Sampling and Estimating Average Pruning Weights in Concord Grapes

2012 ◽  
Vol 63 (4) ◽  
pp. 559-563 ◽  
Author(s):  
James A. Taylor ◽  
Terence R. Bates
Keyword(s):  
Concord Grapes

scholarly journals The Epidemiology of Powdery Mildew on Concord Grapes

2001 ◽  
Vol 91 (10) ◽  
pp. 948-955 ◽  
Author(s):  
David M. Gadoury ◽  
Robert C. Seem ◽  
Andrea Ficke ◽  
Wayne F. Wilcox
Keyword(s):  
Powdery Mildew ◽  
Fruit Set ◽  
Disease Incidence ◽  
The United States ◽  
Seasonal Development ◽  
Peak Period ◽  
Late Season ◽  
Stage Of Development ◽  
Concord Grapes ◽  
Moderately Resistant

Vitis labruscana ‘Concord’ is a grape cultivar widely grown in the United States for processing into juice and other grape products. Concord grapes are sporadically but sometimes severely damaged by the grape powdery mildew pathogen, Uncinula necator. Although the foliage is often reported to be moderately resistant to powdery mildew, severe fruit infection occurs in some years. We observed the seasonal development of powdery mildew on leaves, rachises, and berries of unsprayed Concord grapevines. Inoculations of flower and fruit clusters revealed a brief period of berry susceptibility and a protracted period of rachis susceptibility. The rachis remained highly susceptible to infection, and the severity of rachis infection increased throughout the growing season until the rachis formed a periderm shortly before harvest. In contrast, berries were nearly immune to infection within 2 weeks after fruit set. Rachis and berry infections were detected before the disease was observed on foliage, and the incidence of rachis and berry infection often exceeded disease incidence observed on foliage until after fruit acquired substantial ontogenic resistance. Excellent control of fruit infection, and adequate control of leaf infection, was achieved by two fungicide applications targeted at the peak period of fruit susceptibility. Although Concord is thought to be moderately resistant to powdery mildew, the rachis is highly susceptible, and may be the avenue by which prebloom infections make their way onto the developing fruit. Late-season infection of the rachis neither spread to the fruit, nor did it cause fruit to drop prematurely, and may be of little economic consequence on fruit destined for processing. Although fruit of V. vinifera cultivars have been reported to remain susceptible to infection until berry sugar levels reach 8 to 15%, Concord fruit become nearly immune to infection nearly 6 weeks before this stage of development. Because powdery mildew does not become conspicuous on foliage until late summer, it is generally regarded as a late-season problem on Concord grapes, and previous management programs have reflected this belief. However, the greatest contribution to control of fruit infection is due to fungicides applied during the peak period of fruit susceptibility, from bloom until shortly after fruit set, long before the disease is observed on foliage.

Properties of Concord Grapes Related to Mechanical Harvesting and Handling

1971 ◽  
Vol 14 (2) ◽  
pp. 0373-0376 ◽  
Author(s):  
Dale E. Marshall ◽  
Jordan H. Levin and Burton F. Cargill
Keyword(s):  
Concord Grapes

scholarly journals CHEMICAL MANIPULATION OF GRAPE DORMANCY UNDER SIMULATED TROPICAL CONDITIONS

HortScience ◽  
1995 ◽  
Vol 30 (3) ◽  
pp. 435g-436
Author(s):  
Frank B. Matta ◽  
Obadiah M. Njue
Keyword(s):  
Gibberellic Acid ◽  
Dormancy Breaking ◽  
Ammonium Thiosulfate ◽  
Tropical Conditions ◽  
Concord Grapes

Defoliating chemicals (ammonium thiosulfate, ethrel, and thidiazuron) were evaluated on 8-month-old `Canadice' and `Concord' grapes. The effectiveness of chemical defoliators was determined 20 days after application. Vines were pruned after defoliation and dormancy breaking chemicals (thiourea, cyanamide, and gibberellic acid (GA3) were applied 4 days later. All treatments were applied as sprays. All chemicals were effective in defoliating the vines of both cultivars. Generally, the higher concentrations (ammonium thiosulfate, ethrel, and thidiazuron at 15.15, 3.0, and 0.35 g·liter–1, respectively) were more effective. All chemicals reduced days to maximum budbreak of both cultivars. The higher concentrations (thiourea, cyanamide, and GA3 at 30.3, 15.15, and 0.75 g·liter–1, respectively) resulted in greater reductions in days to maximum budbreak. `Concord' was later in reaching maximum budbreak. Total percent budbreak of both cultivars was increased by all chemicals at the higher concentrations. Cyanamide resulted in greater total percent budbreak in both cultivars.

CHANGES IN NONVAOLATILE ACIDS OF CONCORD GRAPES DURING MATURATION

1977 ◽  
Vol 42 (2) ◽  
pp. 543-544 ◽  
Author(s):  
J. N. CASH ◽  
W. A. SISTRUNK ◽  
C. A. STUTTE
Keyword(s):  
Concord Grapes

INFLUENCE OF THE HARVEST METHOD ON CONTAMINATION OF FRUIT BY BYSSOCHLAMYS ASCOSPORES

1974 ◽  
Vol 37 (8) ◽  
pp. 445-447 ◽  
Author(s):  
D. F. Splittstoesser ◽  
D. L. Downing ◽  
N. F. Roger ◽  
D. I. Murdock
Keyword(s):  
Heat Resistance ◽  
Concord Grapes ◽  
Tart Cherries ◽  
Sources Of Contamination ◽  
Harvest Method

Mechanically-harvested tart cherries and Concord grapes were not more heavily contaminated with Byssochlamys ascospores than were hand-picked fruit. The data suggested, however, that both harvest procedures may be sources of contamination, probably because of soiled surfaces. Studies on various Byssochlamys isolates revealed marked differences in heat resistance.

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