Apple scab: primary infection period details

Scab Infection Period Details
Background Information for this page
Return to Apple list for Westhampton MA
Weather data for Westhampton MA.  Forecast values begin September 18, 2018
  
    Each expected ascospore release is tracked as a separate event.  Infection periods representing separate ascospore releases can overlap.
    Wetting period duration is compared to the Revised MillsTable by MacHardy et al. for daytime rains during the primary scab season to estimate release of ascospores.  Wetting period duration for night-only rains is compared to the Jones revision of the Mills table to estimate if wetting was long enough for infection to occur.
    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 in complete control and resistant scab selection.
  
     Wetting period following  Thursday, April 19, 5 AM rain was too short for scab infection.
     Approximately 0.20 inch rain and 20 leaf wet hours, with 38 F degrees average temperature during wet hours.  
     Cumulative scab ascospore release by end of this wetting period is roughly < 1%.
 
                 ******   Primary  Infection  Period  1  Details   ****** 

   Begin: Wednesday, April 25 at 2 AM    --->     Last rain hour: Friday, April 27 at 9 PM.     
       Growth stage at start of period:  Between Green Tip and Quarter Inch Green
       This infection period accounts for roughly 1% of the year's total primary scab risk.       
       Approximately 1.56 inch rain and 60 leaf wet hours, with 52 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 2%.       

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

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Thursday, April 26, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Thursday, April 26, at 6 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Saturday, April 28, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Saturday, April 28, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Thursday, May 10.  
      
                 ******   Primary  Infection  Period  2  Details   ****** 

   Begin: Friday, April 27 at 11 AM    --->     Last rain hour: Sunday, April 29 at 2 PM.     
       Growth stage at start of period:  Between Half Inch Green and Tight Cluster
       This infection period accounts for less than 1% of the year's total primary scab risk.       
       Approximately 0.27 inch rain and 44 leaf wet hours, with 50 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 Tuesday, April 24, 6 AM, or if strobilurin fungicide applied since Wednesday, April 25, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Saturday, April 28, at 2 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Monday, April 30, at 11 AM.
     
       First generation lesions arising from this infection period would start appearing by Saturday, May 12.  
      
                 ******   Primary  Infection  Period  3  Details   ****** 

   Begin: Saturday, April 28 at 11 PM    --->     Last rain hour: Monday, April 30 at 8 PM.     
       Growth stage at start of period:  Between Half Inch Green and Tight Cluster
       This infection period accounts for less than 1% of the year's total primary scab risk.       
       Approximately 0.08 inch rain and 42 leaf wet hours, with 47 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 24, 6 AM, or if strobilurin fungicide applied since Wednesday, April 25, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Monday, April 30, at 3 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Tuesday, May 1, at 4 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, May 1, at 11 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Wednesday, May 2, at 9 AM.
     
       First generation lesions arising from this infection period would start appearing by Sunday, May 13.  
      
                 ******   Primary  Infection  Period  4  Details   ****** 

   Begin: Monday, April 30 at 8 AM    --->     Last rain hour: Monday, April 30 at 8 PM.     
       Growth stage at start of period:  Between Half Inch Green and Tight Cluster
       This infection period accounts for less than 1% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 22 leaf wet hours, with 45 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 Tuesday, April 24, 6 AM, or if strobilurin fungicide applied since Wednesday, April 25, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Tuesday, May 1, at 6 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Thursday, May 3, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Monday, May 14.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 27.  
                 ******   Primary  Infection  Period  5  Details   ****** 

   Begin: Thursday, May 3 at 6 PM    --->     Last rain hour: Friday, May 4 at 11 PM.     
       Growth stage at start of period:  Open Cluster
       This infection period accounts for roughly 2% of the year's total primary scab risk.       
       Approximately 0.32 inch rain and 25 leaf wet hours, with 69 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 10%.       

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

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Friday, May 4, at 9 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, May 6, at 6 PM.
     
