenhouse. New pesticides are more effective, requiring fewer applications, but the cost of control is still about equal to repeated applications of older compounds. However, as pest problems increase, there is an increase in the use of more expensive products and in the overall cost of control. Good sanitation, exclusion and other cultural practices are important in reducing the incidence of pest problems. Beauveria bassiana, a fungus which kills insects, was introduced to the market in 1995. This is the first natural insecticide of this type to be registered for greenhouse use in the USA. Biological control is used on a small scale, and research is intensifying to provide information on biological control and the compatibility of natural enemies and chemical management tools.

In 1995, the major insect problems on woody ornamentals, both in home landscapes and commercial landscape maintenance, included various species of borers, scale insects, mites, lace bugs, foliage feeding beetles and whiteflies. Populations of scale insects continue to build due to mild winter temperatures. Borer damage was noted on many different species of ornamental trees and shrubs during the year. Damage due to the Asian ambrosia beetle, Xylosandrus crassiusculus, was found in greater incidence and on a wide range of host plants in nursery production and landscapes. Japanese beetle populations were higher in 1995 than in previous years in the northern half of the state, and associated damage and control costs in both nursery production and landscape situations increased significantly. Spider mite problems were severe and widespread throughout the state all year.

The turf industry in Georgia (includes production, sales, installation and maintenance) is estimated to be worth in excess of $1.4 billion annually. There are currently 349 golf courses in operation in the state, with more under construction or in planning. There are 737 football fields, over 16,000 acres of turf on school grounds (public and private), and over 25,000 acres of turf in parks. All total, there are an estimated 1.3 million acres of turfgrass in the state. Increasing urbanization and emphasis on expanding recreational opportunities statewide should lead to continued strong demand for quality sod in the future. Sod production accounts for over 15,000 acres in Georgia, and the trend toward increasing acreage devoted to this crop will continue as long as the demand is there.

Although mole crickets are found only in the coastal plain region of Georgia, they are so destructive and difficult to control that almost half of the losses from insect pests in turf statewide are due to these pests. Dry weather during the spring and early summer affected survival of young nymphs in 1995 but some significant problems developed later. Caterpillar problems were widespread but sporadic in 1995. Spittlebugs continue to be severe pests, but early dry weather helped reduce their populations and impact.

Numbers of Units Considered in Preparing Loss Estimates for 1995

Estimates of Losses and Control Costs

¹ Primarily cutworms, corn earworm, loopers, azalea caterpillars, and leaf rollers.
² Primarily leaf beetles, Japanese weevils, Fuller Rose weevil, Japanese beetle, whitefringed beetle, borers, and carpenterworm.
³ Includes grasshoppers, fungus gnats, millipedes, sowbugs, psocids, springtails, ants, earwigs, and leafminers.
⁴ Sod webworms, armyworms, cutworms.
⁵ Ants (excluding fire ants), billbugs, leafhoppers, and mites.