Fireblight infection conditions - Cougarblight model

Background Information for this page
Return to radar list for Sanford ME
Weather data for Sanford ME.  Forecast values begin September 20, 2011
     This table shows estimates of RELATIVE daily fireblight blossom infection risk based on weather conditions.  Rating criteria are from the Cougarblight 2010 model developed in Washington and Oregon by Dr. Timothy J. Smith.     
      ABSOLUTE risk depends on the amount of fire blight bacteria in the area, the number of open flowers, and cultivar and rootstock susceptibility.  Relative infection risk may be overstated for first few days of bloom because fire blight bacteria may not have been distributed to open flowers.   
      Gray shading indicates dates when most trees will have lost open blossoms, and are therefore no longer susceptible to blossom infection.  These dates included for later blooming cultivars and for late-blooming young trees.  Absolute risk is much lower on these dates than during full bloom, but apple trees with open blossoms on these dates are susceptible to the risk rating shown.  
      Fireblight infection can occur without rain if there is "heavy" dew.  But heavy dew is not defined in weather reports.  As a rough guess, if there is no rain on a day, but leaves are expected to be wet for at least 3 hours, then infection risk is reported with "if dew" attached.  Infection potential may be overstated on days when the "if dew" tag is attached.
     Fire blight risk categories vary by block history:
   I  = No active fire blight within 1 mile of the orchard this year or last year.  Requires 500 – 800 heat units for HIGH rating, 801 – 1000 for EXTREME!, and 1001+ for EXCEPTIONAL!
  
II = Fire blight was present within 1 mile of the orchard last year, but not currently active in the area this year.
Requires 200 – 350 heat units for HIGH rating, 351 – 500 for EXTREME!, and 501+ for EXCEPTIONAL!