       First generation lesions arising from this infection period would start appearing by Wednesday, May 16.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, May 30.  
                 ******   Primary  Infection  Period  6  Details   ****** 

   Begin: Friday, May 4 at 8 PM    --->     Last rain hour: Sunday, May 6 at 11 PM.     
       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 0.39 inch rain and 37 leaf wet hours, with 58 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 Thursday, May 3, 6 AM, or if strobilurin fungicide applied since Thursday, May 3, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Saturday, May 5, at 7 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Monday, May 7, at 8 PM.
     
       First generation lesions arising from this infection period would start appearing by Thursday, May 17.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Thursday, May 31.  
                 ******   Primary  Infection  Period  7  Details   ****** 

   Begin: Sunday, May 6 at 4 AM    --->     Last rain hour: Sunday, May 6 at 11 PM.     
       Growth stage at start of period:  Between Full Pink and King Bloom
       This infection period accounts for roughly 12% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 37 leaf wet hours, with 55 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 25%.       

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

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Monday, May 7, at 12 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Monday, May 7, at 4 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Wednesday, May 9, at 4 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Wednesday, May 9, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Saturday, May 19.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, June 2.  
                 ******   Primary  Infection  Period  8  Details   ****** 

   Begin: Saturday, May 12 at 10 AM    --->     Last rain hour: Tuesday, May 15 at 8 PM.     
       Growth stage at start of period:  Between Full Bloom and Petal Fall
       This infection period accounts for roughly 17% of the year's total primary scab risk.       
       Approximately 1.20 inch rain and 57 leaf wet hours, with 55 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 42%.

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

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Sunday, May 13, at 4 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Wednesday, May 16, at 7 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Tuesday, May 15, at 10 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Friday, May 18, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Thursday, May 24.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, June 8.  
                 ******   Primary  Infection  Period  9  Details   ****** 

   Begin: Tuesday, May 15 at 11 AM    --->     Last rain hour: Tuesday, May 15 at 8 PM.     
       Growth stage at start of period:  Between Full Bloom and Petal Fall
       This infection period accounts for roughly 32% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 35 leaf wet hours, with 61 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 71%.       

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

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Wednesday, May 16, at 10 AM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 18, at 11 AM.
     
       First generation lesions arising from this infection period would start appearing by Monday, May 28.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, June 12.  
                 ******   Primary  Infection  Period  10  Details   ****** 

   Begin: Saturday, May 19 at 9 AM    --->     Last rain hour: Tuesday, May 22 at 6 PM.     
       Growth stage at start of period:  1 - 5 days after Petal Fall
       This infection period accounts for roughly 20% of the year's total primary scab risk.       
       Approximately 0.69 inch rain and 71 leaf wet hours, with 59 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 Wednesday, May 16, 6 AM, or if strobilurin fungicide applied since Thursday, May 17, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Sunday, May 20, at 7 AM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 22, at 9 AM.
     
       First generation lesions arising from this infection period would start appearing by Saturday, June 2.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Thursday, June 14.  
                 ******   Primary  Infection  Period  11  Details   ****** 

   Begin: Tuesday, May 22 at 12 PM    --->     Last rain hour: Tuesday, May 22 at 6 PM.     
       Growth stage at start of period:  Fruit Set
       This infection period accounts for roughly 4% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 23 leaf wet hours, with 59 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 92%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, May 16, 6 AM, or if strobilurin fungicide applied since Thursday, May 17, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Wednesday, May 23, at 8 AM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Friday, May 25, at 12 PM.
     
       First generation lesions arising from this infection period would start appearing by Tuesday, June 5.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, June 16.  
                 ******   Primary  Infection  Period  12  Details   ****** 

   Begin: Sunday, May 27 at 11 AM    --->     Last rain hour: Monday, May 28 at 5 AM.     
       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 0.29 inch rain and 38 leaf wet hours, with 57 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 98%.

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

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Monday, May 28, at 12 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, May 30, at 11 AM.
     
       First generation lesions arising from this infection period would start appearing by Saturday, June 9.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, June 25.  
                 ******   Primary  Infection  Period  13  Details   ****** 

   Begin: Friday, June 1 at 11 AM    --->     Last rain hour: Tuesday, June 5 at 3 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 0.89 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 98%.       

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

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Saturday, June 2, at 8 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Monday, June 4, at 11 AM.
     
       First generation lesions arising from this infection period would start appearing by Wednesday, June 13.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 27.