Fire Recovery for Vines Examined

With North Coast fires fully contained, focus shifts to preparing for winter and 2018 vintage

by Andrew Adams
wine  wineries vineyards fire property land
Flames from the Partrick Fire blazed through this vineyard near Henry Road in Napa, Calif.
Napa, Calif.—With all of the major North Coast wildfires now contained and the 2017 harvest nearly complete, growers in Napa County and elsewhere are beginning to take account of how the blazes affected their vines and property.

Even if few vineyards burned during the fires, growers are dealing with debris cleanup, repairing damaged infrastructure such as melted irrigation lines and plastic culverts and preparing for winter rains expected to begin this weekend.

A crowd of more than 100 people attended a recent Napa Valley Vineyard Technical Group session that focused on wildfire recovery and included presentations by a series of experts.

Andrew McElrone, a plant physiologist with the United States Department of Agriculture at the University of California, Davis, discussed how to assess vineyard health in the aftermath of a fire. Drawing on research from wildfires in Australia, McElrone said growers need to perform a detailed inspection of their vines as soon as possible. In addition to damage from direct contact with flames, vines also can suffer damage from the radiant heat generated by burning trees, structures, vehicles or fences. Less apparent damage can impact the productivity of vines during the following vintage.

Growers can look for internal damage by making a small cut in the trunk of a vine similar to the type of cut for T-budding and inspecting the interior tissue. Healthy tissue is moist and creamy white in appearance, while dead tissue would be brown and dry. Dissecting buds is another useful way to check on the fruitfulness of vines for the next season.

McElrone said most of the crop in Napa appears to have been harvested, and so the vines were going into dormancy at the time of the fires. Vines are well adapted to protect their buds, and if canes and spurs survived the fire, the 2018 crop should not be impacted. “These buds should have been pretty well developed and heading for dormancy and pretty well resilient,” he said.  

Vines with a medium level of damage should receive irrigation as soon as possible, making repairs to that infrastructure more of a priority. The vines should also be closely monitored.  Vineyards with severe damage could be tended back to productivity, but the time and effort may not make economic sense compared to replanting.

Harvesting through the fire
Napa County Agricultural Commissioner Greg Clark said he and his staff issued 598 permits over the course of 10 days for people to harvest grapes and access wineries in areas behind the fire lines.

During the active fire fight, Cal Fire helicopters and air tankers made repeated fire retardant drops throughout the area and advised growers to not pick any grapes covered in pink retardant, which is essentially a mix of chemicals similar to commercial fertilizers. Clark said based on aerial imagery it appears retardant fell on a very limited area of productive acreage. “There was very little impact on vineyards and olives by fire retardant. I’m guessing 10 acres,” he said.

His office was also inundated by requests for testing grapes for potential smoke contamination, but Clark said that appears to have been based on misinformation as the agricultural commissioner’s office does not provide that service.

Starting this week, Clark said he and his staff are reaching out to the owners of 282 parcels within the fire boundaries to try and get some definite numbers on the extent of the fire damage to provide that information to state and federal authorities.

While the Federal Emergency Management Agency and the U.S. Army Corps of Engineers is providing assistance on hazard materials cleanup for homes destroyed in the fire, it’s not clear if similar help will be provided for agricultural or commercial properties. When asked about debris cleanup, Clark acknowledged he’s trying to get more information. “That’s a good question, and we need an answer to that, so I’ll work on that,” he said.

Land-use consultant Phil Blake, who previously worked for more than 30 years with the USDA National Resource Conservation Service, said with the days growing shorter and the rainy season nearly here, it may be too late for reseeding hillsides scorched by the fires.

Growers should reinforce gullies and ephemeral streams with straw bale dikes, weirs and fiber rolls to slow down runoff and capture sediment and ash. Other good resources include the original planting maps with conservation regulations. “Go back to those maps if you still have them,” he said. “They’d be an excellent resource.”

He said one should expect at least double the amount of storm runoff, and in heavy storms it could be two to three times what’s normal. Farm ponds may need to be protected from runoff by temporary diversion ditches.

Bill Birmingham with the Napa County Resources Conservation District said stream crossings are the most vulnerable parts of roads, as plastic culverts may have melted and concrete and metal culverts could have shifted and will no longer carry stream water beneath the road. He suggested installing a post in front of culverts to keep brush and other material carried by storm water from plugging the culvert and eroding the ground around the road.

If the plastic outfalls of subsurface drainage have melted, he suggested those be reinforced with riprap or rock armor through the winter.

Jeff Yasui with the USDA Risk Management Agency urged anyone in the audience who may have suffered crop losses or vine damage to contact their crop insurance agent. He said smoke taint is covered, provided growers have the test results showing the presence of indicator compounds. If the crop had already been harvested but the vines suffered damage, he said insurance may cover losses in the 2018 harvest, too. “Tell your agent, ‘I’m going to pull vines,’ because that crop will probably be covered by crop insurance—the production losses for 2018,” he said. “We just want to try and make this go as smoothly as possible. We just need to make sure bureaucracy doesn’t get in the way of rightful payment. Once again: Talk to your agent, that’s what we keep saying.”

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