Basic information on primary and secondary apple scab infection periods

Background Information for this page

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Weather data for Hancock NH.  Forecast values begin September 15, 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: Saturday, April 23 at 4 AM    --->     End: Tuesday, April 26 at 7 PM.        Growth stage at start of period:  Between Green Tip and Quarter Inch Green       Best guess is that this infection period accounts for 0.2 % of the season's total primary scab infection risk.

Infection period  2.       Begin: Sunday, April 24 at 8 PM    --->     End: Wednesday, April 27 at 4 PM.        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: Tuesday, April 26 at 10 PM    --->     End: Friday, April 29 at 11 AM.        Growth stage at start of period:  Between Quarter Inch Green and 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: Thursday, April 28 at 2 PM    --->     End: Sunday, May 01 at 7 AM.        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  5.       Begin: Wednesday, May 04 at 8 AM    --->     End: Friday, May 06 at 12 AM.        Growth stage at start of period:  Between Open Cluster and Full Pink       Best guess is that this infection period accounts for 4 % of the season's total primary scab infection risk.

Infection period  6.       Begin: Thursday, May 05 at 5 PM    --->     End: Sunday, May 08 at 1 PM.        Growth stage at start of period:  Between Open Cluster and Full Pink       Best guess is that this infection period accounts for 0.3 % of the season's total primary scab infection risk.

Infection period  7.       Begin: Saturday, May 07 at 1 PM    --->     End: Monday, May 09 at 10 AM.        Growth stage at start of period:  full Pink-extended       Best guess is that this infection period accounts for 10 % of the season's total primary scab infection risk.

Infection period  8.       Begin: Sunday, May 08 at 3 PM    --->     End: Wednesday, May 11 at 9 AM.        Growth stage at start of period:  Between Full Pink and King Bloom       Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk.

Wetting period following  May 11, 2 AM rain was too short for scab infection.

Infection period  9.       Begin: Saturday, May 14 at 2 PM    --->     End: Sunday, May 22 at 5 PM.        Growth stage at start of period:  King Bloom       Best guess is that this infection period accounts for 53 % of the season's total primary scab infection risk.

Infection period  10.       Begin: Saturday, May 21 at 1 PM    --->     End: Tuesday, May 24 at 3 PM.        Growth stage at start of period:  Between Full Bloom and Petal Fall       Best guess is that this infection period accounts for 13 % of the season's total primary scab infection risk.

Infection period  11.       Begin: Monday, May 23 at 2 AM    --->     End: Wednesday, May 25 at 1 PM.        Growth stage at start of period:  Between Full Bloom and Petal Fall       Best guess is that this infection period accounts for 3 % of the season's total primary scab infection risk.

Infection period  12.       Begin: Tuesday, May 24 at 5 PM    --->     End: Thursday, May 26 at 11 AM.        Growth stage at start of period:  Between Full Bloom and Petal Fall       Best guess is that this infection period accounts for 6 % of the season's total primary scab infection risk.

Infection period  13.       Begin: Saturday, May 28 at 3 PM    --->     End: Tuesday, May 31 at 7 AM.        Growth stage at start of period:  Fruit Set       Best guess is that this infection period accounts for 3 % of the season's total primary scab infection risk.

