Graham’s invests considerable time and effort into viticultural research, on subjects such as optimum rootstocks or clones of grape varieties, trellising systems, and of course how best to manage issues such as soil erosion, water retention, disease and pest control. Miles Edlmann, our research viticulturist, is busy trying to gather his data today before he turns his attention to wine making and opens the Quinta da Cavadinha winery for our sister brand, Warre’s.
One subject of ongoing research is finding a way to minimise the damage to our Touriga Francesa crop from the caterpillars of the European Grapevine Moth. Readers may remember our coverage of this last year, and 2011 is the fourth season in which Miles has been trialling a proposed methodology for opening up the grape bunches – Touriga Francesa is notorious for its tightly packed bunches. The idea is that the tiny caterpillars, having damaged one berry, would be isolated there and not be able to reach across and move onto the next grape, if there was a little distance between them. Opening up the bunches will also make them less prone to diseases such as mildew or botrytis as both wind and sun will be able to ventilate the bunches and dry off any humidity or dew.
Today Miles and our oenological students gathered bunches from the designated vineyard. Half of the bunches were from treated rows of vines, and half were from untreated, or control vines. To ensure a fair sample, Miles cuts the bunches according to rule: on these unilateral cordons, he cuts the first bunch from the bottom shoot on the first spur of every fifth vine, beginning with the vine after the first post down the row (not the end post).
Back in the lab, we take various measurements for each and every bunch and then the berries are counted, segregating caterpillar-damaged and undamaged grapes and any immature grapes. This year, after counting through 6,191 berries, we found no caterpillars (versus about 89 last year) but one spider that rather startled the team.
In spite of the challenging season, the grapes are extremely healthy. This is good for the grapes and wine making, but bad for the experiment, as this makes it a lot more difficult to wholly credit the experimental procedures with any decrease in caterpillar damage. We actually will need more bad years to really prove the value of the procedure, but naturally we find it hard to really wish for that!