Protectant fungicide Respray Dates for Secondary Scab Suppression

Background Information for this page
Return to Apple list for Easthampton MA
       This table estimates fungicide intervals for suppressing spread of secondary scab if it should occur.  Use the appropriate primary scab respray guidelines instead of this table until ascospore releases are completed.  Rules used to estimate protection depletion change after fruit set and again after terminal bud set.  See Background Information page for details.
      Brown text with grey background indicates dates when 2nd generation scab lesions from the final ascospore release have had time to begin appearing.  After this date it is possible to confirm the status of primary scab control.  If successful control of primary apple scab infections has been confirmed, this table is no longer needed, and fungicide application dates can be made with the extended intervals adequate to prevent flyspeck and other summer diseases. 
      But if there are enough active scab infections present to cause an unacceptable risk of fruit scab infection, this table provides estimates for respray dates to keep scab infections from spreading.  If active lesions are found, fungicide protection is needed until those lesions exhaust their supply of spores, which takes about 4 weeks. 
       Depending on scab severity, market sensitivity, temperature, and proximity to harvest; shorter or longer fungicide intervals to suppress spread from active scab lesions may be more appropriate than the estimates shown below.
      The estimated date for 95+% scab ascsopore release at this site is May 25.   
The estimated McIntosh fruit set date for this site is May 18. 
The approximate terminal bud set date for this site is June 30.
Weather data for Easthampton MA.  Forecast values begin September 24, 2017
Previous
Spray Date

Estimates assume that fungicide
was applied BEFORE rain
on spray date
Inches Rain Protection End Date against Secondary Scab
for full-dose
captan, mancozeb or other protectant fungicide
Percent primary scab potential beginning to show as
(1st generation)
&
2nd gen. lesions by protection end date
Respray Deadline
= Start date for next scab infection period after protection ends
Thu,  May  18 0.15 May 27, Sat (45%) 2% May 29, Mon
Fri,  May  19 0.07 May 30, Tue (68%) 13% May 31, Wed
Sat,  May  20 0 June 1, Thu (69%) 20% June 4, Sun
Sun,  May  21 0 June 1, Thu (69%) 20% June 4, Sun
Mon,  May  22 0.25 June 1, Thu (69%) 20% June 4, Sun
Tue,  May  23 0 June 1, Thu (69%) 20% June 4, Sun
Wed,  May  24 0 June 1, Thu (69%) 20% June 4, Sun
Thu,  May  25 0.52 June 1, Thu (69%) 20% June 4, Sun
Fri,  May  26 1.06 June 6, Tue (83%) 44% June 16, Fri
Sat,  May  27 0 June 7, Wed (83%) 45% June 16, Fri
Sun,  May  28 0 June 7, Wed (83%) 45% June 16, Fri
Mon,  May  29 0.15 June 7, Wed (83%) 45% June 16, Fri
Tue,  May  30 0 June 7, Wed (83%) 45% June 16, Fri
Wed,  May  31 0.57 June 7, Wed (83%) 45% June 16, Fri
Thu,  June  1 0.03 June 7, Wed (83%) 45% June 16, Fri
Fri,  June  2 0 June 7, Wed (83%) 45% June 16, Fri
Sat,  June  3 0 June 7, Wed (83%) 45% June 16, Fri
Sun,  June  4 0.19 June 7, Wed (83%) 45% June 16, Fri
Mon,  June  5 0.76 June 7, Wed (83%) 45% June 16, Fri
Tue,  June  6 1.35 June 18, Sun (100%) 83% June 18, Sun
Wed,  June  7 0.01 June 19, Mon (100%) 83% June 23, Fri
Thu,  June  8 0 June 19, Mon 83% June 23, Fri
Fri,  June  9 0 June 20, Tue 83% June 23, Fri
Sat,  June  10 0 June 22, Thu 83% June 23, Fri
Sun,  June  11 0 June 23, Fri 83% June 23, Fri
