| Pest | Time of Occurrence | Economic Threshold | Management Strategy |
| Alfalfa weevil | Primarily first growth | 1.0 larva/stem and more than 50 percent of the stem tips damaged for alfalfa less than 6 inches tall. | Apply insecticide if thresholds occur before harvest time. |
| Second growth can be affected if no control taken on first growth | Apply insecticide immediately after first harvest. | ||
| Meadow spittlebug | Primarily first growth | 1 spittlebug/stem or 25 to 35/square foot. | Apply insecticide |
| Potato leafhopper | Primarily in 3rd and 4th growth, but may occur in 2nd growth | Plant height Leafhoppers
per Sweep
Less than 6 inches
1.0
|
Apply insecticide or harvest within 3 to 6 days. Harvest should not be made repeatedly prior to bud - 25 percent bloom stage. |
| Spotted alfalfa aphid | Primarily in dry weather, but may occur in any part of season. | 20/stem in 10-in. alfalfa, 40/stem in alfalfa taller than 10 in. and less than 20/stem on seedlings. | |
| Pea aphid | Primarily first growth | Plant height
Aphids Per Stem
Less than 10in. 50 More than 10in. 75 More than 20in. 100 |
|
| 4th and later cuttings. | Heavy foliage feeding (10 percent of stems showing signs of feeding). | Harvest or apply insecticide. | |
| Fall armyworm | Late cuttings and fall seedings. | 10 percent of stems showing signs of damage. | Apply insecticide. |
| Henbit, chickweed, mustard, etc. | October-April | Unknown; 15 to 20 percent cover or two per square foot. | Control in Nov. with herbicides. |
| Crabgrass, goosegrass, and fall panicum | May-September | Unknown; 15 to 20 percent | Apply proper herbicides when grasses are actively growing. |
| Leafspots | April-October | Unacceptable foliage loss (10 to 15 percent defoliation). | Graze or cut rank growth to improve aeration and reduce humidity. |
| Stem, crown, and root rots. | May-October | Unacceptable stand (30 percent loss of stand). | Rotate to nonhost crop. |
| Sclerotinia stem rot | February-April | Unacceptable stand (usually problem in first year fields) (30 percent loss of stand). | Replant and/or rotate to non-host crop. |