Thursday, October 27, 2016

Grape Crop Load Experiment

The right crop load take years to assess and depends on so many variables such as soil, moisture, sunlight, training methods, diurnal temperature fluctuation, humidity, climate (micro and meso), nutrients etc. It really ends up being somewhat of a trial and error that one needs to go through over time.  Crop load is also related to ripening and the general idea is that if a vine is under-cropped it may hasten the ripening process as there is less fruit to ripen. On the other hand over-cropping a variety may slow the ripening process as there is more fruit to ripen. 

This year we conducted an in row trial with Leon Millot to see the how crop load affected grapes chemistry and ripening. We planned to increase the crop load by leaving addition shoots to see if the addition shoots would increase crop load without noticeably affecting the quality of the grapes for this variety.Our noramal amount of shoot is 8 per foot and on part of the row we left 12 per foot. Here are the numbers.

Leon Millot
8 shoots per foot
12 shoots per foot

We saw that there was virtually no difference in production between the two pruning levels as both produced at approximately 1.5LB per linear foot having on average 2 clusters per shoot. The weight of the clusters on the vines pruned to 8 shoots per foot were averaging about 50 grams in size. We didn’t weight those that came from the vines pruned to 12 shoots per foot. However, the vines pruned to 12 shoots per linear foot in general had smaller and less well filled clusters than the clusters on the vines pruned to 8 shoots per foot. We also note that it took a bit more trellis management to train the shoots on the vines with 12 shoots per foot. It also took longer to harvest the vines with 12 shoots per foot.

The extra shoots did not translate into bigger crop but more work and poorer quality grapes. Bottom line - we won’t be doing that again, but good to know that our crop load is pretty good at 8 shoots per foot.

Also important to note is that the shoots on the vines cropped to 12 shoots per foot were generally shorter and as such won’t be as suited for use in long cane pruning next year – which is the pruning style we have been using for Leon Millot.