Basic information on primary and secondary apple scab infection periods |

Background Information for this page |

Return to radar list for Greenville RI |

Weather data for Greenville RI. Forecast values begin September 2, 2013 |

Each expected ascospore release is
tracked as a separate event. Infection
periods representing separate ascospore releases can overlap. Growers counting infection periods for the
Delayed First-Spray Strategy can consider infection periods separated by less
than 24 hours of dry leaves as a single prolonged infection period, as
described in the New England Tree Fruit Management Guide. Wetting period duration is compared against
the Revised MillsTable by MacHardy et al. for daytime rains during the
primary scab season (release of ascospores).
Wetting period duration for night-only rains during primary scab
season, and after the completion of ascospore maturation (secondary scab
season) are evaluated with the Jones revision of the Mills table. The increase in natural resistance to scab infection in the weeks after petal fall is not factored into the Mills table. Because of this, some of the summer wetting periods rated as scab infection periods may in fact have been too sort to cause late season infections. Dry hours in middle of a wet period are not counted toward duration of the wet period. As a result, wetting period duration is not simply the difference between start and end times. The estimates shown below should only be used as supplements to on-site observations. |

Infection period 1.
Begin: Thursday, April 11 at 12 AM ---> End: Saturday, April 13 at 3 PM. Growth stage at start of period: 50% Green Tip Best guess is that this infection period accounts for less than 0.1 % of the season's total primary scab infection risk. |

Infection period 2. Begin: Thursday, April 11 at 11 PM ---> End: Monday, April 15 at 11 AM. Growth stage at start of period: Between Green Tip and Quarter Inch Green Best guess is that this infection period accounts for less than 0.1 % of the season's total primary scab infection risk. |

Infection period 3.
Begin: Wednesday, April 17 at 2 AM ---> End: Friday, April 19 at 2 PM. Growth stage at start of period: Half-inch Green Best guess is that this infection period accounts for less than 0.1 % of the season's total primary scab infection risk. |

Infection period 4. Begin: Friday, April 19 at 4 PM ---> End: Monday, April 22 at 11 AM. Growth stage at start of period: Between Half Inch Green and Tight Cluster Best guess is that this infection period accounts for 0.8 % of the season's total primary scab infection risk. |

Infection period 5.
Begin: Tuesday, April 23 at 8 AM ---> End: Thursday, April 25 at 1 PM. Growth stage at start of period: Between Half Inch Green and Tight Cluster Best guess is that this infection period accounts for 0.5 % of the season's total primary scab infection risk. |

Wetting period following April 25, 2 AM rain was too short for scab infection. |

Infection period 6.
Begin: Wednesday, May 08 at 2 PM ---> End: Sunday, May 12 at 4 PM. Growth stage at start of period: Between Full Bloom and Petal Fall Best guess is that this infection period accounts for 29 % of the season's total primary scab infection risk. |

Infection period 7. Begin: Saturday, May 11 at 4 AM ---> End: Tuesday, May 14 at 12 PM. Growth stage at start of period: 95% Petal Fall Best guess is that this infection period accounts for 14 % of the season's total primary scab infection risk. |

Infection period 8.
Begin: Wednesday, May 15 at 2 PM ---> End: Saturday, May 18 at 8 AM. Growth stage at start of period: 1 - 5 days after Petal Fall Best guess is that this infection period accounts for 8 % of the season's total primary scab infection risk. |

Infection period 9. Begin: Sunday, May 19 at 5 PM ---> End: Tuesday, May 21 at 2 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 12 % of the season's total primary scab infection risk. |

Infection period 10.
Begin: Tuesday, May 21 at 5 PM ---> End: Sunday, May 26 at 9 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 30 % of the season's total primary scab infection risk. |

Infection period 11. Begin: Wednesday, May 29 at 12 AM ---> End: Thursday, May 30 at 1 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for less than 0.1 % of the season's total primary scab infection risk. |

Infection period 12.
Begin: Wednesday, May 29 at 10 PM ---> End: Saturday, June 01 at 9 AM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 0.8 % of the season's total primary scab infection risk. |

Infection period 13. Begin: Monday, June 03 at 3 AM ---> End: Wednesday, June 05 at 9 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 4 % of the season's total primary scab infection risk. |

Infection period 14.
Begin: Thursday, June 06 at 11 PM ---> End: Sunday, June 09 at 10 AM. The 39 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 15. Begin: Monday, June 10 at 2 PM ---> End: Friday, June 14 at 3 PM. The 71 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 16.
Begin: Thursday, June 13 at 8 AM ---> End: Sunday, June 16 at 11 AM. The 28 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 17. Begin: Monday, June 17 at 5 PM ---> End: Friday, June 21 at 8 AM. The 37 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 18.
Begin: Monday, June 24 at 8 PM ---> End: Saturday, June 29 at 4 PM. The 81 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 19. Begin: Wednesday, June 26 at 2 PM ---> End: Sunday, June 30 at 4 PM. The 80 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 20.
Begin: Sunday, June 30 at 8 PM ---> End: Wednesday, July 03 at 2 PM. The 57 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 21. Begin: Sunday, July 07 at 5 PM ---> End: Wednesday, July 10 at 5 PM. The 53 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 22.
Begin: Tuesday, July 09 at 3 PM ---> End: Thursday, July 11 at 8 PM. The 41 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 23. Begin: Thursday, July 11 at 8 AM ---> End: Sunday, July 14 at 2 PM. The 40 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 24.
Begin: Saturday, July 13 at 6 AM ---> End: Monday, July 15 at 12 PM. The 35 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 25. Begin: Saturday, July 20 at 2 PM ---> End: Monday, July 22 at 3 PM. The 31 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 26.
Begin: Tuesday, July 23 at 2 AM ---> End: Saturday, July 27 at 2 PM. The 80 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 27. Begin: Thursday, July 25 at 11 AM ---> End: Sunday, July 28 at 4 PM. The 60 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 28.
Begin: Sunday, July 28 at 2 AM ---> End: Monday, July 29 at 4 PM. The 23 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 29. Begin: Thursday, August 01 at 8 PM ---> End: Sunday, August 04 at 4 AM. The 21 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 30.
Begin: Saturday, August 03 at 8 PM ---> End: Monday, August 05 at 10 AM. The 19 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 31. Begin: Sunday, August 04 at 5 PM ---> End: Wednesday, August 07 at 1 PM. The 21 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 32.
Begin: Thursday, August 08 at 6 AM ---> End: Saturday, August 10 at 12 PM. The 33 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 33. Begin: Friday, August 09 at 8 AM ---> End: Monday, August 12 at 8 AM. The 25 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 34.
Begin: Tuesday, August 13 at 8 AM ---> End: Friday, August 16 at 7 AM. The 24 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 35. Begin: Thursday, August 22 at 12 PM ---> End: Sunday, August 25 at 8 AM. The 21 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 36.
Begin: Monday, August 26 at 9 PM ---> End: Wednesday, August 28 at 3 PM. The 30 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 37. Begin: Sunday, September 01 at 2 AM ---> End: Thursday, September 05 at 12 PM. The 59 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |