VIRUSES IN BEGONIA TUBERHYBRIDA CV. MULTIFLORA

Many varieties of the genus Begonia have been grown in Belgium for more than 100 years on a rather large scale, especially in the region of Ghent. Two main types are grown outdoors, B. tuberhybrida cv. grandiflora types that are multiplied by seed and B. tuberhybrida cv. multiflora, that are multiplied by cuttings derived from corms. Of these multiflora types that are propagated vegetatively, one could easily conclude from symptoms that plants of this type are approximately 100% virus infected. Thus, for the past several years, we have grown them in a field separate from the grandiflora.

Hot water treatment did not cure the infected plants (Welvaert, 1954) and research on meristem-tip culture has only started so some growers have tried for several years to multiply the multiflora varieties by seed. Unfortunately, few if any seeds are produced and those plants that are obtained from seed are not uniform.

Literature on virus diseases of Begonia is in general not extensive and although viruses have been isolated earlier from Begonias, only occasionally is the type of variety of Begonia mentioned. Noordam (1952) reported that tomato spotted wilt virus was transmitted to 10% of the plants and this report has been cited by Smith (1959) and Klinkowski (1968). Tobacco rattle virus was isolated by Brierley and Travis (1958) from Begonia but they did not mention the variety or the group of Begonia. Semal (1960) reported the isolation of cucumber mosaic virus and possibly a mixture of viruses from plants of 'grandiflora' and 'multiflora'. Welvaert (1971) isolated a cucumber mosaic virus strain similar to the Ranunculus type of Devergne, from the Begonia variety R. Galle. Price (1940b) stated that mechanical infection of a tobacco ringspot virus could cause disease symptoms similar to strains of CMV.