Basic information on primary and secondary apple scab infection periods

Background Information for this page

Return to radar list for Monmouth ME

Weather data for Monmouth ME.  Forecast values begin September 8, 2010

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 Apple Pest 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 06 at 11 AM    --->     End: Thursday, April 08 at 3 PM.        Growth stage at start of period:  Between Green Tip and Quarter Inch Green       Best guess is that this infection period accounts for 0.4 % of the season's total primary scab infection risk.

Infection period  2.       Begin: Wednesday, April 07 at 5 PM    --->     End: Saturday, April 10 at 12 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  3.       Begin: Friday, April 09 at 5 AM    --->     End: Monday, April 12 at 8 AM.        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  4.       Begin: Friday, April 16 at 8 AM    --->     End: Monday, April 19 at 10 PM.        Growth stage at start of period:  Between Quarter Inch Green and Half Inch Green       Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk.

Infection period  5.       Begin: Thursday, April 22 at 2 PM    --->     End: Saturday, April 24 at 1 AM.        Growth stage at start of period:  Between Half Inch Green and Tight Cluster       Best guess is that this infection period accounts for 0.2 % of the season's total primary scab infection risk.

Infection period  6.       Begin: Monday, April 26 at 11 PM    --->     End: Saturday, May 01 at 6 AM.        Growth stage at start of period:  Between Tight Cluster and Open Cluster       Best guess is that this infection period accounts for 3 % of the season's total primary scab infection risk.

Infection period  7.       Begin: Tuesday, May 04 at 11 AM    --->     End: Thursday, May 06 at 5 PM.        Growth stage at start of period:  Full Bloom       Best guess is that this infection period accounts for 51 % of the season's total primary scab infection risk.

Infection period  8.       Begin: Thursday, May 06 at 5 AM    --->     End: Sunday, May 09 at 12 PM.        Growth stage at start of period:  Between Full Bloom and Petal Fall       Best guess is that this infection period accounts for 1 % of the season's total primary scab infection risk.

Infection period  9.       Begin: Saturday, May 08 at 2 AM    --->     End: Tuesday, May 11 at 8 AM.        Growth stage at start of period:  Between Full Bloom and Petal Fall       Best guess is that this infection period accounts for 5 % of the season's total primary scab infection risk.

Wetting period following  May 15, 8 AM rain was too short for scab infection.

Infection period  10.       Begin: Wednesday, May 19 at 2 AM    --->     End: Saturday, May 22 at 9 AM.        Growth stage at start of period:  1 - 5 days after Petal Fall       Best guess is that this infection period accounts for 29 % of the season's total primary scab infection risk.

Infection period  11.       Begin: Tuesday, June 01 at 8 AM    --->     End: Friday, June 04 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 8 % of the season's total primary scab infection risk.

Infection period  12.       Begin: Thursday, June 03 at 6 AM    --->     End: Monday, June 07 at 12 PM.               The 86 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  13.       Begin: Saturday, June 05 at 2 AM    --->     End: Wednesday, June 09 at 10 AM.               The 57 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  14.       Begin: Thursday, June 10 at 2 AM    --->     End: Saturday, June 12 at 4 PM.               The 46 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  15.       Begin: Saturday, June 12 at 8 AM    --->     End: Tuesday, June 15 at 11 AM.               The 60 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  16.       Begin: Monday, June 14 at 2 PM    --->     End: Friday, June 18 at 12 PM.               The 55 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  17.       Begin: Wednesday, June 16 at 8 PM    --->     End: Saturday, June 19 at 11 AM.               The 41 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  18.       Begin: Sunday, June 20 at 2 AM    --->     End: Friday, June 25 at 10 AM.               The 84 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  19.       Begin: Wednesday, June 23 at 1 AM    --->     End: Saturday, June 26 at 10 AM.               The 57 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  20.       Begin: Saturday, June 26 at 8 PM    --->     End: Wednesday, June 30 at 10 AM.               The 71 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  21.       Begin: Sunday, June 27 at 11 PM    --->     End: Thursday, July 01 at 7 PM.               The 63 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  22.       Begin: Thursday, July 01 at 8 AM    --->     End: Saturday, July 03 at 12 PM.               The 14 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  23.       Begin: Saturday, July 10 at 8 AM    --->     End: Tuesday, July 13 at 4 PM.               The 65 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  24.       Begin: Tuesday, July 13 at 8 PM    --->     End: Thursday, July 15 at 2 PM.               The 33 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  25.       Begin: Saturday, July 17 at 11 PM    --->     End: Tuesday, July 20 at 2 PM.               The 26 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  26.       Begin: Monday, July 19 at 5 PM    --->     End: Wednesday, July 21 at 1 PM.               The 29 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  27.       Begin: Wednesday, July 21 at 2 PM    --->     End: Sunday, July 25 at 2 PM.               The 52 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  28.       Begin: Saturday, July 24 at 2 AM    --->     End: Tuesday, July 27 at 10 AM.               The 31 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  29.       Begin: Wednesday, July 28 at 11 PM    --->     End: Saturday, July 31 at 10 AM.               The 13 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  30.       Begin: Monday, August 02 at 2 AM    --->     End: Wednesday, August 04 at 3 PM.               Next infection period starts on same day, see next infection period for combined ratings.

Infection period  31.       Begin: Monday, August 02 at 10 PM    --->     End: Friday, August 06 at 1 PM.               The 113 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  32.       Begin: Monday, August 09 at 2 AM    --->     End: Tuesday, August 10 at 1 PM.               Next infection period starts on same day, see next infection period for combined ratings.

Infection period  33.       Begin: Monday, August 09 at 10 PM    --->     End: Wednesday, August 11 at 2 PM.               The 51 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  34.       Begin: Tuesday, August 10 at 5 PM    --->     End: Friday, August 13 at 2 PM.               The 29 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  35.       Begin: Monday, August 16 at 2 AM    --->     End: Thursday, August 19 at 12 PM.               The 38 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  36.       Begin: Sunday, August 22 at 5 PM    --->     End: Thursday, August 26 at 3 PM.               The 69 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  37.       Begin: Wednesday, August 25 at 6 AM    --->     End: Friday, August 27 at 12 PM.               The 46 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  38.       Begin: Thursday, August 26 at 5 PM    --->     End: Sunday, August 29 at 1 PM.               The 24 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  39.       Begin: Friday, September 03 at 8 PM    --->     End: Monday, September 06 at 11 AM.               The 18 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  40.       Begin: Tuesday, September 07 at 3 AM    --->     End: Thursday, September 09 at 1 PM.               The 42 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  41.       Begin: Wednesday, September 08 at 2 AM    --->     End: Friday, September 10 at 3 PM.               The 54 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  42.       Begin: Thursday, September 09 at 2 PM    --->     End: Saturday, September 11 at 11 AM.               The 27 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.

Infection period  43.       Begin: Sunday, September 12 at 4 PM    --->     End: Wednesday, September 15 at 2 PM.               The 51 hours of rain and leaf wetness during this period provided conditions for conidial (secondary) scab infection.