Apple scab: primary infection period details

Scab Infection Period Details

Weather data for Greenville RI. Forecast values begin May 20, 2013

    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: Thursday, April 11 at 12 AM    --->     Last rain hour: Saturday, April 13 at 5 AM.
   Growth stage at start of period: 50% Green Tip
   This infection period accounts for less than 1% of the year's total primary scab risk.
   Approximately 0.03 inch rain and 48 leaf wet hours, with 42 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 10, 12 AM, or if strobilurin fungicide applied since Wednesday, April 10, 12 AM.

This infection period accompanied by daytime rain to release ascospores.

Opportunity for surface fungicide kickback ends Friday, April 12, at 7 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Saturday, April 13, at 8 AM.

Opportunity for sterol inhibitor or strobilurin kickback ends Sunday, April 14, at 12 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Sunday, April 14, at 8 AM.

First generation lesions arising from this infection period would start appearing by Tuesday, April 30.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 20.

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

   Begin: Thursday, April 11 at 11 PM    --->     Last rain hour: Saturday, April 13 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 0.65 inch rain and 35 leaf wet hours, with 40 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 10, 12 AM, or if strobilurin fungicide applied since Wednesday, April 10, 12 AM.

       Wetting period long enough only for ascospores released at night.

       Opportunity for surface fungicide kickback ends Saturday, April 13, at 11 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, April 14, at 11 PM.

       First generation lesions arising from this infection period would start appearing by Tuesday, April 30.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 20.

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

   Begin: Wednesday, April 17 at 2 AM    --->     Last rain hour: Wednesday, April 17 at 5 AM.
       Growth stage at start of period: Half-inch Green
       This infection period accounts for less than 1% of the year's total primary scab risk.
       Approximately 0.02 inch rain and 12 leaf wet hours, with 56 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 10, 12 AM, or if strobilurin fungicide applied since Thursday, April 11, 6 AM.

       Lack of daytime rain reduced the portion of mature ascospores released.

       Opportunity for surface fungicide kickback ends Thursday, April 18, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Saturday, April 20, at 3 AM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Saturday, April 20, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Monday, April 22, at 8 AM.

       First generation lesions arising from this infection period would start appearing by Sunday, May 5.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 20.

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

   Begin: Friday, April 19 at 4 PM    --->     Last rain hour: Saturday, April 20 at 11 AM.
       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 0.60 inch rain and 20 leaf wet hours, with 57 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 Tuesday, April 16, 6 AM, or if strobilurin fungicide applied since Wednesday, April 17, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Saturday, April 20, at 2 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Monday, April 22, at 4 PM.

       First generation lesions arising from this infection period would start appearing by Tuesday, May 7.
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 20.

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

   Begin: Tuesday, April 23 at 8 AM    --->     Last rain hour: Thursday, April 25 at 10 AM.
       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 0.28 inch rain and 31 leaf wet hours, with 45 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 7%.

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

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Wednesday, April 24, at 7 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, April 26, at 8 AM.

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

     Wetting period following Thursday, April 25, 2 AM rain was too short for scab infection.
     Approximately 0.06 inch rain and 8 leaf wet hours, with 50 F degrees average temperature during wet hours.
     Cumulative scab ascospore release by end of this wetting period is roughly 7%.

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

   Begin: Wednesday, May 8 at 2 PM    --->     Last rain hour: Sunday, May 12 at 10 AM.
       Growth stage at start of period: Between Full Bloom and Petal Fall
       This infection period accounts for roughly 29% of the year's total primary scab risk.
       Approximately 0.88 inch rain and 78 leaf wet hours, with 60 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 34%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Tuesday, May 7, 6 AM, or if strobilurin fungicide applied since Wednesday, May 8, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Thursday, May 9, at 9 AM.

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

       First generation lesions arising from this infection period would start appearing by Tuesday, May 21.

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

   Begin: Saturday, May 11 at 4 AM    --->     Last rain hour: Sunday, May 12 at 10 AM.
       Growth stage at start of period: 95% Petal Fall
       This infection period accounts for roughly 14% of the year's total primary scab risk.
       Approximately 0.62 inch rain and 33 leaf wet hours, with 61 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 48%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Tuesday, May 7, 6 AM, or if strobilurin fungicide applied since Wednesday, May 8, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Saturday, May 11, at 11 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Sunday, May 12, at 6 AM.

       Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, May 14, at 4 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Tuesday, May 14, at 11 AM.

       First generation lesions arising from this infection period would start appearing by Friday, May 24.

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

   Begin: Wednesday, May 15 at 2 PM    --->     Last rain hour: Wednesday, May 15 at 7 PM.
       Growth stage at start of period: 1 - 5 days after Petal Fall
       This infection period accounts for roughly 8% of the year's total primary scab risk.
       Approximately 0.08 inch rain and 19 leaf wet hours, with 55 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 57%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 9, 6 AM, or if strobilurin fungicide applied since Friday, May 10, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Thursday, May 16, at 2 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, May 18, at 2 PM.

       First generation lesions arising from this infection period would start appearing by Monday, May 27.

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

   Begin: Sunday, May 19 at 5 PM    --->     Last rain hour: Wednesday, May 22 at 4 AM.
       Growth stage at start of period: 6 or more days after Petal Fall
       This infection period accounts for roughly 16% of the year's total primary scab risk.
       Approximately 0.50 inch rain and 57 leaf wet hours, with 62 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 72%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, May 15, 6 AM, or if strobilurin fungicide applied since Thursday, May 16, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Monday, May 20, at 2 PM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, May 22, at 5 PM.

       First generation lesions arising from this infection period would start appearing by Friday, May 31.

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

   Begin: Tuesday, May 21 at 4 PM    --->     Last rain hour: Friday, May 24 at 9 PM.
       Growth stage at start of period: 6 or more days after Petal Fall
       This infection period accounts for roughly 9% of the year's total primary scab risk.
       Approximately 0.19 inch rain and 72 leaf wet hours, with 64 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 80%.

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

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Wednesday, May 22, at 11 AM.

       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 24, at 4 PM.

       First generation lesions arising from this infection period would start appearing by Sunday, June 2.

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

   Begin: Thursday, May 23 at 4 AM    --->     Last rain hour: Friday, May 24 at 9 PM.
       Growth stage at start of period: 6 or more days after Petal Fall
       This infection period accounts for roughly 19% of the year's total primary scab risk.
       Approximately 0.81 inch rain and 51 leaf wet hours, with 65 F degrees average temperature during wet hours.
       Cumulative scab ascospore release by end of this wetting period is roughly 96%.

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

       This infection period accompanied by daytime rain to release ascospores.

       Opportunity for surface fungicide kickback ends Friday, May 24, at 3 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Friday, May 24, at 7 AM.

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

       First generation lesions arising from this infection period would start appearing by Tuesday, June 4.