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Effect of witch's broom disease on the phenology of Cupuassu

The cupuassu (Theobroma grandiflorum [Willd. ex Spreng.] Schum.) is expanding rapidly as a fruit crop in Brazilian Amazonia. The principal limiting factor is witch's broom disease, caused by Crinipellis perniciosa (Stahel) Singer, the only economic control for which is phytosanitary pruning. The phenology of 10 cupuassu plants grown in a fertilized monoculture on a nutrient poor Oxisol near Manaus, Amazonas, Brazil, was studied from May 1987 to December 1990. The number of flowers was reduced by the witch's broom and the pruning, but the duration and periodicity of flowering were not much affected. The mean number of fruits per tree fell from 36 in 1987 to 6 in 1989 as a result of the disease and its control, but recovered to 15 in 1990. Fruiting was slightly earlier and its duration was shorter than in a previous study, possibly due to the fertilization or the genotype studied. Fruit set fell from 1.4% in 1987 to 0.5% in 1989 and recovered to 1.8% in 1990, suggesting recovery of the plants. Leaf and shoot flushing and leaf fall increased markedly as a result of the disease in late 1987 and 1988 and were markedly reduced by pruning in 1989-90. Phenophases were not much affected by witch's broom disease and its control, although the number of flowers and fruits were.

Theobroma grandiflorum; Crinipellis perniciosa; phytosanitary pruning; flowering; fruiting

Instituto Nacional de Pesquisas da Amazônia Av. André Araujo, 2936 Aleixo, 69060-001 Manaus AM Brasil, Tel.: +55 92 3643-3030, Fax: +55 92 643-3223 - Manaus - AM - Brazil