By releasing a unique species of mites into field bindweed-infested forages, growers in semi-arid areas can likely gain control of the pesky plants that steel moisture and nutrients.
The “field bindweed mite” has been the subject of various bindweed control studies at Texas A&M University and New Mexico State University. Most of the research has been in wheat and native grasses, but Bob Stubbs has been using the mites with great success on his Tucumcari, NM, alfalfa farm.
“My bindweed problem was so bad that nothing would bother it,” says Stubbs, who had tried various herbicide combinations. “But I've had excellent luck using the mites. From what I've seen, I have 100% bindweed control.”
Virtually invisible to the naked eye, the mites are introduced to alfalfa or other forages either naturally or by placing mite-infested bindweed plants in a field. They begin to spread immediately.
“I put them out every 45' — then forgot about them,” says Stubbs. “The infestation process took several months, but the weeds were totally gone after a year.”
Basically, the mites zap the plant's energy by sucking its juices. They overwinter on bindweed roots and attack new growth the following spring. The following year's vine doesn't flower.
Stubbs began his mite program after getting infected bindweed leaf clippings from Texas A&M's Research and Extension Center in Amarillo. Gerald Michels, a Texas A&M research entomologist, conducted studies at several locations around Amarillo.
“In every instance, the mites were found to infest 99-100% of the bindweed,” he says.
Early on, Michels worried about disruption of mite infestations during mowing. But he concluded that mowing might actually benefit the insects.
“Since the mites are almost microscopic, mowing the bindweed probably has little to no effect on the mites themselves,” he says. “Also, if mown or chopped pieces of mite-infested bindweed tissue fall into the unmowed portion of the plant, it's possible that the mites move off the pieces of bindweed and onto the living plant.”
He adds that it's likely that the mites are introduced to new plants with long lengths of bindweed that are pulled up and dragged across the field by mowing equipment.
Stubbs believes that other hay harvesting machines also help distribute infestations throughout a field.
“A hay field is a busy highway during the growing season,” he says.“It's easy to get a rapid spread of the mites once they get established.”
Michels says the insects are most prevalent in semi-arid areas. He knows of no system to actually buy them commercially for bindweed control.
“We get the mites to growers by establishing mite-infested ‘bindweed nurseries’ in virtually every county (in northwestern Texas),” he says. “Growers can go to the nurseries and take some infected plants back to their farms for distribution.”
Leonard Lauriault, a New Mexico State forage agronomist who also has helped establish nurseries, says bindweed in ditches, pastures and other areas may be infected with mites. He suggests that growers cut the plants and put them in their alfalfa fields, perhaps coordinating the effort with neighbors.