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Pathogens can spread through the air, water, or on insect and animal vectors (hosts). Dutch elm disease was spread by elm bark beetles, yet the tree mortality was caused by a pathogen. [4] Chestnut blight is a fungus spread through wind dispersal and rain splatter; the blight traveled up to 50 miles in a year by natural means. [5]
Epidemiology is the study of factors affecting the outbreak and spread of infectious diseases. [10] A disease triangle describes the basic factors required for plant diseases. These are the host plant, the pathogen, and the environment. Any one of these can be modified to control a disease. [11]
Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). [1] Organisms that cause infectious disease include fungi , oomycetes , bacteria , viruses , viroids , virus -like organisms, phytoplasmas , protozoa , nematodes and parasitic plants . [ 2 ]
Plants can show many signs or physical evidence of fungal, viral or bacterial infections. This can range from rusts or molds to not showing anything at all when a pathogen invades the plant (occurs in some viral diseases in plants). [9] Symptoms which are visible effects of diseases on the plant consist of changes in color, shape or function. [9]
An infectious disease agent can be transmitted in two ways: as horizontal disease agent transmission from one individual to another in the same generation (peers in the same age group) [3] by either direct contact (licking, touching, biting), or indirect contact through air – cough or sneeze (vectors or fomites that allow the transmission of the agent causing the disease without physical ...
Wilt diseases in woody plants tend to fall into two major categories, those that start with the branches and those that start with the roots. Those that start with the branches most often start with pathogens that feed on the leaves or bark, those that start with the roots start with wounding or direct entry by the pathogen into the roots, some ...
Fusarium wilt (Panama disease) is the most serious disease of banana, threatening 80% of the world's banana production, most of which is planted with the susceptible Cavendish varieties. Bananas are a staple food in the diet of millions throughout the subtropics and tropics, and the spread of Panama disease could have devastating effects on ...
Cross-species transmission is the most significant cause of disease emergence in humans and other species. [citation needed] Wildlife zoonotic diseases of microbial origin are also the most common group of human emerging diseases, and CST between wildlife and livestock has appreciable economic impacts in agriculture by reducing livestock productivity and imposing export restrictions. [2]