Apricots are suspectible to several diseases: Brown fungus rot, leaf curl, and bacterial canker. Brown rot is a fungus that appears as a water-soaked lesion on a fruit. This lesion spreads until the whole fruit shrivels up like a gray fuzzy mummy. If the fruit is not removed, the spores of the fungus will drop to the ground during the next rain or drizzle and wait till next spring. The only treatment during the growing season is to remove the diseased fruit to reduce spores. During the dormant season, the treatment is to spray a fungicide like Kop-R-Spray.
From my personal experience over 15 years with a Royal Blenheim apricot tree, once the tree gets the fungus, you need to apply the dormant spray the next winter: If you do not, then the tree always has more brown rot. In a normal Sunnyvale California winter (12 inches of rain from November to March), one application of dormant spray in late January is sufficient. In wet winters, two applications of dormant spray may be required: one in December and one in January. I recommend applying in January while the tree is dormant: (the Blenheim apricot has its first bloom between February 15 and February 28).
If you have a dwarf apricot (under 6 feet) you can apply the dormant spray with a hand sprayer. If you have a standard size apricot (taller than 6 feet) you will want to use a air-compressed garden sprayer (available at all garden shops).
Time to Spray one tree:
one to two hours
- Do not spray if rain is expected in 24 hours
- Clear the area to reduce things being covered by spray: Move pots, furniture, barbeques
- If the tree is close to a stucco wall, cover the wall with plastic. Kop-R-Spray stains stucco.
- Wear protective clothing to reduce skin contact with the dormant spray: Long sleeve shirt, long pants, shoes, gloves, cap, painter’s mask, safety glasses
- Use the minimum amount of dormant spray: Two tablespoons of Kop-R-Spray per half-gallon of water is usually sufficient for one tree.
- Apply the dormant spray when it is not windy (In Sunnyvale this is typically in the morning). This is to reduce the drift of the spray that can stain stucco and land on things like lawn furniture.
- Use a step ladder so your face is above where you are spraying
- Safely dispose of excess mixed spray: dilute with water and apply to ground around the base of the tree
- Store the dormant spray and the sprayers away from children and pets
- If you covered walls, plants, or other things with plastic, dispose of that plastic
- Use the water hose to spray surfaces (other than your apricot tree)
- Wash your clothes separately
- Take a shower
- Keep pets out of the area for several days: Our cats like to eat grass