Timothy Gibb, turfgrass integrated pest management specialist at Purdue University, has seen leafhoppers as major pests on agricultural row crops, tree crops and in ornamentals. Several genera are very damaging in those situations, but grasses are resilient plants, and leafhoppers by themselves almost never do significant damage to healthy turfgrass stands.
“They kind of add to the barrage of pests,” Gibb says, however, in some cases can cause visible damage and possibly even kill grass. Both adults and nymphs cause injury by piercing and sucking the juices out of the grass leaves. The adults, because they are larger, may be more damaging, but two generations may be living in a lawn at the same time and feeding on grass.
Leafhoppers may be a pest in any region of the country on all grass species. Gibb sees them feeding on Kentucky bluegrass, fescues, bentgrass and ryegrasses in Indiana from early spring throughout the summer. Adults are small, winged insects up to a .25-inch in length that jump and fly short distances when disturbed, and can build up to large flights. They may be yellow to green to gray in color, depending on the species. The nymphs are smaller and wingless, and when approached can be identified by their characteristic backward or sideways movement.
Even as the leafhoppers puncture grass stems over a wide area and leave a mottled, yellow appearance to a lawn, healthy grass is able to grow out of the temporary feeding damage. In fact, leafhoppers can be more damaging to horticultural flowers, shrubs and trees than to grass, and this can be an early warning sign to turfgrass managers that their grass may also be a target. The same species of leafhoppers may feed on all of the above plant groups.
In Indiana, leafhoppers begin to pop up in the spring, but do the most damage when grasses are under stress, such as midsummer when drought leaves the plants vulnerable. Several species of leafhoppers may operate in the same area, Gibb says, and multiple generations can emerge during the course of the growing season. Damage seldom occurs in the spring because cool-season grasses are growing vigorously at that time and are able to grow out of most leaf-feeding injuries.
“Weather fronts will bring them in from the southern states,” he says, noting turfgrass managers should watch for large populations after one of these summer storms.
Gibb cites three IPM-related methods of to keep populations at levels where they can be tolerated. The first is to avoid broad-spectrum insecticides that will kill off natural enemies of leafhoppers. There are many spiders and predatory insects, such as ants, rove beetles and ground beetles, that prey on leafhoppers. Leafhoppers will be killed by sprays along with their enemies, but are fast-reproducing insects that can return before their enemies do, and become even more of a problem.
Another technique is to watch for symptoms of damage and respond with management techniques that promote plant vigor and allow it to outgrow the damage. For example, when leafhoppers damage drought-stressed plants in the summer, quick irrigation can be applied to revive the plants.
Gibb also points out that allowing grass height to lengthen during an outbreak may be all that is needed to counter it. Tall grass not only provides more habitat for the pest’s natural predators, it also provides much more food for leafhoppers. Therefore, even though many leafhoppers may be present, the effects of their feeding on grass appearance can be minimized.
Gibb says that when treatment becomes necessary for more damaging pests such as sod webworms, aphids or greenbugs, leafhoppers will also be controlled as those other pests are sprayed.
Insecticides such as carbaryl (Sevin), bifenthrin and other pyrethroids (Talstar and others) and acephate (Orthene) that are commonly used to treat other major turfgrass pests are also effective on leafhoppers, Gibb says. Liquid sprays are recommended when trying to kill leafhoppers because they can be targeted to leaf tips where leafhoppers feed.
Don Dale resides in Altadena, Calif., and is a frequent contributor to Turf. He has covered the green industry for more than 10 years.