Apple scab: primary infection period details

Scab Infection Period Details

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Weather data for Middletown RI.  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: Wednesday, April 13 at 12 AM    --->     Last rain hour: Wednesday, April 13 at 10 PM.         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 2.17 inch rain and 36 leaf wet hours, with 46 F degrees average temperature during wet hours.      Cumulative scab ascospore release by end of this wetting period is roughly 1%.    Reliable protection if strobilurin fungicide was applied since Tuesday, April 12, 12 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 Thursday, April 14, at 1 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Thursday, April 14, at 4 PM.         Opportunity for sterol inhibitor or strobilurin kickback ends Saturday, April 16, at 12 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Saturday, April 16, at 8 AM.         First generation lesions arising from this infection period would start appearing by Saturday, April 30.

******   Primary  Infection  Period  2  Details   ******     Begin: Saturday, April 16 at 7 PM    --->     Last rain hour: Monday, April 18 at 1 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 1.14 inch rain and 26 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 14, 6 AM, or if strobilurin fungicide applied since Tuesday, April 12, 12 AM.

Lack of daytime rain reduced the portion of mature ascospores released.          Opportunity for surface fungicide kickback ends Sunday, April 17, at 11 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Monday, April 18, at 1 PM.              Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, April 19, at 7 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Wednesday, April 20, at 8 AM.              First generation lesions arising from this infection period would start appearing by Tuesday, May 3.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Thursday, May 19.

******   Primary  Infection  Period  3  Details   ******     Begin: Sunday, April 17 at 11 PM    --->     Last rain hour: Wednesday, April 20 at 2 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 0.01 inch rain and 50 leaf wet hours, with 45 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 14, 6 AM, or if strobilurin fungicide applied since Thursday, April 14, 6 AM.

Wetting period long enough only for ascospores released at night.          Opportunity for surface fungicide kickback ends Tuesday, April 19, at 9 AM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, April 20, at 11 PM.              First generation lesions arising from this infection period would start appearing by Wednesday, May 4.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 23.

******   Primary  Infection  Period  4  Details   ******     Begin: Tuesday, April 19 at 5 PM    --->     Last rain hour: Saturday, April 23 at 7 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 0.06 inch rain and 72 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 Saturday, April 16, 6 AM, or if strobilurin fungicide applied since Monday, April 18, 6 AM.

This infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Thursday, April 21, at 9 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Thursday, April 21, at 4 PM.              Opportunity for sterol inhibitor or strobilurin kickback ends Friday, April 22, at 5 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Saturday, April 23, at 8 AM.              First generation lesions arising from this infection period would start appearing by Friday, May 6.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 23.

******   Primary  Infection  Period  5  Details   ******     Begin: Saturday, April 23 at 8 AM    --->     Last rain hour: Monday, April 25 at 1 AM.             Growth stage at start of period:  Between Quarter Inch Green and Half Inch Green        This infection period accounts for roughly 2% of the year's total primary scab risk.               Approximately 0.57 inch rain and 46 leaf wet hours, with 52 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 6%.        Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Monday, April 18, 6 AM, or if strobilurin fungicide applied since Tuesday, April 19, 6 AM.

This infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Sunday, April 24, at 2 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, April 26, at 8 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  6  Details   ******     Begin: Sunday, April 24 at 8 PM    --->     Last rain hour: Friday, April 29 at 4 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 0.04 inch rain and 103 leaf wet hours, with 55 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 6%.               Reliable protection if strobilurin fungicide was applied since Monday, April 25, 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, April 25, at 6 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Wednesday, April 27, at 6 AM.              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 Friday, April 29, at 8 AM.              First generation lesions arising from this infection period would start appearing by Tuesday, May 10.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, May 27.

******   Primary  Infection  Period  7  Details   ******     Begin: Wednesday, April 27 at 2 AM    --->     Last rain hour: Friday, April 29 at 4 AM.             Growth stage at start of period:  early Tight Cluster        This infection period accounts for roughly 6% of the year's total primary scab risk.               Approximately 0.89 inch rain and 61 leaf wet hours, with 56 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 19%.        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 11 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, April 30, at 2 AM.              First generation lesions arising from this infection period would start appearing by Friday, May 13.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, May 27.

******   Primary  Infection  Period  8  Details   ******     Begin: Wednesday, May 4 at 2 PM    --->     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 14% of the year's total primary scab risk.               Approximately 0.40 inch rain and 21 leaf wet hours, with 51 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 44%.               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 5 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, May 7, at 2 PM.              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 Wednesday, June 1.

******   Primary  Infection  Period  9  Details   ******     Begin: Monday, May 9 at 11 PM    --->     Last rain hour: Wednesday, May 11 at 10 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 0.02 inch rain and 23 leaf wet hours, with 51 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 45%.        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 1 AM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Thursday, May 12, at 11 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 5.

