By now vineyards should have shown the effects of the May 18 freeze event (and a little damage here and there from the less severe May 26 frost that some sites may have seen) and it appears that, by and large, all is not lost. That isn’t to say that there isn’t extensive, and sometimes massive damage in many vineyards. In some cases secondary or even tertiary shoots are pushing, in some cases we don’t’ even have that. But it does sound like there will be wine from much of the state. Here are some management considerations to think about moving ahead.
First, keep up on your disease management. We are entering the immediate prebloom period where all of the major early season diseases are active. It’s (finally) been wet but not a soaking rain for the past week and next week looks showery. Keep your fungicide coverage on, even if you don’t think you’ll have a crop. Obviously no shoots means no tissues to protect, but even fruitless shoots will be susceptible to disease and unmanaged disease this year will become a big headache next year as you’ll have a large overwintering inoculum.
Next, keep an eye on water. I know most grapes in Vermont are not irrigated but in a year like this. At the UVM Horticulture Center we have received just over an inch of rain in the past month. That’s not enough for sufficient growth and production.
Finally, you should now be looking at any canopy management that the vineyard needs. In areas with little freeze damage, this is the time to thin shoots down to 4-6 per foot of canopy. That foot can be on a cane, cordon, or other structure. The cordons or canes may have been compromised and not pushing any shoots, you may be seeing growth coming from the head at the top of the vine trunk. If that zone, which we may say is about one foot, is all you have that is pushing buds, then I would leave more than the 4-6 that the above formula would call for, but rather leave double that. You will need to be tying and training canes in the next few weeks to manage that growth and reduce shading and moisture buildup. If you decide that the vine needs to be rebuilt from the ground up, keep an eye out for shoots that emerge from the root zone (non-grafted vines only) to train up as new trunks. I know the tissues low to the ground are among the most vulnerable in a frost, but the root system may be a source of new shoots produced from hidden or adventitious buds.
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