Golden Delicious Fruit Research Articles

The effect of post-harvest storage on the weight of Golden Delicious apples

Apples, like other fruits, are exposed to stress during their growth and development in the field, also during harvest and the postharvest environment (processing, storage, and transportation). The refrigeration system allows for bulk handling of food products from harvest to market, ensuring that food products are maintained in their freshness and integrity for an extended period through careful management of storage temperature and humidity. This study investigated the effects of storage on the weight loss of apples (Golden Delicious fruits harvested at maturity), under refrigerated conditions at a temperature of 5±0.5°C and relative humidity of 82% and under ambient storage at a temperature of 25 ±0.5 °C and relative humidity of 60 %, over 3 months. The findings revealed that the two groups of apples experienced weight reduction at different levels. Apples placed at cold storage presented a loss of weight between 3.31g and 4.49g; however, apples stored at ambient temperature showed a significant loss of weight between 21.9g and 31.76g.

Effects of Aculus schlechtendali (Acari: Eriophyidae) population densities on Golden Delicious apple production

Field trials were carried out in order to evaluate the seasonal abundance and the impact on yields of the Apple Rust Mite (ARM) Aculus schlechtendali (Acari: Eriophyidae) in an experimental fruit orchard located in northern Italy (Trentino region). The effect of ARM on yield and market quality parameters were assessed on Golden Delicious apple fruits. Fruit size, fruit weight, round colour hue, presence of russet as well as inside quality, i.e. soluble solids, acidity and Perlim index, were evaluated over two seasons considering three population levels of ARM that were determined applying different pesticide strategies. Effects of rust mites on return bloom and yield efficiency were also evaluated. ARM seasonal abundance showed a peak in mid-summer. Relationships between ARM and predatory mites were weak. Moderate to high ARM densities affected fruits size, fruit weight, and round colour hue of Golden Delicious fruits. In contrast, ARM populations did not affect russet on fruits, return bloom and yield efficiency. Additional studies were conducted in the laboratory, on detached Golden Delicious apple leaves, to evaluate the potential for population increase at temperatures close to those recorded in field conditions. These studies evidenced a high potential for population increase.

The Response of 'Golden Delicious' Apple Grafted on M 9 and MM 106 Rootstock to Chemical Fruit Thinning

The effect of plant growth regulator in early stages of fruit development is to slow or stop the growth of lateral fruits and to cause their early drop. Two commercial plant growth regulator formulations naphthalene-acetamide (NAD) and naphthaleneaceticacid (NAA) were used. The applied doses of plant growth regulator were in accordance with the manufacturer's recommendations, for Amidthin 100-130 g/hl and Nokad 20-25 ml/hl. The first treatment was applied after full bloom, and the second when central fruit was 9-12 mm in size. The biggest effect on fruit weight and size was recorded on treated Golden Delicious fruits grafted on M 9 rootstock. It was found that minimum number of fruits per branch was on M 9 rootstock. Also, the most pronounced effect of fruit thinning regarding fruit weight and size was on trees grafted on M 9. Results showed that fruits had decreased firmness and increased dry matter content. However, it did not show significant differences in values of iodine - starch test and acid content.

DNA-Free Genetically Edited Grapevine and Apple Protoplast Using CRISPR/Cas9 Ribonucleoproteins.

The combined availability of whole genome sequences and genome editing tools is set to revolutionize the field of fruit biotechnology by enabling the introduction of targeted genetic changes with unprecedented control and accuracy, both to explore emergent phenotypes and to introduce new functionalities. Although plasmid-mediated delivery of genome editing components to plant cells is very efficient, it also presents some drawbacks, such as possible random integration of plasmid sequences in the host genome. Additionally, it may well be intercepted by current process-based GMO regulations, complicating the path to commercialization of improved varieties. Here, we explore direct delivery of purified CRISPR/Cas9 ribonucleoproteins (RNPs) to the protoplast of grape cultivar Chardonnay and apple cultivar such as Golden delicious fruit crop plants for efficient targeted mutagenesis. We targeted MLO-7, a susceptible gene in order to increase resistance to powdery mildew in grape cultivar and DIPM-1, DIPM-2, and DIPM-4 in the apple to increase resistance to fire blight disease. Furthermore, efficient protoplast transformation, the molar ratio of Cas9 and sgRNAs were optimized for each grape and apple cultivar. The targeted mutagenesis insertion and deletion rate was analyzed using targeted deep sequencing. Our results demonstrate that direct delivery of CRISPR/Cas9 RNPs to the protoplast system enables targeted gene editing and paves the way to the generation of DNA-free genome edited grapevine and apple plants.

