HPIPM:Greenbug
Author: Frank B. Peairs[1], Gary L. Hein and Michael J. Brewer
Identification (and life cycle/seasonal history)
Greenbugs, Schizaphis graminum (Rondani), are small, 1.6 millimeters (1/16 inch), yellowish green aphids with a darker green stripe down the middle of the back. The cornicles are pale with a dusky tip. The antennae are mostly black and longer than half the body length.
Greenbugs may overwinter as eggs, nymphs, or adults. In early spring, wingless females hatch and within seven to 18 days begin giving birth to live young. These may become either winged or wingless. This aphid produces from five to 14 generations per season with all but the last generation composed entirely of females. As the weather cools in the fall females produce winged males and females.
Plant Response and Damage
Greenbugs can infest small grains at almost any time during the growing season. Infestations may occur at irregular spots within the field or as a general infestation throughout the field. As they suck plant sap, the aphid injects toxic salivary secretions into the plant cells. The toxin kills the cells and results in a yellow or reddish stippling on the leaves.
Management Approaches
Biological Control
Greenbug is attacked by several natural enemies, but the major ones are lady beetles and parasitic wasps. Pale, bloated aphid bodies (mummies) are a sign of aphid parasitism by wasps. It is advisable to delay treatment when parasitism levels reach between 10 and 15 percent (unless greenbug numbers are extremely high).
The scouting technique known as Glance 'n Go and the Greenbug Calculator ([2]) can be used not only to assess the level of biological control, but also to determine the need to treat with an insecticide.
Cultural Control
One observation of greenbug behavior is worth mention. When migrating, winged greenbugs are known to prefer settling in thin stands compared to nearby denser stands. No practical cultural management practices have been derived from this observation.
Chemical Control
Consider an insecticide application if greenbug abundance exceeds the levels indicated below for the current crop growth stage. Glance 'n Go and the Greenbug Calculator ([3]) also can be used to determine the need to treat with an insecticide.
Small grain aphids per stem which justify chemical control:
| Type of aphid | Seedling | Boot to heading | Flowering | Milky ripe | Milk- medium dough |
|---|---|---|---|---|---|
| Greenbug | |||||
| Corn leaf aphid | |||||
| Birdcherry-oat aphid | |||||
| English grain aphid |
Product List for Aphids other than Russian Wheat Aphid:
| Insecticide | Product Per Acre (Fl oz. or oz. product) | Preharvest interval, remarks |
|---|---|---|
| Fastac ECR,1 | 3.2 - 3.9 | 14 days. 12 hour REI. No more than 0.075 lb AI/A/season. W,T3 |
| azadirachtin1,2 | See labels | 0 days. 4 hour REI. B,O,R,W,T3 |
| Beauvaria bassiana1,2 | See labels | 0 days. 4 hour REI. B,O,R,W,T3 |
| beta-cyfluthrinR,1,2 | See labels | 30 days to grain. 3 days graze. 12 hour REI. Do not apply more than 0.076 lb a.i. per season. W,B,R,T3 |
| chlorpyrifos 4ER,1,2 | See labels | 28 days. 14 days graze, hay or forage. 24 hour REI. Not more than 2 applications per season. W3 |
| chlorpyrifos + gamma cyhalothrinR,1,2 | See labels | 28 days. 14 days hay and forage. 7 days graze. 24 hour REI. Not more than 2 applications per season. See labels for additional restrictions for individual active ingredients. W3 |
| Cobalt AdvancedR,1 | 6-13 | 28 days. 14 hay and forage. 7 days graze. 24 hour REI. Not more than 2 applications per season. See labels for additional restrictions for individual active ingredients. W3 |
| clothianidin2 | See labels | Seed treatment. 12 hour REI. B,O,R,W,T3 |
| Grandevo1 | 2-3 lbs | 0 days. 4 hour REI. B,O,R,W,T3 |
| dimethoate1,2 | See labels | 35 days grain. 14 days graze. 48 hour REI. Not more than two applications per season. W3 |
| Sivanto Prime1 | 7 - 10.5 | 21 days. 4 hour REI. Maximum 0.365 lb AI/acre/season. B,O,R,T,W3 |
| gamma cyhalothrinR,1,2 | See labels. | 30 days. 24 hour REI. Not more than 0.06 lb ai/A/season. Best control before
insects roll leaves. After boot stage, suppression only. W,T3 |
| imidacloprid1 | See labels | 45 days to graze. May not perform well in dry soil. W,B,R,T3 |
| lambda cyhalothrinR,1,2 | See labels. | 30 days. 24 hour REI. Not more than 0.06 lb ai/A/season. Best control before
insects roll leaves. After boot stage, suppression only. W,T3 |
| BesiegeR | 6 - 10 | 30 days. 24 hour REI. Not more than 0.06 lb ai/A/season. B,O,R,T,W3 |
| Endigo ZCR,1 | 3.5-4.5 | 30 days. 7 days graze or forage. 24 hour REI. Not more than 9 fl oz product/season. See labels for additional restrictions for individual active ingredients. B3 |
| Transform1 | 0.75 - 1.5 | 14 days grain or straw, 7 days grazing, fodder or hay. 24 hour REI. No more than two applications per season, no more than 0.09 lb a.i./season. B,W,T3 |
| thiamethoxam 2 | See labels | Seed treatment. 12 hour REI. B,O,R,W,T3 |
| zeta cyptermethrin R,1 | See labels | 14 days. See label. B,O,R,W,T3 |
| StallionR,1 | 5.0-11.75 | 14 days forage and hay, 28 days grain and straw. 24 hr REI. Extremely Hazardous to Bees! No more than 11.75 oz per application, 23.5 oz per season. W3 |
| RRestricted use pesticide 1Labeled for chemigation 2Generic active ingredient, several formulations. 3Labeled on W (wheat), B (barley), O (oats), R (rye), T (triticale). | ||
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.
