Basic information on primary and secondary apple scab infection periods

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Weather data for Monmouth ME.  Forecast values begin November 1, 2011

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: Tuesday, April 26 at 12 AM    --->     End: Friday, April 29 at 12 PM.        Growth stage at start of period:  50% Green Tip       Best guess is that this infection period accounts for 0.2 % of the season's total primary scab infection risk.

Infection period  2.       Begin: Wednesday, April 27 at 11 PM    --->     End: Saturday, April 30 at 12 AM.        Growth stage at start of period:  Between Green Tip and Quarter Inch Green       Best guess is that this infection period accounts for 0.3 % of the season's total primary scab infection risk.

Infection period  3.       Begin: Tuesday, May 03 at 11 PM    --->     End: Sunday, May 08 at 2 PM.        Growth stage at start of period:  Between Half Inch Green and Tight Cluster       Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk.

Infection period  4.       Begin: Saturday, May 07 at 3 PM    --->     End: Tuesday, May 10 at 7 AM.        Growth stage at start of period:  early Tight Cluster       Best guess is that this infection period accounts for 2 % of the season's total primary scab infection risk.

Infection period  5.       Begin: Tuesday, May 10 at 8 AM    --->     End: Friday, May 13 at 9 AM.        Growth stage at start of period:  Between Tight Cluster and Open Cluster       Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk.

Infection period  6.       Begin: Saturday, May 14 at 8 PM    --->     End: Tuesday, May 24 at 6 PM.        Growth stage at start of period:  Between Open Cluster and Full Pink       Best guess is that this infection period accounts for 42 % of the season's total primary scab infection risk.

Infection period  7.       Begin: Monday, May 23 at 2 AM    --->     End: Wednesday, May 25 at 10 AM.        Growth stage at start of period:  Between King Bloom and Full Bloom       Best guess is that this infection period accounts for 4 % of the season's total primary scab infection risk.

Infection period  8.       Begin: Friday, May 27 at 1 AM    --->     End: Sunday, May 29 at 5 PM.        Growth stage at start of period:  Between Full Bloom and Petal Fall       Best guess is that this infection period accounts for 2 % of the season's total primary scab infection risk.

Infection period  9.       Begin: Monday, May 30 at 2 AM    --->     End: Thursday, June 02 at 8 AM.        Growth stage at start of period:  95% Petal Fall       Best guess is that this infection period accounts for 2 % of the season's total primary scab infection risk.

Infection period  10.       Begin: Wednesday, June 01 at 8 AM    --->     End: Saturday, June 04 at 4 AM.        Growth stage at start of period:  1 - 5 days after Petal Fall       Best guess is that this infection period accounts for 38 % of the season's total primary scab infection risk.

Infection period  11.       Begin: Thursday, June 09 at 4 PM    --->     End: Monday, June 13 at 8 PM.        Growth stage at start of period:  6 or more days after Petal Fall       Best guess is that this infection period accounts for 7 % of the season's total primary scab infection risk.

Infection period  12.       Begin: Saturday, June 11 at 2 PM    --->     End: Tuesday, June 14 at 1 PM.               The 62 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  13.       Begin: Monday, June 13 at 11 PM    --->     End: Wednesday, June 15 at 12 PM.               The 30 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  14.       Begin: Tuesday, June 14 at 2 PM    --->     End: Thursday, June 16 at 11 AM.               The 23 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  15.       Begin: Friday, June 17 at 2 PM    --->     End: Tuesday, June 21 at 7 AM.               The 39 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  16.       Begin: Wednesday, June 22 at 8 PM    --->     End: Tuesday, June 28 at 2 PM.               The 116 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  17.       Begin: Wednesday, June 29 at 8 PM    --->     End: Friday, July 01 at 12 PM.               The 18 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  18.       Begin: Friday, July 01 at 1 PM    --->     End: Monday, July 04 at 4 PM.               The 57 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  19.       Begin: Sunday, July 03 at 1 PM    --->     End: Tuesday, July 05 at 1 PM.               The 36 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  20.       Begin: Monday, July 04 at 11 PM    --->     End: Wednesday, July 06 at 12 PM.               The 17 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  21.       Begin: Wednesday, July 06 at 5 PM    --->     End: Saturday, July 09 at 2 PM.               The 31 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  22.       Begin: Friday, July 08 at 10 PM    --->     End: Monday, July 11 at 10 AM.               The 13 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  23.       Begin: Tuesday, July 12 at 12 AM    --->     End: Thursday, July 14 at 11 AM.               The 30 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  24.       Begin: Wednesday, July 13 at 2 PM    --->     End: Friday, July 15 at 12 PM.               The 25 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  25.       Begin: Monday, July 25 at 8 PM    --->     End: Thursday, July 28 at 11 AM.               The 42 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  26.       Begin: Friday, July 29 at 5 PM    --->     End: Monday, August 01 at 2 PM.               The 26 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  27.       Begin: Tuesday, August 02 at 11 AM    --->     End: Friday, August 05 at 4 PM.               The 62 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  28.       Begin: Thursday, August 04 at 11 AM    --->     End: Saturday, August 06 at 3 PM.               The 39 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  29.       Begin: Sunday, August 07 at 2 AM    --->     End: Tuesday, August 09 at 12 PM.               The 41 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  30.       Begin: Tuesday, August 09 at 8 PM    --->     End: Friday, August 12 at 11 AM.               The 45 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  31.       Begin: Sunday, August 14 at 11 PM    --->     End: Thursday, August 18 at 2 PM.               The 69 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  32.       Begin: Friday, August 19 at 7 PM    --->     End: Sunday, August 21 at 3 PM.               The 29 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  33.       Begin: Sunday, August 21 at 4 PM    --->     End: Wednesday, August 24 at 12 PM.               The 23 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  34.       Begin: Thursday, August 25 at 8 AM    --->     End: Saturday, August 27 at 5 PM.               The 41 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  35.       Begin: Saturday, August 27 at 8 PM    --->     End: Tuesday, August 30 at 1 PM.               The 45 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  36.       Begin: Wednesday, August 31 at 5 AM    --->     End: Thursday, September 01 at 2 PM.               The 15 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  37.       Begin: Saturday, September 03 at 8 AM    --->     End: Sunday, September 04 at 4 PM.               The 20 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  38.       Begin: Monday, September 05 at 5 AM    --->     End: Friday, September 09 at 3 PM.               The 93 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  39.       Begin: Wednesday, September 07 at 2 AM    --->     End: Sunday, September 11 at 2 PM.               The 65 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  40.       Begin: Thursday, September 15 at 8 AM    --->     End: Sunday, September 18 at 12 PM.               The 31 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  41.       Begin: Tuesday, September 20 at 8 AM    --->     End: Sunday, September 25 at 3 PM.               The 114 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  42.       Begin: Thursday, September 22 at 2 AM    --->     End: Monday, September 26 at 2 PM.               The 95 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.