******   Primary  Infection  Period  10  Details   ******     Begin: Tuesday, May 10 at 9 PM    --->     Last rain hour: Wednesday, May 11 at 10 AM.             Growth stage at start of period:  King Bloom        This infection period accounts for roughly 1% of the year's total primary scab risk.               Approximately 0.04 inch rain and 18 leaf wet hours, with 50 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 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 11 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 13, at 9 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 Monday, June 6.

******   Primary  Infection  Period  11  Details   ******     Begin: Saturday, May 14 at 8 PM    --->     Last rain hour: Friday, May 20 at 7 AM.             Growth stage at start of period:  Between King Bloom and Full Bloom        This infection period accounts for roughly 69% of the year's total primary scab risk.               Approximately 3.72 inch rain and 184 leaf wet hours, with 56 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 96%.        Reliable protection if strobilurin fungicide was applied since Sunday, May 15, 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 7 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Monday, May 16, at 4 AM.              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 Friday, May 27.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, June 13.

******   Primary  Infection  Period  12  Details   ******     Begin: Monday, May 23 at 5 PM    --->     Last rain hour: Wednesday, May 25 at 1 AM.             Growth stage at start of period:  95% Petal Fall        This infection period accounts for less than 1% of the year's total primary scab risk.               Approximately 0.41 inch rain and 82 leaf wet hours, with 62 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 Wednesday, May 18, 6 AM, or if strobilurin fungicide applied since Thursday, May 19, 6 AM.

Lack of daytime rain reduced the portion of mature ascospores released.          Opportunity for surface fungicide kickback ends Tuesday, May 24, at 11 AM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Thursday, May 26, at 5 PM.              First generation lesions arising from this infection period would start appearing by Friday, June 3.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, June 17.

******   Primary  Infection  Period  13  Details   ******     Begin: Wednesday, June 1 at 8 AM    --->     Last rain hour: Thursday, June 2 at 12 AM.             Growth stage at start of period:  6 or more days after Petal Fall        This infection period accounts for roughly 1% of the year's total primary scab risk.               Approximately 0.18 inch rain and 24 leaf wet hours, with 66 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 Saturday, May 28, 6 AM, or if strobilurin fungicide applied since Saturday, May 28, 6 AM.

This infection period accompanied by daytime rain to release ascospores.          Opportunity for surface fungicide kickback ends Thursday, June 2, at 4 AM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, June 4, at 8 AM.              First generation lesions arising from this infection period would start appearing by Wednesday, June 15.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, June 27.

******   Primary  Infection  Period  14  Details   ******     Begin: Sunday, June 5 at 9 PM    --->     Last rain hour: Sunday, June 5 at 11 PM.             Growth stage at start of period:  6 or more days after Petal Fall        This infection period accounts for less than 1% of the year's total primary scab risk.               Approximately 0.02 inch rain and 18 leaf wet hours, with 59 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 30, 6 AM, or if strobilurin fungicide applied since Tuesday, May 31, 6 AM.

Wetting period long enough only for ascospores released at night.          Opportunity for surface fungicide kickback ends Monday, June 6, at 8 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, June 8, at 9 PM.              First generation lesions arising from this infection period would start appearing by Saturday, June 18.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, July 2.

******   Primary  Infection  Period  15  Details   ******     Begin: Wednesday, June 8 at 11 PM    --->     Last rain hour: Friday, June 10 at 12 AM.             Growth stage at start of period:  6 or more days after Petal Fall        This infection period accounts for less than 1% of the year's total primary scab risk.               Approximately 0.15 inch rain and 28 leaf wet hours, with 69 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 Friday, June 3, 6 AM, or if strobilurin fungicide applied since Sunday, June 5, 6 AM.

Wetting period long enough only for ascospores released at night.          Opportunity for surface fungicide kickback ends Friday, June 10, at 2 AM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, June 11, at 11 PM.              First generation lesions arising from this infection period would start appearing by Monday, June 20.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, July 2.

******   Primary  Infection  Period  16  Details   ******     Begin: Thursday, June 9 at 6 PM    --->     Last rain hour: Monday, June 13 at 6 AM.             Growth stage at start of period:  6 or more days after Petal Fall        This infection period accounts for roughly 6% of the year's total primary scab risk.               Approximately 0.42 inch rain and 82 leaf wet hours, with 60 F degrees average temperature during wet hours.          Cumulative scab ascospore release by end of this wetting period is roughly 100%.               Reliable protection if strobilurin fungicide was applied since Wednesday, June 8, 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 Friday, June 10, at 7 PM.              Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, June 12, at 6 PM.              First generation lesions arising from this infection period would start appearing by Tuesday, June 21.          If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, July 2.