How do wildfires affect crops?You have most likely read a lot about the wildfires happening in northern Canada and the effects the smoke is having in all parts of the Northeast, but have you thought about the crops it may be affecting? Plants, much like people, can suffer from the smoke’s effect from increased ozone at the ground level and the reduced sunlight.

Did you also know that copious amounts of smoke in the atmosphere can lead to decreased rainfall events? Combine that all together and you do not have a very great mix for plant life or human life.

Smoke in the air can lead to increased levels of ozone at ground level. Ozone is normally found in the upper part of our atmosphere (the stratosphere) and it absorbs most of the sun’s ultraviolet rays. You can thank ozone for allowing you to use SPF 50 instead of SPF 500 sunscreen, but don’t thank it just yet. Ozone occurs in lower levels of the atmosphere via a photochemical reaction between sunlight and air containing hydrocarbons and nitrogen oxides, thus creating what we know as “smog.”

This smog can cause lung and respiratory problems in people and affect respiration in plants by limiting the amount of oxygen they can take up. When ozone levels are high enough, it can cause oxidative burning to plant leaves, which can be bad for the future development and yield of the plants.

Photo courtesy of Derek Llewellyn

As you may have noticed from pictures and going outside this past week, the increased smoke in the air was limiting some of the sunlight from getting through, contributing to that hazy look. Since plants require sunlight to carry out photosynthesis, the decrease of sunlight will limit plants’ ability to convert carbon dioxide to oxygen. The decrease of sunlight will also decrease surface temperatures, which could have negative effects depending on plant stages of growth.

The largest factor that affects plant growth, especially right now in the Northeast, is smoke interference on rain cloud formation in more than one way. To make a raincloud, dust and small particles attract moisture in the air and slowly get bigger and denser with water until they become too heavy and dump rain. When a large wildfire happens, it creates too many small particles, leading to many smaller cloud formations that don’t produce the large rain events we need.

A second way the smoke decreases rain events is by decreasing the ground surface temperature; lower temperatures mean less water will evaporate and not go up into the atmosphere.

As you can see, wildfire events and the ensuing smoke can have great impacts on the health of people and plants. In Canada, the crops will most likely be much more affected, especially as they get closer to the wildfires, and could see smoke in the air for a longer duration.

The effects of the recent smoke on the Northeast will not be fully realized until the season is over, and we have data from crop reports. It is still early in the growing season for most of New York’s agricultural crops so I presume there will be minimal to no crop loss from the recent wildfire events.

If you have further questions, contact CCE Ontario’s Ag Economics Educator Jacob Maslyn at 585.394.3977 ext. 402 or

by Jacob Maslyn, CCE Ontario