What is in this article?:
- Welcome rains bring unwanted cutworms to Southeast New Mexico
- History of Alfalfa in New Mexico
- Pest management program
- Cutworm scouting is best defense
- Cutworms could threaten New Mexico alfalfa.
- Conditions may favor cutworm survival.
- Alfalfa is New Mexico’s top crop.
Cutworm scouting is best defense
Pierce and Marsalis agree that scouting fields is necessary to control losses caused by cutworms. They recommend scouting in the early morning or late evening. During warmer periods of the day cutworms generally can only be found in the soil, often at depths of an inch or more.
"It's also wise to control weeds along the border of alfalfa fields and anywhere in near proximity. Often eggs will hatch and larvae will survive in weeded areas, so maintaining a weed free environment near forage crops can help control potential damage caused by harmful cutworm populations," Pierce said.
Pierce also recommends staggering hay cuttings.
"We have discovered that fresh cut alfalfa fields can have both a positive and negative impact on cutworm populations. On one hand, cut fields allow the soil to heat up and this helps reduce the number of eggs that hatch. But it also causes the loss of beneficial predatory insects that feed on small larvae, so staggering your cuttings from field to field may prove to be an effective counter measure," she added.
Typically, female moths lay hundreds of eggs, often in small clusters. They deposit them on low-growing plants such as weeds. Migrating moths lay eggs on the soil as well and the larvae hatch to feed on various types of plants. Young larvae feed on the foliage or small roots of weeds and crops until they reach about a half-inch in length.
"When scouting for cutworm in fields the smaller larvae are of the most concern. These small larvae are not only treatable, but once they reach a certain growth stage, nature is going to take care of the problem for us. Damage is caused primarily from the smaller larvae and this is where we need to concentrate our control," Marsalis advises.
In addition to treating fields, another positive strategy is to make certain not to add to the problem by sustaining conditions that contribute to more eggs hatching. For example, growers should avoid irrigating alfalfa fields soon after beneficial rains have fallen. By keeping the soil moist and cool, conditions are better for cutworm development.