Watch out for brown rot on sweet cherries. Photo: K. Peter, Penn State
The sweet cherry season is here! I'm surprised I haven't turned into a giant cherry considering how many sweet cherries I've eaten over the last week. Sounds like folks are enjoying a decent crop this year, but one disease to derail that delicious goodness very quickly is brown rot. Consequently, commercial growers need to be on alert.
The fungus causing brown rot is quite opportunistic: it can kill blossoms and it can also ruin the fruit you have worked hard all season to grow. Brown rot disease is favored by warm, wet weather. Under optimum temperature conditions, fruit infections can occur with only three hours of wetness when inoculum levels are high. Longer wet periods during infection result in shorter incubation times so symptoms develop more rapidly.
Spores produced on early maturing cultivars can fuel a continuing outbreak on late maturing cultivars. To add another headache to the issue, insects can be important vectors of the fungal spores during fruit ripening. Wounded fruit, be it from insects or from fruit cracking, are much more susceptible to brown rot than unwounded fruit.
To protect the delicious sweet cherry goodness and prevent brown rot this season, fungicide options include:
- Captan (FRAC Group M4; 0 day PHI)
- Sulfur (FRAC Group M2; 1 day PHI)
- Ziram (FRAC Group M3 ; 14 day PHI)
- Topsin M (FRAC Group 1; 1 day PHI)
- Inspire Super (FRAC Groups 3 + 9; 2 day PHI)
- Indar (FRAC Group 3; 0 day PHI)
- Orius (FRAC Group 3; 0 day PHI)
- Tilt/Orbit (FRAC Group 3; 0 day PHI)
- Quash (FRAC Group Code 3; 14 day PHI)
- Fontelis (FRAC Group 7; 1 day PHI)
- Gem (FRAC Group 11; 0 day PHI)
- Merivon (FRAC Groups 7 + 11; 0 day PHI)
- Luna Sensation (FRAC Groups 7 + 11; 1 day PHI)
- Luna Experience (FRAC Group 7 + 3; 0 day PHI)
Depending on the number of sprays needed and what you may have used during bloom time, be sure to practice fungicide resistance management and rotate chemistries by FRAC group ("Spray by the Numbers"). Since we are in the middle of the summer storm season, remember 2 inches of rain washes off fungicides.
When controlling for disease, weather and tree growth conditions need to be monitored at a local level within one's own orchard. Before chemical products are applied, be sure to be in compliance by obtaining the current usage regulations and examining the product label. Product information can be easily obtained from CDMS.