De krul- of heksenbezemziekte van Crotalaria

Summary

The curl-disease or witches' broom of Crotalaria was first described in Indonesia bySchwarz in 1927. In 1931 and 1938 what was apparently the same disease was recorded in the U.S.A. byCook and byJohnson & Lefebvre. The last two investigators proved that the disease was due to a virus. In the present investigation, successful transmissions of the virus have been obtained by a modified grafting method and by using the dodderCuscuta australis R. Br.

The disease is characterized by stunting of the plants, by mottling, malformations and atrophy of the leaves, and by excessive branching, giving a witches' broom appearance. Diseased plants do not form seeds, though onCrotalaria striata andC. usaramoensis inflorescences are found. In these plants several types of malformation lead to sterility and in some instances to the production of seedless „pseudo-pods”.

In Bogor (Java), witches' broom has been recorded onCrotalaria usaramoensis, C. striata, C. juncea andC. anagyroides, so far without causing significant economic losses. Cross inoculations by grafting have shown that the witches' broom disease of the four mentioned Crotalaria-species is probably caused by the same virus or virus complex.

Control of the disease has not been found necessary. Nevertheless it is advisable, especially in seed plantations, to remove and destroy diseased plants periodically in order to prevent further spread.