University of California

Botrytis stem rot of tuberous-rooted begonia


C. M. Tompkins

Publication Information

Hilgardia 19(13):401-410. DOI:10.3733/hilg.v19n13p401. February 1950.

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A stem rot of Begonia tuberhybrida Voss is prevalent in greenhouses at Capitola and on the San Francisco peninsula.

Principal environmental factors favoring the disease are relatively cool, foggy weather, overwatering, and crowding of the plants. Disease symptoms consist of dark-brown, watersoaked, occasionally sunken and shriveled, irregular-shaped lesions which usually occur at or near the base of the main stem of the plant. Lesions may also develop at some distance above the soil line, at nodes or internodes, and may coalesce to form larger lesions. In advanced stages, the internal tissues are completely invaded, the stem breaks at the lesion site, and the top of the plant falls. Infection may also occur on the axils of leaves and through leaf scars and growth cracks caused by heavy nitrogenous fertilization.

The causal organism has been identified as Botrytis einerea Pers. Its pathogenicity has been established.

The disease may be controlled by removing all debris, excising all infected areas, and painting them, as well as leaf scars, wounds, and growth cracks, with Ziram (Zerlate) paste. This process is repeated daily from midseason until the seed is harvested. Hairystemmed varieties are generally more resistant to infection than varieties with smooth stems and few hairs.

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Tompkins C. 1950. Botrytis stem rot of tuberous-rooted begonia. Hilgardia 19(13):401-410. DOI:10.3733/hilg.v19n13p401
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