Fireblight infection conditions - Cougarblight model

Background Information for this page
Return to radar list for Hancock NH
Weather data for Hancock NH.  Forecast values begin August 13, 2009
     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 16, then blossom blight would be noticeable by June 3, and shoot blight by June 19.
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
Fri, May 8    0.02'',  12 hrs.,  111 HU Low Low Low Marginal
Sat, May 9    0.79'',  24 hrs.,  190 HU Low Low Marginal Marginal
Sun, May 10    0.'',  7 hrs.,  191 HU Low Low Marginal
(if dew)
Marginal
(if dew)
Mon, May 11    0.'',  0 hrs.,  195 HU 0 0 0 0
Tue, May 12    0.'',  0 hrs.,  96 HU 0 0 0 0
Wed, May 13    0.'',  0 hrs.,  69 HU 0 0 0 0
Thu, May 14    0.21'',  11 hrs.,  68 HU Low Low Low Low
Fri, May 15    0.'',  10 hrs.,  213 HU Low Low Marginal
(if dew)
HIGH!
(if dew)
Sat, May 16    0.14'',  4 hrs.,  248 HU Low Low Marginal HIGH!
Sun, May 17    0.46'',  12 hrs.,  196 HU Low Low Marginal Marginal
Mon, May 18    0.'',  0 hrs.,  196 HU 0 0 0 0
Tue, May 19    0.'',  0 hrs.,  92 HU 0 0 0 0
Wed, May 20    0.'',  0 hrs.,  262 HU 0 0 0 0
Thu, May 21    0.'',  0 hrs.,  614 HU 0 0 0 0
Fri, May 22    0.'',  0 hrs.,  922 HU 0 0 0 0
Sat, May 23    0.'',  0 hrs.,  905 HU 0 0 0 0
Sun, May 24    0.03'',  12 hrs.,  824 HU EXTREME! EXTREME! EXTREME! EXTREME!
Mon, May 25    0.'',  0 hrs.,  595 HU 0 0 0 0
Tue, May 26    0.'',  0 hrs.,  290 HU 0 0 0 0
Wed, May 27    0.76'',  22 hrs.,  262 HU Low Low Marginal HIGH!
Thu, May 28    0.34'',  24 hrs.,  126 HU Low Low Low Marginal
Fri, May 29    0.46'',  24 hrs.,  17 HU Low Low Low Low
Sat, May 30    0.'',  11 hrs.,  129 HU Low Low Low Marginal
(if dew)
Sun, May 31    0.07'',  4 hrs.,  180 HU Low Low Marginal Marginal
Mon, June 1    0.'',  0 hrs.,  207 HU 0 0 0 0
Tue, June 2    0.'',  0 hrs.,  318 HU 0 0 0 0
Wed, June 3    0.'',  0 hrs.,  265 HU 0 0 0 0
Thu, June 4    0.'',  0 hrs.,  316 HU 0 0 0 0
Fri, June 5    0.'',  4 hrs.,  330 HU Low Low HIGH!
(if dew)
HIGH!
(if dew)
Sat, June 6    0.'',  0 hrs.,  349 HU 0 0 0 0
Sun, June 7    0.'',  0 hrs.,  395 HU 0 0 0 0
Mon, June 8    0.'',  0 hrs.,  407 HU 0 0 0 0
Tue, June 9    0.59'',  20 hrs.,  366 HU Low Marginal HIGH! EXTREME!
Wed, June 10    0.'',  16 hrs.,  231 HU Low Low Marginal
(if dew)
HIGH!
(if dew)
Thu, June 11    0.32'',  21 hrs.,  133 HU Low Low Low Marginal
Fri, June 12    1.07'',  15 hrs.,  126 HU Low Low Low Marginal
Sat, June 13    0.62'',  14 hrs.,  300 HU Low Low Marginal HIGH!
Sun, June 14    0.86'',  24 hrs.,  315 HU Low Low HIGH! HIGH!
Mon, June 15    0.47'',  23 hrs.,  310 HU Low Low HIGH! HIGH!
Tue, June 16    0.'',  12 hrs.,  246 HU Low Low Marginal
(if dew)
HIGH!
(if dew)