It’s really great to have Patrick Williamson, Orchardist/Vineyardist at Williamson Orchards and Vineyard submit these articles A Note From The Vineyard – The Weather Factor. Thanks Patrick!
by Patrick Williamson, Vineyardist
Well It has been a while but a lot has been going on out in the Vineyards and Orchards. Many frustrating and nail biting days and nights watching the weather and praying for more snow and for cold temps to stay for another month. Alas more people were asking for warmer weather than cold and snow. While we were watching the weather warm up we started to think about pruning the vines and how to proceed with the increased chance of frost damage.
Before I get into this spring, let’s go back to November last year, we had this great warm fall where the week before Thanksgiving the highs were in the 60’s and then by the weekend we went from 60 to 0 for three days and then jumping back to 60. That did a big number on tree fruit and grapes and there is really nothing that a farmer can do to reduce damage done to the plants in a sudden cold snap. It is best for a gradual decrease in the temperature to allow the vines to get adjusted to the cold. It also did not help when many of the vines still had green leaves and had not “gone to bed” for the year. With the long warm fall and the fact that irrigation water was shut off in the beginning of September and many farmers were not able to really saturate the soil after harvest to help the vines have plenty of water to insulate the soil from getting too cold. Which can also help prevent or reduce the amount of frost damage to fruit buds as well but to a lesser degree.
With the early warm spring many farmers had a longer than normal period of danger for frost. Which will kill fruit blooms in tree fruit and dormant grape buds that are starting to wake up and are weaker and more susceptible to frost damage. The best way to prevent frost damage is to run overhead sprinklers during a frost event. A layer of ice will form and protect the buds from freezing. The water will continue to run until the ice melts and we watch the weather and see when the next frost event will be. This only works for vineyards that have overhead sprinklers with or without drip tape. The other big thing is the vineyard needs to have water sourced from a well. Most of the frost period is during a time when there is no irrigation water in canals.
Besides irrigation to help reduce frost damage many growers will alter their normal pruning practices by leaving 1-2 extra buds per spur. I will do my best to explain without images what a spur is. A spur starts out as a bud which becomes a shoot, which, is where the fruit grows. Then that shoot will harden or lignify by the end of the season. The next spring the old shoot will be pruned leaving 2-3 buds behind to grow into shoots. And this goes on for several years. But growers want to keep the fruiting zone from those left over bud to be as close to the cordon/trunk so if a dormant bud that is growing on the cordon starts a new shoot and will allow for the spur to be “renewed” and lowers the fruiting zone. This year many red wine grapes were pruned to 3-4 bud spurs to enable vines to push more buds to grow and help counter the damage and crop loss from frost damage.
This year several places got hit hard by the subzero event in November. We will be removing an apple block due to the damage from that, and we are retraining most of our Viognier which took the most damage of all of the grapes from the freeze event. The Syrah, Cabernet Sauvignon, Petite Sirah, Sangiovese, and Mourvedre got varying degrees of frost damage. Grapes fortunately have three buds the primary, secondary and tertiary buds.
The Primary being the best producing bud; the Secondary being able to produce about half of what the primary bud can produce it also starts growing a little later than the primary. The tertiary bud has very little fruitfulness and normally never grows but when the two bigger buds die then it will be the last bud to start growing. With these different growing start points can make a vine not look very good but the shoots will eventually catchup to each other and look the same within an month or so.
There is much more going on between February and May that I will save it for another post. And there is going to be much more to come. Thank you for reading. Feel free to ask questions. I will do my best to answer.