Bean common mosaic virus

Bean common mosaic virus is an infectious viral disease of beans. French bean (Phaseolus vulgaris) is the common natural host, but runner bean (P. coccineus) is also naturally infected.

Symptoms
Bean cultivars may be tolerant, sensitive or hypersensitive, but the kind of reaction depends greatly on the virus strain.

Tolerant cultivars
May show only slight narrowing of systemically infected leaves.

Sensitive cultivars
May show a reddish rugose mosaic in lower leaves, a rolling or curling mosaic with dark green areas along the main veins in the upper leaves and mottled or malformed pods. Severe stunting and black-root symptoms occur with typical strains at temperatures above 30°C (86°F) and with virulent strains at 20°C (68°F)and above ; the vascular necrosis often extends into surrounding stems and pods or leaves.

Hypersensitive cultivars
React with necrotic local lesions at normal temperatures and with black-root symptoms at high temperature; this type of reaction gives field resistance, is genetically dominant and is derived from the cultivar Corbett Refugee.

Control
Control of bean common mosaic virus includes the use of resistant seed varieties and buying seeds from reputable sources. Controlling the population of aphids near beans also helps to reduce chances of virus in bean plants.