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Current Situation 6/7/2012


Frontenac shoot with 3 clusters, close to bloom on 6/6/2012.
Photo by Chrislyn Particka.

 

 

 

Zac Shirk, our summer intern, based in Watertown, started becoming acquainted with local vineyards where he’ll be scouting for insects and diseases, as well as collecting data on shoot and cluster counts (among other projects).  Zach will be visiting 5 locations each week, and will contribute to this report.

Vine Development:  Bloom has started in NNY vineyards and with it the most critical period for disease management (see Disease section below).  By now, those who left extra buds to compensate for potential bud injury this spring should have an excellent idea of how many shoots and clusters you have, and we are nearing the end of the period in which shoot thinning is ‘easy’.  After shoots start to lignify (lignin=a substance that gives shoots their rigidity), then it may be necessary to use a pruning shears to remove extra shoots.  At our research plots in Clayton (crop load adjustment and training systems in Marquette and Frontenac), Chrislyn Particka and Bill Wilsey completed shoot thinning this week with the goal of adjusting to 5-6 shoots per foot of canopy.

Growing Degree-Days At Watertown: Growing degree-day accumulations are a measure of heat unit accumulations that correspond to vine development.  They are calculated by adding up the average of daily minimum and maximum temperatures and subtracting a ‘minimum’ threshold (50 degrees F in this case) below which vine growth does not occur.  Degree-days are more accurate than calendar date for predicting dates of bloom, veraison, and insect development.
Access GDD at Network for Weather Awareness, for more weather data and disease/insect forecasting models.

Current GDD at Watertown: June 7, 2012: 501 growing degree-days

Last year:  June 7, 2011: 364 growing degree-days

Date in 2011 at which 501 growing degree-days were accumulated:  June 16, 2011

Heat Unit accumulations are 9 days ahead of last year’s at this date.

Degree-day range for ‘Concord’ bloom in Western NY:  Average = 587  (Range 513-686)

Degree Day Forecast  through 6/8-6/14 – 133 GDD – should be toward the end of bloom by Thursday, June 14.

Disease Management:  Bloom to 4 wk after bloom is the MOST CRITICAL PERIOD FOR DISEASE MANAGEMENT. Immediately following bloom is when grape clusters are most susceptible to powdery mildew, downy mildew, black rot, phomopsis, and anthracnose infection.  As grapes develop, they become resistant to fungal infections.  Make sure you have good coverage with fungicides, use the best materials, and pay close attention to spray intervals 7-10 d during this period.  This holds true even for organic producers using organically-approved materials such as sulfur and others. Sprays applied at this time (2 postbloom sprays) will cover most of the time when diseases can infect clusters.

Botryticides – are typically applied at bloom, but may not be critical (dry weather) for most varieties – except tight clustered ones such as Marquette.  Not much is known about botrytis susceptibility of MN or Swenson cultivars.

For specific information on materials and options, consult 2012 NY/PA Pest Management Guidelines or Wayne Wilcox’s annual Disease Management Guidelines – 2011 version is still good and posted online.  

Insect Management: 

Grape Berry Moth (GBM)2nd generation still a few weeks away.       See Grape Berry Moth Spray Timing post for more information.

Grape Phylloxera: Foliar phylloxera still not evident.  Examine shoot tips (unfolded leaves at the very tip) for new galls – and use their presence in significant numbers as a ‘signal’ on when to start insecticide treatments if needed.  If you don’t see any there is no point in applying an insecticide to control them.  Factsheet is available from Ohio State (Note Thioadan insecticide recommendation is obsolete) and University of Arkansas has a list of varieties susceptible to foliar phylloxera.

Rose Chafer:  Rose Chafer adults feed on leaves and clusters and emerge around this time.  Observed in NY Champlain region.  This pest is most common (and almost exclusively present) in sandy soils.  See Ohio State factsheet.

Fertility:  If you plan on applying N fertilization, avoid applications during bloom.  To date, vines will not have taken up much nitrogen from the soil and postbloom application will be as effective – if even modest amounts of rainfall occur.  Be cautions about N additions to vineyards with substantial bud injury and few grape clusters.  Excessive N applications are likely to lead to excessive vine growth in many situations – particularly without a developing crop to hold back

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