Includes
Bean aphid (Aphis fabae)
Bird-cherry oat aphid (Rhopalosiphum padi)
Corn leaf aphid (Rhopalosiphum maidis)
Green peach aphid (Myzus persicae)
Potato aphid (Macrosiphum euphorbiae)
Pest description and crop damage Aphids suck plant sap, causing leaf deformation and stunting of plants. They may become very abundant on leaves, especially in eastern Oregon. However, corn leaf aphids can cause damage while feeding within the whorl before large populations are found on exposed leaf surfaces. Therefore, begin to monitor for aphids before tasseling. Slowly unroll whorls to count aphids. Bird-cherry oat aphid is the dark gray-green species that has been most destructive on corn in recent years. The shiny black bean aphid has been less common for a number of years. Correct species identification is important for optimal control; however, there are no established economic thresholds for the PNW. The following guide provides easy-to-use diagnostics for key pest aphid species: https://agresearch.montana.edu/wtarc/producerinfo/entomology-insect-ecol....
Please contact your local extension office for assistance with identification.
Management-chemical control
abamectin/thiamethoxam (Avicta Duo, other formulations of Avicta that also contain fungicides)-Apply only for use in certified seed treatment facilities. Applied as a slurry to corn seed. Consult label. (Groups 6 and 4A)
alpha-cypermethrin (Fastac CS) at 0.017 to 0.025 lb ai/A. REI 12 hr. PHI 30 days. If crop residue is to be fed to livestock, PHI is 30 days grain & stover. Retreatment interval 3 days. Do not exceed 0.075 lb ai/A per season. Not for use on sweet corn seed. This product is highly toxic to bees and other pollinators exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees or other pollinating insects are foraging in the treatment area. (Group 3A)
azadirachtin (Neemix 4.5) at 0.01 to 0.02 lb ai/A. PHI 0 days. REI 4 hr. Begin applications at first sign of infestation. Neemix is OMRI-listed for organic use. (Unidentified MOA group)
bifenthrin (Bifenthrin 2EC, numerous other products) at 0.033 to 0.1 lb ai/A. Do not exceed 0.3 lb/A. PHI 30 days. REI 12 hr. Highly toxic to bees and other pollinators exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees or other pollinating insects are foraging in the treatment area. Extremely toxic to fish and aquatic invertebrates. (Group 3A)
bifenthrin/zeta-cypermethrin (Hero) at 0.04 to 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. Refer to product labels for application limits if multiple products containing zeta-cypermethrin are to be used in the same season. This product is highly toxic to bees and other pollinators exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees or other pollinating insects are foraging in the treatment area. (Group 3A)
Chromobacterium subtsugae (Grandevo) at 0.6 to 0.9 lb ai/A per 100 gal. PHI 0 days. REI 4 hr. Grandevo is OMRI-listed for organic use. (Unidentified MOA group)
dimethoate (numerous products) at 0.33 to 0.5 lb ai/A. PHI 28 days. If crop residue is to be fed to livestock, PHI 14 days for forage; 28 days for grain. REI 48 hr. Do not exceed 0.5 lb ai/A per season. Not for use on sweet corn seed. This product is highly toxic to bees and other pollinators exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees or other pollinating insects are foraging in the treatment area. Workers are prohibited from entering the treated area to perform detasseling tasks for 4 days in nonarid areas and for 15 days in outdoor areas where the average annual rainfall is less than 25 inches per year. (Group 1B)
esfenvalerate (Asana XL; other products) at 0.03 to 0.05 lb ai/A. PHI 21 days. REI 12 hr. Do not exceed 0.25 lb ai/A per season. Esfenvalerate 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 or weeds if bees are visiting the treatment area. Esfenvalerate is highly toxic to fish and aquatic invertebrates. (Group 3A)
flupyradifurone (Sivanto 200 SL; Sivanto Prime) at 0.137 to 0.183 lb ai/A. PHI 21 days. REI 4 hr. Do not exceed 0.365 lb ai/A per season. Minimum interval between applications is 7 days. This pesticide is toxic to aquatic invertebrates. (Group 4D)
methomyl (Lannate LV; other products) at 0.225 to 0.45 lb ai/A. PHI 21 days for ears or stover. REI 48 hr. Do not exceed 2.25 lb ai/A per season. This product is highly toxic to bees and other pollinators exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees or other pollinating insects are foraging in the treatment area. (Group 1A)
zeta-cypermethrin (Mustang, Mustang Maxx) at 0.034 to 0.05 lb ai/A (Mustang) or 0.017 to 0.025 lb ai/A (Mustang Maxx). PHI 7 days. REI 12 hr. Do not exceed 0.2 lb ai/A per season (Mustang) or 0.1 lb ai/A per season (Mustang Maxx). Refer to product labels for application limits if multiple products containing zeta-cypermethrin are to be used in the same season. Degree of control will depend on the species present and plant-insect interactions. Mustang and Mustang Maxx are not for use on sweet corn seed. Zeta-cypermethrin is highly toxic to bees and other pollinators exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees or other pollinating insects are foraging in the treatment area. (Group 3A)