Etiology of the false Broomrape in the tobacco (Nicotiana tabacum L.) in the central region of Cuba

False Broomrape, which is a disease affecting tobacco plants (Nicotiana tabacum L.), is increasing its incidence to the central provinces of the country. The symptoms are expressed by root-tumours that can be accompanied or not by plant stunting and dwarfing. An element hindering the control of this disorder is due to its causal agent is still unidentified. The aetiology nature could be biotic or abiotic. The aim of this work was to determine the aetiology nature of false Broomrape disease that affects tobacco plantations in the central provinces of the country. An experiment was carried out to establish the presence of the causal agent on the tobacco plantation soils affected and to determine its biotic or abiotic nature. The rhizospheric soil of the tobacco plants affected was used in the three treatments of this experiment. One treatment was based on sterilizing the soil and keeping plants at 30 degrees C. Some plants were sown on no sterilized soil, one group kept at 30 degrees C and the other at 18 degrees C, being the other two treatments. These tests were complemented with a comparative histological study of the radical systems of healthy and sick plants. Only the plants sown on no sterilized soil and kept at 30 degrees C developed the disease. The histological study revealed that the agent acts at specific root sites. It has been concluded that false Broomrape is caused by a biotic agent living on tobacco plantation soils where the disease is present.