The apple cultivar Enterprise is a product of the Purdue–Rutgers–Illinois (PRI) disease-resistant apple breeding program. It has field immunity to apple scab, has a high level of resistance to cedar apple rust and fire blight, and is moderately resistant to apple powdery mildew. This resistance to these diseases makes the production of this cultivar desirable, especially on the popular fire blight-susceptible M.26 rootstock. Compared to many other scab-resistant cultivars, `Enterprise' has performed well in the mid-Atlantic area. However, this cultivar has been reported to be susceptible to low-Ca disorders when grown in New Jersey and Virginia. The mid-Atlantic area is notorious for the production of fruit with high levels of corking and bitter pit. This may be due to factors such as vigorous tree growth and low transpirational flow, which may be weather-related. Circumstantial evidence based on the production of clean `Enterprise' at Biglerville, Pa., where moderately high rates of CaCl2 have been applied in cover sprays, indicate that this disorder may be a Ca deficiency symptom. A replicated trial of many scab-resistant cultivars was established in 1990, 1991, and 1992. Due to the common incidence of low-Ca disorders, CaCl2 has been added to the cover spray program that is applied for insect control. Low-Ca disorders have never been seen in fruit produced at Biglerville, and the cover spray program applied 67 and 73 kg·ha–1 of CaCl2 (77% to 80% CaCl2, flake) in 1993 and 1994, respectively.
When applied as a dilute spray (at 125 and 250 ppm), BAS 125W effectively reduced shoot extension growth on `York' Imperial (YI) and `Spartan' (S) apple trees but was less effectively on `Delicious' (D). In 1994, lateral shoot growth of YI/M.26 trees (1 to 2 m tall) from 10 May to 7 July was reduced (35 vs. 7 cm) by sprays applied on May 13. The initial surge of growth by vertical shoots was suppressed by the treatments (16 vs. 35 cm), but there was more regrowth (6.5 vs. 0.5 cm). Some leaf injury was seen on YI. The 1995 experiments were conducted on S/M.111 and D/M.111 in an orchard spaced 3.7 m by 7.3 m. On S, lateral shoot length on five dates from 7 June to 20 Sept. was reduced by the sprays (44 vs. 32 cm on 20 Sept.). The initial surge of growth by vertical shoots was suppressed by the treatments (30 vs. 85 cm), but there was more regrowth (34 vs. 4 cm). There were fewer apples that were <25% red and more that were 25% to 40% and 66% to 85% red. On D, lateral shoot length on five dates from 7 June to 20 Sept. was reduced by the sprays (51 vs. 38 cm on 20 Sept.). The growth of vertical shoots was not influenced by the treatments, possibly due to a light fruit load in the tops of the trees. Growers viewing the 1995 plots estimated enhanced income of $933/ha for D and $780/ha for S.
Excessive tree vigor is a significant production problem for the PA apple industry. A series of experiments were conducted from 1994 to 1999, which indicated that Apogee® could effectively reduce vegetative shoot growth. Results from 1994 to 1996 have previously been reported (HortScience 31:598, 32:558). In 1997, 16 treatments composed of four rates (0, 63, 125, and 250 ppm) and four timings (22 May; 4, 11, and 24 June) in various combinations, were applied as dilute handgun sprays. These treatments were applied to sixth leaf `York Imperial' apple trees. Ten peripheral shoots, at a height of 2 m, were tagged and measured on 21 May, 9 and 30 June, 16 July, 12 Aug., and on 10 Oct. Shoots treated with 63, 125, or 250 ppm on 22 May followed by 0, 63, or 125 ppm on 4, 11, or 24 June were from 65% to 76% of the length of the controls (25.5 cm). Treated shoots were from 69% to 78% of the length of the controls following sprays with 63 ppm on 22 May followed by 0, 63, or 125 ppm on 4, 11, or 24 June. Shoots treated with 125 ppm on 22 May followed by 0 or 63 ppm on 4, 11, or 24 June were from 69% to 73% of the length of the controls. The later applications (11 and 24 June) of 250 ppm gave no growth control but the 22 May treatment gave a 30% reduction in growth. In 1999, dilute handgun sprays of 125, 125, 83, and 83 ppm were made on 22 May and on 4, 11, and 24 June, respectively. Cultivars treated were `Spartan', `Delicious', `York Imperial', `Gala', and `Mutsu'. The length of 10 peripheral shoots at 2 and 3 m were measured on 28 July and on 12 Aug. All cultivars responded and on 12 Aug. treated terminal shoot lengths ranged from 33% to 55% of the controls. With reduced vegetative tree vigor many horticultural factors will be improved. In addition, the severity of shoot fire blight can be reduced and the control of all pests that prosper on young succulent leaves will be easier, especially apple aphids and obliquebanded leafrollers. Major factors to be considered in developing an efficacious Apogee® program appear to be initial tree vigor, length of growing season, and crop load. An initial application at 1 to 3 inches of terminal growth is probably the most critical factor.
