Weed & Pest
Management choices can help curb hayland pestWritten by Jennifer Womack
Containers of Black Grass Bugs (BGB), an economically important insect that Kneeland plans to learn more about, also share the shelf space. Discovering quickly that there weren’t enough hours in the day to count the insects and watch population trends by hand, the UW master’s candidate is instead looking at aerial image tools to track the insects’ presence.
As Kneeland explains it, BGBs are a native insect that found an environmental niche to grow upon when crested wheatgrass was introduced from Russia. The insect lays its eggs in the year-old grass stems of wheatgrasses, which have become plentiful on Eastern Wyoming rangelands, much dryland hayground included. Kneeland says the BGB has also affected wheat and barley crops in Southeast Wyoming.
Kneeland says controlling the insect may be a matter of reducing year-old vegetation to diminish the habitat where the insects lay their eggs. Hundreds of eggs can be laid in each year-old stem. Wintertime feeding of hay over standing stems or harrowing after the insects lay their eggs in July are a couple of lower cost options he says might aid in management. Insecticide application in the spring is another option, but Kneeland says that really comes down to the value of what the land is producing.
Most of his work thus far, he says, has been on Conservation Reserve Program (CRP) acres. “That’s where they concentrate,” he says of the bugs. “You have grass that’s growing there and in some cases nobody has removed it for years.”
Reducing the presence of crested wheatgrass is among those management practices Kneeland recommends on CRP land. “If it’s about habitat for other animals then wheatgrass isn’t going to be your best option,” he says of reseeding. “Increase other grasses, anything with a real thin blade and steam. Also increase your forbs and flowering plants.” Increases in flowers and forbs, says Kneeland, attracts the parasitoid wasp that researchers haven’t yet identified, but know preys on BGB.
Damage has also been seen in wheat and barley fields where Kneeland says the BGB often hatches in roadside ditches and then moves into cropland. “They consume what’s on the roadways and then hike into barley and wheat field laying eggs in the stalks,” he explains.
Kneeland says shortcomings remain in what the University is able to recommend to producers. Of research he says, “There’s not a lot of funding because it isn’t a pest yet.” Integrated Pest Management (IPM) approaches are difficult since the cost of control needs to make financial sense on rangeland.
Damage can sometimes look as though it occurred over night. “They’re mouthparts are so small you don’t see the damage,” says Kneeland of the early stages. “Once they hit the fifth instar the spots become much larger.”
An end to the drought, he says, wouldn’t entirely curb the population but would help make the effects less noticeable. “The population would likely stay the same, maybe less because of moisture causing fungal growth and killing eggs and young insects. It’s more that the grass would be healthier and you wouldn’t notice the BGB’s impacts as much.”