Caution: The observations and conditions reported for Kearneysville, W.Va., are provided as a guide to fire blight risk assessment and symptom development for the immediate area near Kearneysville, West Virginia. Use of the information reported here for making orchard management decisions outside of that area is not our intent. Fruit producers outside the eastern West Virginia area are encouraged to consult their state extension specialists for information similar to that provided here.

Fire blight: Here is a graphic from the Maryblyt program that can be used to summarize the current fire blight situation at the Kearneysville TFREC. This is a prediction for later cultivars or those with extended open bloom and showing latest petal fall date as May 11, 2009. All updates beginning today and for the next 2 weeks will be for forecasting blossom blight symptom development and first symptoms of shoot blight.

The temperature and rainfall data are current through Monday morning, May 11, 2009 (although we had a clog in our rain gauge that was not cleared until Monday morning, so we are not certain of the exact amounts). Conditions at the end of last week were true to forecast, with warmer temperatures on Thursday, Friday, and Saturday pushing EIP back over the threshold of 100. Conditions on Friday, May 8, and Saturday May 9, were favorable for fire blight blossom infection if rain (or dew or fog) occurred at your location and you still had blossoms at a susceptible stage. We will track these infections as BBS "c" and BBS "d" in the graphic below.

 The 5-day forecast for this week, May 11 - May 15, shows cooler conditions and wetting events for today and Wednesday. With blossom stage at PF (petal fall), no more blossom infections will be forecasted. First symptoms of blossom blight (bacterial ooze and flower stem darkening) from the April 29 infection period ("a") are forecast to appear on Friday, May 15.

Here is a summary of our 2009 blossom infection events:

1) Any rain or other wetting event that occurred on Saturday April 25 and Sunday April 26 could have caused fire blight infection. Scattered showers were reported on Friday April 24. According to Maryblyt, showers accumulating less than 0.10 inch of rain on April 24 would not be sufficient for infection. Showers accumulating 0.10 inch or more could have resulted in an infection for the following day, April 25. This potential infection is NOT tracking in the BBS column below, but be aware of it as a possibility at your location. Scout for early symptoms of this potential infection period beginning on Tuesday May 5.

2 and 3) Conditions were highly favorable for blossom infection if wetting occurred on Tuesday night/Wednesday morning (April 28-29) at your location. This infection period is tracking (letter "a") in the BBS column below. Begin scouting when BBS reaches 100. The May 1 infection is tracking (letter "b") and will appear after the first infection period ("a") reaches 100. Today's forecast predicts first BBS on May 15 and 16.

4 and 5) Friday May 8 and Saturday May 9 on late bloom of late blooming cultivars. These will be tracking as "c" and "d" in the BBS column.

When using these predictions, be aware that risks can increase quickly with warm temperatures and unpredicted wetting. See the Fire Blight "fact sheet" for more information and disease photos. 

Web Site Author: Alan R. Biggs
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