Apple scab: primary infection period details

Scab Infection Period Details
Background Information for this page
Return to Apple list for Easthampton MA
Weather data for Easthampton MA.  Forecast values begin July 3, 2017
  
    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.
  
                 ******   Primary  Infection  Period  1  Details   ****** 

   Begin: Wednesday, April 12 at 11 AM    --->     Last rain hour: Wednesday, April 12 at 4 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 0.16 inch rain and 10 leaf wet hours, with 60 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 Tuesday, April 11, 12 AM, or if strobilurin fungicide applied since Tuesday, April 11, 12 AM.

  Wetting period long enough only for ascospores released at night.  

  Opportunity for surface fungicide kickback ends Thursday, April 13, at 2 PM.  
   
  Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Saturday, April 15, at 11 AM.
     
  First generation lesions arising from this infection period would start appearing by Friday, April 28.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Tuesday, May 16.  
                 ******   Primary  Infection  Period  2  Details   ****** 

   Begin: Sunday, April 16 at 5 PM    --->     Last rain hour: Monday, April 17 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 0.12 inch rain and 16 leaf wet hours, with 64 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 Tuesday, April 11, 12 AM, or if strobilurin fungicide applied since Tuesday, April 11, 12 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Monday, April 17, at 1 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, April 19, at 5 PM.
     
       First generation lesions arising from this infection period would start appearing by Monday, May 1.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Friday, May 19.
 

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

   Begin: Wednesday, April 19 at 5 PM    --->     Last rain hour: Friday, April 21 at 9 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 0.65 inch rain and 61 leaf wet hours, with 47 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 Tuesday, April 11, 12 AM, or if strobilurin fungicide applied since Tuesday, April 11, 12 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Thursday, April 20, at 9 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Friday, April 21, at 9 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Saturday, April 22, at 5 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Sunday, April 23, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Thursday, May 4.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 21.  
                 ******   Primary  Infection  Period  4  Details   ****** 

   Begin: Thursday, April 20 at 11 PM    --->     Last rain hour: Friday, April 21 at 9 PM.     
       Growth stage at start of period:  early Tight Cluster
       This infection period accounts for roughly 1% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 43 leaf wet hours, with 47 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 4%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Tuesday, April 11, 12 AM, or if strobilurin fungicide applied since Tuesday, April 11, 12 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Saturday, April 22, at 1 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Saturday, April 22, at 8 PM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Sunday, April 23, at 11 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Monday, April 24, at 9 AM.
     
       First generation lesions arising from this infection period would start appearing by Friday, May 5.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, May 22.  
                 ******   Primary  Infection  Period  5  Details   ****** 

   Begin: Tuesday, April 25 at 5 AM    --->     Last rain hour: Friday, April 28 at 6 AM.     
       Growth stage at start of period:  Open Cluster
       This infection period accounts for roughly 11% of the year's total primary scab risk.       
       Approximately 0.71 inch rain and 69 leaf wet hours, with 55 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 20%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Tuesday, April 11, 12 AM, or if strobilurin fungicide applied since Tuesday, April 11, 12 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Wednesday, April 26, at 11 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Wednesday, April 26, at 1 PM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Friday, April 28, at 5 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Friday, April 28, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Wednesday, May 10.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, May 28.  
                 ******   Primary  Infection  Period  6  Details   ****** 

   Begin: Friday, April 28 at 5 AM    --->     Last rain hour: Sunday, April 30 at 2 PM.     
       Growth stage at start of period:  Between Full Pink and King Bloom
       This infection period accounts for less than 1% of the year's total primary scab risk.       
       Approximately 0.15 inch rain and 17 leaf wet hours, with 57 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 20%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Tuesday, April 25, 6 AM, or if strobilurin fungicide applied since Wednesday, April 26, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Saturday, April 29, at 4 AM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Monday, May 1, at 5 AM.
     
       First generation lesions arising from this infection period would start appearing by Monday, May 15.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, May 31.  
                 ******   Primary  Infection  Period  7  Details   ****** 

   Begin: Sunday, April 30 at 11 AM    --->     Last rain hour: Tuesday, May 2 at 12 PM.     
       Growth stage at start of period:  Between King Bloom and Full Bloom
       This infection period accounts for roughly 7% of the year's total primary scab risk.       
       Approximately 0.88 inch rain and 25 leaf wet hours, with 55 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 41%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, April 26, 6 AM, or if strobilurin fungicide applied since Thursday, April 27, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Monday, May 1, at 3 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, May 3, at 11 AM.
     
