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 27.   
The estimated McIntosh fruit set date for this site is May 22. 
The approximate terminal bud set date for this site is July 1.
Weather data for Easthampton MA.  Forecast values begin July 16, 2018
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
Tue,  May  29 0 June 10, Sun (97%) 65% June 13, Wed
Wed,  May  30 0 June 11, Mon (97%) 65% June 13, Wed
Thu,  May  31 0 June 13, Wed (97%) 65% June 13, Wed
Fri,  June  1 0.03 June 14, Thu (97%) 85% June 15, Fri
Sat,  June  2 0 June 15, Fri (100%) 89% June 15, Fri
Sun,  June  3 0 June 16, Sat (100%) 89% June 18, Mon
Mon,  June  4 0.79 June 17, Sun   89% June 18, Mon
Tue,  June  5 0.07 June 17, Sun 89% June 18, Mon
Wed,  June  6 0 June 18, Mon 89% June 18, Mon
Thu,  June  7 0 June 18, Mon 89% June 18, Mon
Fri,  June  8 0 June 20, Wed 89% June 23, Sat
Sat,  June  9 0 June 21, Thu 89% June 23, Sat
Sun,  June  10 0 June 22, Fri 89% June 23, Sat
Mon,  June  11 0 June 23, Sat   89% June 23, Sat
Tue,  June  12 0 June 24, Sun 89% June 24, Sun
Wed,  June  13 0.01 June 25, Mon 97% June 27, Wed
Thu,  June  14 0 June 25, Mon 97% June 27, Wed
Fri,  June  15 0.05 June 25, Mon 97% June 27, Wed
Sat,  June  16 0 June 25, Mon 97% June 27, Wed
Sun,  June  17 0 June 25, Mon 97% June 27, Wed
Mon,  June  18 0.84 June 25, Mon   97% June 27, Wed
Tue,  June  19 0.18 June 29, Fri 100% July 6, Fri
Wed,  June  20 0 June 29, Fri July 6, Fri
Thu,  June  21 0 June 29, Fri July 6, Fri
Fri,  June  22 0 June 29, Fri July 6, Fri
Sat,  June  23 0.03 June 29, Fri July 6, Fri
Sun,  June  24 1.22 June 29, Fri July 6, Fri
Mon,  June  25 0.15 June 29, Fri     July 6, Fri
Tue,  June  26 0 June 29, Fri July 6, Fri
Wed,  June  27 0.39 June 29, Fri July 6, Fri
Thu,  June  28 2.01 June 29, Fri July 6, Fri
Fri,  June  29 0 July 13, Fri July 15, Sun
Sat,  June  30 0 July 14, Sat July 15, Sun
Sun,  July  1 0 July 15, Sun July 17, Tue
Mon,  July  2 0 July 16, Mon     July 17, Tue
Tue,  July  3 0 July 17, Tue July 22, Sun
Wed,  July  4 0 July 18, Wed July 22, Sun
Thu,  July  5 0 July 19, Thu July 22, Sun
Fri,  July  6 0.20 July 20, Fri July 22, Sun
Sat,  July  7 0 July 21, Sat July 22, Sun
Sun,  July  8 0 July 22, Sun July 22, Sun
Mon,  July  9 0 July 23, Mon     Too early to estimate
Tue,  July  10 0 July 24, Tue  
Wed,  July  11 0 July 24, Tue  
Thu,  July  12 0 July 24, Tue  
Fri,  July  13 0 July 24, Tue  
Sat,  July  14 0 July 24, Tue  
Sun,  July  15 0.22 July 24, Tue  
Mon,  July  16 0 July 25, Wed      
Tue,  July  17 1.13 July 25, Wed  
Wed,  July  18 0.03 Too early  
Thu,  July  19 0 Too early  
Fri,  July  20 0 Too early  
Sat,  July  21 0 Too early  
Sun,  July  22 0.29 Too early  
Mon,  July  23 0.48 Too early      
Tue,  July  24  
Wed,  July  25  
Thu,  July  26  
Fri,  July  27  
Sat,  July  28  
Sun,  July  29  
Mon,  July  30          
Tue,  July  31  
Wed,  August  1  
Thu,  August  2  
Fri,  August  3  
Sat,  August  4  
Sun,  August  5  
Mon,  August  6          
Tue,  August  7  
Wed,  August  8  
Thu,  August  9  
Fri,  August  10  
Sat,  August  11  
Sun,  August  12  
Mon,  August  13          
Tue,  August  14  
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Thu,  August  16  
Fri,  August  17  
Sat,  August  18  
Sun,  August  19  
Mon,  August  20          
Tue,  August  21  
Wed,  August  22  
Thu,  August  23  
Fri,  August  24  
Sat,  August  25  
Sun,  August  26  
Mon,  August  27          
Tue,  August  28  
Wed,  August  29  
Thu,  August  30  
Fri,  August  31