May days are busy, busy days!
The vineyard is leafing out, which means a lot of handwork to get the canopy off to the right start!
Powdery Mildew is the biggest pest issue worldwide for Vitis vinifera, the traditional wine grape. Vitis v. evolved in Europe and the Middle East, and Powdery Mildew evolved with the many species of grapes in the Americas. Consequently, vinifera has very little resistance to Powdery Mildew, PM.
When people started moving vines around, we inadvertently took American pests to Europe with devastating results.
Our approach to control of PM is tipping all the environmental factors we can in our favor.
Pick an arid site with high-intensity sunlight, good air movement, fertile soil, and good-quality water for irrigation.
Choose a trellis design and training system to expose all of the plant to high levels of direct sunlight. PM doesn’t like bright, sunny places!
Do lots of shoot thinning and leaf pulling!
Irrigate very carefully to keep low vigor, and don’t short the plants on any nutrient but H2O.
It has worked well since 2013. Some varieties are very susceptible to PM and have some infections of leaves and canes. We, MOSTLY, have not had it on fruit. Some years, we have dropped as much as 20% of some varieties during harvest because of PM on the fruit. We haven’t made wine from grapes treated with a pesticide since 2013. We have multiple cultivars that have never been treated with any sort of pesticide since planting in 2011 and 2012.
Currently, it takes lots of hours of careful removal of unwanted shoots. Fortunately, Bertha has been working with me for 20+ years and is really, really knowledgeable. I rely on her hands, eyes, and mind.
This year, we have a lot of restoration work to do after the January 2024 sub-zero weather. There has been much head-scratching as we try to determine the optimal approach. One experiment in the temperamental Temprañillo is to cut some to the ground and regrow the above-ground part of the vine.