       First generation lesions arising from this infection period would start appearing by Friday, May 19.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, June 3.  
                 ******   Primary  Infection  Period  8  Details   ****** 

   Begin: Monday, May 1 at 11 PM    --->     Last rain hour: Tuesday, May 2 at 12 PM.     
       Growth stage at start of period:  Between King Bloom and Full Bloom
       This infection period accounts for roughly 6% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 16 leaf wet hours, with 57 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 52%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, April 26, 6 AM, or if strobilurin fungicide applied since Thursday, April 27, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Tuesday, May 2, at 8 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Wednesday, May 3, at 5 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Thursday, May 4, at 11 PM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Friday, May 5, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Friday, May 19.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Saturday, June 3.  
                 ******   Primary  Infection  Period  9  Details   ****** 

   Begin: Friday, May 5 at 4 AM    --->     Last rain hour: Sunday, May 7 at 12 PM.     
       Growth stage at start of period:  Between Full Bloom and Petal Fall
       This infection period accounts for roughly 18% of the year's total primary scab risk.       
       Approximately 1.54 inch rain and 44 leaf wet hours, with 52 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 63%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, May 3, 6 AM, or if strobilurin fungicide applied since Monday, May 1, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Saturday, May 6, at 8 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Saturday, May 6, at 9 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Monday, May 8, at 4 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Monday, May 8, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Tuesday, May 23.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 7.  
                 ******   Primary  Infection  Period  10  Details   ****** 

   Begin: Saturday, May 6 at 11 PM    --->     Last rain hour: Sunday, May 7 at 9 PM.     
       Growth stage at start of period:  Between Full Bloom and Petal Fall
       This infection period accounts for roughly 1% of the year's total primary scab risk.       
       Approximately 0.02 inch rain and 18 leaf wet hours, with 49 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 64%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Wednesday, May 3, 6 AM, or if strobilurin fungicide applied since Monday, May 1, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Monday, May 8, at 2 AM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 9, at 11 PM.
     
       First generation lesions arising from this infection period would start appearing by Wednesday, May 24.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 7.  
     Wetting period following  Sunday, May 07, 8 PM rain was too short for scab infection.
     Approximately 0.00 inch rain and 7 leaf wet hours, with 44 F degrees average temperature during wet hours.  
     Cumulative scab ascospore release by end of this wetting period is roughly 65%.
 
                 ******   Primary  Infection  Period  11  Details   ****** 

   Begin: Saturday, May 13 at 2 PM    --->     Last rain hour: Monday, May 15 at 11 AM.     
       Growth stage at start of period:  95% Petal Fall
       This infection period accounts for roughly 21% of the year's total primary scab risk.       
       Approximately 1.66 inch rain and 38 leaf wet hours, with 48 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 76%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 11, 6 AM, or if strobilurin fungicide applied since Monday, May 8, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Sunday, May 14, at 11 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Tuesday, May 16, at 2 PM.
     
       First generation lesions arising from this infection period would start appearing by Monday, May 29.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Wednesday, June 14.  
                 ******   Primary  Infection  Period  12  Details   ****** 

   Begin: Sunday, May 14 at 11 PM    --->     Last rain hour: Monday, May 15 at 11 AM.     
       Growth stage at start of period:  1 - 5 days after Petal Fall
       This infection period accounts for roughly 2% of the year's total primary scab risk.       
       Approximately 0.00 inch rain and 14 leaf wet hours, with 51 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 84%.

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 11, 6 AM, or if strobilurin fungicide applied since Monday, May 8, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Monday, May 15, at 10 PM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Wednesday, May 17, at 11 PM.
     
       First generation lesions arising from this infection period would start appearing by Tuesday, May 30.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Thursday, June 15.  
                 ******   Primary  Infection  Period  13  Details   ****** 

   Begin: Thursday, May 18 at 9 PM    --->     Last rain hour: Friday, May 19 at 2 AM.     
       Growth stage at start of period:  Fruit Set
       This infection period accounts for roughly 1% of the year's total primary scab risk.       
       Approximately 0.22 inch rain and 13 leaf wet hours, with 69 F degrees average temperature during wet hours.  
       Cumulative scab ascospore release by end of this wetting period is roughly 85%.       

       Reliable pre-infection protection during this period expected if full dose + good coverage captan or EBDC fungicide applied since Thursday, May 11, 6 AM, or if strobilurin fungicide applied since Saturday, May 13, 6 AM.

       Wetting period long enough only for ascospores released at night.  

       Opportunity for surface fungicide kickback ends Saturday, May 20, at 12 AM.  
   
       Opportunity for sterol inhibitor or strobilurin fungicide kickback ends Sunday, May 21, at 9 PM.
     
       First generation lesions arising from this infection period would start appearing by Thursday, June 1.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Sunday, June 18.  
                 ******   Primary  Infection  Period  14  Details   ****** 

   Begin: Monday, May 22 at 2 AM    --->     Last rain hour: Tuesday, May 23 at 12 AM.     
       Growth stage at start of period:  6 or more days after Petal Fall
       This infection period accounts for roughly 13% of the year's total primary scab risk.       
       Approximately 0.25 inch rain and 39 leaf wet hours, with 53 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 Tuesday, May 16, 6 AM, or if strobilurin fungicide applied since Wednesday, May 17, 6 AM.

       This infection period accompanied by daytime rain to release ascospores.  

       Opportunity for surface fungicide kickback ends Tuesday, May 23, at 3 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), opportunity for surface fungicide kickback ends Tuesday, May 23, at 8 AM.  
   
       Opportunity for sterol inhibitor or strobilurin kickback ends Thursday, May 25, at 2 AM.   Counting from beginning of daytime ascospore release (low inoculum blocks), kickback window ends Thursday, May 25, at 8 AM.
     
       First generation lesions arising from this infection period would start appearing by Sunday, June 4.  
       If conidia from 1st generation lesions spread infection, 2nd generation lesions could show as early as Monday, June 19.