CO-LATERAL HOSTS OF CRINIPELLIS PERNICIOSA IN BAHIA, BRAZIL
JL BEZERRA and OC DE ALMEIDA
CEPLAC/CEPEC/SEFIT Cx. Postal 07, Itabuna, Bahia, Brazil. 45600-000
Background and objectives
The fungus C. perniciosa (Stahel) Singer was found for the first time in Bahia, Brazil, in 1989, causing an outbreak of the dread disease known as cacao witches' broom. Since then the pathogen spread throughout cacao plantations of Bahia causing enormous economic and social losses in all localities where cacao was grown in the state. Aiming to a better understanding of the disease that could generate more efficient control measures, studies on the pathogen biology are under course.
Materials and methods
Samples of plants with witches' broom symptoms were brought to laboratory for direct examination of hyphae with clamp-conections (squash mounts and cross sections of broom tissues) and for isolation of C. perniciosa in selective medium (PDA+0.01% benomyl). Part of each sample was hung in moist cabinets under controlled conditions of light, temperature and humidity to induce basidioma formation. Identification of the fungus was based on the appearance of colonies, basidioma morphology and types of hyphae and basidiospores.
Results and conclusions
These studies have showed that the fungus is able to infect and survive on other hosts of the families Sterculiaceae (5 spp.), Solonaceae (10 spp.) and Malpighiaceae (1 spp.). Crossing inoculation with these colateral hosts showed that inoculum from some of them can infect cacao and the other way round . The importance of these hosts to the biology of the fungus and to the epidemiology of the disease are yet to be analysed. A solanaceous host was found constantly infected outside the range of cacao growing areas of Brazil and, another one (Solanum paniculatum), is extremely susceptible to the pathogen which in this case, acts like a mycoherbicide.