Basic information on primary and secondary apple scab infection periods |

Background Information for this page |

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Weather data for Easthampton MA. Forecast values begin November 1, 2017 |

Each
expected ascospore release is tracked as a separate event. Infection periods representing separate
ascospore releases can overlap.
Wetting period duration is compared against the Revised MillsTable by
MacHardy et al. for daytime rains during the primary scab season to estimate
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 compared to
the Jones revision of the Mills table to estimate if wetting was long enough
for infection to occur. 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: Wednesday, April 12 at 11 AM ---> End: Friday, April 14 at 9 PM. Growth stage at start of period: Between Green Tip and Quarter Inch Green Best guess is that this infection period accounts for 0.1 % of the season's total primary scab infection risk. |

Infection period 2. Begin: Sunday, April 16 at 5 PM ---> End: Wednesday, April 19 at 9 AM. Growth stage at start of period: Half-inch Green Best guess is that this infection period accounts for 0.1 % of the season's total primary scab infection risk. |

Infection period
3. Begin: Wednesday, April 19 at 5 PM ---> End: Saturday, April 22 at 8 PM. Growth stage at start of period: Between Half Inch Green and Tight Cluster Best guess is that this infection period accounts for 0.1 % of the season's total primary scab infection risk. |

Infection period 4. Begin: Thursday, April 20 at 11 PM ---> End: Monday, April 24 at 12 PM. Growth stage at start of period: early Tight Cluster Best guess is that this infection period accounts for 0.7 % of the season's total primary scab infection risk. |

Infection period
5. Begin: Tuesday, April 25 at 5 AM ---> End: Friday, April 28 at 5 PM. Growth stage at start of period: Open Cluster Best guess is that this infection period accounts for 8 % of the season's total primary scab infection risk. |

Infection period 6. Begin: Friday, April 28 at 5 AM ---> End: Monday, May 01 at 12 AM. Growth stage at start of period: Between Full Pink and King Bloom Best guess is that this infection period accounts for less than 0.1 % of the season's total primary scab infection risk. |

Infection period
7. Begin: Sunday, April 30 at 11 AM ---> End: Tuesday, May 02 at 7 PM. Growth stage at start of period: Between King Bloom and Full Bloom Best guess is that this infection period accounts for 5 % of the season's total primary scab infection risk. |

Infection period 8. Begin: Monday, May 01 at 11 PM ---> End: Thursday, May 04 at 3 PM. Growth stage at start of period: Between King Bloom and Full Bloom Best guess is that this infection period accounts for 5 % of the season's total primary scab infection risk. |

Infection period
9. Begin: Friday, May 05 at 4 AM ---> End: Sunday, May 07 at 2 PM. Growth stage at start of period: Between Full Bloom and Petal Fall Best guess is that this infection period accounts for 17 % of the season's total primary scab infection risk. |

Infection period 10. Begin: Saturday, May 06 at 11 PM ---> End: Monday, May 08 at 7 AM. Growth stage at start of period: Between Full Bloom and Petal Fall Best guess is that this infection period accounts for 0.8 % of the season's total primary scab infection risk. |

Wetting period following May 07, 8 PM rain was too short for scab infection. |

Infection period 11. Begin: Saturday, May 13 at 2 PM ---> End: Monday, May 15 at 5 PM. Growth stage at start of period: 95% Petal Fall Best guess is that this infection period accounts for 19 % of the season's total primary scab infection risk. |

Infection period
12. Begin: Sunday, May 14 at 11 PM ---> End: Wednesday, May 17 at 1 PM. Growth stage at start of period: 1 - 5 days after Petal Fall Best guess is that this infection period accounts for 2 % of the season's total primary scab infection risk. |

Infection period 13. Begin: Thursday, May 18 at 9 PM ---> End: Sunday, May 21 at 10 AM. Growth stage at start of period: Fruit Set Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk. |

Infection period
14. Begin: Monday, May 22 at 2 AM ---> End: Wednesday, May 24 at 3 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 17 % of the season's total primary scab infection risk. |

