Witches' broom disease on cocoa in Rondonia, Brazil: basidiocarp production on detached brooms in the field

Fruiting of Crinipellis perniciosa was assessed in relation to various climatic factors using dead witches' brooms detached from cocoa, either suspended in the canopy or laid on leaf litter under cocoa. Induction of basidiocarp production occurred over approximately 60 days with rain. Basidiocarps were finally observed on about 85% of brooms in all samples examined and induction of fruiting required at least 17 rainy days, although brooms with a minimum age of 2 years produced basidiocarps about 25 days before brooms with a minimum age of 1 year. Groups of brooms showed distinct cycles of basidiocarp production, and up to 50% of fruiting occurred on dead, attached leaves, Fruiting was reduced on brooms on leaf litter and basidiocarps survived for less time than when brooms were suspended in canopy. Brooms were most productive with moderate amounts of wetness per day, and less than 4 h or more than 20h was inhibitory. No fruiting occurred at mean air temperatures higher than 30°C or lower than 20°C. The microclimate of the litter layer is discussed in relation to reduction of fruiting caused by pruning of brooms.