Featured Research

from universities, journals, and other organizations

Early defoliation of Great Lakes wine grapes tested

Date:
December 12, 2011
Source:
American Society for Horticultural Science
Summary:
Economically significant varieties of wine grapes in eastern North America can be susceptible to harvest season cluster rot. Researchers designed experiments to determine whether leaf removal or a temporary reduction in carbon assimilation at the beginning of bloom would reduce fruit set and cluster compactness. Vines subjected to removal of four or six basal leaves had an average fruit set reduction of 45 percent from the control. Cluster weight and berries per cluster were similarly reduced.

Wine grape production in the Great Lakes Viticultural Region can be a challenging enterprise. Spring frost, winter injury, short and variable growing seasons, and cool, humid growing conditions subject grape vines to disease, including harvest season cluster rot. Tight-clustered wine grape varieties in the region show varying susceptibility to cluster rot; cultivars such as Pinot gris, Pinot noir, Riesling, Seyval, and Vignoles are all susceptible, making it difficult to achieve maximum fruit maturity for these economically important varieties.

Leaf removal in the fruiting zone has been used successfully as a vineyard management practice during the summer season. When used on high-density canopies, leaf removal techniques improve clusters' microclimate, reducing conditions that can cause bunch rot complex diseases and improving fruit quality. However, leaf removal can also affect fruit quality negatively. Excessive leaf removal can lead to overexposed clusters (high light intensity and high temperature) and reduced berry color in red cultivars. Moreover, the effects of leaf removal on yield vary depending on timing and severity.

Paolo Sabbatini and G. Stanley Howell from the Department of Horticulture at Michigan State University conducted experiments to determine whether early leaf removal influences vine performance, or if non-destructive, short-term photosynthesis reduction at the beginning of bloom would influence vine performance in a manner similar to leaf removal. The experiments were conducted at the Horticulture Teaching Research Center in East Lansing and the Southwest Michigan Research and Extension Center in Benton Harbor, Michigan. The research findings were published in HortScience.

Fruit set reduction resulting from early leaf removal, in all the cultivars except Pinot noir, confirmed the importance of carbohydrate supply during the fruit set period. Vines subjected to removal of four or six basal leaves had an average fruit set reduction of approximately 45% from a non-treated control. "Cluster weight and berries per cluster were similarly reduced with a greater effect on the basal than the apical cluster of the shoot. Reduced fruit set was associated with a reduction in cluster compactness and harvest season rot," said Sabbatini. "This was also reflected in yield and basic fruit chemistry parameters associated with the importance of basal leaves to the developing cluster."

The experiments showed a strong negative effect of early leaf removal in year one of the study on vine performance in year two. This "carryover effect" increased shootless nodes per vine, reduced the number of clusters per shoot and per vine, and dramatically reduced fruit set and yield per vine.

"From our data, we cannot assess whether this carryover is related to reduced bud cold hardiness or bud damage resulting from the leaf removal practice," the researchers added. "Unless these negative carryover responses can be ameliorated, this approach to reduce cluster compactness and cluster rot will not be acceptable. We speculate that this could be readily accommodated through retaining non-fruiting shoots at the head with all leaves retained that serve as canes to be retained for production in the next year."


Story Source:

The above story is based on materials provided by American Society for Horticultural Science. Note: Materials may be edited for content and length.


Cite This Page:

American Society for Horticultural Science. "Early defoliation of Great Lakes wine grapes tested." ScienceDaily. ScienceDaily, 12 December 2011. <www.sciencedaily.com/releases/2011/12/111212124553.htm>.
American Society for Horticultural Science. (2011, December 12). Early defoliation of Great Lakes wine grapes tested. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2011/12/111212124553.htm
American Society for Horticultural Science. "Early defoliation of Great Lakes wine grapes tested." ScienceDaily. www.sciencedaily.com/releases/2011/12/111212124553.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
What's To Blame For Worst Ebola Outbreak In History?

What's To Blame For Worst Ebola Outbreak In History?

Newsy (July 27, 2014) A U.S. doctor has tested positive for the deadly Ebola virus, as the worst-ever outbreak continues to grow. Video provided by Newsy
Powered by NewsLook.com
The New York Times Backs Pot Legalization

The New York Times Backs Pot Legalization

Newsy (July 27, 2014) The New York Times has officially endorsed the legalization of marijuana, but why now, and to what end? Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins