Vintage Update 4-13-2012- Slowly Springing
Wet weather continued this past week, further delaying budbreak. At this point, we are even a few days behind 2011, one of the latest budbreaks in recent history. The earliest blocks have 3 to 5 inches of growth, but some of the later blocks are just starting to push buds out.
Last week, we experienced some frosty mornings, but in most areas temperatures did not creep below 31°, and damage was limited to a few singed leaves. The wetter weather this week has allowed growers who were up all night turning on wind machines and sprinklers to catch back up on much needed sleep.
Fortunately, we are starting the season with a fully drenched soil profile, which will allow the vines to build strong canopies. Hopefully, the rain will stop soon so the canopies don’t experience excessive vegetative growth.
The rain and slow vine growth has delayed vineyard operations. Some growers have had a chance to mow their cover crops between the periods of unsettled weather. If the cover crop is perennial, it makes sense to not mow again or to delay mowing until the cover goes to seed.
Although it is best to reduce the amount of cultivation in soils to build healthier soils and reduce erosion and soil run-off, young blocks or very low vigor sites may benefit from cultivation to reduce the competition from the cover crop. Hillsides should wait until the rainy season is over, and many Napa vineyards have ordinances preventing hillside cultivation until after April 15.
The earliest blocks are ready for their first mildew prevention spray. Although it is common and acceptable to use a wettable sulfur and copper to start the season, I think it is even better to use oil sprays in the first few sprays. Sulfur needs heat to activate and the cooler weather we are having will cause the sulfur to be less effective. Plus, oil has efficacy against mites and thrips, which I have already seen on some young leaves.
Voles and other rodents have been an increasing concern in Napa vineyards in recent years with wet springs. As soon as the ground dries out enough and we get some warmer weather, I expect to see these varmints. It is good to start trapping earlier in the season before they begin their reproduction, so keep an eye out for voles.
The warmer weather forecasted for next week should really push vine growth into full gear and we'll be busy mowing, spraying, and suckering!
Please share your thoughts and observations- frost damage, insect sightings, etc. We welcome an interactive dialogue!