Replicated trials were conducted in Summers 1998 and 1999 at two commercial orchards (A and B) to determine the influence of a metalized, high density polyethylene reflective film (SonocoRF) and aminoethoxyvinylglycine (ReTain), on fruit red skin coloration and maturity of `Gala' apples (Malus sylvestris var. domestica). There were four experimental treatments: 1) nontreated control; 2) reflective film (RF); 3) ReTain; and 4) RF + ReTain. RF was applied 4 weeks before anticipated start of harvest by laying a 5-ft-wide (150-cm) strip on each side of the tree row in the row middle. ReTain was applied 4 weeks before harvest at the commercial rate in one orchard and at 60% of the commercial rate in a second test. ReTain delayed fruit maturity. Fruit from RF trees had a significantly greater percent surface red color than fruit from trees not treated with RF. Fruit from RF + ReTain were significantly redder and had higher soluble solids concentration (SSC) than fruit from trees treated with ReTain alone. There were no differences in size, fruit firmness or starch content between fruit from RF and RF + Retain. RF appears to be a method to increase red skin coloration in `Gala' apples treated with ReTain without adversely impacting maturity.
Durations of ultrasound treatments were evaluated for efficacy in removing or destroying external pests of apples (Malus sylvestris var domestica). Egg hatch of codling moth (Cydia pomonella; Lepidoptera: Tortricidae), was inversely related to time of ultrasound exposure, although egg mortality was less than 60% after 45 min of treatment. Mortality of twospotted spider mite (Tetranychus urticae; Acari: Tetranychidae), and western flower thrips (Frankliniella occidentalis; Thysanoptera: Thripidae), was directly related to ultrasound durations; adding detergent to the ultrasound bath increased treatment efficacy. Ultrasound did not remove san jose scale (Quadraspidiotus perniciosus; Homoptera: Diaspididae), from the fruit surface. Ultrasound, which can be incorporated in the packing line, shows promise as a postharvest phytosanitation treatment against external pests.
`Honeycrisp' apples (Malus × domestica) were harvested over 3-week periods in 2001 and 2002. Maturity and quality indices were determined at harvest. Fruit quality was evaluated after air storage [0.0 to 2.2 °C (32 to 36 °F), 95% relative humidity] for 10-13 weeks and 15-18 weeks for the 2001 and 2002 harvests, respectively. Internal ethylene concentrations (IEC), starch indices (1-8 scale), firmness and soluble solids content (SSC) did not show consistent patterns of change over time. Starch hydrolysis was advanced on all harvest dates, but it is suggested that a starch index of 7 is a useful guide for timing harvest of fruit in western New York. After storage, firmness closely followed that observed immediately after harvest, and softening during storage was slow. No change in SSC was observed during storage in either year. Incidence of bitter pit and soft scald was generally low and was not affected consistently by harvest date. The incidence of stem punctures averaged 18.5% over both years, but was not affected by harvest date. Development of stem end cracking in both years, and rot development in one year, increased with later harvest dates. A panel of storage operators, packers, growers, and fruit extension specialists evaluated the samples for appearance and eating quality after storage, and results suggested that a 2-week harvest window is optimal for `Honeycrisp' apples that are spot picked to select the most mature fruit at each harvest.
Experiments were performed over 3 years to examine the effect that particle film (PF) treatment had on fruit quality of several apple (Malus ×domestica) cultivars in Washington and West Virginia. In the first study, a highly reflective, white, hydrophilic particle-based kaolin mineral (Surround WP) was applied to `Empire' apple in May and June, on a season-long basis, or not at all. Red fruit color was increased by both the PF treatments compared with no treatment in all years. In a second study, the PF material was applied, starting at petal fall, every week for 6 weeks and then every 2 weeks until harvest to `Empire', `Gala', and `Fuji' trees in West Virginia and to `Cameo', `Fuji', and `Gala' trees in Washington. In the latter study, cultivar response to season-long applications varied by year and location. `Empire' consistently had improved red color with season-long applications of PF materials. `Gala' had greater fruit weight and red color with PF application in 1 of 2 years in West Virginia but not in Washington. `Fuji' had greater fruit weight and soluble solids content and `Cameo' had greater soluble solids, higher starch indices, and greater red color in Washington with the PF application. In these studies, application of a PF never reduced the surface red color in apples. A taste panel did not identify quality differences in `Empire' apples treated with PF vs. the control. Cultivar responses to PF applications were variable due to location and yearly environmental characteristics. While particle film technology has value for insect control and reducing sunburn, it has limited value to enhance fruit color due to the inconsistent response.
Mg, Zn, and Mn ( Barber, 1995 ). For efficient uptake of plant nutrients, fertilizers should generally be placed as close to the plant roots as possible. Research on apple ( Malus × sylvestrisvar. domestica ), grapefruit ( Citrus × paradisi on