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Ornamentals and Turf |
Bagworms are approaching the last instar where they have the potential for major defoliation. Scout trees for bagworms before major damage appears and while caterpillars are still treatable. Bagworms have a wide host range, however, in landscapes they are usually associated with arborvitae, cedars or junipers. Heavy populations can do considerable defoliation. In spring, the newly-hatched caterpillars spin down from bags on silken threads and are blown about by early spring breezes. Upon reaching a suitable host, the bagworm begins to spin its bag and as it grows it incorporates some of the host plant foliage into the bag for camouflage. Plants such as Leyland cypress do not recover well from severe defoliation. Ornamentals and Turf Insect Information Note No. 81 provides information on the biology and control of bagworms. Treating bagworms with insecticide while they are small is an effective means of control. Hand picking bagworms, when practical, is a safe and effective means of control. You can collect them in either a paper or plastic bag, or just step on them.
Recently we received a sample containing oak spider mites. Occasionally the oak spider mite becomes very abundant and can even cause defoliation by mid summer. The oak spider mite is in the same genus (Oligonychus) as the southern red mite and the spruce spider mite. Apparently a number of coincidentally-occurring factors made this a good year for the oak spider mite. This mite will not feed on the twigs or stems of oak, only the green leaves. It evidently overwinters as a nonfeeding hibernating stage or as eggs on the fallen leaves and on the twigs. There is probably more damage to the lower leaves. Relatively humid weather encourages entomopathic fungi (Neozygites) to destroy these mites. On a small or specimen tree, insecticidal soap may be applied this coming fall when temperatures are cooler. Be sure the tree is not in sun during treatment and not under drought stress. With a widespread infestation, there is probably not much to be done on such a large scale. Hopefully, it will not reoccur next year and damage to the tree will be minimal.
We also received an oak sample from New Hanover County containing phyloxerans. Phyloxerans are similar to aphids and suck sap from plants. On oak they are most often found feeding along the leaf midrib. They may or may not have wings and have a more spiny appearance than aphids. Some phyloxerans found on oak may be alternating from another host. Terminal growth may show some distortion. For more information and pictures, you may visit a Forest Service publication on the Internet at the following location: http://fhpr8.srs.fs.fed.us/pubs/oakpests/p28.html. It is uncertain how effective pesticides sprayed this year will be to prevent damage next year, but on small or specimen plants, standard treatments for aphids should be applicable.
Fall armyworms have been present in turfgrass for the past week or so and it appears they are now in full gear. There are a variety of sizes present and the larger armyworms are the most damaging. They typically begin near the edge of a turf area and invade across the turf leaving serious damage behind. This edge effect is due to the fact that the moths typically lay eggs on fences, shrubs, signs, buildings, etc. and the larvae must move into the turf. The easiest way to detect the armyworms (larger armyworms may hide during the day to escape birds) is the drench the area with a 2 percent soapy water solution. The armyworms will immediately wiggle to the surface and become easy to see. The presence of many birds in a turf area may also be an indicator that fall armyworms are present. Treatments are usually most effective if applied late in the day and if the area is not mowed for several days. If a spray is used, hold off on irrigation for at least 24 hours. Newly-sprigged and sod areas are at greatest risk for serious damage from this pest.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on July 22, 2002 by Stephen J. Toth, Jr.
