Apple scab: primary infection period details

Scab Infection Period Details

Weather data for Sanford ME. Forecast values begin September 20, 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 evaluated with the Jones revision of the Mills table.
    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 time and end time.
    The estimates shown below should only be used as supplements to on-site observations.
    Postinfection time limit for sterol inhibitor or strobilurin fungicides is capped at 72 hours maximum to reduce the chance of selecting for resistant strains of scab. Application of these fungicides up to 96 hours or more after the start of an infection period may still provide control, but at increasing risk of resistant scab selection.

                 ******   Primary Infection Period 1 Details   ******

   Begin: Saturday, April 23 at 6 AM    --->     Last rain hour: Wednesday, April 27 at 5 AM.
   Growth stage at start of period: Between Green Tip and Quarter Inch Green
   This infection period accounts for less than 1% of the year's total primary scab risk.
   Approximately 0.56 inch rain and 74 leaf wet hours, with 47 F degrees average temperature during wet hours.
   Cumulative scab ascospore release by end of this wetting period is roughly < 1%.

   Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, April 21, 12 AM, or if strobilurin fungicide applied since Thursday, April 21, 12 AM.

This infection period accompanied by daytime rain to release ascospores.

Opportunity for surface fungicide kickback ends Sunday, April 24, at 6 PM.

Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, April 26, at 6 AM.

First generation lesions arising from this infection period would start appearing by Monday, May 9.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, May 24.

                 ******   Primary Infection Period 2 Details   ******

   Begin: Monday, April 25 at 5 PM    --->     Last rain hour: Thursday, April 28 at 6 PM.
       Growth stage at start of period: Between Green Tip and Quarter Inch Green
       This infection period accounts for less than 1% of the year's total primary scab risk.
       Approximately 0.33 inch rain and 75 leaf wet hours, with 55 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 1%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Sunday, April 24, 6 AM, or if strobilurin fungicide applied since Monday, April 25, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Wednesday, April 27, at 12 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Wednesday, April 27, at 12 PM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Thursday, April 28, at 5 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Friday, April 29, at 8 AM.

       First generation lesions arising from this infection period would start appearing by Wednesday, May 11.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, May 27.

                 ******   Primary Infection Period 3 Details   ******

   Begin: Thursday, April 28 at 2 PM    --->     Last rain hour: Thursday, April 28 at 6 PM.
       Growth stage at start of period: Between Half Inch Green and Tight Cluster
       This infection period accounts for roughly 2% of the year's total primary scab risk.
       Approximately 0.11 inch rain and 18 leaf wet hours, with 60 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 4%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Sunday, April 24, 6 AM, or if strobilurin fungicide applied since Monday, April 25, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Friday, April 29, at 11 AM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, May 1, at 2 PM.

       First generation lesions arising from this infection period would start appearing by Sunday, May 15.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, May 28.

                 ******   Primary Infection Period 4 Details   ******

   Begin: Wednesday, May 4 at 7 AM    --->     Last rain hour: Thursday, May 5 at 10 AM.
       Growth stage at start of period: Between Open Cluster and Full Pink
       This infection period accounts for roughly 3% of the year's total primary scab risk.
       Approximately 0.65 inch rain and 30 leaf wet hours, with 49 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 11%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Friday, April 29, 6 AM, or if strobilurin fungicide applied since Saturday, April 30, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Thursday, May 5, at 2 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Thursday, May 5, at 3 PM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Saturday, May 7, at 7 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Saturday, May 7, at 8 AM.

       First generation lesions arising from this infection period would start appearing by Saturday, May 21.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, June 3.

                 ******   Primary Infection Period 5 Details   ******

   Begin: Saturday, May 7 at 1 PM    --->     Last rain hour: Sunday, May 8 at 6 PM.
       Growth stage at start of period: Between Open Cluster and Full Pink
       This infection period accounts for roughly 8% of the year's total primary scab risk.
       Approximately 0.37 inch rain and 38 leaf wet hours, with 52 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 23%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Monday, May 2, 6 AM, or if strobilurin fungicide applied since Tuesday, May 3, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Sunday, May 8, at 1 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 10, at 1 PM.

       First generation lesions arising from this infection period would start appearing by Tuesday, May 24.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 7.

