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 October 17, 2008
     Weather-based RELATIVE daily fireblight blossom infection risk values below are according to criteria of the Cougarblight model developed in Washington state by Dr. Timothy J. Smith.     
      ABSOLUTE risk also depends on cultivar and rootstock susceptibility, and on the number of flowers open. Infection risk may be overstated for first few days of bloom because fire blight bacteria may not have been distributed to open flowers.
      Cougarblight heat units are similar to degree hours base 60 F.
   
NOTICE! - Fireblight infection can occur without rain if there is "heavy" dew.  But "heavy" dew in relation to fireblight is not defined.  As a rough guess, if there is no rain on a day, but leaf wetness is expected to exceed 3 hours for that day, then infection conditions are reported with "if dew" attached.  Infection potential may be overstated on days when the "if dew" tag is attached.
Range of
potential
open-blossom dates
Gray box indicates dates when most trees will have lost open blossoms and susceptibility to blossom infection.  Gray box dates included for late cultivars and late-blooming young trees.
Fire blight risk categories by block history
 I  = No FB in the area during last two seasons
      requires 500+ heat units for HIGH! rating, 800+ for EXTREME!

 
II = FB present in the area, but not within 1 mile of your orchard last
    year requires 400+ heat units for HIGH! rating, 650+ for EXTREME!

 
III = FB in this orchard block or neighboring orchard last year
      requires 300+ heat units for HIGH! rating, 500+ for EXTREME!

 
IV = Active FB strikes or cankers present in this or neighboring block
      requires 200+ heat units for HIGH! rating, 350+ for EXTREME!
   If fire blight blossom infection occurred on May 31, then blossom blight would be noticeable by June 10, and shoot blight by June 21.
Inches Rain &
Leaf Wet Hours &
Heat Units
No FB in area for last two years
I
FB in area
last year,
but over 1 mile away
II
FB last year within 1 mile
III
Currently active FB
IV
Wed, May 14    0.'',  0 hrs.,  28 HU 0 0 0 0
Thu, May 15    0.'',  0 hrs.,  45 HU 0 0 0 0
Fri, May 16    0.04'',  4 hrs.,  55 HU Low Low Low Low
Sat, May 17    0.12'',  10 hrs.,  96 HU Low Low Low Low
Sun, May 18    0.'',  0 hrs.,  88 HU 0 0 0 0
Mon, May 19    0.'',  0 hrs.,  72 HU 0 0 0 0
Tue, May 20    0.'',  0 hrs.,  75 HU 0 0 0 0
Wed, May 21    0.'',  0 hrs.,  47 HU 0 0 0 0
Thu, May 22    0.'',  0 hrs.,  26 HU 0 0 0 0
Fri, May 23    0.02'',  4 hrs.,  34 HU Low Low Low Low
Sat, May 24    0.'',  0 hrs.,  40 HU 0 0 0 0
Sun, May 25    0.'',  0 hrs.,  85 HU 0 0 0 0
Mon, May 26    0.'',  0 hrs.,  305 HU 0 0 0 0
Tue, May 27    0.'',  0 hrs.,  493 HU 0 0 0 0
Wed, May 28    0.'',  0 hrs.,  485 HU 0 0 0 0
Thu, May 29    0.'',  0 hrs.,  552 HU 0 0 0 0
Fri, May 30    0.'',  0 hrs.,  374 HU 0 0 0 0
Sat, May 31    0.45'',  19 hrs.,  215 HU Low Low Marginal HIGH!
Sun, June 1    0.'',  11 hrs.,  351 HU Low Marginal
(if dew)
HIGH!
(if dew)
EXTREME!
(if dew)
Mon, June 2    0.'',  0 hrs.,  321 HU 0 0 0 0
Tue, June 3    0.04'',  3 hrs.,  433 HU Marginal HIGH! HIGH! EXTREME!
Wed, June 4    0.31'',  20 hrs.,  397 HU Low Marginal HIGH! EXTREME!
Thu, June 5    0.01'',  24 hrs.,  253 HU Low Low Marginal HIGH!
Fri, June 6    0.49'',  24 hrs.,  160 HU Low Low Marginal Marginal
Sat, June 7    0.'',  12 hrs.,  309 HU Low Low HIGH!
(if dew)
HIGH!
(if dew)
Sun, June 8    0.'',  0 hrs.,  763 HU 0 0 0 0
Mon, June 9    0.'',  0 hrs.,  1212 HU 0 0 0 0
Tue, June 10    0.31'',  14 hrs.,  1629 HU EXTREME! EXTREME! EXTREME! EXTREME!
Wed, June 11    0.36'',  9 hrs.,  1642 HU EXTREME! EXTREME! EXTREME! EXTREME!
Thu, June 12    0.'',  0 hrs.,  1355 HU 0 0 0 0
Fri, June 13    0.'',  0 hrs.,  1154 HU 0 0 0 0
Sat, June 14    0.41'',  4 hrs.,  894 HU EXTREME! EXTREME! EXTREME! EXTREME!
Sun, June 15    1.09'',  24 hrs.,  577 HU HIGH! HIGH! EXTREME! EXTREME!
Mon, June 16    0.51'',  24 hrs.,  435 HU Marginal HIGH! HIGH! EXTREME!
Tue, June 17    0.73'',  21 hrs.,  269 HU Low Low Marginal HIGH!
Wed, June 18    0.'',  9 hrs.,  194 HU Low Low Marginal
(if dew)
Marginal
(if dew)
Thu, June 19    0.'',  0 hrs.,  294 HU 0 0 0 0
Fri, June 20    0.27'',  15 hrs.,  348 HU Low Low HIGH! HIGH!
Sat, June 21    0.21'',  21 hrs.,  431 HU Marginal HIGH! HIGH! EXTREME!
Sun, June 22    0.66'',  21 hrs.,  471 HU Marginal HIGH! HIGH! EXTREME!
Mon, June 23    0.49'',  24 hrs.,  493 HU Marginal HIGH! HIGH! EXTREME!
Tue, June 24    0.22'',  21 hrs.,  561 HU HIGH! HIGH! EXTREME! EXTREME!