Some bacterial diseases of plants

disease causative agent hosts symptoms and signs additional features

Granville wilt Pseudomonas solanacearum tobacco, tomato, potato, eggplant, pepper, and other plants stunting, yellowing, and wilting of parts above ground; roots decay and become black or brown occurs in most countries in temperate and semitropical zones; causes crop losses of hundreds of millions of dollars

fire blight Erwinia amylovora apple and pear blossoms appear water-soaked and shrivel; spreads to leaves and stems, causing rapid dieback first plant disease proved to be caused by a bacterium

wildfire of tobacco Pseudomonas syringae tobacco yellowish green spots on leaves wildfire of tobacco occurs worldwide; causes losses in seedlings and field plants

blight of beans Xanthomonas campestris beans (common blight) yellowish green spots on leaves most phytopathogenic xanthomonads and pseudomonads cause necrotic spots on green parts of susceptible hosts; may be localized or systemic

Pseudomonas syringae beans (brown spot) small water-soaked spots on lower side of leaves enlarge, coalesce, and become necrotic

soft rot Erwinia carotovora many fleshy-tissue fruits—e.g., cabbage, carrot, celery, onion soft decay of fleshy tissues that become mushy and soft occurs worldwide; causes major economic losses

crown gall Agrobacterium tumefaciens more than 100 genera of woody and herbaceous plants initially a small enlargement of stems or roots usually at or near the soil line, increasing in size, becoming wrinkled, and turning brown to black the conversion of a normal cell to one that produces excessive cell multiplication is caused by a plasmid (a small circular piece of DNA) carried by the pathogenic bacterium

aster yellows Mycoplasma-like organism (MLO) many vegetables, ornamentals, and weeds chlorosis; dwarfing malformations greatest losses suffered by carrots; transmission by leafhoppers

citrus stubborn disease Spiroplasma citri (MLO) citrus and stone fruits and vegetables chlorosis, yellowing of leaves, shortened internodes, wilting first MLO pathogen of plant disease cultured