By Peter Oudemans
June 4-6 and June 12 showed some significant downy mildew infection periods and we are now beginning to see the effects. Since berries are susceptible until about a month after capfall this is something we need to be concerned about. The question is how to handle this now?
Rules:
- Hitting the target: Make sure the sprayer is set up to hit the target.
- Longevity: Fungicides work best if they can dry after application. Rainfall before drying will wash them off
- Resistance: Downy Mildew is a high risk pathogen and fungicides must be rotated
Eradicants
- Ridomil has been used as an eradiacant and is reported to be very effective for rescue applications. This material is HIGHLY vulnerable to resistance and its use should be limited to once per season.
- Ridomil Gold Copper
- Ridomil Gold
Protectants
- Several fungicides belong to this class and work by protecting the tissue. An analogy is putting on a raincoat to keep from getting wet and it is diminishing returns if you put it on after it starts to rain. These need to be applied on a schedule and could be timed using an infection model.
- Examples: Zampro, Revus, Ranman, LifeGard Manzate, Copper fungicides, Captan
Phosphonates
- Sytemic fungicides with curative effects. Can also help reduce sporilation in active lesions
