Fireblight infection conditions - Cougarblight model

Background Information for this page
Return to radar list for Monmouth ME
Weather data for Monmouth ME.  Forecast values begin August 3, 2010
     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 4, then blossom blight would be noticeable by May 27, and shoot blight by June 16.
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
Sun, May 2    0.01'',  2 hrs.,  110 HU Low Low Low Marginal
Mon, May 3    0.'',  0 hrs.,  310 HU 0 0 0 0
Tue, May 4    0.19'',  13 hrs.,  373 HU Low Marginal HIGH! EXTREME!
Wed, May 5    0.'',  7 hrs.,  433 HU Marginal
(if dew)
HIGH!
(if dew)
HIGH!
(if dew)
EXTREME!
(if dew)
Thu, May 6    0.18'',  9 hrs.,  341 HU Low Low HIGH! HIGH!
Fri, May 7    0.'',  0 hrs.,  142 HU 0 0 0 0
Sat, May 8    0.52'',  22 hrs.,  79 HU Low Low Low Low
Sun, May 9    0.'',  9 hrs.,  19 HU Low Low Low Low
Mon, May 10    0.'',  0 hrs.,  1 HU 0 0 0 0
Tue, May 11    0.'',  0 hrs.,  0 HU 0 0 0 0
Wed, May 12    0.'',  2 hrs.,  0 HU 0 0 0 0
Thu, May 13    0.'',  0 hrs.,  10 HU 0 0 0 0
Fri, May 14    0.'',  0 hrs.,  10 HU 0 0 0 0
Sat, May 15    0.02'',  11 hrs.,  11 HU Low Low Low Low
Sun, May 16    0.'',  0 hrs.,  42 HU 0 0 0 0
Mon, May 17    0.'',  0 hrs.,  87 HU 0 0 0 0
Tue, May 18    0.'',  3 hrs.,  105 HU Low Low Low Marginal
(if dew)
Wed, May 19    0.77'',  22 hrs.,  104 HU Low Low Low Marginal
Thu, May 20    0.'',  10 hrs.,  256 HU Low Low Marginal
(if dew)
HIGH!
(if dew)
Fri, May 21    0.'',  0 hrs.,  249 HU 0 0 0 0
Sat, May 22    0.'',  0 hrs.,  264 HU 0 0 0 0
Sun, May 23    0.'',  10 hrs.,  335 HU Low Low HIGH!
(if dew)
HIGH!
(if dew)
Mon, May 24    0.'',  11 hrs.,  397 HU Low Marginal
(if dew)
HIGH!
(if dew)
EXTREME!
(if dew)
Tue, May 25    0.'',  7 hrs.,  708 HU HIGH!
(if dew)
EXTREME!
(if dew)
EXTREME!
(if dew)
EXTREME!
(if dew)
Wed, May 26    0.'',  0 hrs.,  1036 HU 0 0 0 0
Thu, May 27    0.'',  3 hrs.,  1044 HU EXTREME!
(if dew)
EXTREME!
(if dew)
EXTREME!
(if dew)
EXTREME!
(if dew)
Fri, May 28    0.'',  0 hrs.,  847 HU 0 0 0 0
Sat, May 29    0.'',  8 hrs.,  561 HU HIGH!
(if dew)
HIGH!
(if dew)
EXTREME!
(if dew)
EXTREME!
(if dew)
Sun, May 30    0.'',  7 hrs.,  301 HU Low Low HIGH!
(if dew)
HIGH!
(if dew)
Mon, May 31    0.'',  0 hrs.,  269 HU 0 0 0 0
Tue, June 1    0.51'',  16 hrs.,  239 HU Low Low Marginal HIGH!
Wed, June 2    0.'',  15 hrs.,  204 HU Low Low Marginal
(if dew)
HIGH!
(if dew)
Thu, June 3    0.35'',  24 hrs.,  102 HU Low Low Low Marginal
Fri, June 4    0.'',  12 hrs.,  178 HU Low Low Marginal
(if dew)
Marginal
(if dew)
Sat, June 5    0.98'',  23 hrs.,  238 HU Low Low Marginal HIGH!
Sun, June 6    1.09'',  24 hrs.,  200 HU Low Low Marginal Marginal
Mon, June 7    0.'',  9 hrs.,  245 HU Low Low Marginal
(if dew)
HIGH!
(if dew)
Tue, June 8    0.04'',  0 hrs.,  134 HU Low Low Low Marginal
Wed, June 9    0.'',  2 hrs.,  107 HU 0 0 0 0
Thu, June 10    0.4'',  22 hrs.,  107 HU Low Low Low Marginal
Fri, June 11    0.'',  11 hrs.,  98 HU Low Low Low Low
Sat, June 12    0.01'',  14 hrs.,  132 HU Low Low Low Marginal