Jornal de Patologia Vegetal e Microbiologia

Abstrato

Effects of Plant Extracts and Synthetic Fungicides on the Radial Growth of Phoma oryzae on Rice (Oryza sativa L.) in Some Rice Growing Areas of South Eastern Nigeria

Iwuagwu CC, Onejeme FC, Ononuju CC, Umechuruba CI and Nwogbaga AC

An in-vitro experiment was conducted at the Plant Pathology Laboratory of National Root Crop Research Institute, Umudike, Abia State. The aim of the experiment was to test the effect of some plant extracts and synthetic fungicides on the radial growth inhibition of some fungi isolated from rice plant materials sampled from rice growing areas of South Eastern Nigeria. These pathogenic fungi cause serious yield as well as economic losses in rice production in the region. The treatments were arranged in a Completely Randomized Design (CRD) with three replicates. The experiment was conducted using both water and alcohol extracts of test plants and the synthetic fungicides (Benomyl and Apron plus). These were tested on the radial growth of three fungal pathogens namely; Fusarium moniliforme. The 3 mm disc of each test fungus was placed in the center of 9 cm Petri dish containing 10, 15, 25% of the plant extract mixed thoroughly in a molten PDA. The crude aqeous extract of Azadiractha indica gave the highest mycelial growth inhibition of F. moniliforme (52%) at extract concentration of between 10-30% while ethanol extract of Garcinia cola had the best mycelial growth inhibition of Fusarium moniliforme 50%. Aqeous extract of Azardiractha indica (neem) had the highest mycelial growth inhibition of Helminthosporium oryzae up to 52.80% while Zinginber officinale (Ginger) in ethanol extract gave the best inhibiting effect in the same organism. Also aqeous extract of A. indca had the best inhibitory effect (60.90%) in Phoma oryzae while Piper guineensis (Alligator pepper) performed best in radial growth inhibition of Phoma oryzae (69.30%) with ethanol extract. The plant extracts were as effective as the synthetic fungicides in inhibiting the radial growth of the test fungi. Therefore, extracts of the test plant materials which are readily available to the farmers should be used rather than depending on the synthetic fungicides which are not always available and expensive for rice farmers.