The objective of the present study was to examine the effect of a reflective, aluminized plastic film (APF), a reflective, particle-based film applied to the tree (PFT), a reflective, particle film applied to the west side of the tree (PFW), or a particle-based reflective film applied to the grass between tree rows (RPF) on ‘Empire’ apple [Malus domestica (Borkh.)] color and fruit weight in a multiyear study. The APF treatment consistently increased red color and was the only treatment to increase fruit red color from the lower portion of the west side of the tree. The PFT, PFW, and RPF treatments inconsistently improved apple red color. The APF treatment reflected ≈6 times the amount of photosynthetically active radiation (PAR) as the RPF and reflected different red/far-red light ratios (R/FR). In all years, average fruit weight was increased by the RPF, PFT, and PFW treatments compared with the untreated control and APF treatment. The mechanism responsible for the increased fruit weight may be the altered light quality, not quantity, reflected from the RPF treatments. The reflected light has enhanced far-red radiation, which may have beneficial effects on both fruit color and fruit weight. The effect of enhanced far-red radiation on increased fruit weight may be a phytochrome-mediated process affecting dry matter partitioning.
G.J. Puterka, R. Scorza and M.W. Brown
Damage by lesser Peachtree borer (LPB) (Synanthedon pictipes Grote & Robinson) and Leucostoma canker that had accumulated during 6 (Orchard A) and 8 (Orchard B) years were compared in peach (Prunus persica L.) and peach-almond [P. amygdalus (Mill.) D. A. Webb] hybrids. Afterward, the main trunk and scaffold limbs of the trees received 10 wounds 26 mm in diameter and a subset of these trees in Orchard A had wounds inoculated with Leucostoma persoonii Hohn. Before wounding, Leucostoma canker infection and LPB infestations that had accumulated for 6 to 8 years on peach-almond hybrids was ≈60% and 98% less than on peach in Orchard A and B, respectively. One month after wounding the trees, no significant differences in Leucostoma canker infection and LPB infestations were found among the peach-almond hybrids, treated or not treated with L. persoonii, or untreated peach. Yet, Leucostoma- treated and untreated peach-almond hybrids had 33% and 25% less Leucostoma canker and LPB, respectively, when compared with Leucostoma- treated peach. Ten months after wounding, peach-almond hybrids treated with L. persoonii still had significantly less Leucostoma canker (60%) and LPB (25%) when compared with Leucostoma- treated peach. Wound gumming and wound closure rates seemed to influence the degree of LPB infestation and Leucostoma canker. Based on these data, peach-almond hybrids could be valuable sources of resistance to LPB and Leucostoma canker.