Sooty blotch and flyspeck and other summer diseases

Early signs of sooty blotch and flyspeck were observed in lower elevation areas at our AREC Monday, June 29. At this elevation (909 ft) we had reached the 250-hour total accumulated wetting hour (ACW) action threshold June 10. At higher elevations, the dates that the 250-hr threshold was reached and ACW totals June 29 were: 952 ft elevation- June 13, 332 hr ACW; 983 ft elevation- June 21, 297 ACW. Note that the threshold had been reached by June 21 at all AREC locations ranging from 909 to 983 ft elevations.

At our AREC we had two more extended wetting periods that favored summer disease development: June 25-26, 14 hr wetting at 72-64° with 0.02 in. of rain; June 26-28, 32 hr wetting at 72-59° with 1.62 in. of rain. This latter volume of rainfall would have depleted most fungicide residue available for sooty blotch, flyspeck and rot control.

At Tyro in Nelson County, a sensor placed at at 941 ft elevation had already recorded the 250-hr ACW threshold by June 3 for a total of 384 hr by June 29. By June 29, the ones at higher elevations, 1465 ft and 1165 ft, had not yet reached the 250-hr threshold with only 216 and 212 wetting hours, respectively.