2003 Season Review: Ornamentals - Insect Problems

Cliff Sadof, Professor, Entomology, Purdue University

Outbreaks of half wing geometers and linden looper were found in south central Indiana in Jackson, Washington, Floyd, Perry, Harrison, Crawford and Clark counties this spring. Further to the east toward Madison, an outbreak of forest tent caterpillar defoliated ridge tops along the Ohio River. More red elms (Ulmus rubrum) continue to enter an age class that is more susceptible to outbreaks of Dutch Elm Disease.

A late frost in April and a hot wind in Early May caused widespread scorch in wide range of conifers in landscapes and Christmas tree plantations.

The rainy weather this spring stopped long enough during May and June to foster a healthy gypsy moth population. This year's survey of gypsy moth larvae in northern Indiana of 7 sites failed to find a single caterpillar with Entomophaga maiamaga in parts of the state where we have previously found the fungus. Although outbreaks of gypsy moth barely defoliated a dozen trees in the Fort Wayne area, urban residents were quite concerned about sharing their home yards with gypsy moths for the first time.

Widespread informal reports of gypsy moth egg masses throughout northern in Indiana counties suggests that the gypsy moth population is poised to flare under appropriate weather conditions.

Despite a cold January through March, marginally hardy species such as bagworm and mimosa webworm continued to thrive in north of their traditional areas.

Heavy rains over the 4th of July weekend dumped over 10" of rain along the Wabash Valley causing a 50 year flood event in North Central Indiana. Another 10" of rain fell on Labor Day weekend in Indianapolis causing more record flood events.

Cool weather in July fostered an outbreak of soybean aphid in much of northern Indiana. This was closely followed by complaints of slow flying" sweat bees" in much of the state in late August. These sweat bees turned out to be that turned out to be syrphid flies whose population boomed due to the presence of so many aphid prey. Aphids in the landscape turned out to be somewhat normal.

Cool weather in July and early August failed to produce substantial flights of Japanese beetles. Although defoliation was spotty as usual, overall it seemed to be lighter than normal. White grubs were hard to find in many turf research plots this August.

August also brought about another outbreak year of fall webworms. The outbreak seems to have spread from the north to as far south as Evansville. Dry weather in August caused a good scare for expression of borer and mite infestations.

Emerald ash borer is now only 2 miles east of Indiana in Hicksville, OH. Surveys of injured ash show in Indiana to date only show outward signs of native borers, with one exception. A regulatory action was taken in Winchester, IN, where 1 tree with EAB damage symptoms was detected. Live beetles or larvae have yet to be found on trees in our state.

Heavy rains and generally cool weather seemed to dampen outbreaks of both warm season and cool season mites. Eriophyid mite problems on baldcypress continue to be problematic.