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Clusterless shoots and crop potential in 2014.

by Tim Martinson

In 2013, we were able to harvest 2.5-5.0 tons per acre of fruit from our Clayton training trials  (See 2013 Marquette results here) .

In 2014 it may be a different story.

Clusterless Shoots: Last week  Chrislyn Particka and Bobby Hunt counted (adjusted) shoots, and also counted the number of shoots without grape clusters.  This is significant, as many of the buds that pushed in 2014 may have been secondary or tertiary shoots that pushed because (more fruitful) primary buds suffered winter injury.

1.  Total Shoots and shoots with clusters,  Marquette and Frontenac.  Normally a certain percentage of shoots do not carry clusters.  But this percentage is often higher in ‘winter injury’ years. This was the case this year,  and it varied by training system.

Marquette (left) had 25-30 shoots of 45 (Umbrella and TWC) that pushed – but note that the number dropped to 11 of 35 in the VSP.  So there is potential for at least a moderate crop in the TWC and UK marquette this year.  Different story with the Frontenac (right).  In all the treatments, only 10 of the 40 shoots had clusters.  Most were ‘clusterless shoots’.

More graphically, if we look at percentages on the Marquette and Frontenac, we see about 65% of shoots with at least one cluster on the TWC and UK, and about 30% on the VSP for the Marquette.  For the Frontenac, the range is 25-30% for TWC and UK, and 12% for the VSP.



The shoot at left shows clusterless 2ndary and tertiary shoots on Frontenac.  This appears to be the norm in the Frontenac block, which had a much lower proportion of shoots with clusters than did Marquette at this site in Clayton.

But the high training systems (TWC and UK) in both varieties had a higher proportion of shoots with clusters than did the mid-wire trained VSP vines.

Conclusion:  Frontenac showed more severe effects than Marquette, either because 2ndary buds on Marquette are more fruitful than 2ndaries on Frontenac, or some site specific factor affected the frontenacs more than the marquettes.


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