                 ******   Primary Infection Period 6 Details   ******

   Begin: Sunday, May 8 at 2 PM    --->     Last rain hour: Wednesday, May 11 at 7 AM.
       Growth stage at start of period: Between Open Cluster and Full Pink
       This infection period accounts for roughly 2% of the year's total primary scab risk.
       Approximately 0.13 inch rain and 34 leaf wet hours, with 50 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 28%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 5, 6 AM, or if strobilurin fungicide applied since Friday, May 6, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Monday, May 9, at 3 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, May 11, at 2 PM.

       First generation lesions arising from this infection period would start appearing by Tuesday, May 24.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 7.

                 ******   Primary Infection Period 7 Details   ******

   Begin: Tuesday, May 10 at 8 PM    --->     Last rain hour: Wednesday, May 11 at 7 AM.
       Growth stage at start of period: full Pink-extended
       This infection period accounts for less than 1% of the year's total primary scab risk.
       Approximately 0.05 inch rain and 23 leaf wet hours, with 49 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 28%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 5, 6 AM, or if strobilurin fungicide applied since Friday, May 6, 6 AM.

       Wetting period long enough only for ascospores released at night.

       Opportunity for surface fungicide kickback ends Wednesday, May 11, at 9 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 13, at 8 PM.

       First generation lesions arising from this infection period would start appearing by Wednesday, May 25.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 21.

                 ******   Primary Infection Period 8 Details   ******

   Begin: Saturday, May 14 at 8 PM    --->     Last rain hour: Tuesday, May 24 at 6 AM.
       Growth stage at start of period: Between Full Pink and King Bloom
       This infection period accounts for roughly 63% of the year's total primary scab risk.
       Approximately 3.97 inch rain and 223 leaf wet hours, with 53 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 82%.

       Reliable protection if strobilurin fungicide was applied since Wednesday, May 18, 6 AM. But over 2 inches rain during infection period caused captan or EBDC coverage depletion before end of infection period. In this case, a fungicide with post-infection activity should be used as soon as possible.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Monday, May 16, at 12 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Monday, May 16, at 2 PM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, May 17, at 8 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Wednesday, May 18, at 8 AM.

       First generation lesions arising from this infection period would start appearing by Saturday, May 28.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 21.

                 ******   Primary Infection Period 9 Details   ******

   Begin: Monday, May 23 at 2 AM    --->     Last rain hour: Wednesday, May 25 at 10 AM.
       Growth stage at start of period: Between Full Bloom and Petal Fall
       This infection period accounts for roughly 7% of the year's total primary scab risk.
       Approximately 0.49 inch rain and 51 leaf wet hours, with 57 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 87%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 19, 6 AM, or if strobilurin fungicide applied since Friday, May 20, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Tuesday, May 24, at 4 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Tuesday, May 24, at 7 AM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Thursday, May 26, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Thursday, May 26, at 8 AM.

       First generation lesions arising from this infection period would start appearing by Monday, June 6.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 21.

                 ******   Primary Infection Period 10 Details   ******

   Begin: Tuesday, May 24 at 5 PM    --->     Last rain hour: Wednesday, May 25 at 10 AM.
       Growth stage at start of period: Between Full Bloom and Petal Fall
       This infection period accounts for roughly 6% of the year's total primary scab risk.
       Approximately 0.35 inch rain and 25 leaf wet hours, with 61 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 91%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 19, 6 AM, or if strobilurin fungicide applied since Friday, May 20, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Wednesday, May 25, at 2 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 27, at 5 PM.

       First generation lesions arising from this infection period would start appearing by Tuesday, June 7.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 21.

     Wetting period following Wednesday, June 01, 8 AM rain was too short for scab infection.
     Approximately 0.07 inch rain and 4 leaf wet hours, with 71 F degrees average temperature during wet hours.
     Cumulative scab ascospore release by end of this wetting period is roughly 96%.

                 ******   Primary Infection Period 11 Details   ******

   Begin: Thursday, June 9 at 2 PM    --->     Last rain hour: Sunday, June 12 at 10 PM.
       Growth stage at start of period: 6 or more days after Petal Fall
       This infection period accounts for roughly 8% of the year's total primary scab risk.
       Approximately 0.51 inch rain and 75 leaf wet hours, with 58 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 100%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Monday, June 6, 6 AM, or if strobilurin fungicide applied since Tuesday, June 7, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Friday, June 10, at 1 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, June 12, at 2 PM.

       First generation lesions arising from this infection period would start appearing by Wednesday, June 22.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Thursday, July 7.