Twenty peach and nectarine (Prunus persica [L.] Batsch) varieties (Morettini No. 1, Coronet, Dixired, Jerseyland, Gialla Precoce Morettini, Cardinal, Golden Jubilee, Red Haven, Belle di Georgia, Early Elberta, Elberta, J.H. Hale, Rio Oso Gem, Desert Gold, Spring Time, June Gold, Red Cup, Flavor Top, Fantasia, Flame Kist) grafted on wild peach seedlings were evaluated for 10 years in the Greek island Kos. The results showed that some peach and nectarine varieties with high chilling requirements such as Red Haven (950 hrs) gave satisfactory yield in the soil and climatic conditions of Kos, where the mean duration of temperatures below 7°C was found to be about 150 hr. Bloom and maturity dates were different in the same varieties in Kos compared to their standard bloom and maturity dates in Naoussa. Regarding a response to Plum pox virus the varieties Jerseyland, Gialla Precoce Morettini, Desert Gold and Spring Time were the most resistant whereas Dixired, Red Haven, Belle Di Georgia and Red Cup were the most susceptible to the disease. No significant difference was found in the susceptibility of peach and nectarine varieties to Phytophthora citrophthora.

Leaf samples from 12 peach cultivars (Prunus persica [L.] Batsch.) (Early Crest, May Crest, Flavor Crest, Sun Crest, Fayette, Katherina, Loadel, Andross, Everts, May Grand, Firebrite and Fairlane) grafted on four peach rootstocks were analyzed for their nutrient content. The analysis of variance for leaf nutrient concentrations indicated very significant effects and interactions among cultivars and rootstocks. The rootstock effect on the absorption of nutrient elements was higher for Ca, K, P, Mg, N, and lower for Cu, Zn, Fe, Mn, and B. Generally cultivars grafted on GF 677 had higher N, K, Fe, Cu and lower Zn, Mn, and B, while leaves from cultivars grafted on wild seedlings were found to contain higher Mg and lower P, K, Fe concentrations. Leaf B and Ca were higher for cultivars grafted on Sant Julien GF 655/2, while cultivars on Damas GF 1869 had higher P, Zn, Mn and lower N, B, Ca, Cu concentrations. Leaf N was lower for Fayette on all four rootstocks and significantly different from all other cultivars. Leaf P was lower for Everts and higher for Katherina. Lower concentrations were observed in Early Crest for Fe and Zn, in Andross for Mn, and in Loadel for B, while Flavor Crest had higher concentrations of all these elements. Leaf Zn was the highest for Sun Crest on wild seedling and the lowest for Early Crest on the same rootstock. Similarly leaf N was the highest for Katherina on Damas and the lowest for Fayette on the same rootstock. Also leaf Mg was the highest for Fayette on Damas and the lowest for Fairlane on Damas. Peach tree mortality was the highest for Damas 1869 and lowest for Sant Julien. Also tree mortality was highest for Early Crest and Sun Crest and lowest for May Grand, Firebrite, and Katherina. The observed trends in the leaf nutrient composition, as regards the cultivars, rootstocks and their interactions, emphasize the importance of these factors on a new peach orchard establishment and macro-microelement fertilization.

Forty two peach-nectarine (Prunus persica [L.] Batsch.) varieties (i.e Spring Time, Precocissima Morettini, Southhaven, Halehaven, Blazing Gold, Cardinal, Gialla Precoce Morettini, Dixired, Fertilia Morettini, Golden Jubilee, Coronet, Red Haven, Red Globe, Cotonia Massima, Morettini 5/14, Peach of Station, Alexander, Early Elberta, Elberta of Middle Season, Beauty of Georgia, J.H. Hale, Late Elberta, Gold Drest, Morettini No. 1, Jerseyland, Desert Gold, Red Cup, Spring Crest, Loring, June Gold, Merril Gem Free, Early Red, Red Skin, Merril Fortyminer, Roubidoux, Fantasia, Sunhaven, Flavour Top, Merril Franciscan, Blake, Fairtime, Fayette) were studied for 12–18 years in three experimental orchards of Peripheral Agricultural Research Station of Rhodes (PARSR). Their degree of adaptation to the soil and climatic conditions of PARSR was evaluated in terms of yield per tree, time of bloom, time of fruit ripening, fruit quality etc. These results have been compared with related experimental data recorded at the Pomology Institute (PI) at Naoussa. The results indicate that: many peach-nectarine varieties with quite high chilling requirements (Loring, Blake) gave satisfactory yield in PARSR, where the mean average of temperatures below 7°C over one decade was found to be 147 hours (range 52–226). Some peach-nectarine varieties in experimental orchards of PARSR ripened more than ten days earlier (Desert Gold, Early Red, Peach of Station, Loring, Merril Gem Free), of others at about the same time (Coronet, Cotonia Massima, Red Skin, Fertilia Morettini, Red Globe) and at others on a later date (Merril Fortyminer, Early Elberta, J.H. Hale, Cardinal, Southhaven) than they would ripen in northern Greece (PI). Similar differences were also found for the time of blooming.