b'TATER TALES Beware of Air Pollution and Acid Rain Injury to Potatoes!POTATO PLANTS CAN be injured when exposed to high concentrations of various air pollutants. Injury can range from visible markings on the foliage to the death of the plant. Growth and yield can also be reduced. The development and severity of injury depends mainly on the concentration of the pollutants in the atmosphere. Crop injury can occur over large areas.The following environmental conditions are conducive to a build-up of injurious levels of pollutants.EUGENIA BANKS,1.Atmospheric ozone levels over 80 parts per billion potato specialist(ppb) for four or five consecutive hours, or 70 ppb for with the Ontario Potato Board a day or two are usually sufficient to injure exposed foliage at a susceptible stage of growth.2.High levels of automobile exhausts. Crop injury is often visible in fields located close to heavily travelled highways, especially after long weekends.3.Cloudy, hazy overcast days with high humidity and little wind lead to a high concentration of pollutantsPotato leaves that have been hit by acid rain.at ground level and in low spots in fields PHOTO: EUGENIA BANKS4.Foggy conditions and heavy dews often contribute to an increase in concentration of air pollutants. The most important air pollutants in Ontario are: Ozone (O3) Peroxyacetyl nitrate (PAN) Sulfur dioxide (SO2)Ozone InjuryOzone is the major component of oxidants in Ontario. Its formed by the action of sunlight on products of fuel combustion and is moved by wind from roads to nearby fields. Symptoms vary depending on the concentration of ozone in the air and the length of exposure. They range from pepper spotting to flecking.Potato leaves that have been damaged by air pollution. Injury occurs on the most recently emerged leaves.PHOTO: EUGENIA BANKSVarietal susceptibility to ozone is another key factor. Yukon Gold, Atlantic and Shepody are very susceptible. PAN InjuryPAN, like ozone, is produced whenAcid rainSulfuric and nitric acid can fall from the sunlight reacts with the gasses in vehicle exhaust. PANatmosphere as rain, snow, fog, hail or even dust. Acidic causes tissue collapse on the lower surface of leaves ofcompounds cause interveinal necrotic spots on upper many plant species. On potatoes, blotches form with asurface of leaves, yellowing of lower leaves, upward leaf distinctive bronzing, glazing, or silvering. PAN is therolling, early maturity, and yield reduction due to early most toxic to young leaves. maturity.Sulfur dioxideCoal burning power plants, smeltersWhat can growers do to help potato plants recover and internal-combustion engines produce sulfur dioxide.from air pollution and acid rain injuries? If the crop Exposure to high levels of sulphur dioxide will resultisnt stressed due to nutrient deficiencies, many growers in light tan to white necrotic areas in leaves. Yield mayspray Epsom salts (magnesium sulfate) which greatly be reduced. Losses in sensitive cultivars may be severehelp potato plants to recover from oxidants and acidic following exposure early in the season. pollutants.42SPUDSMART.COMSummer 2023'