VOLATILE COMPOUNDS IN GOLDEN DELICIOUS APPLE FRUIT (Malus domestica) DURING COLD STORAGE

Biosynthesis of volatile compounds (VC), as well as activity of related enzymes (lipoxygenase LOX, alcohol acyltransferase AAT, and alcohol dehydrogenase ADH), and fatty acids (palmitic, stearic, oleic, linoleic and linolenic acids) were assessed in Golden Delicious fruit apples (Malus domestica Borkh.) during 1 ºC storage at different atmosphere conditions. Three atmosphere conditions were used: 21 % O2 and > 1 % CO2 (Regular Atmosphere, RA), 3 % CO2 and 2 % O2 (Controlled Atmosphere, CA), and CA, with 7 d under RA conditions (CA + RA), to evaluate the effect of shorts periods under air storage. CA conditions inhibited the production of butyl acetate and hexyl acetate esters, and increased hexanol concentration. Production of the branched ester 2-methyl butyl acetate did not decrease under CA conditions. As a result of 7 d under RA, butyl acetate and hexyl acetate in CA + RA increased, mainly after one month of storage. Storage under CA conditions inhibited LOX and AAT activity at some stages whereas ADH activity increased during CA storage. LOX activity showed high correlation with production of aldehydes (r2 = 0.85) and cis-2-hexenal (r2 = 0.94), during storage of apples under CA conditions. Good correlation was found between AAT activity and total esters and butyl acetate content under CA storage of apples (r2 = 0.92 and r2 = 0.93, respectively). While most fatty acids increased in concentration during RA and CA storage, linolenic acid content decreased. No correlation between volatile compounds content and fatty acid production was found.

Cell wall metabolism and related gene expression inMalus domesticaBorkh. during fruit growth and softening

Introduction. Pre-harvest fruit development of apple can have a great effect on its storable quality. However, little research has focused on fruit metabolism during growth. Our objective was to study cell wall metabolism during the various stages of fruit growth and softening to gain more insight into the nature of fruit development and ripening. Materials and methods. Apple varieties Fuji and Golden Delicious (GD) were used to investigate cell wall metabolism and related gene expression during fruit growth and softening. Results and discussion. During fruit growth, cell wall components underwent similar changes in the two cultivars although the covalent soluble pectin (CSP) content in Fuji fruit was much higher than that in GD fruit. The activities of cell wall enzymes and the related gene expression indicated that cell wall degradation was involved in fruit growth. However, these changes showed significant differences between the two cultivars during storage. The water soluble pectin (WSP) content increased more rapidly and the content of CSP and hemi-cellulose decreased more obviously, showing a more significant correlation with firmness loss in GD fruit than with Fuji. Accordingly, the activities of cell wall enzymes and the related gene expression were significantly higher in the GD fruit. Conclusion. Cell wall metabolism and the related gene expression showed significant differences between Fuji and GD fruit during growth and softening. Both acted on fruit growth and enlargement but revealed a significant cultivar-dependency with regards to fruit softening.

Age-Related Resistance to Phytophthora Fruit Rot in 'Dickenson Field' Processing Pumpkin and 'Golden Delicious' Winter Squash Fruit.

