Scouting time
Frequent observations are needed to make accurate treatment decisions. The scouting table below is based on average number of greenbugs per plant.
Sampling method
|
Plant growth stage |
Threatening level |
Treatment level |
Based on visual rating |
|
0-1 leaf |
10-25 |
25-50 |
Colonies or numerous winged adults present of majority of plants. May be risky to wait until visible damage obvious. |
|
3 leaf |
25 |
50-100 |
As above, before general signs of stress occur. Light to threatening levels often decline naturally. |
|
5 leaf |
50 |
150-300 |
When majority of plants are infested with rapidly increasing colonies of greenbugs and initial signs of reddening appear. |
|
mid-whorl stage, about one month after emergence |
200 |
300-600 |
When majority of plants are infested with rapidly increasing colonies, but before leaves begin to die. Damaging levels uncommon at this stage, but beginning infestations are often starting to appear. |
|
late whorl through soft dough stages |
700 |
1,000 |
Some lower leaves beginning to become wet and sticky with honeydew. Some leaves yellowing and reddening with occasional leaves drying. Small to large colonies present and increasing on the majority of plants. |
Thresholds
See above table.
Chemical control
|
Greenbug Management Options |
|
|
Insecticide |
Rate |
|
Alpha-cypermethrin (Fastac EC) |
0.02 to 0.025 lb. a.i./acre (3.2 to 3.9 fl. oz./acre) |
|
Chlorpyrifos (numerous products) |
Check label, but generally 0.5 to 2 pints/acre |
|
Chlorpyrifos plus gamma-cyhalothrin (Cobalt Advanced) |
11.0 to 38.0 fl. oz./acre |
|
Chlorpyrifos plus zeta-cypermethrin (Stallion) |
9.25 to 11.75 fl. oz./acre |
|
Dimethoate (Dimethoate or Dimate) |
0.25 to 0.5 lb. a.i./acre |
|
Malathion |
57 1.5 pints/acre |
|
Methidathion (Supracide 2E) |
Section 24(C), 2 pints/acre |
Non-chemical controls
Resistant hybrids can be a useful way of reducing greenbug damage. Currently, hybrids with resistance to biotypes I and K offer the best protection. While resistant hybrids are not a perfect or complete solution, they delay greenbug development and reproduction, allowing natural enemies more time to respond, and should be considered for a portion of the acreage in areas prone to greenbug infestations. Check with local seed suppliers for greenbug resistant hybrids adapted to your area.
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