Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 14: 775 - 781. Published February 2, 2009.
Mechanism of reaction of cowpea varieties to Alectra vogelii (Benth) and its control
ABSTRACT
Objective: To study the mechanism of reaction of cowpea varieties to Alectra vogelii and how this impacts on the control of the parasitic plant.
Methodology and results: In the first trial eighteen cowpea varieties were evaluated for resistance/tolerance to A. vogelii in a randomized complete design. The second trial was made up of 25 herbicide treatments compared to hoe – weeding at 3 and 6 weeks after sowing (WAS) and untreated check using cowpea variety SAMPEA – 7. The third trial was laid out in a split – plot design, with three cowpea varieties (B301, TN93 – 80 and VITA – 3) with three levels of N and P in the main and sub–plot treatments, respectively. The results showed that variety B301 and the derivatives of its crosses with IT84S – 2246 – 4 (IT90K – 59 and IT90K – 76) did not support Alectra emergence, while SAMPEA – 7 and TVX3236 supported high infestation with consequent high susceptibility to the parasite. Pre – emergence herbicide application of a mixture containing pree (metazachlor + antidote) followed by imazaquin at 0.18kg a.i/ha resulted in significantly lower number of plants infected by the parasite. Highest level of N (60kg N/ha) significantly reduced the number of plants infected by the parasite at harvest while grain yield increased with P levels.
Conclusion and application of findings: This investigation showed that variety B301 and the derivative of its crosses with IT84S – 2246 – 4 (IT90k – 59 and IT90k – 76) did not support the emergence of Alectra, and thus exhibits resistance. Cowpea variety VITA – 3 has potential to tolerate Alectra, while higher dose of N (³60kg/ha) is detrimental to cowpea grain yield. Farmers can reduce cowpea infection by Alectra when pre–emergence herbicide mixtures containing pree (metazachlor + antidote) are applied followed by post–emergence application of imazaquin at 0.18kg a.i/ha.
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