Infection period  14.       Begin: Wednesday, June 01 at 2 PM    --->     End: Saturday, June 04 at 4 AM.        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  15.       Begin: Sunday, June 05 at 8 PM    --->     End: Wednesday, June 08 at 9 AM.               The 14 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  16.       Begin: Wednesday, June 08 at 8 PM    --->     End: Monday, June 13 at 4 PM.               The 96 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  17.       Begin: Saturday, June 11 at 2 AM    --->     End: Wednesday, June 15 at 1 PM.               The 95 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  18.       Begin: Monday, June 13 at 10 PM    --->     End: Thursday, June 16 at 1 PM.               The 54 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  19.       Begin: Wednesday, June 15 at 4 PM    --->     End: Saturday, June 18 at 3 PM.               The 43 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  20.       Begin: Friday, June 17 at 11 AM    --->     End: Sunday, June 19 at 11 AM.               The 39 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  21.       Begin: Saturday, June 18 at 6 PM    --->     End: Tuesday, June 21 at 7 AM.               The 14 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  22.       Begin: Wednesday, June 22 at 10 AM    --->     End: Monday, June 27 at 1 PM.               The 111 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  23.       Begin: Tuesday, June 28 at 11 PM    --->     End: Friday, July 01 at 10 AM.               The 12 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  24.       Begin: Sunday, July 03 at 11 AM    --->     End: Tuesday, July 05 at 1 PM.               The 40 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  25.       Begin: Monday, July 04 at 6 PM    --->     End: Thursday, July 07 at 1 PM.               The 33 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  26.       Begin: Wednesday, July 06 at 5 PM    --->     End: Friday, July 08 at 11 AM.               The 20 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  27.       Begin: Friday, July 08 at 7 PM    --->     End: Monday, July 11 at 9 AM.               The 15 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  28.       Begin: Wednesday, July 13 at 5 PM    --->     End: Saturday, July 16 at 9 AM.               The 17 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  29.       Begin: Monday, July 18 at 5 AM    --->     End: Tuesday, July 19 at 1 PM.               The 20 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  30.       Begin: Tuesday, July 19 at 5 AM    --->     End: Thursday, July 21 at 11 AM.               The 7 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  31.       Begin: Saturday, July 23 at 5 AM    --->     End: Monday, July 25 at 10 AM.               The 6 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  32.       Begin: Monday, July 25 at 2 PM    --->     End: Wednesday, July 27 at 1 PM.               The 40 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  33.       Begin: Tuesday, July 26 at 5 PM    --->     End: Thursday, July 28 at 12 PM.               The 24 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  34.       Begin: Thursday, July 28 at 2 AM    --->     End: Saturday, July 30 at 1 PM.               The 25 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  35.       Begin: Friday, July 29 at 4 PM    --->     End: Sunday, July 31 at 12 PM.               The 22 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  36.       Begin: Monday, August 01 at 5 AM    --->     End: Tuesday, August 02 at 9 AM.               Next infection period starts on same day, see next infection period for combined ratings.

Infection period  37.       Begin: Monday, August 01 at 2 PM    --->     End: Wednesday, August 03 at 1 PM.               The 56 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  38.       Begin: Tuesday, August 02 at 3 PM    --->     End: Thursday, August 04 at 1 PM.               The 25 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  39.       Begin: Saturday, August 06 at 8 PM    --->     End: Monday, August 08 at 3 PM.               The 32 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  40.       Begin: Sunday, August 07 at 11 PM    --->     End: Wednesday, August 10 at 5 PM.               The 46 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  41.       Begin: Tuesday, August 09 at 2 PM    --->     End: Thursday, August 11 at 1 PM.               The 33 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  42.       Begin: Sunday, August 14 at 12 PM    --->     End: Thursday, August 18 at 2 PM.               The 82 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  43.       Begin: Friday, August 19 at 5 PM    --->     End: Monday, August 22 at 1 PM.               The 49 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  44.       Begin: Sunday, August 21 at 2 PM    --->     End: Wednesday, August 24 at 1 PM.               The 27 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  45.       Begin: Thursday, August 25 at 11 AM    --->     End: Monday, August 29 at 10 AM.               The 77 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  46.       Begin: Saturday, August 27 at 4 PM    --->     End: Tuesday, August 30 at 2 PM.               The 49 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  47.       Begin: Monday, September 05 at 2 PM    --->     End: Saturday, September 10 at 12 PM.               The 97 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  48.       Begin: Wednesday, September 14 at 11 PM    --->     End: Sunday, September 18 at 9 AM.               The 35 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  49.       Begin: Tuesday, September 20 at 4 AM    --->     End: Thursday, September 22 at 1 PM.               The 36 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.