Abiotic Agents Associated With Forest Diseases Abiotic Agents

Abiotic Agents Associated With Forest Diseases

Abiotic Agents • Any non living factor that causes disease i. e. § § § Air pollution Frost Winter injury Drought and flooding Nutrient deficiency Salinity, lightning etc.

Air Pollution Types of Air Pollutants Primary Pollutants Secondary Pollutants Acid Rain Excess Nitrogen

Primary & Secondary Pollutants Primary Pollutants • Sulfur Dioxide - SO 2 • Hydrogen Fluorides – HF Secondary pollutants • Ozone O 3 • NO + O 2 = NO 3 • NO 2 and O 3 in the atmosphere = SMOG • PAN - Peroxyacetyl nitrate

Secondary Pollutants Acid Rain • SO 2 + H 2 O = H 2 SO 4 • CO 2 + H 2 O = H 2 CO 3 Excess Nitrogen • NO + H 2 O = NHO 3

Frost Late Spring Frost • Occur during subfreezing temperatures in the growing season • Common , difficult to detect • Young tender shoots droop and go dark, then fall off. Early Autumn Frost • Less common • Occur prior to hardening of shoots and buds Or Buds don't not completely set • Lead to some extent shoot damage.

Winter Injury • • Extreme temperature fluctuation make such trees much more susceptible to such injury. Reddening and browning of foliage Dieback of shoot tips Bark injury also called sunscald

Water Drought • Wilting, • Slower growth, • Twig and branch dieback Flooding • Insufficient O 2 • Rootlet mortality • Attack by oomycetes

Nutrient Deficiency Nitrogen • Interveinal chlorosis in hardwoods. • Slow growth, stunted leaves. • Chlorosis >older growth. Iron • Chlorosis • Symptoms > newest foliage • Alkaline soil is cause.

Salinity Effects plants via two routes: Through The Soil • Na+ • Leaf scorch • Premature defoliation • Dieback Salt Spray • Cl- • Needles brown at the tips, drop early. • Hardwoods- buds die, twigs die back

Chronic Wind Stress • Root damage Due to rocking of trees in the wind • crown shyness Due to collisions between branches in the crown of two trees • crown damage Due to ice storms

Lightning • Causes mortality of tops, branches or whole trees • Creates large wounds for decay, and often leads to a slow death • Bark splitting and outer sapwood blowing off the surface.