Wetting period, hail and trauma blight prediction, and sooty blotch/flyspeck wetting hours

Last night we recorded an apple scab infection period (8 hr wet, mean 67°F).

Last Tuesday afternoon, May 17, scattered hail occurred with 1.6” of rain in some areas of Frederick County. Tracking Maryblyt prediction for this single event with this week's highs in the mid-80s and lows in the mid-60s, indicates that trauma blight symptoms should begin to appear May 25. Typically trauma blight is more common in affected areas that also had some blossom blight from infection during bloom. The plant growth regulator, Apogee, applied at petal fall on king bloom, helps to reduce the amount of shoot tip infection (shoot blight) in these situations.

Since May 8 we now have accumulated 109 hr toward the 250 wetting hour threshold for specific treatment against the sooty blotch and flyspeck fungal complex.