Phytophthora fruit rot, caused by Phytophthora capsici, is a major constraint to cucurbit production for the processing industry in Michigan. Age-related resistance to Phytophthora fruit rot has been identified in pepper and some cucurbit fruit. In this study, 'Dickenson Field' processing pumpkin (Cucurbita moschata) and 'Golden Delicious' winter squash (C. maxima) were evaluated for age-related resistance to Phytophthora fruit rot. Hand-pollinated fruit were harvested 3, 7, 10, 14, 21, 28, 42, or 56 days post pollination (dpp), and inoculated with P. capsici isolate 12889. Susceptibility to Phytophthora fruit rot decreased with fruit age in Dickenson Field processing pumpkin, whereas Golden Delicious winter squash remained susceptible to fruit rot even as fruit reached full physiological maturity. Less than 15% of Dickenson Field fruit 21 dpp or older became diseased. Conversely, about 80% of Golden Delicious fruit 21 dpp or older became diseased. Lesion diameter and pathogen growth density ratings differed significantly (P < 0.0001) among fruit ages for both cultivars, and were negatively correlated (ρ = -0.37 to -0.87) with fruit age. Lesion diameter and pathogen growth were generally greater on younger fruit than older fruit. Lesion diameter was greatest on 7- and 10-dpp-old fruit of Dickenson Field and Golden Delicious, respectively. Pathogen growth density ratings were greatest on 3-dpp-old fruit of both cultivars. Several morphological and physiological changes were observed as fruit matured. Soluble solids content and exocarp firmness of both cultivars increased with fruit age. Lesion diameter and pathogen growth density ratings were negatively correlated (ρ = -0.29 to -0.73) with soluble solids content and exocarp firmness.

Postharvest Fruit Rots of Apple in Greece: Pathogen Incidence and Relationships Between Fruit Quality Parameters, Cultivar Susceptibility, and Patulin Production

The incidence of pathogens associated with postharvest fruit rots on the four most extensively cultivated apple cultivars (Red Delicious, Golden Delicious, Granny Smith, and Fuji) in Greece was surveyed during two consecutive storage periods (2008-09 and 2009-10) in five packinghouses located in northern Greece. The fungi isolated were identified based on their morphological characteristics and internal transcribed spacer gene sequencing. In the four cultivars sampled, Penicillium expansum and Botrytis cinerea were the predominant pathogens, accounting for averages of 44.2 and 23.6%, respectively, of the pathogens isolated from the sampled fruit. Two other important rot pathogens were Alternaria tenuissima and Mucor pyriformis, accounting for 16.1 and 6.6%, respectively, of the diseased apple fruit. Other pathogens such as Monilinia laxa, M. fructigena, Botryosphaeria obtusa, Geotrichum candidum, Fusarium avenaceum, and F. proliferatum were isolated at low frequencies and are considered of minor importance. Measurements of the resistance level of the four apple cultivars to fruit rot caused by P. expansum and Botrytis cinerea revealed that Golden Delicious was the most susceptible to blue mold while Fuji was the most susceptible to gray mold infections. Susceptibility to gray mold was negatively correlated with flavonoid and phenol concentration as well to fruit antioxidant activity, while susceptibility to blue mold was negatively correlated with fruit firmness and phenol concentration. Patulin production was significantly higher in Red Delicious and Golden Delicious fruit than in Granny Smith and Fuji fruit and was negatively correlated with the acidity of the fruit. The high incidence of P. expansum and A. tenuissima along with the presence of F. avenaceum and F. proliferatum, all of which are potentially mycotoxin producers, emphasize the risk for mycotoxin contamination of apple fruit juices and by-products. Furthermore, information on the distribution of the pathogens on the main cultivars may be useful for the implementation of strategies to control the diseases and minimize the threat of mycotoxin contamination on each cultivar.

The effect of gibberellins on russeting in golden delicious apples

-1 and GA4+7 at 5-10 mgL -1 during petal- fall at 7-10 days 3 time again. All applied concentration of GA3 and GA4+7 reduced russeting in Golden Delicious cultivar significantly and significant difference was found between GA3 and GA4+7 actions. The application of GA3 or GA4+7 caused fruits to shift to elongated shape due to increase of L/D ratio. The application of GA3 or GA4+7 caused to increase the weight of Golden Delicious fruit significantly. When GA3 or GA4+7 were separately sprayed on Golden Delicious, it resulted in considerable decrease in russeting neither return bloom nor were fruit set influenced by treatment.

Thermal and pulsed electric fields pasteurization of apple juice: Effects on physicochemical properties and flavour compounds

Apple juice, extracted from golden delicious fruits, was pasteurized using a pulsed electric field (PEF) treatment and compared with a conventional high temperature-short time (HTST) method. The PEF treatment was carried out using a PEF laboratory unit, set with a bipolar pulse (4 μs wide), an intensity of 35 kV/cm, and a frequency of 1200 pulses per second (pps). The thermal pasteurization was performed at 90 °C for 30 s with an adapted laboratory set-up. Effects of variables of both treatments on pH, total acidity, phenolics content, and volatile compounds were investigated. While minimal variability was observed in pH and no significant changes were detected in acidity, phenolics content and volatile compounds concentration showed statistical significant differences between treatments. In general, these measured variables were less affected by the PEF treatment than by the thermal pasteurization.