The Mid-Atlantic area has a long, warm growing season and a reputation for grainy or firm, yellow apple products. There is interest in varieties that are large, firm, yellow-fleshed, that store and process well. The attributes of four NY selections, grown in PA, are described. NY 179 (Loop Red Rome X Yorking) fruit firmness (FF) dropped from 9 to 8.5 kg from 270 to 300 Julian days (JD). Over this same period, soluble solids (SS) rose from 13-15%. At 270 JD dropped fruit (DF) ranged from 0-5% while at 300 JD they ranged from 0-10%. Mean fruit weight was 285 g. NY 180 (Loop Red Rome X Yorking) averaged 351 g and FF was similar to NY 179. From 270 to 300 JD SS rose from 12-15%. Dropped fruit rose from 0-10% at 270 JD to 35% by 285 JD but to 95% by 300 JD. NY 88 (Melrose X Monroe) had a FF of 8.5 kg at 255 JD which decreased to about 7.5 kg at 300 JD. Over this same period SS rose from 13 -14.5%. At 255 JD DF were 0%; they ranged from 0-10% at 300 JD and never exceeded 10%. NY 151 (Red Spy X Yorking) averaged 171 g. At 270 JD FF was 12 kg falling to 11 kg at 330 JD. Over this period SS rose from 11-16%. Drops increased from 0% at 270 JD to 10-20% at 330 JD. These selections are undergoing regular and CA storage and processing tests.
The Mid-Atlantic region consists of the states of Pennsylvania, Maryland, West Virginia, Virginia, and New Jersey, and produces about as many apples as New York or Michigan. The climate in this region in the summer often has warm days and relatively warm nights. Light intensity can often be reduced by clouds from tropical air masses, and this is usually accompanied with high relative humidity. Most orchards are not irrigated, and rainfall can varies widely. The predominant cultivars are `Delicious', `Golden Delicious', `Rome', and `York Imperial'. With these cultivars and this set of climatic conditions, excessive vegetative growth and fluctuating return bloom are common problems. This climate and apple variety assortment are markedly different from more northerly apple production regions in the U.S. The need for an effective growth-control chemical has been obvious for years. The development of BAS-125 appears to have made this a possibility and has caused much interest among pomologists and growers that are aware of this chemical. Research was conducted from 1994 to 1995 on `York Imperial', `Delicious', and `Spartan', and was reported in HortScience (31:191). Research in 1996 dealt with `Law Rome' and `Golden Delicious'. On `Law Rome', treated shoots were ≈24 cm in length, while untreated shoots were 38 cm in length. On `Golden Delicious' this compound controlled shoots to ≈29 cm in length, while untreated shoots had about 39 cm of total shoots growth. BAS-125 can effectively reduce shoot growth, which will improve the light regime in mid-Atlantic apple tree canopies. This should result in savings in pruning, increased fruit quality, and increased cropping levels due to enhanced fruit bud production.
An inexpensive, versatile, and simple recirculating controlled atmosphere storage system was designed, constructed and tested. It is demonstrated that this controlled atmosphere storage system has minimal variation in O2 and CO2 composition. In addition, the system allows controlled atmosphere research to be conducted in conventional storages that are otherwise unsuited for this type of research.
In both experiments. 20-apple samples from 6 commercial orchards were harvested and stored in 208 liter containers at 0C for 4, 6, and 8 months. Additional samples were removed from CA and held at 0C for 14 days before evaluation. Gas composition was measured and controlled 6 times per day using automatic control equipment.
In the first experiment, samples were stored at constant 0.0% CO2 and one of three O2 regimes (constant 2.0%. 0.5 rising to 3.5%. or 3.5% falling to 0.5% O2). Apples stored at 3.5% falling to 0.5% O2 during the storage period were softer than apples held at constant 2.0% or those held at 0.5% rising to 3.5% O2 during the storage period. Variable O2 concentrations did not influence weight loss during storage and insignificant scald, flesh browning, core browning, rot, and low 02 injury were observed.
In the second experiment, samples were stored at constant 2.0% O2 and one of three CO2 regimes (constant 0%, constant 5%. or 0% rising to 6% CO2). Constant 5% or rising CO2 conditions did not significantly influence flesh softening or weight loss during storage. Negligible CO2 injury was observed.
This study quantifies the discounts and premiums associated with various quality factors for processing apples (Malus domestica Borkh.). Discounts and premiums were estimated using a hedonic price model and quality data from a total of 137 samples representing three processing apple cultivars (45 `York Imperial', 43 `Rome Beauty', and 49 `Golden Delicious'). Price discounts in the sample were statistically significant for fruit size, bruising, bitter pit, decay, misshapen apples, and internal breakdown. Commonly cited defects, such as insect damage and apple scab, did not cause significant price discounts.
A two year study of `Golden Delicious' and `York Imperial' apple responses to delayed cooling and CA storage imposition after harvest was completed in 1991. Apples from six to eight commercial orchards were harvested at an acceptable maturity level for long-term storage, subjected to a delay in refrigeration (0,3, or 6 days) followed by a delay in CA storage imposition (0,14, or 28 days), and then stored at 0°c, 2.4% oxygen, and 1.6% carbon dioxide for up to eight months. Fruit acidity, soluble solids content, bitter pit incidence, scald, internal breakdown, and the development of low oxygen injury were not influenced by the delays. Delays often resulted in more rot and excessive weight loss during storage. Delays in both cooling and CA storage imposition had an additive effect on fruit softening, such that the longest delays resulted in the softest fruit.