Small grain-Aphid

Includes

Bird-cherry oat aphid (Rhopalosiphum padi)
Cereal grass aphid (Metopolophium festucae cerealium)

Corn leaf aphid (Rhopalosiphum maidis)
English grain aphid (Sitobion avenae)
Greenbug (Schizaphis graminum)
Rose-grass aphid (Metopolophium dirhodum)

Pest description and crop damage Aphids are of various colors-green, yellow, reddish. They frequently show black on portions of the body such as legs, antennae, or base of cornicles (tube-like structures on the posterior abdomen). Some species are important as vectors of barley yellow dwarf virus (BYDV), which can negatively impact yield and quality of small grains, especially winter wheat and winter barley. Attempts to reduce incidence of BYDV by controlling established populations of aphids have not been successful. Seed treatment insecticides of the neonicotinoid group have reduced BYDV incidence especially when used in combination with delayed fall planting.

Sampling and thresholds To control aphids, insecticide application may be considered when aphids average from 5 (early growth) to ten per tiller, per stem, or per head, prior to boot and > 25 after boot. However, there is rarely need to spray for aphids in small grains. Insecticide applications after grain is in the milk stage of ripening are of no value. In rare instances, foliar insecticide may need to be applied prior to harvest if the honeydew produced by heavy aphid presence could interfere with combine function.

Management-biological control

Occasionally aphids have been sufficiently abundant to cause localized damage to grain prior to grain fill, but usually they are held in check by predators and parasitoids.

Aphid predators and parasitoid wasps are important. Do not apply broad-spectrum foliar insecticides until you have examined the field for the presence of predators or parasitized aphids (a.k.a "mummified" aphids). Syrphid fly larvae and ladybird beetle larvae are common predators of value that reduce aphid populations, therefore it is important to familiarize yourself with all developmental stages of these beneficial insects. The wasp Diaeretiella rapae is a common and effective parasitoid of Russian wheat aphid in intermediate rainfall in southeast Washington.

Management-chemical control

Some success has been achieved with systemic granules drilled in at fall seeding time for winter wheat. This practice helps prevent in-field multiplication and spread of aphids that may transmit BYDV. It does not prevent aphids from migrating into the wheat from other areas.

Some aphids such as bird cherry-oat aphid, English grain aphid and the Russian wheat aphid produce rolling on the leaves. Best control with insecticides is obtained before aphids begin to roll leaves.

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.
  • imidacloprid (Gaucho 600F) slurry 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.
  • imidacloprid/captan/carboxin (Enhance AW) at 4 oz per 100 lb seed. Wheat, oats, barley.
  • imidacloprid/metalaxyl/tebuconazole (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. Groundwater advisory: metalaxyl is known to leach through soil into groundwater under certain conditions as a result of agricultural use. Do not graze or feed livestock on treated areas within 45 days after planting. Wheat, oats and barley only.
  • thiamethoxam (Cruiser 5FS, Warden Cereals 360) at 0.75 to 1.33 fl oz (0.029 to 0.052 lb ai) /100 lb seed; (Crusier Vibrance Quattro) at 0.02 to 0.032 lb ai/100 lb seed. CruiserMaxx for cereals has a groundwater advisory for Washington. Do not graze or feed livestock within 45 days of application.

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.

  • alpha-cypermethrin (Fastac EC) at 0.02 to 0.025 lb ai/a. PHI 14 days. REI 12 hr. Retreatment interval 14 days. Do not exceed 0.075 lb ai/a per season. Wheat and triticale.
  • azadirachtin (Aza-Direct, Ecozin 3EC) at 0.43 lb ai/a. PHI 1 day. REI 4 hr. Retreatment interval 7 days. OMRI-listed for organic use.
  • Beauveria bassiana GHA (Mycotrol ESO) at 0.5 to 2 pint/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. 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. RESTRICTED USE IN OREGON.
  • chlorpyrifos/gamma cyhalothrin (Cobalt) at 0.14 to 0.26 lb ai/a as foliar or chemigation application. REI 24 hr. PHI 14 days forage and hay, 30 days grain and straw. Do not exceed 1 lb ai/a chlorpyrifos per season. Limit 2 treatments per year. Wheat only. RESTRICTED USE IN OREGON.
  • Chromobacterium subtsugae (Grandevo) at 0.6 to 0.9 lb ai/a. PHI 0 days. REI 4 hr. OMRI-listed for organic use.
  • cyfluthrin (Tombstone) at 0.028 to 0.038 lb ai/a. 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. Wheat only.
  • dimethoate (Dimethoate 400) at 0.25 to 0.375 lb ai/a, PHI 35 days. REI 48 hr. Do not exceed 0.5 lb ai/a per season. Wheat only.
  • flupyradifurone (Sivanto 200SL) at 0.09 to 0.14 lb ai/a. PHI 7 days forage; 21 days grain, stover or straw. Retreatment interval 7 days. Do not exceed 0.365 lb ai/a per year.
  • gamma-cyhalothrin (Declare) at 0.01 to 0.015 lb ai/a. PHI 30 days. REI 24 hr. Maximum 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 0.14 lb ai/a per season. Barley, triticale and wheat.
  • lambda-cyhalothrin/chlorantraniliprole (Besiege) at 0.059 to 0.098 lb ai/a. PHI 30 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 0.06 lb ai lambda-cyhalothrin or 0.2 lb ai chlorantraniliprole per year. Feeding restrictions.
  • 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.
  • malathion (Malathion 8) at 1 to 1.25 lb ai/a. PHI 7 days. REI 12 hr. Retreatment interval 7 days. Do not exceed 2 applications per season. Barley, oat, rye and wheat.
  • 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.
  • pyrethrin-There are several pesticides containing various amounts of pyrethrins. Check each label for the use and amount needed. Some formulations are OMRI-listed for organic use.
  • sulfoxaflor (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) at 0.0625 lb ai/a. PHI 21 days. REI 12 hr. Allow at least 7 days between applications. Do not exceed 0.125 lb ai/a per season. Barley only.
  • zeta-cypermethrin (Mustang) at 0.04 to 0.05 lb ai/a. PHI 14 days, also for forage and hay. REI 12 hr. Retreatment interval 14 days. Do not apply more than 0.25 lb ai/a per year.
  • zeta-cypermethrin/chlorpyrifos (Stallion) at 0.12 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 chlorpyrifos per season. Wheat only.