Effect of Inoculum Concentration and Calcium Salts on Infection of Apple Fruit by Botryosphaeria dothidea.

The objective of this study was to determine the effects of calcium salts on growth of Botryosphaeria dothidea and incidence of white rot. The relative virulence of five B. dothidea isolates was determined using the apple cultivars Fuji, Gala, Golden Delicious, Liberty, and York. Cultivar and isolate differences in lesion diameter were significant. Cultivar differences occurred between Fuji, which was most susceptible, and Gala, which was least susceptible. Isolates PA-1 and PA-2 were most virulent. Isolate PA-4 was used at conidia concentrations of 1 × 104, 1 × 105, 1 × 106, and 1 × 107 conidia per ml on Golden Delicious fruit to test the effects of four inoculum concentrations on fruit infection by B. dothidea. Incidence of infection on detached, nonwounded fruit increased as inoculum concentration increased. The effects of four calcium salts on infection of wounded fruit by conidia were examined in field and laboratory experiments. In the field experiments, lesion size was slightly reduced on fruit treated with either calcium hydroxide or calcium silicate after wounding and prior to inoculation with conidia of B. dothidea, whereas lesions that developed at wounds treated with calcium chloride or calcium propionate were similar to those of the control. In the laboratory experiments, in several instances supplementation with calcium salts resulted in increased lesion diameter relative to the control. Two of five isolates tested showed increased percent germination with all four calcium salts, and one isolate showed increased germination in the presence of two of the four calcium salts. Germ tube elongation was not affected by calcium salts for four out of five isolates tested. There was significant variation among isolates and calcium salts on the growth of B. dothidea in liquid culture. Calcium chloride and calcium hydroxide enhanced the growth of three isolates and had no effect on the other three isolates. Calcium propionate inhibited the growth of four isolates and had no effect on the other two isolates. Calcium silicate inhibited the growth of one isolate and had no effect on the other five isolates.

Factors affecting mummification and sporulation of pome fruit infected by Monilinia fructigena in Dutch orchards

A 2‐year field experiment (1997–98, 1998–99) was conducted to study mummification and subsequent sporulation in spring of apple (cvs James Grieve, Golden Delicious) and pear (cv. Conference) fruits infected by Monilinia fructigena. Most mummified fruits were found in James Grieve and Conference, whereas in late‐infected Golden Delicious, fruits were still soft when examined in April. In the first year, these late‐infected fruits had a significantly higher sporulation intensity per sporulating fruit (P = 0·05) compared with Golden Delicious fruits infected 9 and 5 weeks before harvest maturity, which were partly mummified. It was concluded that early‐ and late‐infected fruits contributed to primary inoculum in the next season. In a postinfection regime of 25°C and 65–75% relative humidity under controlled conditions, the number of Conference fruits sporulating decreased rapidly, and after 12 weeks’ incubation sporulation had completely ceased. After 8 weeks’ incubation, sporulation intensity in the postinfection regime at 10°C was significantly higher than that at 20 and 25°C in a first experiment with inoculated unripe fruit (P = 0·05). Results of a second experiment with ripe fruit were less clear. These results are discussed in relation to orchard disease management.

An allele of the ripening-specific 1-aminocyclopropane-1-carboxylic acid synthase gene (ACS1) in apple fruit with a long storage life.

An allele of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene (Md-ACS1), the transcript and translated product of which have been identified in ripening apples (Malus domestica), was isolated from a genomic library of the apple cultivar, Golden Delicious. The predicted coding region of this allele (ACS1-2) showed that seven nucleotide substitutions in the corresponding region of ACS1-1 resulted in just one amino acid transition. A 162-bp sequence characterized as a short interspersed repetitive element retrotransposon was inserted in the 5'-flanking region of ACS1-2 corresponding to position -781 in ACS1-1. The XhoI site located near the 3' end of the predicted coding region of ACS1-2 was absent from the reverse transcriptase-polymerase chain reaction product, revealing that exclusive transcription from ACS1-1 occurs during ripening of cv Golden Delicious fruit. DNA gel-blot and polymerase chain reaction analyses of genomic DNAs showed clearly that apple cultivars were either heterozygous for ACS1-1 and ACS1-2 or homozygous for each type. RNA gel-blot analysis of the ACS1-2 homozygous Fuji apple, which produces little ethylene and has a long storage life, demonstrated that the level of transcription from ACS1-2 during the ripening stage was very low.

