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Status of the Second Crop – June 29

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Frontenac on High Cordon June 29

In my previous post on June 15, secondary shoots were just starting to emerge in our Marquette and Frontenac training trial at Clayton. Chrislyn Particka and I visited again on Monday, June 29, to check on progress and do some counting of shoots and clusters.

1. “Second Crop” just starting to bloom. Some shoots were at about 50% bloom – 2 weeks past the normal window centered on June 15. Others had not yet started to bloom, but are probably through bloom at this point. These shoots and clusters were interspersed with clusters from primary shoots that were past fruit set, and at the ‘pea sized’ stage.

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Frontenac ‘second crop’ blooming, June 29,2015

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Frontenac ‘first crop’ with pea-sized berries, June 29, 2015.

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Other ‘second crop’ clusters had not yet started bloom.

 

2. Shoot and Cluster counts. We counted the total number of shoots, and separated them into ‘first crop’ (survived the May 22 frost without freezing) and ‘2nd crop’ (shoots that emerged after the frost from secondary and latent buds on cordons) categories. We also recorded how many of the first and second crop shoots were carrying clusters.

Tables shoot counts

TWC= Top wire cordon (High cordon); UK= Umbrella Kniffen; VSP= Midwire cordon with vertical shoot positioning

Frontenac. An average of 1.8 to 3.1 shoots per vine survived the frost, and we saw 30-50 secondary shoots per vine emerge after the frost. 80% of the TWC (Top wire cordon) ‘first crop’ shoots had clusters – numerically more than the UK (cane-pruned umbrella kniffen; 66%) and VSP (mid-wire cordon with vertical shoot positioning; 41%). Of the‘ second-crop’ shoots. 30-38% had clusters. The net result was 31 clusters/vine on the TWC and roughly half that number (15.3-17.2) on the UK and VSP vines.

Marquette: The overall pattern was similar to Frontenac, but we ended up with roughly half as many shoots, and one-third as many clusters per vine (9.2-13.5). Again, within training systems, TWC produced the highest % of shoots with clusters for the 1st crop shoots, but VSP produced a higher % of shoots with clusters on the 2nd Crop.

The upshot: Secondary shoots and latent buds from the cordon produced about half as many shoots with clusters, probably produced fewer clusters per shoot, and the 2nd crop clusters will probably be smaller than the 1st crop clusters. So at a vine spacing of 622 (7 x 10 ft spacing), the upper limit of the crop we can expect would be about 0.6 to 1.5 tons/acre (Frontenac) or 1/3 to ½ Tons/acre (Marquette).

Assuming the ‘second crop’ reaches harvestable maturity, the actual crop will be substantially lower.  We will continue to track crop development over the course of the growing season.

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