ABSTRACT

investigation were carried out to test the potency of some plant

extracts for the control of cassava tuber rot caused by Botryodiplodia

acerina and Rhizopus oryzae which were isolated from rotted tissues of

cassava tubers obtained from local farms in Umudike. Extracts used were

obtained from four-plant materials-leaf and seed of Piper nigrurn, seed of

Afrarnorn urn melegueta and leaf of Ageraturn con zoides. The three

extracting solvents were, ethanol, water and petroleum ether. Extracts of

the four test plant materials were found fungitoxic both in vitro and in vivo

against the two pathogens tested. P. nigrurn seed extracts were the best

(99.2-100% and 7 1.1-100% for R. oryzae and B. acerina respectively)

followed by those of A. meleguela seed (28.9-100% and 49.7-100% for R.

oryzae and B. acerina respectively), A. conyzoides leaf and then P.

nigrurn leaf (0-100% for both R. oryzae and B. acerina) .The extracts were

more effective (0-10 rot index for both R. oryzac and B. acerina) in

controlling rot development by both pathogens in unwounded tubers

especially when they were applied before the inoculation with the test

pathogens. Solvent of extraction influenced the efficacy of the extracts. In

the in vitro test, ethanol ranked the best solvent followed by water and then

petroleum ether. Water extracts showed marked superiority (0,0,0-6 and 0-

10 rot index for A. conyzoides leaf, A. meleguela seed, P. nigrurn seed and

leaf respectively) over others by completely checking rot development in

cassava tuber in vivo irrespective of time of application. Hence water and

ethanol extracts of P. nigrurn seed and leaf, A. melegueta seed and A.

conyzoides leaf could be used successfully to control Botrydiplodia and

Rhizopus rot of cassava tuber in storage.