The luck of the leprechauns may have been with growers this St. Patrick’s Day. By that I mean apples and peaches in Southern Illinois were/are all in bud development stages sensitive to below freezing temperatures, and we definitely got below freezing. Where the luck came in is temperatures did not drop to the low end of the confidence interval of the prediction model; they stayed to the high end of the prediction. See below the map provided by Trent Ford, IL State Climatologist, for lows throughout the state. Most apples in the St. Louis Metro East were/are in silver tip (critical temperature (15°F/2°F) to green tip (18°F/10°F), so at most we hopefully only had what would be acceptable thinning. Growers are just now making assessment following the freeze event, to be reported later. Trees with buds already at ¼” green (23°F/15°F) to tight cluster (27°F/21°F) will see a higher degree of thinning, but hopefully still within acceptable limits.
Peaches were really the main concern. I noted some young peach trees in first pink (25°F/15°F) to full bloom (27°F/24°F) just prior to the freeze event, so anything else in a similar stage will see some bud thinning to complete bud kill for the later stage. Most peach trees in the area were/are anywhere from bud swell (18°F/1°F) to red calyx (23°F/9°F).
The region received significant rainfall the week prior to St Patrick’s Day, bringing the northern St Louis Metro East collar counties out of drought status but still abnormally dry. The southern collar counties are all caught up. Soil temperatures are at 48°F at the 2-inch and 4-inch bare ground measurement, sufficient for direct seeding of early crops like sweet pea. Temperatures have been an extreme roller coast, with highs in the upper eighties, to a crash on St. Patrick’s Day giving a high in the mid-twenties, then quickly rising with highs in the upper 80s to low 90s.