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JoAnne Skelly: Smoke, plants and people

By JoAnne Skelly

With all the smoke lingering lately and on hearing that Napa grape growers lucky enough to still have grapes may not harvest them due to smoke contamination, I wondered how smoke affects plants as well as people. I found some interesting articles.

The first was from University of California Cooperative Extension (UCCE) of Sonoma County that addressed “Produce Safety After a Fire.”

UCCE pointed out was there can be contaminants in ash and debris that land on edible plants during and after a fire depending on “what built environment and natural materials burned.”

These can include:

“Hydrocarbons such as petroleum products from roads, car garages, or auto industries

Heavy metals like lead, cadmium, nickel and arsenic in metals, old building paint and piping, electronics, batteries and many industrial manufacturing processes

Other chemicals in farm or landscape settings, machinery and/or equipment

Hazardous chemicals used or stored on industrial sites and buildings in the fire area.”

Although the above contaminants on plants and soil are of concern, we in Northern Nevada are not experiencing ash drop, which means they shouldn’t present plant or soil contamination risk. If we were experiencing ash falling from the sky, soil testing and possibly produce testing for heavy metals deposition might be called for.

Another article reported that although smoke generally blocks sunlight by approximately 4 percent, it also diffuses sunlight allowing it to spread out over a greater surface area of leaves throughout the plant. This can increase photosynthesis efficiency and improve growth.

And while smoke does increase ozone production, which negatively impacts plant growth, the increase in photosynthesis is of greater benefit (Thompson, E. (2020), Wildfire smoke boosts photosynthetic efficiency, Eos, 101, https://doi.org/10.1029/2020EO139985. Published on Feb. 12).

However, another research study found ozone production to be quite detrimental to plant health.

On the other hand, there can be a health risk to people from all the smoke in that “particulate matter (PM) is the major pollutant for relatively short-term exposures from wildfire smoke (hours to weeks). PM influences health differently based on size, with smaller particles having more damaging effects to the respiratory and cardiovascular systems” (January 2018. countyofnapa.org. Napa County Cancer Report Supplement C: Wildfire exposure and cancer).

Although, we are irritated by the smoke, unfortunately, it can do significant damage to wine grapes causing a foul taste, a ruined crop and less wine availability in the future. Now that’s a sad state of affairs in this already challenging year!

JoAnne Skelly is associate professor & extension educator emerita of University of Nevada Cooperative Extension. She can be reached at skellyj@unr.edu