Establishment performance of the 2017 NC-140 vigor-limiting peach rootstock trial across ten sites in North America

Eight vigor-limiting, standard, and vigorous Prunus rootstocks budded with ‘Cresthaven’ peach were planted at 10 locations in North America (nine in US and one in Canada) in spring 2017. During the first three years of establishment, significant differences among rootstocks and sites were found for survival, root suckers, tree growth, yield, fruit size, and yield efficiency. Tree survival was high (>96%) in SC, PA, MI, AL, CO, and UT and low (<75%) in NY, NC, and GA. ‘Rootpac^® 40’ had the lowest overall survival (72%), followed by ‘Controller™ 7’, ‘Rootpac^® 20’, and ‘MP-29’. Rootstock suckering was excessive on ‘Rootpac^® 20’ with ‘Lovell’ a distant second. The largest trees were in AL, followed by NY, SC, and UT, while the smallest trees were in CO, a short growing season site with calcareous soils and high soil pH. Averaged across all sites, the largest trees were on ‘Guardian^®’, followed by ‘Lovell’, ‘Rootpac^® 20’ and ‘Controller™ 6’ (76, 72, and 60% of ‘Guardian^®’, respectively), whereas smallest trees were on ‘Rootpac^® 40’ and ‘MP-29’ (both 41% of ‘Guardian^®’). In 2019, the first year that trees were cropped, 90% bloom varied across sites by 77 days, whereas 10% maturation differed by 55 days. However, no differences in bloom or harvest date were observed across rootstocks. Yield was highest in UT and AL (10-11 kg tree^-1) and lowest in NC, CO, and GA (1-3 kg tree^-1). The highest yields were on the most vigorous rootstocks ‘Guardian^®’, ‘Lovell’, and ‘Rootpac^® 20’, while lowest yield was on ‘Rootpac^® 40’. The rootstock with the highest yield efficiency was ‘MP-29’ while the lowest was ‘Rootpac^® 40’. Fruit size was large (227-298 g) in UT, SC, AL, moderate (195-213 g) in NC, PA, CO, and NY, and small (127 g) in GA. Averaged across sites, ‘Controller™ 6’ produced the largest fruits (249 g) while ‘Guardian^®’ and ‘MP-29’ produced the smallest (210 g).