Types of Injuries to Plants. Effect of Air Pollution on Plants. Cross section of Leaf Showing Air Spaces where Pollution can Move.

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1 Types of Injuries to Plants Effect of Air Pollution on Plants Necrosis - killing of leaf cells abscission - premature dropping of leaves epinasty -down curve of leaf (due to growth rate imbalance - top fast & bottom slow) chlorosis - color change from chlorophyll destruction acute - sudden, severe visible change chronic - gradual change from long-term exposure Cross section of Leaf Showing Air Spaces where Pollution can Move Sulfur Dioxide Acute - Dead tissue between veins or at margins (e.g..3 ppm SO 2 for 8 hr) Chronic - Chlorosis (Brownish red or white areas on leaf) or Epinasty (e.g..03 ppm SO 2 annual average) Especially sensitive during periods of intense light and high relative humidity Young leaves hit first, but middle age leaves hit hardest Sulfur Dioxide Injury to Hickory Castor Bean Leaf Injury from Sulfur Dioxide 1

2 Sulfur Dioxide Injury to Fox Grapes Sulfur Dioxide Damage to Mature Careless Weed Leaves Sulfur Dioxide Injury to Sonora Wheat Acute Damage to Bracken Fern Caused by Sulfur Dioxide Sulfur Dioxide Damage to Tulip Sulfur Dioxide Damage to Loblolly Pine 2

3 Hydrangea Leaf Damage from Fly Ash Ozone First symptom often water-soaked appearance flecks or stipple of dead or pigmented cells growth suppression, early abscission more damage with more light oldest leaves most sensitive Ozone Damage to Sensitive Plants Stipple on Tobacco Leaves caused by Ozone Time Concentration 0.5 hr ppm Light Colored Stipple on Underside of Tobacco Leaf from Ozone Enlargement of Ozone Damage on Tobacco After Several Days Exposure 3

4 Ozone Injury to Tomato Severe Ozone Injury to Ponderosa Pine Peroxyacetyl Nitrate (PAN) Bronze-like Damage to Pinto Bean from PAN (peroxyacetyl nitrate) like Ozone comes from photochemical smog glazing, silvering or later bronzing of lower surface of leaf major damage during high sunlight youngest leaves most sensitive.01 ppm for 6 hr damages lettuce, tobacco, beans and petunias Silvering Damage to Underside of Pinto Bean Leaf from PAN Top and Bottom of Bean Leaf Damaged by PAN 4

5 Bronze-like Under Leaf of Pinto Bean damaged by PAN Nitrogen Dioxide Takes higher concentration to do damage since NOx produced in the soil Chronic - gray green water soaked looking leaves followed by chlorosis Acute - irregular white or brown collapsed lesions near leaf margins 4 hr at 2.5 ppm or 1-2 days at 1 ppm affected pinto bean 240 days at.25 ppm greatly reduces naval orange yield Nitrogen Dioxide Damage to Tomato Plant Damage to Cherry Belle Radish exposed to 7.7 ppm Nitrogen Dioxide for 4 hr Synergistic Air Pollutants Two pollutants whose combined effect is much greater than sum of individual effects If have both an acid maker which needs oxidizing like sulfur dioxide and an oxidizer like ozone or nitrogen dioxide then damage can be great Example -.25 ppm SO 2 which does little damage by itself and.03 ppm O 3 which damages 12% of Tobacco leaf in 4 hr. Combined they damage 38% in 2 hr & 75% in 4 hr Synergistic Injury to Tobacco from.05 ppm O 3 &.10 ppm SO 2 5

6 Synergistic Damage to Lower Surface of Soy Bean Leaf From.10 ppm O 3 &.50 ppm SO 2 Synergistic Damage to Top of Soy Bean Leaf from.10 ppm O 3 and.50 ppm SO 2 Synergistic Damage to Pinto Bean from.05 ppm SO 2 &.10 ppm NO 2 Fluorides (especially HF) from brick, tile, steel, phosphate, aluminum and coal plants tip & margin burn, chlorosis, dwarfing, early abscission, lower yeild peach fruit suture red spot - soft or rotten 5 wk at.1 ppb affected blueberry, corn, fir, prune and pine Grape Leaf Damage from Fluoride Fluoride Damage to Gladiolus 6

7 Fluoride Damage to Fir Suture Red Spot Syndrome of Peach Fruit caused by Hydrogen Fluoride Chlorine Chlorine Injury on Sassafras spotting of dark green later turning brown bleaching between veins tip and margin burn occasional flecking and early abscission more damage with high relative humidity 2 hr at.1 ppm injured alfalfa and radish Chlorine Injury to Italian Prune Cucumber leaf exposed to.75 ppm Chlorine for 4 hr 7

8 Ammonia Ammonia Injury on Cotton Acute tissue collapse - dark green then turning brown or black need higher concentration since ammonia is also formed by rotting vegetation and plants have evolved to be used to it 4 hr at 20 ppm affected cotton Ammonia Injury on Poison Ivy Ethylene (C 2 H 4 ) Sepal withering flower dropping and failure of flower to open properly leaf abnormalties 24 hr at.005 ppm affected orchids 6 hr at.05 ppm affected orchids & marigolds several hours at.01 ppm caused loss of buds in tomatoes and peppers Sepal Damage of Orchid Caused by Ethylene Azalea Damage from Ethylene Control plant on left 8

9 Particles Cement Dust Injury on Fir particles may clog leaf stoma or block light for photosynthesis alkalinity of cement dust causes problems lead can collect on plants and while not affecting plants, it can cause problems in animals that eat plants Defoliants 2, 4-D is ingredient in agent orange known to drift as far as 15 mi from target Defoliant 2, 4-D 9