Apple scab: primary infection period details

Scab Infection Period Details

Weather data for Hancock NH. Forecast values begin July 3, 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 4 AM    --->     Last rain hour: Tuesday, April 26 at 6 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 0.57 inch rain and 72 leaf wet hours, with 49 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 Wednesday, April 20, 12 AM, or if strobilurin fungicide applied since Wednesday, April 20, 12 AM.

This infection period accompanied by daytime rain to release ascospores.

Opportunity for surface fungicide kickback ends Sunday, April 24, at 4 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Sunday, April 24, at 5 PM.

Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, April 26, at 4 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Tuesday, April 26, at 8 AM.

First generation lesions arising from this infection period would start appearing by Sunday, May 8.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, May 28.

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

   Begin: Sunday, April 24 at 8 PM    --->     Last rain hour: Wednesday, April 27 at 8 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 0.24 inch rain and 56 leaf wet hours, with 54 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, 6 AM, or if strobilurin fungicide applied since Friday, April 22, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Monday, April 25, at 9 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Tuesday, April 26, at 12 PM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Wednesday, April 27, at 8 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Thursday, April 28, at 11 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 Saturday, May 28.

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

   Begin: Tuesday, April 26 at 10 PM    --->     Last rain hour: Thursday, April 28 at 6 PM.
       Growth stage at start of period: Between Quarter Inch Green and Half Inch Green
       This infection period accounts for less than 1% of the year's total primary scab risk.
       Approximately 0.29 inch rain and 35 leaf wet hours, with 58 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 Monday, April 25, 6 AM, or if strobilurin fungicide applied since Monday, April 25, 6 AM.

       Wetting period long enough only for ascospores released at night.

       Opportunity for surface fungicide kickback ends Wednesday, April 27, at 10 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, April 29, at 10 PM.

       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 Saturday, May 28.

                 ******   Primary Infection Period 4 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 1% of the year's total primary scab risk.
       Approximately 0.16 inch rain and 18 leaf wet hours, with 58 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 5%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Monday, April 25, 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 12 PM.

       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 Saturday, May 14.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, May 28.

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

   Begin: Wednesday, May 4 at 8 AM    --->     Last rain hour: Thursday, May 5 at 7 PM.
       Growth stage at start of period: Between Open Cluster and Full Pink
       This infection period accounts for roughly 4% of the year's total primary scab risk.
       Approximately 0.53 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 13%.

       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.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, May 7, at 8 AM.

       First generation lesions arising from this infection period would start appearing by Friday, May 20.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, June 4.

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

   Begin: Thursday, May 5 at 5 PM    --->     Last rain hour: Saturday, May 7 at 11 PM.
       Growth stage at start of period: Between Open Cluster and Full Pink
       This infection period accounts for less than 1% of the year's total primary scab risk.
       Approximately 0.02 inch rain and 25 leaf wet hours, with 54 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 13%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Sunday, May 1, 6 AM, or if strobilurin fungicide applied since Monday, May 2, 6 AM.

       Wetting period long enough only for ascospores released at night.

       Opportunity for surface fungicide kickback ends Friday, May 6, at 10 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, May 8, at 5 PM.

       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 Sunday, June 5.

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

   Begin: Saturday, May 7 at 1 PM    --->     Last rain hour: Sunday, May 8 at 7 PM.
       Growth stage at start of period: full Pink-extended
       This infection period accounts for roughly 10% of the year's total primary scab risk.
       Approximately 0.24 inch rain and 37 leaf wet hours, with 53 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 29%.

       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 12 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 Monday, May 23.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Thursday, June 9.

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

   Begin: Sunday, May 8 at 3 PM    --->     Last rain hour: Wednesday, May 11 at 4 AM.
       Growth stage at start of period: Between Full Pink and King Bloom
       This infection period accounts for roughly 1% of the year's total primary scab risk.
       Approximately 0.05 inch rain and 20 leaf wet hours, with 51 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 32%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, May 4, 6 AM, or if strobilurin fungicide applied since Thursday, May 5, 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 3 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 Sunday, June 12.

     Wetting period following Wednesday, May 11, 2 AM rain was too short for scab infection.
     Approximately 0.01 inch rain and 8 leaf wet hours, with 49 F degrees average temperature during wet hours.
     Cumulative scab ascospore release by end of this wetting period is roughly 33%.

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

   Begin: Saturday, May 14 at 2 PM    --->     Last rain hour: Saturday, May 21 at 7 PM.
       Growth stage at start of period: King Bloom
       This infection period accounts for roughly 53% of the year's total primary scab risk.
       Approximately 3.10 inch rain and 187 leaf wet hours, with 54 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 79%.

       Reliable protection if strobilurin fungicide was applied since Monday, May 16, 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 Sunday, May 15, at 12 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 17, at 2 PM.

       First generation lesions arising from this infection period would start appearing by Sunday, May 29.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 15.

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

   Begin: Saturday, May 21 at 1 PM    --->     Last rain hour: Tuesday, May 24 at 4 AM.
       Growth stage at start of period: Between Full Bloom and Petal Fall
       This infection period accounts for roughly 13% of the year's total primary scab risk.
       Approximately 0.23 inch rain and 59 leaf wet hours, with 57 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 89%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Tuesday, May 17, 6 AM, or if strobilurin fungicide applied since Wednesday, May 18, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Sunday, May 22, at 1 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 24, at 1 PM.

       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 Monday, June 20.

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

   Begin: Monday, May 23 at 2 AM    --->     Last rain hour: Tuesday, May 24 at 9 PM.
       Growth stage at start of period: Between Full Bloom and Petal Fall
       This infection period accounts for roughly 3% of the year's total primary scab risk.
       Approximately 0.32 inch rain and 51 leaf wet hours, with 60 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 Wednesday, May 18, 6 AM, or if strobilurin fungicide applied since Thursday, May 19, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Tuesday, May 24, at 12 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Tuesday, May 24, at 2 PM.

       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 5 PM.

       First generation lesions arising from this infection period would start appearing by Thursday, June 9.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 22.

                 ******   Primary Infection Period 12 Details   ******

   Begin: Tuesday, May 24 at 5 PM    --->     Last rain hour: Tuesday, May 24 at 9 PM.
       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 0.27 inch rain and 20 leaf wet hours, with 62 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 95%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, May 18, 6 AM, or if strobilurin fungicide applied since Thursday, May 19, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Wednesday, May 25, at 3 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 Friday, June 10.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 22.

                 ******   Primary Infection Period 13 Details   ******

   Begin: Saturday, May 28 at 3 PM    --->     Last rain hour: Saturday, May 28 at 5 PM.
       Growth stage at start of period: Fruit Set
       This infection period accounts for roughly 3% of the year's total primary scab risk.
       Approximately 0.05 inch rain and 17 leaf wet hours, with 68 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 97%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Monday, May 23, 6 AM, or if strobilurin fungicide applied since Tuesday, May 24, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Sunday, May 29, at 7 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 31, at 3 PM.

       First generation lesions arising from this infection period would start appearing by Tuesday, June 14.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, June 26.