Whole-shoot water potential, osmotic potential of the xylem fluid, and
bark water potential were examined from late winter through early spr
ing for six peach [Prunus persica (L.) Batsch.] cultivars varying in r
elative susceptibility to Leucostoma canker. There were significant di
fferences among cultivars for whole-shoot water potential on all 11 da
tes tested in 1986, but not in 1985. The date effect was not consisten
t among cultivars, although when averaged across dates, the whole-shoo
t water potential of 'Loring' was significantly more negative than tha
t of 'Candor' or 'Garnet Beauty'. There were significant differences a
mong cultivars for xylem fluid osmotic potential on one of five dates
tested in 1985 and three of 11 dates tested in 1986, although cultivar
differences were not consistent between years. Cultivars exhibited di
fferences in bark water potential on three of five dates tested in 198
5, with 'Loring' exhibiting the least negative values when averaged ac
ross dates. There were only occasional significant correlations of the
water status characteristics with relative susceptibility to Leucosto
ma canker or suberin accumulation. Measurements of plant water status
among cultivars or genotypes in peach do not appear to be reliable ind
icators of susceptibility to Leucostoma spp. or wound response.