About a month ago, I mused about the possible five variables responsible for a high incidence of rootstock suckers in my vineyard.
Since both the Aglianico and Montepulciano vines are getting rootstock suckers, I am fairy sure that depth of planting is not likely a cause. The Aglianico vines were planted a bit too deep, but the Montepulciano ware not.
Thinking about one suggestion that this all may be due to greater than average winter and spring rainfall, I had a light bulb moment.
As I struggled to keep the mucky mud underneath the dripper from falling back into the hole I was digging to remove yet another rootstock sucker, I realized all the rootstock suckers seem to be popping up under irrigation drippers.
As an aside, what I find really surprising is just how much water the soils tend to hold. But staying on topic, it also occurred to me that each time I was digging to remove a rootstock sucker, the soil was particularly saturated.
The video below suggests that the high soil saturation under around the trunk (due to the close proximity of the emitters to the trunks) is conducive to the emergence of rootstock suckers:
I had been cautioned not to set my irrigation emitters too close to the vines. I guest this was one of the reasons. But this vineyard’s very existence is a compromise between the ideal and the amount of water my father is willing to provide as well as his insistence on how he thinks a vineyard should be put together and run… You take what you can get.
But consequences must be dealt with. The most immediate solution is to move the drippers farther from the trunk. This may involve returning to the original two-drippers-per-vine setup. Of course, duration of irrigation will have to be adjusted to watch water consumption.
Returning to a broader scope of vineyard management, I am also thinking about matching rootstock vigor to scion vigor and site vigor. In my case, this entails learning to manipulate the site (via soil supplementation, irrigation, canopy interventions such as pruning, hedging (or not)) as well as altering irrigation (amounts and methods) or possbly changing the trellising system.
It takes a long time for changes attributable to each of those interventions to take effect. That also means that effects of interventions will linger longer and will be impossible to revers or stop on a dime. It’s like doing a hairpin turn with an aircraft carrier.
So, I’ll take it one step at a time, applying the “measure twice, cut once” approach as I consult with as many growers as I can.