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Current Situation – 6/1/2012

Vine Development:  Vineyards in Clayton area at 6-15 inch growth stages.  Varying amounts of bud injury are evident, with many clusterless shoots in some cultivars (LaCrescent, Marquette notable in some blocks visited on 5/29; Frontenac less so) – indicating many ‘secondary’ shoots pushed after primaries were frosted.  Shoot thinning should be completed in next week for those vineyards where extra buds were left in anticipation of frost injury.  Aim for 4-6 shoots per linear foot of canopy and preferentially remove ‘double’ shoots (2 shoots from same node), weak shoots, and shoots without grape clusters.

Insect Management:  It’s looking like wild grapes in the Clayton area will be at 50% bloom by this Friday, June 1.  (possibly delayed inland and to the SE by a few days).  If so, June 1 will be the ‘biofix’ or starting point for using grape berry moth (GBM) forecasting to time the 2nd generation spray (according to growing degree day accumulations after the biofix).  First  generation GBM larvae develop mostly on wild grapes and vineyard borders adjacent to woodlots. See Grape Berry Moth Spray Timing post for more information.  Foliar phylloxera is not evident yet.  Examine shoot tips 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.

Disease Management:  As we move into the prebloom period, disease management is the most critical vineyard task. Grape clusters after bloom are most susceptible to downy mildew, powdery mildew, black rot, and (on botrytis-sensitive varieties – particularly tight-clustered ones such as Marquette) botrytis.  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;  2012 version should be out soon.

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 vegetative growth.

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