Common Leaf Spot
Symptoms:
- Typical lesions are small brown spots about 1-3 mm in diameter that usually remain as separate lesions.
- Causes leaves to drop, resulting in mild or severe defoliation and reduced forage quality. Lower leaves are attacked first.
- Yield losses up to 40 % have been reported.
- More than one leaf disease often occurs at the same time on a plant.
Pathogen Involved:
- Pseudopeziza medicaginis (a fungus)
- Survives on dead leaves between crops where it produces spores that are spread to new growth.
Time of Occurrence:
- All season
Conditions Favoring Disease:
- Prolonged periods of cool and wet weather
Disease Management:
- Most alfalfa cultivars have low levels of resistance, although some newer cultivars may have improved tolerance to leaf diseases.
- Harvesting early can reduce disease development as well as yield and quality losses.
- Early harvest helps reduce drop of infected leaves that can be a source of inoculum for infection of new growth.