Epidemiology Of Witches' Broom (crinipellis Perniciosa (stahel) Singer) On Grafted Cocoa In Uruçuca
(Alves, Silvio André Meirelles)
Epidemiology of witches' broom (Crinipellis perniciosa (STAHEL) Singer) on grafted cocoa in Uruçuca, BA, Brazil.Witches' broom is the most important disease of cocoa, in the countrieswhere it occurs. In 1989, it was verified for the first time thepresence of the pathogen in the main producing area of Brazil. The lackof efficient control measures resulted, in the last years, in losses inthe production, changes in the use of the soil, sale of properties,decrease of the employment level and damages to the environment. Inview of the little knowledge on epidemic aspects of the disease in theconditions of the southeast of Bahia, the present work was elaboratedwith the following objectives: to study the gradient of the witches'broom infection in flushes and pods in grafted cocoa; to compare theeffect of genotypes and three treatments (half-yearly phytosanitation,monthly phytosanitation and monthly phytosanitation allied to fungicideapplication) in the control of the disease; to study the witches' broomtemporal progress, quantified in flushes and pods. Trials were carriedout in Uruçuca, BA, in area contends 16 different genotypes, adjacentan area with abandoned cocoa with high incidence of the disease. Theexperimental area was divided in three parts, which received thefollowing treatments: half-yearly phytosanitation, monthlyphytosanitation and monthly phytosanitation allied to fungicideapplication. At least once a month, flushes and pods with broom werecounted. Results showed the absence of clear evidence of the existenceof disease gradient. The levels of genetic resistance to the witches'broom of flushes and pods were not correlated to each other. There wasgood adjustment of progress of the disease to the monomolecular model.The smallest growth rates were obtained in the treatment with monthlyphytosanitation and fungicide application. The treatment that alliedphytosanitation and fungicide application presented significantdifference in the reduction of the percentage of witches' broominfected pods. The genotypes NO-34, NO-17 and NO-02 presented smallerpercentages of diseased pods, being significantly different from thegenotypes NO-24 and NO-13.
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