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`Redhaven' trees on 10 rootstocks planted in 1984 were annually evaluated for growth and cropping as part of the NC-140 national cooperative rootstock troial. All trees on Citation have died, 60 % of trees on GF-43 have died and only a single tree of Lovell, Halford, and GF-677 have died. Trees on Damas GF-1869 and GF-655.2 had significantly more root suckers than other trees. Redhaven own-root, Halford and GF-677 were largest in height, spread, canopy volume or TCSA while the smallest trees were GF-43, Damas, and GF-655.2. Damas, GF-43 and GF-655.2 bloomed 3-4 days before trees on Lovell. Fruit on Redhaven own-root matured 4 days before fruit on Lovell while fruit on Halford, GF-677 and GF-43 ripened 2 days later than Lovell. Trees on Halford had the highest annual yield and accumulated yield while GF-655.2, Damas and GF-43 had the lowest yields. Redhaven own-root and Halford had the highest yield efficiencies (kg/cm2TCSA). Trees on Lovell consistently produced the largest individual fruit size.

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Authors: and

Abstract

Trunk protectors which reduced light (black polyethlene, perforated cardboard or 60% Saran shade cloth) applied to field grown Malus rootstocks (Mailing (M) 26, M 7 and Merton Mailing (MM) 106 an dMM 111) increased burrknot development. Root nodules and subsequent burrknots were formed in bud gap areas. MM 111 had the greatest tendency to produce large burknots.

Open Access

Higher education curricula should be alert to trends in production and science, and responsive to needs of producers and consumers in our society. A recent trend has emerged nationally and internationally for the production and consumption of certified organic produce which is increasing at a significant rate. Following the creation of the National Organic Program and formal federal regulations for certification which govern production, it has been questioned whether horticulture programs in land grant institutions have adjusted curricula appropriately to train producers, consultants, extension specialists, teachers and research scientists to be engaged in organic production systems. According to USDA statistics, several states in the southern region have significantly fewer certified organic farms and certifying agencies than the northeast, Midwest or western regions. A review horticulture and crops programs at 36 land grant universities (1862 and 1890) in 14 southern region states indicated although several institutions had research and outreach programs for sustainable and organic production, there were only three classes on organic gardening, two classes on organic crops production, and one field-based organic production course that could be identified in existing curricula. It appears that with the growth of the organic industry worldwide that students in programs in the southern region may be under-served in this educational area. Further, it may be questioned whether the lack of production and certifying agencies in the southern region is associated with the lack of science-based education provided by the land grant universities. A recent survey of faculty indicated a perceived need for stand-alone coursework on organic, sustainable, and ecologically-based production systems.

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Abstract

Current season shoots of 5-year-old ‘Redhaven’ peach trees were pruned in half on 1 July, 1 Aug., or both dates (50, 80 days after growth shoot initiation). Pruning reduced current season shoot length compared to unpruned shoots, but only 1 July pruning reduced current season shoot diameter, and increased lateral shoot growth. All pruning treatments reduced flower bud number proportional to shoot length removed; however, 1 Aug. pruning increased flower bud density per node. The previous summer season pruning did not influence the amount of winter injury on 1-year-old shoots after exposure to severe winter temperatures (-27.8°C). Summer pruning did not influence number of new shoots formed the following spring.

Open Access

Abstract

The net photosynthesis (Pn) rate of intact spur leaves of greenhouse-grown ‘Golden Delicious’ apple trees were similar, regardless of the fruiting condition of the spur. Similarly, the transpiration (Tr) rate of spur leaves was independent of the spur's fruiting condition. Therefore, Pn and Tr were not correlated to the number of flowers or fruit per spur, but Pn was significantly correlated to Tr. Rates of Pn and Tr were highest during the period of full bloom until shortly after bloom. Sorbitol, soluble reducing sugars, starch fractions, and total carbohydrates of spur leaves were unaffected by the presence or absence of fruit on the spur. Fruiting did not affect the number, area, or size of spur leaves. Spur leaf area and Pn could be limiting to early fruit development.

