The swarm of locusts proved to be a blight upon the land. The denial of her scholarship application effectively blighted her dream of attending her first-choice college. It can also take on the meaning of something that is in a state of decay or ruin, such as in the phrase "urban blight." In the adjective use, if something is blighted, it is severely damaged or destroyed. In botany, blight can also refer to a fungal plant disease. (n.) disease, devastation, poison, (v.) spoil, ruin, damage, destroy, halt, frustrate, decay
For greenhouse production, early blight has been reduced by as much as 50% by covering houses with UV-absorbing vinyl film.(n.) a destructive force that inflicts severe damage (v.) to frustrate or end hope. In the fall, remove or bury infected plants to reduce the likelihood of the pathogen surviving into the following year. Apply plastic or organic mulch to provide a barrier between contaminated soil and leaves. 
Carefully prune infected leaves, take care to wash and sanitize tools as you prune, and dispose of infected leaves far away from your tomato production areas. Staking will also reduce contact between the leaves and spore-contaminated soil. Stake or trellis and prune the plants to increase airflow around the plant and facilitate drying. Use drip irrigation instead of overhead irrigation to keep foliage dry. Avoid working in plants when they are wet from rain, irrigation, or dew. Do not over-fertilize with potassium and maintain adequate levels of both nitrogen and phosphorus. Fertilize properly to maintain vigorous plant growth. Control susceptible weeds such as black nightshade and hairy nightshade, and volunteer tomato plants throughout the rotation. Rotate out of tomatoes and related crops for at least two years. Use pathogen-free seed, or collect seed only from disease-free plants. Spores can be spread throughout a field by wind, human contact or equipment, resulting in many reinfection opportunities throughout a growing season. Spores infect plants and form leaf spots as small as 1/8 inch diameter in as little as five days. BLIGHT DEFINITION FREE
Spores (reproductive structures) can germinate between 47° and 90° F and need free water or relative humidity of 90% or greater.
Lower leaves become infected when they come into contact with contaminated soil, either through direct contact or when raindrops splash soil onto the leaves. The pathogen also survives on tomato seed or may be introduced on tomato transplants. The early blight pathogens both overwinter in infected plant debris and soil in Minnesota. The pathogen is most likely to spread with any weather or heavy dew, or when relative humidity is 90% or greater. Disease develops at moderate to warm (59 to 80 F) temperatures 82 to 86 F is its optimum temperature range. Both pathogens can infect tomatoes, potatoes, peppers, and several weeds in the Solanaceae family including black nightshade ( Solanum ptycanthum), and hairy nightshade ( Solanum physalifolium). Early blight can be caused by two closely related species: Alternaria tomatophila and Alternaria solani. Fruit spots are leathery and black, with raised concentric ridges. Fruit can be infected at any stage of maturity. Stem infections on older plants are oval to irregular, dry brown areas with dark brown concentric rings. If the infection girdles the stem, the seedling wilts and dies. The stem turns brown, sunken and dry (collar rot). Seedling stems are infected at or just above the soil line. 
Severely infected leaves turn brown and fall off, or dead, dried leaves may cling to the stem.The tissue around spots often turns yellow. Larger spots have target-like concentric rings.Leaf spots are round, brown and can grow up to 1/2 inch in diameter. Initially, small dark spots form on older foliage near the ground.Tomato stem with brown lesions with concentric circles Identification
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