Since we rarely treat for the southern corn stalk borer, be sure to pull out the whorls of 10-20 plants per field to determine which insect is causing the damage. Southern corn stalk borer larvae will appear spotted compared to the cream colored body of the corn borer. Ambush, Pounce, Penncap-M or Warrior will provide the best control. If bees are foraging in the area, Penncap should not be used. Bean leaf beetles continue to be the main pest feeding on seedling beans.
Damage appears as small circular holes in the leaves.
In comparison, Mexican bean beetle feeding will appear as a lacey pattern on the leaves. No controls are needed unless you find at least 2 bean leaf beetles per plant and they are reducing the stand by 25 percent. A pyrethroid or Sevin will provide control. Grasshopper nymphs can also be found in no-till fields and along field edges. Treatment of non-crop areas may also help to prevent whole field infestations at a later date.