Open Access

Abstract

Young peach trees 1) trained to a single shoot or 2) allowed to branch, were pruned by removing 50% of current growth at either or both of 2 summer dates. Another group of trees had 0%, 25%, 50%, and 75% shoot growth removed by pruning in midseason. Net photosynthesis (Pn) and transpiration (Tr) were increased within 3 days after pruning at either date. Plants pruned twice at 30-day intervals had a 2nd cycle of increased Pn and Tr, with rates returning to levels of unpruned controls within 24 days. Distribution of water soluble carbohydrates in various plant tissues was not altered by pruning. Pruning at 60 days reduced root starch, whereas pruning again at 90 days increased total root carbohydrate content. Pruning early in the season increased lateral shoot formation, and terminal bud formation was delayed by pruning. Plant dry weight was reduced by all pruning treatments, with delayed pruning and increasing pruning severity resulting in greatest reductions. Distribution of dry weight was not altered substantially by pruning, and a balance of growth was maintained between different plant parts.

Open Access

Abstract

Leaves of spurs and/or shoots of small fruiting ‘Starkrimson Delicious’ apple trees were exposed to light or shade treatments from 60 days after petal fall until fruit maturity. Shading spurs reduced spur leaf photosynthesis (Pn) and transpiration (Tr), but shading shoots had no effect on spur leaf Pn. There was no difference between fruiting and nonfruiting spur Pn and Tr. Shading shoots reduced fruit growth and delayed maturity, but shading spurs had no effect on either. Fruiting reduced—but did not eliminate—spur flowering the following year. Light conditions late in the season had no effect on flowering or spur leaf development the following spring.

Open Access
Authors: and

Abstract

Ethephon applications at 250 to 1500 ppm rates during final swell of ‘Babygold-9’, a clingstone peach, accelerated maturation as measured by firmness and skin and flesh color changes and reduced titratable acidity. High rates were phytotoxic and detrimental to fruit quality. Increased immature fruit abscission appears to limit the practical use of ethephon at this growth stage in peach.

Open Access
Authors: , , and

Virulence of morphologically diverse isolates of Glomerella cingulata (anamorph: Colletotrichum gloeosporioides) and Collectotrichum sp. was examined by inoculating apple fruit. Three morphologically distinct fungal pathogens were examined on Red Delicious, Golden Delicious, or Idared. Fruit were inoculated by either placing a 100 ul spore suspension (106 spores/ml) into wounds or spraying the inoculum onto wounded fruit. All fruit were incubated at 25C on 100% RH. Free moisture was maintained on spray inoculated fruit. Virulence was quantified by measuring both lesion diameter and depth every 2-5 days for 2-4 weeks after inoculation. Overall, all of the teleomorphic isolates (G. cingulata) were significantly (p=.05) more virulent than the nonchromogenic or chromogenic isolates on fruit of all three cultivars. Genetically and morphologically diverse isolates of the bitter rot pathogen(s) are being selected and used to evaluate cultivar resistance to fruit rot.

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Authors: , , and

Bitter rot, an economically important disease of apples in the southeastern U.S., is caused by a complex of plant pathogenic fungi. Fruit infection can result in large yield losses. Control of this disease is contingent upon the effectiveness of several commonly used fungicides. Two fungal species, Colletotrichum gloeosporioides (C.g.) and C. acutatum (C.a.), cause bitter rot. Isolates of both species also show a large degree of genotypic variation. The objective of this study was to determine the effect of several fungicides: benomyl (Benlate), Captan, Mancozeb (a combination of zinc ion and manganese ethylene bisdithiocarbamate, Dithane), and zinc dimethyldithiocarbamate (Ziram). Four concentrations (0, 0.5, 1, and 2 ppm) of each fungicide were used. Fungal growth was quantified by measuring colony diameters 3 and 6 days after incubation. Among the fungicides tested, only Benlate and Ziram significantly reduced fungal growth. Average growth reductions of C. gloeosporioides with Benlate and Ziram were 87% and 29%, respectively. In contrast, average growth reductions of C.a. with Benlate and Ziram were 60% and 52%, respectively. In conclusion, Benlate was the most effective fungicide in reducing overall fungal growth, while Ziram was more effective in reducing the growth of C.a.

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