Prerequisites for Spray Decision:
1. Past history of Monilinia Blight on the farm.
2. Flower buds become susceptible to infection at the F2 stage (bud scales separating).
3. Once fields reach 40-50% F2 and beyond, a fungicide is required within 72 hrs of the start of an infection period. This application will provide 7-10 days protection.
Observations at Tim Strong’s farm as of April 22nd, 2011:
Early varieties are at 10% F2 stage; apothecia cups are just emerging and are at pinhead stage of development; extended wet period from 7 p.m. April 20th until 8:30 a.m. April 21st (13.5 hrs) with average temperature of 2 °C presented a very low risk condition for infection.
Recommendations:
Still too early to spray as of April 22nd (at Tim’s farm), but if conditions warm up (as forecast) buds and apothecia cups will develop quickly creating the plant and inoculum conditions suitable for infection. We are getting close and should have our sprayers ready to go for the coming week!
Refer to “Management of Mummy Berry in Highbush Blueberry” factsheet for pictures of F2 stage and temperature and wetness requirements for an infection period.
Refer to AgraPoint’s “Hishbush Blueberry Insect and Disease Management Schedule” for list of registered products for mummy berry (Monilinia) control in highbush blueberry.
