1. Insect
  2. Agronomic Crops
  3. Small Grain Pests

Small grain-Russian wheat aphid

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Diuraphis noxia

Pest description and crop damage The Russian wheat aphid is relatively easy to identify. The aphid is light green, elongated, and spindle-shaped. Antennae are very short. It has a wart-like projection above the tail that gives it a two-tail appearance. Dorsal tubes (cornicles) are very short and not obvious.

Russian wheat aphids cause distinctive damage to grain. The aphids secrete a toxin that causes leaf rolling and white (warm weather) or purple (cool weather) streaking on the leaves. Heavily infested plants are stunted severely and sometimes flattened. Heads of infested plants may become twisted and distorted and sometimes fail to emerge properly. Sometimes a large colony inside the flat leaf sheath can kill the head while leaving the rest of the tiller green.

Damage in the field appears first as patches of stunted or discolored plants which resemble drought-stressed areas. Whole fields can be lost if infestations are not detected and controlled early. Early detection is difficult because the pest tends to hide in the plant. Colonies are found most often in tightly rolled leaves near the base of the leaf, in leaf whorls, or concealed on the stem inside the flag leaf sheath. The easiest way to detect Russian wheat aphids is to look for the characteristic damage. Thoroughly inspect plants from several areas of the field for symptoms of aphid infestation.

Sampling and thresholds Economic thresholds for the Russian wheat aphid are:

Fall-seedlings (1 tiller); 10% of plants infested.

Fall-larger plants; treat if plants are stressed or there is danger of winter kill.

Spring-winter grain green-up to appearance of first node; 5% of plants with reproducing populations and fresh damage.

Spring-winter grain appearance of first node to head emergence; 10% of tillers infested.

Spring-spring grain emergence to head emergence; 10% of tillers infested.

Spring-head emergence to soft dough; treat only if heavy populations (i.e., more than 20 aphids per plant) develop on 10 to 20% of flag leaves or stems. After the soft dough stage, insecticide treatment will have little or no benefit.

Management-chemical control

Seed treatment

Seed treatments used on wheat and barley seed may provide some control of aphids.

  • clothianidin (NipsIt Inside) at 0.75 to 1.79 fl oz (0.029 to 0.07 lb ai) /100 lb seed on-farm application. REI 12 hr. Do not exceed 0.2 lb ai/A clothianidin per year.
  • imidacloprid (Gaucho 600F) at 0.8 to 2.4 fl oz (0.031 to 0.094 lb ai) /100 lb seed. Do not graze or feed livestock on treated areas within 45 days after planting. REI 12 hr.
  • imidacloprid/captan/carboxin (Enhance AW) at 4 oz per 100 lb seed. Do not graze or feed livestock on treated areas within 45 days after planting. REI 12 hr. Wheat, oats, barley.
  • imidacloprid/metalaxyl/tebuconazole (GauchoXT) at 3.4 to 4.5 fl oz (0.031 to 0.041 lb ai) /100 lb seed; early season protection. Do not graze or feed livestock on treated areas within 45 days after planting. REI 24 hr. Groundwater advisory: metalaxyl is known to leach through soil into groundwater under certain conditions as a result of agricultural use. Wheat, oats, barley.
  • thiamethoxam (Cruiser 5FS) at 0.75 to 1.33 fl oz (0.029 to 0.052 lb ai) /100 lb seed. REI 12 hr. Ground water advisory.

Foliar spray

Aphid control with foliar sprays is more successful when materials are applied during the warmer part of the day. Adequate coverage also is necessary: 5 gal water/A increases spray coverage and effectiveness.

  • Beauveria bassiana GHA (Mycotrol ESO) at 0.5 to 2 pints/A. PHI 0 days. REI 4 hr. Repeat application may be necessary 2 to 5 days. Do not apply more than 6 pints/A. OMRI-listed for organic use.
  • beta-cyfluthrin (Baythroid XL) at 0.014 to 0.019 lb ai/A. PHI 30 days, 3 days for grazing or foraging. REI 12 hr. Retreatment interval 3 days. Do not exceed 0.038 lb ai/A per season. For best control, applications must be made before aphids damage the plants.
  • cyfluthrin (Tombstone) at 0.028 to 0.038 lb ai/A. PHI 30 days, 3 days for grazing or foraging. REI 12 hr. Retreatment interval 3 days. Do not exceed 0.076 lb ai/A per season of cyfluthrin alone, or the combined total of cyfluthrin plus beta-cyfluthrin. Wheat only.
  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/A. PHI 30 days, 7 days for grazing or foraging. REI 24 hr. Do not exceed 0.03 lb ai/A per season. Best control is obtained before insects begin to roll leaves.
  • lambda-cyhalothrin (Silencer, Warrior II) at 0.02 to 0.03 lb ai/A. PHI 30 days, 7 days for grazing or foraging. REI 24 hr. Do not exceed 0.06 lb ai/A per season. Best control is obtained before insects begin to roll leaves.
  • lambda-cyhalothrin/chlorantraniliprole (Besiege) at 0.059 to 0.098 lb ai/A. PHI 30 days, 7 days for grazing or foraging. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.06 lb ai lambda-cyhalothrin or 0.2 lb ai chlorantraniliprole per year. Best control is obtained before insects begin to roll leaves.
  • lambda-cyhalothrin/thiamethoxam (Endigo ZC) at 0.056 to 0.072 lb ai/A. PHI 30 days, 7 days for grazing or foraging. REI 24 hr. Retreatment interval 7 days. Do not exceed 0.06 lb ai/A lambda-cyhalothrin or 0.125 lb ai/A thiamethoxam per season. Groundwater advisory. Barley only.
  • methomyl (Lannate SP) at 0.225 to 0.45 lb ai/A. PHI 7 days. REI 48 hr. Do not exceed 1.8 lb ai/A per season. Do not exceed 4 applications per season. Wheat only.
  • sulfoxaflor (Transform WG) at 0.023 to 0.047 lb ai/A. PHI 14 days grain or straw, 7 days grazing, forage, fodder, hay harvest. REI 24 hr. Retreatment interval 14 days. Do not exceed 0.09 lb ai/A per year. Limit 2 treatment per crop.