  
III = Active fire blight cankers within 1 mile of the orchard this year. 
Requires 100 – 200 heat units for HIGH rating, 200 – 300 for EXTREME!, and 301+ for EXCEPTIONAL!
 If blossom infection occurred May 24, then blossom blight would be noticeable by June 1, and shoot blight by June 16.
Range of potential open blossom dates
for McIntosh and similar cultivars
Cougarblight Heat Units,
Inches Rain, & 
Leaf Wet Hours
I - No FB within
one mile last year
or this year
II - FB within one mile last year, but not active within one mile this year III - FB active within one mile of orchard this year.
Mac King Bloom
 Mon, May 16 
0 HU,  0.25'',  24 hrs Low Low Caution
Tue, May 17  0 HU,  0.61'',  24 hrs Low Low Caution
Wed, May 18  2 HU,  0.65'',  24 hrs Low Low Caution
Thu, May 19  9 HU,  0.43'',  24 hrs Low Low Caution
Fri, May 20  17 HU,  0.0'',  24 hrs Low Low Caution
Sat, May 21  29 HU,  0.39'',  23 hrs Low Low Caution
Sun, May 22  27 HU,  0.13'',  17 hrs Low Low Caution
Mon, May 23  25 HU,  0.36'',  23 hrs Low Low Caution
Tue, May 24  133 HU,  0.31'',  19 hrs Low Caution HIGH
Wed, May 25  169 HU,  0.04'',  10 hrs Caution Caution HIGH
Thu, May 26  264 HU,  0.0'',  8 hrs Caution (if dew) HIGH (if dew) EXTREME! (if dew)
Fri, May 27  529 HU,  0.0'',  10 hrs HIGH (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Sat, May 28  431 HU,  0.0'',  15 hrs Caution (if dew) EXTREME! (if dew) EXCEPTIONAL! (if dew)
Sun, May 29  701 HU,  0.0'',  12 hrs HIGH (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Mon, May 30  940 HU,  0.0'',  0 hrs Low Low Low
Tue, May 31  825 HU,  0.0'',  0 hrs Low Low Low
Wed, June 1  1050 HU,  0.07'',  4 hrs EXCEPTIONAL! EXCEPTIONAL! EXCEPTIONAL!
Thu, June 2  742 HU,  0.0'',  0 hrs Low Low Low
Fri, June 3  418 HU,  0.0'',  0 hrs Low Low Low
Sat, June 4  272 HU,  0.0'',  0 hrs Low Low Low
Sun, June 5  46 HU,  0.0'',  6 hrs Low Low Caution
Mon, June 6  132 HU,  0.0'',  6 hrs Low Caution (if dew) HIGH (if dew)
Tue, June 7  325 HU,  0.0'',  2 hrs Low Low Low
Wed, June 8  732 HU,  0.0'',  6 hrs HIGH (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Thu, June 9  1033 HU,  0.51'',  10 hrs EXCEPTIONAL! EXCEPTIONAL! EXCEPTIONAL!
Fri, June 10  1001 HU,  0.0'',  10 hrs EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Sat, June 11  802 HU,  0.86'',  16 hrs EXTREME! EXCEPTIONAL! EXCEPTIONAL!
Sun, June 12  389 HU,  0.07'',  24 hrs Caution EXTREME! EXCEPTIONAL!
Mon, June 13  81 HU,  0.01'',  15 hrs Low Low Caution
Tue, June 14  20 HU,  0.03'',  19 hrs Low Low Caution
Wed, June 15  79 HU,  0.0'',  9 hrs Low Low Caution
Thu, June 16  424 HU,  0.0'',  2 hrs Low Low Low
Fri, June 17  476 HU,  0.21'',  10 hrs Caution EXTREME! EXCEPTIONAL!
Sat, June 18  627 HU,  0.38'',  19 hrs HIGH EXCEPTIONAL! EXCEPTIONAL!
Sun, June 19  638 HU,  0.0'',  8 hrs HIGH (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Mon, June 20  415 HU,  0.0'',  0 hrs Low Low Low
Tue, June 21  563 HU,  0.0'',  0 hrs Low Low Low
Wed, June 22  463 HU,  0.88'',  10 hrs Caution EXTREME! EXCEPTIONAL!
Thu, June 23  397 HU,  0.50'',  24 hrs Caution EXTREME! EXCEPTIONAL!
Fri, June 24  276 HU,  0.79'',  24 hrs Caution HIGH EXTREME!
Sat, June 25  80 HU,  0.32'',  24 hrs Low Low Caution
Sun, June 26  90 HU,  0.0'',  14 hrs Low Low Caution
Mon, June 27  335 HU,  0.0'',  10 hrs Caution (if dew) HIGH (if dew) EXCEPTIONAL! (if dew)
Tue, June 28  532 HU,  0.13'',  7 hrs HIGH EXCEPTIONAL! EXCEPTIONAL!
Wed, June 29  699 HU,  0.0'',  12 hrs HIGH (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Thu, June 30  716 HU,  0.0'',  0 hrs Low Low Low
Fri, July 1  552 HU,  0.06'',  10 hrs HIGH EXCEPTIONAL! EXCEPTIONAL!
Sat, July 2  515 HU,  0.0'',  10 hrs HIGH (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Sun, July 3  418 HU,  0.03'',  14 hrs Caution EXTREME! EXCEPTIONAL!
Mon, July 4  663 HU,  0.14'',  21 hrs HIGH EXCEPTIONAL! EXCEPTIONAL!
Tue, July 5  1024 HU,  0.0'',  10 hrs EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Wed, July 6  1301 HU,  0.23'',  7 hrs EXCEPTIONAL! EXCEPTIONAL! EXCEPTIONAL!
Thu, July 7  1470 HU,  0.0'',  10 hrs EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Fri, July 8  1214 HU,  0.19'',  2 hrs EXCEPTIONAL! EXCEPTIONAL! EXCEPTIONAL!
Sat, July 9  973 HU,  0.0'',  10 hrs EXTREME! (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Sun, July 10  833 HU,  0.0'',  0 hrs Low Low Low
Mon, July 11  1275 HU,  0.0'',  0 hrs Low Low Low
Tue, July 12  1829 HU,  0.0'',  0 hrs Low Low Low
Wed, July 13  1855 HU,  0.69'',  10 hrs EXCEPTIONAL! EXCEPTIONAL! EXCEPTIONAL!
Thu, July 14  1629 HU,  0.0'',  9 hrs EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew) EXCEPTIONAL! (if dew)
Fri, July 15  1153 HU,  0.0'',  2 hrs Low Low Low
Sat, July 16  937 HU,  0.0'',  0 hrs Low Low Low
Sun, July 17  1385 HU,  0.0'',  0 hrs Low Low Low