Grasshopper infestations are cyclical; the population rapidly escalates for two or three years before it peaks and then drops down for two or three years of normal population levels. The sharp decline in numbers occurs when the insects run out of food or disease spreads throughout the swarms. But after the lull in reproduction, the numbers begin to mount again and the cycle continues.
Coming into the summer, growers are reminded of this circle of life. The 2010 season is being labeled as a “peak” year for grasshopper infestations; some states are even predicting high population levels not seen since 1980.
“Grasshoppers in the Western prairie and mountain states look to be setting themselves up for populations of what they call ‘Biblical proportions,’” said Roy Boykin, technical brand manager, insecticides, at Syngenta Crop Protection. “Researchers who study these grasshoppers and watch the populations are saying that this may be the largest population that they’ve seen in 30 years.”
According to the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS), the unusually high population of adult grasshoppers at the end of the summer of 2009 indicates that a large number of eggs were laid. Scientists are currently surveying and monitoring the 17 states, including Nebraska, North Dakota, South Dakota and Wyoming, which are expected to have the heaviest outbreaks.
Grasshoppers are a healthy part of the ecosystem when found at sustainable and non-threatening levels, or about eight insects per square yard. It’s when population levels rise to upwards of 20 grasshoppers per square yard that they can have a debilitating effect on rangeland and crops, according to the Texas A&M Agricultural Extension Service. In large numbers, swarms can become particularly damaging, with some species known to be capable of eating up to seven times their body weight in vegetation daily. The latest surveys also note that migratory species—those that can fly up to 60 miles in a day—are now prevalent.
In the West, researchers are keeping a close eye on rangeland and pasture grasses. Grasshopper eggs tend to survive better in untilled soil, but it’s not uncommon for them to then move into cropland containing corn, soybean, wheat and barley. The prevalence of migratory grasshoppers may mean the likely spread of grasshoppers into croplands throughout the summer.
Boykin recommends that growers keep their ears to the ground about the spread of grasshoppers and about how severe the problem actually becomes.
“Assuming that these populations do develop the way the USDA is predicting, it’s very likely that these grasshoppers will move into their soybean crops…and if they do move into soybean or any other crops, the populations will be devastating, and the growers need to be prepared to take action,” said Boykin.
Boykin proposes using Warrior II with Zeon Technology® insecticide on both pasture grass and crops. It not only provides quick knockdown but also long residual control of pests, which is key to keeping population numbers low from the start of the season. Endigo® ZC insecticide is also being touted for its consistent and reliable control of grasshoppers and other pests on soybean. Endigo ZC will control pest populations for an extended period of time and fits easily into a resistance management plan.
“The best thing growers can do is be on the lookout and make early applications to try to keep these grasshoppers under control,” said Boykin.
For additional information or interviews, please contact Roy Boykin at 336-632-6000; or Molly Alderfer at 919-870-5718 or [email protected]