Apple scab: primary infection period details

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Weather data for Middletown RI.  Forecast values begin July 30, 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 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: Friday, April 9 at 8 AM    --->     Last rain hour: Saturday, April 10 at 10 PM.             Growth stage at start of period:  Between Tight Cluster and Open Cluster        Infection period conditions rating is 5.  This infection period accounts for roughly 1% of the year's total primary scab risk.               Approximately 0.68 inch rain and 20 leaf wet hours, with 48 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 3%.               Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Sunday, April 4, 6 AM, or if strobilurin fungicide applied since Monday, April 5, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Saturday, April 10, at 5 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Monday, April 12, at 8 AM.              First generation lesions arising from this infection period would start appearing by Monday, April 26.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 9.

******   Primary  Infection  Period  2  Details   ******     Begin: Friday, April 16 at 3 AM    --->     Last rain hour: Saturday, April 17 at 10 PM.             Growth stage at start of period:  Between Open Cluster and Full Pink        Next infection period starts on same day, see next infection period for combined ratings.               Approximately 0.08 inch rain and 48 leaf wet hours, with 43 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 3%.               Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Friday, April 9, 6 AM, or if strobilurin fungicide applied since Sunday, April 11, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Sunday, April 18, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Sunday, April 18, at 7 AM.              Opportunity for sterol inhibitor or strobilurin kickback ends Monday, April 19, at 3 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Monday, April 19, at 8 AM.              First generation lesions arising from this infection period would start appearing by Sunday, May 2.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 16.

******   Primary  Infection  Period  3  Details   ******     Begin: Friday, April 16 at 7 PM    --->     Last rain hour: Sunday, April 18 at 7 PM.             Growth stage at start of period:  Between Open Cluster and Full Pink        Infection period conditions rating is 3.  This infection period accounts for roughly 1% of the year's total primary scab risk.               Approximately 0.44 inch rain and 41 leaf wet hours, with 43 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 Saturday, April 10, 6 AM, or if strobilurin fungicide applied since Monday, April 12, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Sunday, April 18, at 4 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Monday, April 19, at 12 AM.              Opportunity for sterol inhibitor or strobilurin kickback ends Monday, April 19, at 7 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Tuesday, April 20, at 8 AM.              First generation lesions arising from this infection period would start appearing by Sunday, May 2.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 16.

******   Primary  Infection  Period  4  Details   ******     Begin: Thursday, April 22 at 5 PM    --->     Last rain hour: Tuesday, April 27 at 9 PM.             Growth stage at start of period:  Between Full Pink and King Bloom        Infection period conditions rating is 40.  This infection period accounts for roughly 9% of the year's total primary scab risk.               Approximately 0.16 inch rain and 82 leaf wet hours, with 49 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, April 19, 6 AM, or if strobilurin fungicide applied since Wednesday, April 21, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Friday, April 23, at 6 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, April 25, at 5 PM.              First generation lesions arising from this infection period would start appearing by Thursday, May 6.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, May 21.

******   Primary  Infection  Period  5  Details   ******     Begin: Sunday, April 25 at 8 AM    --->     Last rain hour: Tuesday, April 27 at 9 PM.             Growth stage at start of period:  Between King Bloom and Full Bloom        Infection period conditions rating is 113.  This infection period accounts for roughly 26% of the year's total primary scab risk.               Approximately 0.62 inch rain and 66 leaf wet hours, with 48 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 50%.               Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Monday, April 19, 6 AM, or if strobilurin fungicide applied since Wednesday, April 21, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Monday, April 26, at 1 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, April 28, at 8 AM.              First generation lesions arising from this infection period would start appearing by Saturday, May 8.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, May 25.

******   Primary  Infection  Period  6  Details   ******     Begin: Monday, May 3 at 5 AM    --->     Last rain hour: Tuesday, May 4 at 7 PM.             Growth stage at start of period:  95% Petal Fall        Infection period conditions rating is 185.  This infection period accounts for roughly 42% of the year's total primary scab risk.               Approximately 0.31 inch rain and 22 leaf wet hours, with 63 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 82%.               Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, April 28, 6 AM, or if strobilurin fungicide applied since Thursday, April 29, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Tuesday, May 4, at 1 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Tuesday, May 4, at 4 AM.              Opportunity for sterol inhibitor or strobilurin kickback ends Thursday, May 6, at 5 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Thursday, May 6, at 8 AM.              First generation lesions arising from this infection period would start appearing by Monday, May 17.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, May 29.

******   Primary  Infection  Period  7  Details   ******     Begin: Tuesday, May 4 at 4 PM    --->     Last rain hour: Tuesday, May 4 at 7 PM.             Growth stage at start of period:  100% Petal Fall        Infection period conditions rating is 10.  This infection period accounts for roughly 2% of the year's total primary scab risk.               Approximately 0.05 inch rain and 21 leaf wet hours, with 60 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 86%.               Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, April 28, 6 AM, or if strobilurin fungicide applied since Thursday, April 29, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Wednesday, May 5, at 12 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 7, at 4 PM.              First generation lesions arising from this infection period would start appearing by Tuesday, May 18.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 30.

******   Primary  Infection  Period  8  Details   ******     Begin: Saturday, May 8 at 2 AM    --->     Last rain hour: Saturday, May 8 at 3 PM.             Growth stage at start of period:  1 - 5 days after Petal Fall        Infection period conditions rating is 51.  This infection period accounts for roughly 12% of the year's total primary scab risk.               Approximately 0.60 inch rain and 21 leaf wet hours, with 57 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 2, 6 AM, or if strobilurin fungicide applied since Monday, May 3, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Saturday, May 8, at 10 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Sunday, May 9, at 7 AM.              Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, May 11, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Tuesday, May 11, at 8 AM.              First generation lesions arising from this infection period would start appearing by Saturday, May 22.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, June 4.

******   Primary  Infection  Period  9  Details   ******     Begin: Friday, May 14 at 2 AM    --->     Last rain hour: Saturday, May 15 at 4 AM.             Growth stage at start of period:  6 or more days after Petal Fall        Infection period conditions rating is less than 1.  This infection period accounts for less than 1% of the year's total primary scab risk.               Approximately 0.27 inch rain and 30 leaf wet hours, with 55 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 Thursday, May 6, 6 AM, or if strobilurin fungicide applied since Saturday, May 8, 6 AM.

Lack of daytime rain reduced the portion of mature ascospores released.          Opportunity for surface fungicide kickback ends Saturday, May 15, at 1 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Saturday, May 15, at 5 AM.              Opportunity for sterol inhibitor or strobilurin kickback ends Monday, May 17, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Monday, May 17, at 8 AM.              First generation lesions arising from this infection period would start appearing by Tuesday, May 25.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, June 4.

******   Primary  Infection  Period  10  Details   ******     Begin: Tuesday, May 18 at 11 AM    --->     Last rain hour: Wednesday, May 19 at 10 AM.             Growth stage at start of period:  6 or more days after Petal Fall        Infection period conditions rating is 26.  This infection period accounts for roughly 6% of the year's total primary scab risk.               Approximately 1.39 inch rain and 48 leaf wet hours, with 54 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, May 17, 6 AM, or if strobilurin fungicide applied since Thursday, May 13, 6 AM.

Infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Wednesday, May 19, at 1 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 21, at 11 AM.              First generation lesions arising from this infection period would start appearing by Sunday, May 30.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, June 11.