Nematodes and fungi associated with roots of papaya Carica papaya L cv Solo in Jamaica and the influence of plastic mulches on their occurrence and plant vigour 91

A survey of papaya (Carica papaya L.) cv. Solo farms was conducted in Jamaica to determine the abundance of rhizosphere-soil-inhabiting phyto-nematodes and root-inhabiting fungi. Field trials were conducted to evaluate the effects of pre- and post-plant mulching of soil with clear and black plastic sheeting on the abundance of these organisms, shoot growth, and root rot. The most abundant phyto-nematodes were Rotylenchulus spp and mean farm population densities ranged from 12 to 5600 nematodes 100 cm-3 soil. Fusarium solani and Macrophomina phaseolina, the more frequently occurring fungi, were detected in 71 and 29% of the farms, respectively. Soil mulched with black plastic for two months before planting stimulated papaya shoot growth. The three-month-long post-plant treatment caused no adverse effects on papaya growth, and resulted in significantly lower soil nematode population densities and less root necrosis at three and five months after the start of mulching, respectively, than the control. The percentage occurrence of fungi in roots was not affected by any treatment.