Ethephon (100 mg·liter-1) was applied to mature peach trees [Prunus persica (L.) Batsch. cv Redhaven] on 13 Oct. 1989. Ethephon-treated and non-treated trees were pruned on 12 Dec. 1989, or left not pruned. Flower bud hardiness was assessed via exotherm analysis from Dec. through Mar. on buds taken directly from the orchard and on buds deacclimated / reacclimated under controlled conditions. Buds from ethephon-treated trees were consistently hardier than buds from non-treated trees. After a warm spell in Jan., buds from pruned trees not previously treated with ethephon were less hardy than those from non-pruned trees. Hardiness of buds from ethephon-treated trees after the warm spell was not affected by pruning. All buds rehardened with the return of low temperatures. Under controlled conditions, buds from pruned trees were less hardy than those from non-pruned trees. Pruning resulted in a rapid loss of hardiness at warm temperatures (21C). If trees had been treated with ethephon the previous fall, significant rehardening of dehardened buds from pruned trees occurred at 5 or -1C. Buds from pruned, non-treated trees did not reharden.
If the inline PDF is not rendering correctly, you can download the PDF file here.