4.4.1
REACTION OF CACAO GENOTYPES TO INOCULATION WITH CRINIPELLIS PERNICIOSA IN BAHIA, BRAZIL

EDMN LUZ, SDVM SILVA, PSB ALBUQUERQUE, JL PIRES, KP GRAMACHO and JL BEZERRA

CEPLAC/CEPEC, Cx Postal 07, Itabuna, Bahia, 45600-000 Brazil

Background and objectives
Severe losses and abandonment of plantings of Cacao have occurred in Bahia, Brazil due to witches' broom disease, caused by Crinipellis perniciosa. Possible strategies for the management of Cacao in the presence of witches' broom include integrated management methods: phytosanitation, the use of resistant plant materials, chemical and biological control. Since all forms of control applied to very susceptible plants are useless, the search of resistant cultivars is fundamental for a successful and durable disease control program. Therefore a screening project to detect resistant material was undertaken.

Materials and methods
In 1993 an assessment of progenies of open-pollinated clones from the CEPLAC germplasm collection was begun. 112 plants of each progeny at the F-1 or F-2 flushing phase, divided in four replications of 28 plants each, were inoculated using a belt system [1] with 75,000 basidiospores/ml. After inoculation, all plants were incubated in a moist chamber for 24 h to allow for basidiospore penetration and colonization. Symptoms were evaluated 60 days after inoculation. So far 204 progenies have been assessed, using Catongo as a standard susceptible cultivar and SCA 6 and SCA 12 as resistant standards.

Results and conclusions
53 progenies were selected as resistant. They belong to the series AB(1), CA(1), CAB(16), CC(1), CCN(1), CEPEC(6), CHUAO(1), CJ(1), CSUL(1), EEG(2), EET(4), ICS(2), IMC(1), MA(2), OC(1), RB(2), SC(1), SCA(2), SGU(2), SIAL(2), SIC(2) and TSA(1), originating mainly from the Amazon basin. These results confirm that Cacao populations do present different reactions to the pathogen, demonstrating that a breeding programme for resistance is feasible.

References
1. Frias GA, Purdy LH, Schmidt RA, 1995. Plant Disease 79, 787-791.