Screening maize germplasm for resistance against fusarium moniliforme and management strategy using neem biopesticides
Shitabule, Eveline Wanguba
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Maize is the most important cereal crop in Western Kenya, whole production is limited by many diseases such as ear rot and loses, can be up to 70%. Test were conducted in the laboratory to investigate the efficacy of neem extract (neemros) and in combination with Folicur on mycelial growth and conidia germination of F. moniliforme. Greenhouse and field experiment were done to investigate the efficacy of neemros on maize ear not caused by F. moniliforme. One 5 mm diameter mycelial plug from periphery of a 10 day old fungal culture was transfered asceptically to center of PDA plates amended with neemros 12.5g/l, 25g/l, 50g/l, 75g/l, 100g/l, neemros50 + Folicur 50, neemros 75 + Folicur 25 and neemros 25 + Folicur 12.5. The diameter of mycella was measured on the second, fourth, sixth, eight and tenth days after inoculation. Percent inhibition of mycelial growth was calculated. Maize variety H622 was planted in 21cm diameter pots. The effective concentrations of neemros (from in vitro tests) were prepared and sprayed on silk thus the treatments were; neemros 50g/l, 50g/l + Folicur12.5, Folicur12.5, Folicur100 and spray with distilled water (control) each treatment was replicated four times. At physiological maturity, the ears were harvested, percent rotting of kernels rated and F. moniliforme re-isolated from the kernels. Similar experiment was laid in the field at KARI-Kakamega. Results showed that treatments that had neemros and Folicur combined had 100% reduction on growth. Concentrations of neemros of 50g/l had the next highest inhibition percent (mean of 51%). Treatment that combined 50g/l neemros + Folicur12.5, gave the highest yield. The control had most the rot (mean of 17.5%) followed by neemros 50g/l and Folicur12.5 (mean of 12.5% for both). 50g/l had least re-isolations. From the field, yield loss was highest for neemros 50g/l (mean of 43%) and lowest for Folicur12.5 (mean of 19.4%). Re-isolation percentages and means for severity did not differ with treatments. Neemros showed suppressive effect on growth of F. moniliforme and a reduction in ear rot occurrence. Greenhouse and field experiments were done to screen maize germplasm for resistance against F. moniliforme. Thirty-six different maize germplasm, lines and varieties were disinfected and planted in sterilized inoculated soil, in pots. Controls were not inoculated. Re-isolation of F. moniliforme was done from the first nodes after 8 weeks. A similar experiment was laid in the field with natural inoculum at KARI Kakamega. At physiological maturity, the ears were harvested, evaluated for disease incidence, severity, yield, and F. moniliforme was re-isolated from kernels. Line SADVILA was most resistant and H513 was least, form the greenhouse experiment. E12 had most rot and yield loss. Maseno DC, PHb 3253 and ECAVL7 has least rot. ECAVL1 and PAN 5243 had severe rot. Fumonism B1 levels were significant ranging from 0 to > 1000ng/g in rotten maize samples and 0 to 555ng/g in clean samples. Varieties above identified with low levels of rotting; re isolation percentages and yield loss should be further improved for resistance.
- MST-Zoological Sciences