Fungal organisms associated with common tropical weeds in Choba Rivers State Nigeria

Resumo

The research was conducted to investigate fungal species associated with common tropical weeds in Choba, Rivers State of Southern Nigeria. Weed samples were collected from plots previously cropped with maize, soybean, cassava, aerial yam and plantain at the University of Port Harcourt, Teaching and Research Farm, Choba, Nigeria. The samples were chopped into pieces (5 mm), sterilized in 2% of sodium hypochlorite (NaOCl) solution for 2 mins, rinsed in three changes of sterile distilled water and
thereafter placed on potato dextrose agar (PDA) and incubated at 28 ± 2°C in complete darkness for 5 days. Repeated sub-culturing was done to get pure cultures. These were identified microscopically and morphologically in line with standard techniques. A total of thirty-five weeds species, comprising of twenty-seven broadleaves, five grasses and three sedges were collected from the plots. Three fungal pathogens namely; Aspergillus spp, Fusarium sp, Penicillium sp known to produce toxins (aflatoxin, fumonisin and patulin, respectively), were isolated from the weed samples. Common weeds such as Cyperus esculentus, Phyllanthus amarus var niruri and Panicum maximum were all associated with the commonly isolated fungal pathogens. These weeds were well distributed across plots and therefore could serve as alternate host in the field and also pose serious risk on crop production and quality.