Fireblight infection conditions - Eastern model

Background Information for this page
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Weather data for Easthampton MA.  Forecast values begin August 3, 2017
     This table shows estimates of RELATIVE daily fire blight blossom infection risk based on weather conditions.  Rating criteria are derived from the work of Dr. Paul W. Steiner and Gary W. Lightner at the University of Maryland. 
      ABSOLUTE risk depends on the amount of fire blight bacteria in the area, the number of open flowers, age (trees < 6 years old most vulnerable), 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.   
      Individual cutltivar may start bloom a day or two later, or finish a day or two earlier, than full range of open blossom dates shown. Gray shading indicates dates when most trees will have lost open blossoms, but late blooming cultivars or young trees may still have open flowers and be susceptible to blossom blight.  
      Fireblight infection can occur without rain if there is "heavy" dew.  If there are enough heat units for infection but no rain, if leaves are expected to be wet for 2 or more hours, then infection risk is reported with "if dew" attached.  Infection potential "dew risk" days is not well understood.  Infection potential may increase with high relative humidty prior to and during infection events, and be reduced by an extended period of low relative humidity.
Shoots near overwintered fire blight cankers would start showing obvious symptoms around
 Monday, June 12
 If canker blight infection spreads to other shoots,
symptoms on those secondary shoot infections would become obvious around Sunday, June 18
Open blossom dates for common cultivars.
"Date" is from 8am to 8am the following day, not midnight to midnight.
Cumulative Fire blight bacteria potential (FBP).
100% = minimum threshold level for infection.

Cumulative % FBP,
(single day value),
Inches Rain,
Leaf Wet Hours
Values are for 8am to 8am the next day.
          In absence of rain, 3 or more hours of leaf wetness is counted as possible dew conditions for adequate wetting, which may overstate risk on such days. See Cougarblight model for additional comments.
Eastern Fire blight Model Rating
Infection Requirements:
100% FBP
(>198 degree hours > 65F), &
> 0" rain, or > 0.1 inch rain on previous day.
SEVERE RISK = 200% FBP and wetting.
Dates
Blossom Blight
(& Shoot Blight) would be obvious if infection occurred
possible early cultivar
King Bloom: April 28 
52% (52%),  0.0'',  5 hrs.  No blossom infection  
McIntosh King Bloom:
Sat, April 29 
105% (53%),  0.0'',  0 hrs.  Infection Potential
(if wetting)
May 24, (June 11)
Sun, April 30  70% (0%),  0.15'',  9 hrs.  No blossom infection  
Mon, May 1  47% (0%),  0.77'',  9 hrs.  No blossom infection  
Tue, May 2  52% (5%),  0.11'',  7 hrs.  No blossom infection  
Wed, May 3  35% (0%),  0.0'',  0 hrs.  No blossom infection  
Thu, May 4  23% (0%),  0.05'',  4 hrs.  No blossom infection  
Fri, May 5  16% (0%),  1.35'',  24 hrs.  No blossom infection  
Sat, May 6  6% (2%),  0.13'',  14 hrs.  No blossom infection  
Sun, May 7  4% (0%),  0.03'',  9 hrs.  No blossom infection  
Mon, May 8  3% (0%),  0.0'',  0 hrs.  No blossom infection  
Tue, May 9  2% (0%),  0.0'',  0 hrs.  No blossom infection  
Wed, May 10  1% (0%),  0.0'',  0 hrs.  No blossom infection  
Thu, May 11  1% (0%),  0.0'',  0 hrs.  No blossom infection  
Fri, May 12  0% (0%),  0.0'',  0 hrs.  No blossom infection  
McIntosh 95% Petal Fall
on Sat, May 13 
0% (0%),  1.32'',  18 hrs.  No blossom infection  
Sun, May 14  0% (0%),  0.27'',  15 hrs.  No blossom infection  
McIntosh 100% Petal Fall
on Mon, May 15 
0% (0%),  0.07'',  5 hrs.  No blossom infection  
McIntosh 100% Petal Fall
on Mon, May 15 
43% (43%),  0.0'',  0 hrs.  No blossom infection  
Wed, May 17  180% (136%),  0.0'',  0 hrs.  Infection Potential
(if wetting)
June 4, (June 13)
Late Cultivar Petal Fall
on Thu, May 18 
341% (161%),  0.22'',  11 hrs.  SEVERE INFECTION RISK! June 9, (June 14)
Fri, May 19  390% (93%),  0.0'',  2 hrs.  SEVERE INFECTION RISK! June 10, (June 15)
Sat, May 20  263% (9%),  0.0'',  0 hrs.  SEVERE Infection Potential
(if wetting)
June 10, (June 16)
Sun, May 21  271% (8%),  0.10'',  6 hrs.  SEVERE INFECTION RISK! June 11, (June 17)
Mon, May 22  181% (0%),  0.15'',  21 hrs.  INFECTION RISK June 11, (June 17)
Tue, May 23  117% (8%),  0.0'',  9 hrs.  INFECTION RISK June 11, (June 17)
Wed, May 24  40% (16%),  0.0'',  3 hrs.  No blossom infection  
Thu, May 25  21% (0%),  1.34'',  24 hrs.  No blossom infection  
Fri, May 26  14% (0%),  0.24'',  24 hrs.  No blossom infection  
Sat, May 27  21% (7%),  0.0'',  4 hrs.  No blossom infection  
Sun, May 28  36% (15%),  0.0'',  0 hrs.  No blossom infection  
Mon, May 29  15% (0%),  0.15'',  21 hrs.  No blossom infection  
Tue, May 30  10% (0%),  0.01'',  16 hrs.  No blossom infection  
Wed, May 31  21% (11%),  0.59'',  22 hrs.  No blossom infection  
Thu, June 1  55% (34%),  0.0'',  3 hrs.  No blossom infection  
Fri, June 2  54% (9%),  0.0'',  0 hrs.  No blossom infection  
Sat, June 3  61% (7%),  0.0'',  0 hrs.  No blossom infection  
Sun, June 4  70% (9%),  0.46'',  15 hrs.  No blossom infection  
Mon, June 5  40% (0%),  0.80'',  24 hrs.  No blossom infection  
Tue, June 6  17% (0%),  1.05'',  24 hrs.  No blossom infection  
Wed, June 7  36% (20%),  0.0'',  9 hrs.  No blossom infection  
Thu, June 8  63% (33%),  0.0'',  2 hrs.  No blossom infection  
Fri, June 9  99% (46%),  0.0'',  0 hrs.  No blossom infection  
Sat, June 10  177% (97%),  0.0'',  0 hrs.  Infection Potential
(if wetting)
June 17, (June 23)
Sun, June 11  297% (154%),  0.0'',  0 hrs.  SEVERE Infection Potential
(if wetting)
June 18, (June 24)
Mon, June 12  430% (179%),  0.0'',  0 hrs.  SEVERE Infection Potential
(if wetting)
June 19, (June 25)
Tue, June 13  495% (163%),  0.0'',  0 hrs.  SEVERE Infection Potential
(if wetting)
June 21, (June 28)
Wed, June 14  410% (68%),  0.0'',  0 hrs.  SEVERE Infection Potential
(if wetting)
June 22, (June 29)
Thu, June 15  270% (39%),  0.0'',  0 hrs.  SEVERE Infection Potential
(if wetting)
June 22, (June 30)
Fri, June 16  273% (4%),  0.43'',  18 hrs.  SEVERE INFECTION RISK! June 23, (June 30)