Monday, April 23, 2012


ORNAMENTALS AND TURF From: Steve Franks, Extension Entomologist Elm Pests Get Going Right now a lot is happening on elm trees. For those of you who still have elm trees you can look for elm leaf miner, Fenusa ulmi, and woolly elm aphid, Eriosoma americanum. Elm leaf miner is a sawfly that lays eggs in elm leaves. The larvae mine tissue creating blotchy, brown translucent areas on the leaves. In late spring the larvae exit leaves, drop to the ground and borrow an inch down to pupate. Affected leaves will remain on the trees and become brown as mined tissue dies. They may drop prematurely. This time of year you can find a few adults left but mostly you will find larvae in various stages of development. Mines are small so far but expand rapidly. Imidacloprid and orthene can be used to kill larvae in mines but they are protected from contact insecticides such as bifenthrin. If adults are present in your area, foliar applications of these products can reduce oviposition. Woolly elm aphids are an interesting aphid that manipulates host foliage to create a shelter. The foliage is not altered into a true gall like those on witch hazel but as you can see in the picture that are pretty snug and protected from the elements. These aphids use serviceberry (Amelanchier spp.) roots as alternate hosts. They overwinter as eggs on elm bark. A female aphid emerges as elm leaves are expanding. She feeds on the underside of a leaf and at maturity produces 200 eggs. The infested leaves begin to curl and accumulate waxy debris that makes the aphids look woolly. Mid-summer a winged generation develops that migrates to Amelanchier trees. These colonies of twisted leaves can be easily pruned out. In the case they are over abundant or there are other pests present an insecticide application may be warranted. A recent blog post contains other information and pictures IPM Blog.
Tulip Poplar Aphids in the Landscape
Tulip poplar aphids are becoming abundant in their annual cycle of boom and bust. They start to boom in spring since natural enemies are not very active or abundant. As aphids become abundant, predators and parasitoids home in on them and tend to keep numbers under control. However, trees in highly urban areas or those tended by fire ants may become more abundant since nature predation and parasitism will be limited. General information about managing aphids in the landscape may be found at Aphids. Other aphids to watch out for soon are crape myrtle aphids and rose aphids.
Fire Ant Mounds Abound
Fire ants seem to be extra abundant this year with larger than normal mounds. I think this is due to the mild winter. Fire ants are usually relatively inactive in winter months. They rely on resources within the mound to survive and reproduction slows down. I witnessed fire ants foraging throughout the winter meaning they could gather more food and maintain mound size. A frequent location for fire ant mound is in the mulch around landscape trees. Particular when too much mulch is applied as in this video Fire Ant Mulch . General information on fire ant management is available at Fire Ant Management. Help choosing insecticides is Fire Ant Chemical Control Chooser.
Azalea Lacebugs
Azalea lace bugs (Stephanitis pyrioides) are one of the most damaging pests of evergreen azaleas. They overwinter as eggs in azalea leaves and begin hatching around now. Control is best targeted early in the season when nymphs are present for two reasons. First, nymphs are easier to kill than adults and if you kill nymphs before they mature and lay eggs you have a better chance of clearing up the infestation. Second, the longer azalea lace bugs are on your plant the more damage they do. On evergreen azaleas this damage sticks around for a long time so plants may be permanently damaged. So scout your azaleas and get those lace bugs cleared up before damage occurs. For more information and control options, click here: Azalea Lace Bug For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.