Abstract

S UMMARY. Production of peaches (Prunus persica) in southwestern Idaho and other states in the intermountain western United States has increased during recent years, requiring information on the performance of modern cultivars in the region. Thus, a long-term project was conducted to investigate bloom date, harvest date, cumulative growing degree-days, fruit quality, and yield of various yellow- and white-fleshed peaches under conditions of southwestern Idaho during 2003 to 2007. The analysis of average response over these years indicated that ‘Snow Giant’, ‘Jupiter’, ‘Yuko King’, ‘Burpeach Six’, ‘Fairtime’, ‘Coral Star’, ‘July Sun’, and ‘Zee Lady’ bloomed earlier (5–7 Apr.), while ‘Sierra Gem’, ‘Fancy Lady’, and ‘Red Star’ bloomed later (11–12 Apr.) than other cultivars. ‘Crimson Lady’, ‘May Sun’, and ‘Sierra Gem’ were the earliest cultivars, had smaller fruit, and on average were harvested on 11, 13, and 24 July and needed 94, 96, and 103 days from full bloom to harvest, respectively. ’Opal Moncav’, ‘August Flame’, ‘August Lady’, ‘Ryan Sun’, ‘September Snow’, ‘Yukon King’, and ‘Fairtime’ were harvested during the second half of September. The periods between bloom and harvest for these cultivars on average were 160, 163, 163, 168, 171, 173, and 177 days, respectively, and these cultivars often had greater soluble solids concentrations than other cultivars. ‘PF12B’ and ‘PF15A’ were ‘‘mid-season,’’ but ‘PF 20–007’ and ‘PF 24–007’ were ‘‘late-season’’ cultivars. ‘PF12B’, ‘PF15A’, ‘PF 20–007’, ‘Star Fire’, ‘Burapeach Six’, ‘Coral Star’, ‘All Star’, and ‘Zee Lady’ had higher yield than many of the other cultivars. While the ‘‘early-season’’ cultivars can be planted for regional and local market, the ‘‘mid-season’’ and ‘‘late-season’’ peaches are excellent choices for marketing during September and early October when production of the similar cultivars are already completed in warmer regions. Overall, ‘Sweet Dream’, ‘August Lady’, ‘August Flame’, ‘Snow Giant’, ‘Saturn’, ‘Jupiter’, and ‘PF24–007’ showed satisfactory to great performance in this long-term evaluation.