As alfalfa seed crops come out of winter and begins to grow, weeds and insects are often the first concern. But after that, it’s important to think about managing diseases that can impact seed yield, seed quality, and stand longevity. Alfalfa can be affected by several damaging diseases in Western Canada, especially under cool, wet conditions.
Common Diseases in Alfalfa #
Here are some of the major diseases to watch for:
1. Common Leaf Spot
Shows up as brown to black spots on leaf surfaces. Leaves turn yellow and drop. This disease is common in cool, wet conditions and overwinters in plant residue.
2. Black Stem
Presents as small dark brown spots on leaves and stems. Leaves yellow and wither, and in some cases, seed pods may be infected. It also favors cool, wet conditions and overwinters on residue.
3. Blossom Blight
Blossoms wilt, turn brown, and drop early. This is promoted by cool, damp conditions.
4. Verticillium Wilt
Causes V-shaped yellowing on leaflet tips. Stems yellow and become stunted as the disease progresses.
*Images sourced from Manitoba Agriculture
Tips for Managing Disease #
Controlling disease in alfalfa can be a challenge and usually requires several strategies working together:
- Start with strong seed. Use pedigreed seed from varieties that have good disease resistance.
- Rotate your crops. Avoid planting alfalfa on a short rotation. Rotate with non-host crops for at least three years.
- Watch for insects. Some diseases can be spread by insects, so controlling insect populations is also part of disease management.
- Maintain good fertility. A healthy, well-fed stand is better able to resist stress and disease.
- Use fungicides when needed. Apply fungicides as a preventative measure, and make sure timing is right for maximum benefit.
Keeping Your Stand Productive #
Taking steps to manage disease in your alfalfa seed crop can go a long way toward improving seed yield, seed quality, and the overall health of your stand over time. A bit of prevention can make a big difference in long-term success.
Have questions about disease concerns, fungicide timing, or how your crop is coming along? Get in touch with your local BrettYoung Seed Production Specialist.