Mon,  June  12 0 June 24, Sat 83% June 24, Sat
Tue,  June  13 0 June 25, Sun 83% June 25, Sun
Wed,  June  14 0 June 25, Sun   83% June 25, Sun
Thu,  June  15 0 June 25, Sun 83% June 25, Sun
Fri,  June  16 0.35 June 25, Sun 83% June 25, Sun
Sat,  June  17 0.08 June 26, Mon 83% June 27, Tue
Sun,  June  18 0.05 June 28, Wed 100% June 30, Fri
Mon,  June  19 1.42 June 28, Wed June 30, Fri
Tue,  June  20 0.08 July 4, Tue July 7, Fri
Wed,  June  21 0 July 5, Wed     July 7, Fri
Thu,  June  22 0 July 6, Thu July 7, Fri
Fri,  June  23 0.01 July 7, Fri July 7, Fri
Sat,  June  24 0.24 July 8, Sat July 11, Tue
Sun,  June  25 0.18 July 8, Sat July 11, Tue
Mon,  June  26 0 July 9, Sun July 11, Tue
Tue,  June  27 0.54 July 9, Sun July 11, Tue
Wed,  June  28 0 July 12, Wed     July 12, Wed
Thu,  June  29 0 July 12, Wed July 12, Wed
Fri,  June  30 0.65 July 12, Wed July 12, Wed
Sat,  July  1 0 July 13, Thu July 18, Tue
Sun,  July  2 0.09 July 13, Thu July 18, Tue
Mon,  July  3 0 July 13, Thu July 18, Tue
Tue,  July  4 0 July 13, Thu July 18, Tue
Wed,  July  5 0 July 13, Thu     July 18, Tue
Thu,  July  6 0 July 13, Thu July 18, Tue
Fri,  July  7 0.65 July 13, Thu July 18, Tue
Sat,  July  8 0.25 July 19, Wed July 20, Thu
Sun,  July  9 0 July 23, Sun July 24, Mon
Mon,  July  10 0 July 24, Mon July 27, Thu
Tue,  July  11 0.60 July 25, Tue July 27, Thu
Wed,  July  12 0.54 July 25, Tue     July 27, Thu
Thu,  July  13 0.31 July 27, Thu July 27, Thu
Fri,  July  14 0.08 July 28, Fri August 2, Wed
Sat,  July  15 0 July 29, Sat August 2, Wed
Sun,  July  16 0 July 30, Sun August 2, Wed
Mon,  July  17 0 July 31, Mon August 2, Wed
Tue,  July  18 0.35 August 1, Tue August 2, Wed
Wed,  July  19 0 August 2, Wed     August 2, Wed
Thu,  July  20 0.10 August 3, Thu August 4, Fri
Fri,  July  21 0 August 4, Fri August 4, Fri
Sat,  July  22 0 August 5, Sat August 7, Mon
Sun,  July  23 0 August 6, Sun August 7, Mon
Mon,  July  24 0.97 August 6, Sun August 7, Mon
Tue,  July  25 0 August 6, Sun August 7, Mon
Wed,  July  26 0 August 6, Sun     August 7, Mon
Thu,  July  27 0.14 August 6, Sun August 7, Mon
Fri,  July  28 0 August 6, Sun August 7, Mon
Sat,  July  29 0 August 6, Sun August 7, Mon
Sun,  July  30 0 August 6, Sun August 7, Mon
Mon,  July  31 0 August 6, Sun August 7, Mon
Tue,  August  1 0 August 6, Sun August 7, Mon
Wed,  August  2 0.71 August 6, Sun     August 7, Mon
Thu,  August  3 0 August 16, Wed Too early to estimate
Fri,  August  4 0.03 August 16, Wed  
Sat,  August  5 1.32 August 16, Wed  
Sun,  August  6 0 August 20, Sun  
Mon,  August  7 0.10 August 21, Mon  
Tue,  August  8 0.05 August 22, Tue  
Wed,  August  9 0 August 23, Wed      
Thu,  August  10 0 August 24, Thu  
Fri,  August  11 0.03 August 25, Fri  
Sat,  August  12 0.34 August 26, Sat  
Sun,  August  13 0.09 August 27, Sun  
Mon,  August  14 0 August 28, Mon  
Tue,  August  15 0.17 August 29, Tue  
Wed,  August  16 0 August 30, Wed      
Thu,  August  17 0 August 31, Thu  
Fri,  August  18 0.31 September 1, Fri  
Sat,  August  19 0 September 2, Sat  
Sun,  August  20 0 September 3, Sun  
Mon,  August  21 0 September 4, Mon  
Tue,  August  22 0.36 September 5, Tue  
Wed,  August  23 0.21 September 6, Wed      
Thu,  August  24 0 September 7, Thu  
Fri,  August  25 0 September 7, Thu  
Sat,  August  26 0 September 7, Thu  
Sun,  August  27 0 September 7, Thu  
Mon,  August  28 0 September 7, Thu  
Tue,  August  29 0.02 September 7, Thu  
Wed,  August  30 0.02 September 7, Thu      
Thu,  August  31 0 September 7, Thu