Airblast Concentrate Insecticide Evaluation on Apple, 1997

Abstract Experimental insecticide sprays were applied to 2-tree plots in a RCB design consisting of 3 replicates of ‘Golden Delicious’ (only 2 replicates for the control plot) and 2 replicates of ‘Yorking’ with a buffer row between plots. Trees were planted to a spacing of 20 X 30 ft and were 22 years old. All samples were taken from one tagged tree in each plot. Experimental sprays were applied with a Friend Airmaster ‘309’ calibrated to deliver 100 gpa at 2.0 mph. Application dates for all materials are given in the table containing data on WALH. The 5 Jun application for all plots corresponded to approximately 250° DD (base 50° F) after the first emergence of coding moth adults during the first brood. All applications were complete sprays. A routine schedule of fungicides (Benlate 50 DF, Dithane 75 DF, Nova 40 WP, and Ziram 76 WP) was maintained throughout the experiment. The effect of the sprays on WALH was evaluated by counting the number of nymphs/25 injured leaves/tree. Effectiveness of the treatments on SA was evaluated by counting the number of aphid-infested leaves/10 top actively growing shoots, and the number of aphids/most infested leaf, where a rating scale (0-4) was used instead of counting live aphids (see table footnotes for scale). The total number of aphid natural enemies was determined by counting the number observed on 10 shoots per tree. Effectiveness of the test chemicals on ERM and AF was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 125 leaves/treatment. The predator S. punctum was observed by making 3-min counts of adults and larvae around the periphery of the trees. STLM was evaluated by counting the number of tissue-feeding mines present during a 5 minute examination around the periphery of one tree/replicate. OFM shoot injury was assessed by determining the number of injured shoots per tree in a 5-min examination. Effectiveness of chemicals on all fruit feeders was assessed by scoring dropped apples for injury on 8 and 21 Jul; 4, 11 and 19 Aug; and 3 Sep, and picked samples of 40 and 100 fruit per replication on 19 Aug and 18 Sep, respectively. Russet evaluations were made on Golden Delicious fruits (30 per replicate). Each replicate (2) was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (&amp;gt;51% russeted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of % of surface russeted) are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface, 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to &amp;gt;51% russeted surface). Pest pressure was high throughout the season.

Apple, Airblast Evaluation of Insecticides, 1995

Abstract Experimental insecticide sprays were applied to 3-tree plots in a randomized block design consisting of 2 replicates of ‘Golden Delicious’ and 3 replicates of ‘Yorking’ with a buffer row between plots. Trees were planted to a spacing of 20 X 30 ft and were 20 yr old. All samples were taken from the center tree in each plot. Experimental sprays were applied with a Friend Airmaster ‘309’ calibrated to deliver 100 gpa at 2.0 mph. Applications dates for all materials can be found in the first table. The second application of the 2 Comply 40 WP treatments was timed for 250° DD after the first emergence of codling moth adults during the first brood. All applications were complete sprays. A routine schedule of fungicides (Benlate 50DF, Dithane 75DF, Nova 40WP, and Ziram 76WP) was maintained throughout the experiment. The effect of the sprays on WALH was evaluated by counting the number of nymphs/25 injured leaves/tree. Effectiveness of the treatments on SA was evaluated by counting the number of aphid-infested leaves/ten top terminals, and the number of aphids/most infested leaf, except the first count where a rating scale (0-4) was used instead of counting live aphids (see table footnotes for scale). The total number of aphid natural enemies was determined by counting the number observed on 10 terminals per tree. Effectiveness of the test chemicals on the ERM was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 125 leaves/treatment. The predator, S. punctum, was observed by making 3 min counts of adults and larvae around the periphery of the trees. STLM was evaluated on 6 Jun by counting the number of tissue-feeding mines present on spur leaves only during a 5 min examination around the periphery of one tree/replicate. On 28 Jul and 18 Aug STLM were counted by observing the number of tissue-feeding mines present on shoot leaves only in a 5 min examination. OFM shoot injury was assessed by determining the number of injured shoots per tree in a 5 min examination. Effectiveness of chemicals on all fruit feeders was assessed by scoring for injury on dropped apples on 27 Jun; 3, 17 and 31 Jul; and 22 Aug and picked samples of 35 and 100 fruit per replication on 14 Aug and 25 Sep, respectively. Larvae found feeding internally on all drop and pick samples were collected and identified by treatment. Russet evaluations were made on Golden Delicious fruits (30 per replicate). Each apple was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (&amp;gt;51 % russeted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of % of surface russeted) are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface), 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to &amp;gt;51% russeted surface).