Infection period 15. Begin: Thursday, May 25 at 8 AM ---> End: Sunday, May 28 at 12 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 21 % of the season's total primary scab infection risk. |

Infection period
16. Begin: Monday, May 29 at 11 AM ---> End: Thursday, June 01 at 3 PM. Growth stage at start of period: 6 or more days after Petal Fall Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk. |

Infection period 17. Begin: Wednesday, May 31 at 2 AM ---> End: Saturday, June 03 at 11 AM. The 31 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
18. Begin: Sunday, June 04 at 5 PM ---> End: Thursday, June 08 at 2 PM. The 74 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 19. Begin: Friday, June 16 at 2 PM ---> End: Tuesday, June 20 at 2 PM. The 81 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
20. Begin: Sunday, June 18 at 11 PM ---> End: Thursday, June 22 at 10 AM. The 33 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 21. Begin: Friday, June 23 at 5 PM ---> End: Saturday, June 24 at 5 PM. The 15 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
22. Begin: Saturday, June 24 at 1 AM ---> End: Sunday, June 25 at 7 PM. The 13 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 23. Begin: Sunday, June 25 at 8 PM ---> End: Wednesday, June 28 at 2 PM. The 43 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
24. Begin: Tuesday, June 27 at 8 AM ---> End: Friday, June 30 at 10 AM. The 25 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 25. Begin: Friday, June 30 at 5 PM ---> End: Sunday, July 02 at 2 PM. The 30 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
26. Begin: Sunday, July 02 at 8 PM ---> End: Wednesday, July 05 at 9 AM. The 13 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 27. Begin: Friday, July 07 at 7 AM ---> End: Tuesday, July 11 at 6 PM. The 59 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
28. Begin: Tuesday, July 11 at 2 AM ---> End: Saturday, July 15 at 6 PM. The 97 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 29. Begin: Wednesday, July 12 at 12 PM ---> End: Sunday, July 16 at 2 PM. The 80 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
30. Begin: Tuesday, July 18 at 11 AM ---> End: Thursday, July 20 at 12 PM. The 25 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 31. Begin: Thursday, July 20 at 5 PM ---> End: Sunday, July 23 at 10 AM. The 17 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
32. Begin: Monday, July 24 at 5 AM ---> End: Wednesday, July 26 at 3 PM. The 48 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 33. Begin: Thursday, July 27 at 11 AM ---> End: Sunday, July 30 at 11 AM. The 24 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
34. Begin: Wednesday, August 02 at 2 PM ---> End: Friday, August 04 at 9 PM. The 35 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 35. Begin: Friday, August 04 at 2 PM ---> End: Sunday, August 06 at 9 AM. The 27 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
36. Begin: Saturday, August 05 at 5 AM ---> End: Tuesday, August 08 at 5 PM. The 54 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 37. Begin: Monday, August 07 at 2 PM ---> End: Wednesday, August 09 at 1 PM. The 28 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
38. Begin: Friday, August 11 at 10 PM ---> End: Sunday, August 13 at 3 PM. The 27 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 39. Begin: Saturday, August 12 at 11 PM ---> End: Monday, August 14 at 3 PM. The 20 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
40. Begin: Tuesday, August 15 at 4 AM ---> End: Wednesday, August 16 at 2 PM. The 22 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 41. Begin: Friday, August 18 at 8 AM ---> End: Monday, August 21 at 2 PM. The 34 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
42. Begin: Tuesday, August 22 at 10 PM ---> End: Thursday, August 24 at 2 PM. The 19 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 43. Begin: Tuesday, August 29 at 11 PM ---> End: Thursday, August 31 at 3 PM. The 21 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
44. Begin: Sunday, September 03 at 12 AM ---> End: Thursday, September 07 at 4 PM. The 78 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 45. Begin: Tuesday, September 05 at 5 PM ---> End: Friday, September 08 at 3 PM. The 61 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period
46. Begin: Thursday, September 07 at 5 PM ---> End: Saturday, September 09 at 3 PM. The 27 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |

Infection period 47. Begin: Thursday, September 14 at 8 PM ---> End: Saturday, September 16 at 6 PM. The 32 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection. |