University of Vermont

by Terence Bradshaw

Grape maturity
We have begun weekly preharvest sampling of the winegrapes at the UVM Horticulture Research and Education Center. Right now, grapes are about a week ahead of last year’s ripeness schedule, and with warm/hot, dry weather this week, ripening should advance quickly. I still don’t expect harvest to begin for another couple of weeks for most varieties.
Sampling results for 2015 can be found at: http://www.uvm.edu/~fruit/grapes/uvmvineyard/2015UVMfieldtesting.pdf

Past year’s sampling may be found at: http://www.uvm.edu/~fruit/?Page=grapes/uvmvineyard/uvmvineyardhorticulturearchives.html&SM=gr_submenu.html

Petiole sampling
Growers may ascertain overall nutritional status in their vineyards at two times through petiole analysis: bloom and 70-100 days post-bloom.Now is the time for late (post-veraison/pre harvest) petiole sampling for plant nutrient status. Dr. Joe Fiola form the University of Maryland has posted some good recommendations in his latest Timely Viticulture newsletter:

• Grape petiole analysis is recommended along with soil samples and visual observations as part of a complete nutrient management program.
• A three year cycle of sampling all of the varieties in a vineyard is typically recommended.
• Tissue/petiole analyses reveal the actual nutrients in the vines.
• Spring tissue sampling is a good time to sample, as you can make nutrient adjustments to the vineyard that will influence this year’s crop quality.
• Nitrogen status is best evaluated with tissue sampling not soil sampling.

Some specifics on sampling:

• Each sample should be less than 5 acres; less if there are major changes in soil or topography
• Sample different varieties separately. Samples should represent plants that are planted on the same soil type and are of the same age, variety and rootstock.
• Vines should represent that portion of a block that is maintained under the same cultural practices, i.e. fertilizer, irrigation and vigor control practices. For example, irrigation blocks are not to be combined with non-irrigated blocks even if they are on the same soil type.
• Do not sample vines on the border of the block or near dusty roads.
• For the late-season sampling period, sample the petiole of the most recent- FULLY EXPANDED leaf (NOT the one across from the first blossom cluster as during bloom).
• About 75-100 (depending on size) petioles are needed as they are typically smaller at the end of the shoot.
• Gently wash petioles with water and gentle detergent, pat dry and place in OPEN paper bag (lunch, #6 size) to dry for a few days.
• The closest analytical lab for grape petiole analysis is the Cornell Nutrient Analysis Laboratory . Please note that they now have partnered with Agro-One Services. It is recommended that you contact them before you send any samples to confirm that recommendations will be sent along with the analysis and to confirm costs.
  Video about petiole sampling: https://www.youtube.com/watch?v=8EHbojLfXek

August issue of Northern Grapes News.  Here’s the direct link:

http://northerngrapesproject.org/wp-content/uploads/2015/08/NG-News-Vol4-I3-Aug-2015.pdf

In this Issue:

-Does Production Region Matter?

-NGP Team Profile: Mike White.

-NGP Team Profile: Paul Read.

-I Have Galls in my Vineyard: Should I Call my Nursery?

-Cold Climate Wine Quality Assurance Program. 

Northern Grapes Project Homepage: http://northerngrapesproject.org/

Northern Grapes Project Facebook page: https://www.facebook.com/NorthernGrapesProject

Sister “e-Viticulture Homepage: http://eviticulture.org/

Chrislyn A. Particka, PhD

Extension Support Specialist

Cornell University

School of Integrative Plant Science, Horticulture Section

630 W. North Street

Geneva, NY 14456

cap297@cornell.edu

315-787-2449 (desk)

315-787-2216 (fax)

www.northerngrapesproject.org

by Terence Bradshaw

After one of the driest Mays on record, we are closing out June as one of the wettest in many areas, and that means the potential for diseases in Vermont vineyards. Recent weather has been excellent for development of our major diseases: phomopsis, black rot, powdery mildew, downy mildew, and anthracnose. I have often relied upon my predecessor Dr. Lorraine Berkett’s recommended initial vineyard IPM program to get us through spring and early summer, but the past few weeks would likely test that minimal approach. Here’s a recap of those recommendations:

By now, growers should be at or approaching the second post-bloom application, and I do not recommend skipping this one. Since this was written in 2009, several other fungicides have been released that may replace Sovran/ Abound or Pristine on the program, including Revus Top and the two Luna products (Experience & Tranquility). Please refer to the 2015 New York and Pennsylvania IPM Guidelines for Grapes for specific materials and rates, or contact me directly with specific questions. Also, consider shortening intervals when excessive excessive rain has fallen: the rule of thumb is that 2″ of rain washes off all fungicide protection, and newly emerged leaves since the last application will have only minimal fungicide coverage from redistribution of weathered, previously applied sprays. Organic growers who are relying on copper, sulfur, and/or biofungicide materials this season should be really tightening their schedules, and planning carefully scouting for and removing disease infected foliage and fruit. The good news is that within a couple of weeks berries will be building resistance to black rot, but downy and powdery mildew and botrytis still demand attention.

The main insects of concern are rose chafers and foliar phylloxera, although the latter are not something I would be too concerned about. Again, specific materials for use against these pests are listed in the NY/PA guide. Growers often use carbaryl against foliar-feeding beetles like rose chafer and Japanese beetle, but in many cases, tolerance is also effective as long as foliage feeding doesn’t get too overwhelming (and less tolerance should be given on young vines).