Corn seed-Mite

Includes

Banks grass mite (Oligonychus pratensis)

Twospotted spider mite (Tetranychus urticae)

Pest description and crop damage Tiny, spiderlike animals, on underside of leaves, that cause yellowing or silvering of leaves. They feed on plant juices and may contribute to early maturity and poor quality of corn. Mite infestations typically are first observed near field edges or where plants are stressed. Mite populations can build rapidly during hot, dry weather. Monitor mite populations carefully if synthetic pyrethroids (Group 3A insecticides) are used for mites or other pests as these insecticides may flare outbreaks of mites. Because twospotted spider mite populations are often more resistant to miticides/insecticides than are Banks grass mite populations, it is essential to determine which species are present in a field before treatment.

Management-chemical control

  • bifenthrin (Bifenthrin 2EC; other products) at 0.08 to 0.1 lb ai/a. PHI 30 days. REI 12 hr. Do not apply more than 0.3 lb ai/a per season. ULV application is prohibited. Do not apply if heavy rain is imminent. Bifenthrin is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area. Extremely toxic to fish and aquatic invertebrates. (Group 3A)
  • bifenthrin/zeta-cypermethrin (Hero) at 0.1 lb ai/a. PHI 3 days for sweet corn seed. Do not graze livestock in treated areas or cut treated sweet corn seed crops for feed within 3 days of the last application. For non-sweet corn seed crops, there is a PHI of 30 days for crop residues harvested for stover; do not allow livestock to graze on crop residues for 30 days after treatment. REI 12 hr. Do not exceed 0.4 lb ai/a per season. This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area. (Group 3A)
  • etoxazole (Zeal) at 0.045 to 0.135 lb ai/a. PHI 21 days. REI 12 hr. Apply before or at tassel stage. Retreatment interval 14 days. Make no more than two applications per season and do not exceed 0.27 lb ai/a per season. Not for use on sweet corn seed. (Group 10B)
  • propargite (Comite) at 1.64 to 2.4 lb/ ai/a. PHI 30 days. REI 13 days, or 2 days if wearing personal protective equipment. Comite is most effective when applications are made when mite populations are low and plants are small enough to allow thorough coverage. It is best to use Comite is pH 7 or lower. To minimize risk of phytoxicity, make applications when foliage is dry. One application only per season. (Group 12C)

For additional information

http://extension.colostate.edu/topic-areas/insects/spider-mites-in-corn-....