Low-Temperature Survival of ‘Cresthaven’ Peach Flower Buds and Fruit Yield on Eight Rootstocks in the 2017 NC-140 Rootstock Trial

Abstract

‘Cresthaven’ budwood was collected from Biglerville, PA on 13 Jan., 24 Feb., and 16 Nov. 2020 and 11 Jan., 1 Mar., and 15 Nov. 2021 for controlled freezing tests to evaluate the relative cold tolerance of peach flower buds on eight Prunusrootstocks in the 2017 NC-140 trial. Fruit yield was also recorded annually to determine if crop load affected the low temperature survival of fruit buds in the successive dormant period. Size-controlling rootstocks evaluated were ‘Controller™ 6, 7 and 8’, ‘MP-29’, and ‘Rootpac® 20’ and 40’, as well as two seedling rootstocks, Lovell and Guardian® Brand ‘BY520-9’. In January 2020, T ₅₀values (temperature at which 50% of flower buds are killed) of Lovell trees were ≥ 2.7 °C lower than those of all other rootstocks, except for ‘MP-29’, ‘Controller™ 6’, and ‘Controller™ 7’. However, in January 2021, only buds of Guardian® trees were less cold-tolerant than those on Lovell. In February 2020, none of the flower buds on any rootstock had T ₅₀values lower than those from Lovell trees. Also, flower buds from Lovell trees were 4.4 °C hardier than those of Guardian® trees collected on 1 Mar. 2021. Flower buds from trees on all rootstocks had similar T ₅₀values when tested in November 2020 or 2021. Annual fruit yield varied by rootstock in the first two years of bearing, but by the third year, the annual yield was similar among all rootstocks, except ‘MP 29’. Based on the early results of this trial, no rootstock was superior to Lovell in cold tolerance with high fruit yield at this site.