Apple, Airblast Evaluation Experiment of Acaricides, 1995

Abstract A number of experimental and registered acaricides were evaluated for activity against two phytophagous mites and toxicity to a number of mite natural enemies. The acaricide treatments were applied to single-tree plots in a randomized block design consisting of 1 replicate of ‘Golden Delicious’ and 3 replicates of ‘Yorking’. The trees were planted to a spacing of 20 X 20 ft and were 22 yr old. All treatments were applied with a Myers Mity Mist sprayer calibrated to deliver 100 gpa, driven at 2 mph. Spray dates were 30 Jun all treatments and 13 Jul TD-2365, Agri-Mek and Kelthane treatments. All plots received a regular maintenance schedule of fungicides (Nova 40WP, Penncozeb 80WP, Topsin 85DF and Ziram 76WP) and nutrients (CaCl). Post-bloom insecticides (Guthion 50WP, Swat 8EC) were applied as needed at I - to 2-week intervals beginning at petal-fall in early May. Effect of the treatments on ERM, TSSM and ZM was evaluated by counting the mites at approximately weekly intervals during the season on samples of 25 leaves/tree, 100 leaves/treatment. Stethorus was observed by making 3-min counts of adults and larvae around the periphery of the trees. Russet evaluations were made on Golden Delicious fruits (30 per replicate). The apples were rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (&amp;gt;51% russeted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of percentage of surface russeted) are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface, 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to &amp;gt;51% russeted surface).

Apple, Secondary Pest Evaluation, 1995

Abstract Experimental and registered insecticides and acaricides were applied to single-tree plots in a randomized block design consisting of 2 replicates of ‘Golden Delicious’ and 2 replicates of ‘Yorking’. Treated single trees were separated by others not sprayed with insecticides and/or acaricides. The trees were 11 yr old and planted at a spacing of 20 X 30 ft. The CGA-215944 treatments were applied with a handgun at 400 psi on a truck mounted sprayer equipped with Kohler 23 gpm pump. All other treatments were applied with a Myers Mity Mist sprayer calibrated to deliver 80 GPA at 2.0 mph for a complete spray. Dates of applications for the treatments were: 17 May (all airblast treatments), 13 Jun (CGA and Provado treatments only), 28 Jun (CGA treatments only) and 26 Jul (Omite and Vydate treatments). All plots received a regular fungicide maintenance schedule of Benlate 50DF, Dithane 75DF, Nova 40WP and Ziram 76WP and the insecticide Imidan 70WP. All maintenance materials were applied using the alternate row middle method. The effect of the sprays on WALH was evaluated by counting the number of nymphs/25 injured leaves/tree. Effectiveness on SA was evaluated by counting the number of aphid-infested leaves/10 top terminals and the number of aphids/most infested leaf. Effectiveness of the test chemicals on ERM and ZM was evaluated by counting the mites several times during the season on samples of 25 random leaves/tree, 100 leaves/treatment. The predator Stethorus was evaluated by making 3-min counts of adults and larvae around the periphery of the trees. STLM was evaluated by a 5-min count of tissue-feeding mines around the periphery of the trees at the end of each generation. On 8 Jun, only spur leaves were examined, on 25 Jul and 18 Aug only shoot leaves were examined for mines. Russet evaluations were made on Golden Delicious fruits (30 per replicate). Each replicate (2) was rated as 0 (no russet), 1 (raised lenticels), 2 (1-10% russeted surface), 3 (11-25% russeted surface), 4 (26-50% russeted surface), or 5 (&amp;gt;51% russeted surface). The individual ratings were added to calculate a russet rating for each replicate. Possible ranges for the replicate russet ratings (and estimate of range of percentage of surface russeted) are 0-30 (none to raised lenticels), 31-60 (raised lenticels to 1-10% russeted surface), 61-90 (1-10% to 11-25% russeted surface), 91-120 (11-25% to 26-50% russeted surface), and 121-150 (26-50% to &amp;gt;51% russeted surface).

