Protectant fungicide Respray Dates for Secondary Scab Suppression

Background Information for this page
Return to radar list for Sanford ME
       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 June 1.   
The estimated McIntosh fruit set date for this site is May 30. 
The approximate terminal bud set date for this site is July 11.
Weather data for Sanford ME.  Forecast values begin November 1, 2011
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,  June  2 0 June 16, Thu (91%) 15% June 17, Fri
Fri,  June  3 0 June 17, Fri (91%) 15% June 17, Fri
Sat,  June  4 0 June 18, Sat (91%) 15% June 18, Sat
Sun,  June  5 0 June 19, Sun (91%) 15% June 22, Wed
Mon,  June  6 0 June 19, Sun (91%) 15% June 22, Wed
Tue,  June  7 0 June 19, Sun (91%) 15% June 22, Wed
Wed,  June  8 0 June 19, Sun (91%) 15% June 22, Wed
Thu,  June  9 0.51 June 19, Sun (91%) 15% June 22, Wed
Fri,  June  10 0 June 23, Thu (100%) 91% June 29, Wed
Sat,  June  11 0.63 June 23, Thu (100%) 91% June 29, Wed
Sun,  June  12 0.30 June 24, Fri 91% June 29, Wed
Mon,  June  13 0 June 25, Sat 91% June 29, Wed
Tue,  June  14 0.04 June 25, Sat 91% June 29, Wed
Wed,  June  15 0 June 25, Sat   91% June 29, Wed
Thu,  June  16 0 June 25, Sat 91% June 29, Wed
Fri,  June  17 0.21 June 25, Sat 91% June 29, Wed
Sat,  June  18 0.38 June 25, Sat 91% June 29, Wed
Sun,  June  19 0 June 26, Sun 91% June 29, Wed
Mon,  June  20 0 June 26, Sun 91% June 29, Wed
Tue,  June  21 0 June 26, Sun 91% June 29, Wed
Wed,  June  22 0.49 June 26, Sun   91% June 29, Wed
Thu,  June  23 0.62 June 30, Thu 91% July 1, Fri
Fri,  June  24 0.69 July 8, Fri 100% July 8, Fri
Sat,  June  25 0.69 July 8, Fri July 8, Fri
Sun,  June  26 0 July 9, Sat July 13, Wed
Mon,  June  27 0 July 11, Mon July 13, Wed
Tue,  June  28 0 July 12, Tue July 13, Wed
Wed,  June  29 0.13 July 13, Wed     July 13, Wed
Thu,  June  30 0 July 14, Thu July 18, Mon
Fri,  July  1 0.06 July 15, Fri July 18, Mon
Sat,  July  2 0 July 16, Sat July 18, Mon
Sun,  July  3 0.03 July 17, Sun July 18, Mon
Mon,  July  4 0.14 July 18, Mon July 18, Mon
Tue,  July  5 0 July 19, Tue July 23, Sat
Wed,  July  6 0.22 July 20, Wed     July 23, Sat
Thu,  July  7 0.01 July 21, Thu July 23, Sat
Fri,  July  8 0.04 July 22, Fri July 23, Sat
Sat,  July  9 0.15 July 23, Sat July 25, Mon
Sun,  July  10 0 July 24, Sun July 25, Mon
Mon,  July  11 0 July 25, Mon July 25, Mon
Tue,  July  12 0 July 26, Tue July 29, Fri
Wed,  July  13 0.62 July 27, Wed     July 29, Fri
Thu,  July  14 0.07 July 28, Thu July 29, Fri
Fri,  July  15 0 July 29, Fri July 29, Fri
Sat,  July  16 0 July 30, Sat August 2, Tue
Sun,  July  17 0 July 30, Sat August 2, Tue
Mon,  July  18 0.10 July 30, Sat August 2, Tue
Tue,  July  19 0 July 31, Sun August 2, Tue
Wed,  July  20 0 July 31, Sun     August 2, Tue
Thu,  July  21 0 July 31, Sun August 2, Tue
Fri,  July  22 0 July 31, Sun August 2, Tue
Sat,  July  23 0.04 July 31, Sun August 2, Tue
Sun,  July  24 0 July 31, Sun August 2, Tue
Mon,  July  25 0.34 July 31, Sun August 2, Tue
Tue,  July  26 0.93 August 8, Mon August 8, Mon
Wed,  July  27 0 August 10, Wed     August 14, Sun
Thu,  July  28 0 August 11, Thu August 14, Sun
Fri,  July  29 0.62 August 11, Thu August 14, Sun
Sat,  July  30 0.33 August 13, Sat August 14, Sun
Sun,  July  31 0 August 14, Sun August 14, Sun
Mon,  August  1 0 August 15, Mon August 19, Fri
Tue,  August  2 0.07 August 16, Tue August 19, Fri
Wed,  August  3 0 August 16, Tue     August 19, Fri
Thu,  August  4 0 August 16, Tue August 19, Fri
Fri,  August  5 0.03 August 16, Tue August 19, Fri
Sat,  August  6 0.02 August 16, Tue August 19, Fri
Sun,  August  7 0.50 August 16, Tue August 19, Fri
Mon,  August  8 0.15 August 16, Tue August 19, Fri
Tue,  August  9 0.28 August 16, Tue August 19, Fri
Wed,  August  10 0.41 August 17, Wed     August 19, Fri
Thu,  August  11 0 August 20, Sat August 21, Sun
Fri,  August  12 0 August 20, Sat August 21, Sun
Sat,  August  13 0 August 20, Sat August 21, Sun
Sun,  August  14 0.01 August 20, Sat August 21, Sun
Mon,  August  15 1.58 August 22, Mon August 25, Thu
Tue,  August  16 0.30 August 26, Fri August 27, Sat
Wed,  August  17 0.01 August 26, Fri     August 27, Sat
Thu,  August  18 0 August 26, Fri August 27, Sat
Fri,  August  19 0.11 August 26, Fri August 27, Sat
Sat,  August  20 0 August 26, Fri August 27, Sat
Sun,  August  21 1.03 August 26, Fri August 27, Sat
Mon,  August  22 0.38 August 29, Mon September 5, Mon
Tue,  August  23 0 August 29, Mon September 5, Mon
Wed,  August  24 0 August 29, Mon     September 5, Mon
Thu,  August  25 0.81 August 29, Mon September 5, Mon
Fri,  August  26 0 August 29, Mon September 5, Mon
Sat,  August  27 0.32 August 29, Mon September 5, Mon
Sun,  August  28 2.72 August 29, Mon September 5, Mon
Mon,  August  29 0 September 8, Thu Too early to estimate
Tue,  August  30 0 September 8, Thu  
Wed,  August  31 0 September 8, Thu