Every season is pest season, really, but these early months of spring hold promise for detecting — and perhaps preventing — some emerging nuisances.
With vigilant scouting and early identification, a full-blown infestation may be averted. Some of the stars debuting or returning this spring are given the spotlight here.
The Pennsylvania Department of Agriculture (PDA) and the USDA have issued alerts for spotted lanternfly; the USDA, in fact, has announced $17.5 million in emergency funding to help stop the spread of the pest in southeastern Pennsylvania. Secretary of Agriculture Sonny Perdue stated, “We’ve seen a dramatic expansion in the range of this pest over the last year and we need to take decisive action to prevent the spotted lanternfly from spreading throughout Pennsylvania and into neighboring states. We have the tools to fight this invasive insect and — together with the Pennsylvania Department of Agriculture— we have developed an area-wide approach that will begin before the pest starts to re-emerge in the spring.”
The colorful, invasive insect, which sports distinctive and colorful wings as well as black and/or white spots, feeds on Ailanthus altissima (tree of heaven), so it might also be thought to be an ally in the fight against the invasive tree. But it’s also a threat to orchard trees and vines, including apples, grapes, peaches and stone fruits; more than 70 types of food and ornamental plants are believed to be affected.
Spotted lanternfly is a plant hopper that sucks sap from trees; infestations often are detected by sighting sooty mold and honeydew. The feeding can reduce fruit production as well as stunt growth.
Woolly alder aphids
Joe Boggs, assistant professor with The Ohio State University Extension and OSU Department of Entomology, says that some bare Alnus species this winter sported what appeared to be unusually situated traces of snow — on the undersides of bare branches. These fuzzy white infestations, however, likely were woolly alder aphids. The pests form colonies that are covered in whitish fuzz or strands of fi laments. Silver maple (Acer saccharinum) is an alternate host; nymphs that successfully mature into adults with wings will leave alders and settle on nearby silver maples.
For the most part, these pests are considered nuisances, more likely to cause ornamental damage than systemic harm that could threaten the health of the trees. Little control is required. Heavy infestations can cause leaf curl, and sticky honeydew can be terribly annoying, especially on a client’s patio.
Rose stem girdler
In the Northwest, Robin Rosetta says, “Out our way we are tracking the movement of a new pest in our valley, rose stem girdler. It has shown up for us this summer in the valley on caneberries, but it can certainly damage roses, its namesake, and we’ll need to get it on the radar.” Rosetta, associate professor and Extension entomologist at Oregon State University’s North Willamette Research and Extension Center, has her eye on a few lurking pests, including Japanese flower thrips and allium leafminer (see below).
A common pest of raspberries and blackberries, rose stem girdler poses a threat to cultivated roses: Canes that are injured by the boring larvae, which feed on the cambium beneath the cane bark, can wilt and snap off.
Overwintering larvae remain inside the cane; mature adults, which feed on leaves and tend to cause ornamental injury, are slender, copper-colored beetles with metallic green “faces.” These also are diffi cult to spot, since they are only about a quarter of an inch long.
Evidence of rose stem girdlers can be detected by the presence of gall-like swellings that appear at the base of wilted top growth — usually appearing in June and July. Spiral grooves that girdle the cane also betray the presence of this pest.
Japanese flower thrips
Hosta plants were shipped around the country from a nursery in Michigan before it was learned they were infested with Japanese flower thrips (JFT), Rosetta says. “Now a few more states have detected this new thrips species (including in Oregon in one nursery which received the hostas, under eradication there). One of the reasons it was detected is that the usual thrips biocontrol program was not working with this thrips species.”
JFT feeds on about 14 plant families, including the ornamentals chrysanthemum, hellebore, hosta, hydrangea, impatiens, petunia and poinsettia. Damage to foliage appears as silvery streaks and spots, and in some hosta in Oregon, streaking and deformed leaves have been detected.
The tiny pest — adults are less than 1/16 of an inch long) can be identified in the field using magnification. They’re found in flowers and on the underside of leaves. The body and most of the wing appear dark brown; females have a lighter wing color.