Detection of Latent Infections in Apple Fruit with Paraquat

Biggs, A. R. 1995. Detection of latent infections in apple fruit with paraquat. Plant Dis. 79:1062-1067. This research was conducted to assess the effect of paraquat on the breakdown of apple fruit (pre- and postharvest), to identify the fungi recovered from paraquat-treated fruit, and to determine the potential use of paraquat in a rapid quantitative measure of the pathogenic component of fruit storability. In 1992, a greater incidence of Golden Delicious and Nittany apple fruit developed acervuli of Colletotrichum acutatum, conidiophores of Alternaria alternata, and pycnidia of Botryosphaeria dothidea after treatment with paraquat than without treatment. In 1993, fungi observed on both cultivars were C. acutatum, B. dothidea, Phoma spp., Phyllosticta solitaria, Penicillium expansum, and A. alternata. Treatment of asymptomatic fruit sections with paraquat facilitated the detection of only B. dothidea, Phoma spp., and P. solitaria on Golden Delicious fruit. Exposure of Nittany fruit to paraquat facilitated the detection of B. dothidea, P. expansum, Phoma spp, and P. solitaria, but not that of C. acutatum or A. alternata. Golden Delicious fruit inoculated with B. dothidea or C. acutatum, harvested when asymptomatic, and treated with paraquat, yielded 80 and 20% infection, respectively, compared with only 6.7 and 0%, respectively, for the untreated controls. Following exposure to paraquat, naturally infected symptomatic Golden Delicious fruit exhibited signs of B. dothidea, P. expansum, A. alternata, Phoma spp., and P. solitaria. The incidence of C. acutatum on paraquat-treated fruit was positively correlated with the incidence after cold storage (r = 0.98) and after cold storage followed by a 4-week incubation at 22 ± 2°C (r = 0.79). The incidence of B. dothidea on paraquat-treated fruit was not correlated with the incidence after cold storage; however, there was a positive correlation after fruit removed from cold storage were incubated at 22°C for 4 weeks (r = 0.95). The incidences of P. expansum and A. alternata after paraquat treatment were correlated with their incidences after only cold storage (r = 0.81 and r = 0.85, respectively). The incidences of Phoma spp. and P. solitaria on paraquat-treated fruit were not correlated with their respective incidences after any storage and incubation conditions.

Cumulative effect of time of hand-thinning on fruit size of Golden Delicious and Granny Smith apples

The cumulative effect of time of hand-thinning on fruit size of Golden Delicious and Granny Smith apple trees was studied during seven consecutive seasons for Golden Delicious and four consecutive seasons for Granny Smith. Trees were thinned to single flowers or fruitlets per cluster at full bloom, and 25 days and 50 days from full bloom. Thinning at full bloom improved yields significantly during the seven consecutive seasons in Golden Delicious compared with later thinning dates. Similar results were obtained with Granny Smith except during the first season of the trial. The average fruit size of Golden Delicious fruit thinned at full bloom was improved compared with later thinning dates despite the heavier yield of the early-thinned trees. Time of thinning had no significant effect on fruit size of Granny Smith apples. Income from early-thinned trees was consistently higher than from later-thinned trees.

APPLE FRUIT CUTICULAR WAX INFLUENCE ON FLYSPECK, SOOTY BLOTCH, AND RUSSETING

Fruit from six cultivars of mature apple trees were evaluated for cuticular wax characteristics. Incidence of flyspeck, sooty blotch and russet was compared to the wax component of the cuticle. Three cultivars of Golden Delicious: Sundale Spur, Pure Gold, and Lys Golden; and three cultivars of Red Delicious: Starkspur Supreme, Oregon I, and Starkrimson, were examined.Incidence of flyspeck on Golden Delicious apples was negatively correlated to cuticular wax per unit area. Sooty blotch appearance was greater on Golden Delicious fruit as compared to Red Delicious. Incidence of sooty blotch was positively correlated to cuticular wax weight per unit area among the cultivars of Red Delicious. Russeting was negatively correlated to wax weight per unit area for the Red Delicious cultivars. Wax compositional analysis will also be discussed.