Small grain-Russian wheat aphid

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 aphid damage to grain is easy to recognize. 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 flagleaves 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/100 lb seed on-farm application.
  • imidacloprid (Gaucho 600F) seed treatment 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 (wheat and barley).
  • imidacloprid/metalaxyl/tebuconzole (GauchoXT) as seed treatment 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. Wheat, oats and barley only.
  • imidacloprid/captan/carboxin (Enhance AW) at 4 oz per 100 lb seed. Wheat, oats, barley.
  • thiamethoxam (Cruiser 5FS) at 0.75 to 1.33 fl oz (0.029 to 0.052 lb ai) /100 lb seed. Do not graze or feed livestock within 45 days of application.

Foliar treatment

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. 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. For best control, applications must be made before aphids damage the plants. PHI 30 days. REI 12 hr. Do not forage or graze within 3 days of application. Retreatment interval 3 days. Do not exceed 0.038 lb ai/a per season.
  • chlorpyrifos (Lorsban Advanced) at 0.23 to 0.47 lb ai/a. PHI 14 days forage and hay; 28 days grain and straw. REI 24 hr. Do not exceed 2 treatments per acre per year. Wheat only.
  • chlorpyrifos/gamma-cyhalothrin (Cobalt) at 0.16 to 0.3 lb ai/a (wheat only). PHI 14 days forage and hay, 30 days grain and straw. REI 24 hr. Not more than 2 applications per year. Do not exceed 1 lb ai/a chlorpyrifos per season. Wheat only.
  • cyfluthrin (Tombstone) at 0.028 to 0.038 lb ai/a (wheat only). PHI 30 days. Pre-grazing or foraging interval 3 days. REI 12 hr. Retreatment interval 3 days. Do not exceed 0.076 lb ai/a per season.
  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/a. PHI 30 days. REI 24 hr. Do not apply more than 0.03 lb ai/a per season. Do not graze or forage within 7 days of application. Do not feed straw within 30 days.
  • lambda-cyhalothrin (Silencer, Warrior II) at 0.02 to 0.03 lb ai/a. PHI 30 days. REI 24 hr. Do not graze or forage within 7 days of application. Do not feed straw within 30 days. Do not exceed 0.06 lb ai/a per season.
  • lambda-cyhalothrin+tebuconazole (Crossover) at 0.14 lb ai/a. PHI 30 days. REI 24 hr. Do not exceed 0.11 lb ai/a tebuconazole or 0.06 lb ai/a lambda cyhalothrin per season. Feeding restrictions apply. Do not exceed 8 fl oz/a or 0.139 lb ai/a per season.
  • lambda-cyhalothrin/thiamethoxam (Endigo ZC) at 0.056 to 0.072 lb ai/a. PHI 30 days. 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. 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.
  • sulfoxyflor (Transform WG) at 0.023 to 0.047 lb ai/a. REI 24 hr. PHI 14 days grain or straw, 7 days grazing, forage, fodder, hay harvest. Retreatment interval 14 days. Limit 2 treatment per crop. Do not exceed 0.09 lb ai/a per year. Barley, triticale and wheat only.
  • thiamethoxam (Actara) 0.0625 lb ai/a. PHI 21 days (barley only). Do not exceed 0.125 lb ai/a per season. Wait 5 days before placing beehives in a treated field. Barley only.
  • zeta-cypermethrin/chlorpyrifos (Stallion) at 0.22 to 0.28 lb ai/a. PHI for forage or hay 14 days; grain and straw 28 days. REI 24 hr. Retreatment interval 14 days. Do not allow meat or dairy animals to graze within 28 days of application. Do not exceed 0.05 lb ai/a zeta-cypermethrin or 0.5 lb ai/a chlopyrfos per season. Wheat only.