LOOK FOR SPOTTED ALFALFA APHIDS

Spotted aphids are a mild weather pest often associated with dry conditions. This, however, does not mean that they will suddenly disappear when cold weather arrives.  

Spotted aphids provide additional stress for plants already under poor growing conditions. The lack of rainfall, in conjunction with insect pressure, does not favor plant survival. This is particularly true in seedling alfalfa stands. Plants less than 5 inches tall may not have sufficient moisture to establish strong root systems. Infestation with an insect that injects a toxin only compounds problems.  

In addition to lack of moisture and insect pressure, producers who try to combat their aphid problems run into other constraints. Three items should be considered before making an insecticide application for alfalfa aphids.  

1) Use the right material. Producers should consider using either Lorsban or Pounce. If Pounce is chosen, then use at least 0.15 lb a.i./acre. One-half pound a.i./acre of Lorsban should also work and is probably the best choice.  

2) Adequate Gallonage. Regardless of your choice of insecticide, if you have a new stand or you are treating an established stand with a high population of aphids, then apply the chemical by ground, and use at least 10 gallons of water per acre.  

3) Treat when conditions are favorable for control. Do not apply in cold conditions (less than 50⁰ F), or use material stored for a prolonged period in hot conditions (90⁰ F or hotter). During cold weather, aphid activity is somewhat depressed. Efficacy of improperly stored insecticides can be dramatically affected.  

Producers trying to control spotted alfalfa aphids should consider all of these factors to obtain the best results. Dry conditions do not favor insecticide efficacy, especially if we ignore other factors.