| Category | Bacterial wilt | Verticillium wilt | Fusarium wilt | Anthracnose | Phytophthora root rot | Root-knot nematode | Aphanomyces root rot | Sclerotinia crown and stem rot | Leaf and stem spots |
|---|---|---|---|---|---|---|---|---|---|
| Outbreak probability | Low | Moderate | Moderate | Moderate | Moderate | Low | Unknown 3 | No-till fall seeding High | High |
| Recommended minimum resistance 1 | MR | MR | MR | R | R | Soil test 2 | MR | NA | NA |
1 Always get the highest level of resistance available whenever possible. Recommended minimums will not prevent serious losses in the event of a major outbreak. Consider the recommendation as a guideline for choosing between varieties when HR is not available across the board.
2 Nematode risk can be determined with a soil test prior to planting. When root-knot nematode is a threat and you must plant alfalfa, choose a variety with as high a level of resistance as you can find.
3 Aphanomyces root rot has not been formally identified or surveyed for in the mid-Atlantic. It is, however, likely to be a problem. In general, plant cultivars that have at least an MR rating, except if planting in spring in which case select cultivars with at least an R rating.
Key: S = susceptible (0 to 5 percent resistant); LR = low resistance (6 to 14 percent resistant); MR = moderate resistance (15 to 30 percent resistant); R = resistant (31 to 50 percent resistant); HR = high resistance (more than 50 percent resistant).
