VIRUS ATTACK IN DANISH CULTURES OF SWEET PEPPER (CAPSICUM ANNUUM, L.) SPECIALLY CONCERNING TOBACCO MOSAIC VIRUS

To avoid virus infection TMV-resistant varieties are grown, but new TMV-strains found in European countries, are able to attack these varieties.

In Danish greenhouse cultures of pepper attack by cucumber mosaic virus (CMV) was found in a few cases, while TMV occured more frequently during a 2 year survey, the frequency being 5 per cent in sensitive varieties on average.

The tomato-, tobacco- and pepper-strains of TMV were found, the latter for the first time as a severe strain causing systemic necrosis in the indicator plant Capsicum frutescens.

TMV-strains were diagnosed by the ELISA-method using TMV-immuno reagents against a Danish tomato and tobacco strain and 2 Dutch pepper strains 8 and 11.

The pepper TMV-strains infect systemically Nicotiana clevelandii, N. tabacum 'Samsun' and 'White Burley', causing visible symptoms only in N. clevelandii.

All the TMV-strains caused deformed fruits in the virus sensitive variety 'Superset', the tomato- and pepper strain 11 producing milder symptoms, the tobacco- and the pepper-strain 8 more vigorous symptoms.

TMV-tomato strain infection was found in 8 of 23 commercial seed samples. TMV-infection occurred in all seed samples from artificially infected pepper plants regardless of the used TMV-strain and harvest method.

Resistance against the tomato- and the tobacco TMV-strains was shown in most of the pepper varieties resistant until now, while resistance against the pepper strains was found only partly in one variety, and only against the pepper strain 11.

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