A dry fall and spring up the potential for grasshopper problems this year — and putting cattle on pasture too early greatly improves their habitat and increases their resulting damage.
“From work by Llewellyn Manske from North Dakota, grazing before plants are ready sets back plant growth, and creates an open plant canopy with areas of bare ground between plants for the sun to heat,” said provincial forage specialist Grant Lastiwka. “The grasshoppers take advantage of these sites to warm up in the morning which speeds up their metabolic and growth rates.”
But waiting until forages are growing and pastures ready to graze positively affects the plants’ ability to maintain humidity near the soil and keep soils cooler.
“This will reduce grasshopper hatching success, likely slow their growth, increase their death rates and reduce the time grasshoppers are in advanced growth stages causing the most damage and laying eggs,” said Lastiwka.
Studies have found there are 70 per cent fewer grasshoppers under a twice-over rotation (grazing pastures for short periods two times per season) than with season-long grazing and there are 3.3 times more grasshoppers under season-long grazing than under rotational.
“With season-long grazing, the warm spots that are created by overgrazing are used by grasshoppers to congregate in the mornings, get a quicker start to the day, eat more, grow faster, and cause more damage,” said Lastiwka.
Even later in the season, the number of grasshoppers that lays eggs is lower under rotational grazing, he said.
“If pastures are grazed only after the 3-1/2-leaf stage in spring, using a system with wise twice-over rotational grazing management gives plants the needed biological time for recovery. You will have less grasshoppers, a healthier plant/soil relationship that is drought adverse, and more forage for your cattle or sheep to graze.”