Insects are causing problems for alfalfa. From alfalfa weevil larvae and adults, to potato leafhoppers, armyworms, cutworms, alfalfa caterpillars and all kinds of aphids, somebody somewhere has had enough of each of these insects feeding on their alfalfa, damaging new seedlings or regrowth. 

If you have been lucky enough to avoid these pests thus far, don’t assume you are safe for the remainder of the year. 

Be sure to get out and scout your fields. I’d love to be able to generalize and tell you exactly how many insects per square foot or sweep of a net is needed to economically justify a control treatment for alfalfa. But each insect and disease are different. 

It can range from one spotted alfalfa aphid per seedling to 100 pea aphids on 20-inch alfalfa. Or from one or two armyworms per square foot in new stands to at least 10 alfalfa caterpillars per sweep in established stands. 

Not all diseases cause issues. What we use for control also varies. Simply cutting often works for many soft-bodied insects. Control using natural organisms such as the Bt in Dipel and Thuricide will work for some insects, and, of course, insecticides. But what insecticide or fungicide to use will be different depending on the insect or disease. 

So, my take-home message today is scout and identify what is plaguing your field. Look for slow regrowth or weak seedlings, and scout for insects or diseases that might be causing the issue. Be sure to dig in the soil and dead litter to find insects hiding during the day.

Then identify exactly what you are dealing with. If you need help, stop in at your Extension office. Remember, many insects you find will be beneficial, and some diseases don’t cause yield issues.  And finally, use appropriate treatments to protect your alfalfa.

Source: UNL Pasture and Forage Minute, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.