Evaluation Of Cassava Cultivars And Intercropping With Legumes As An Integrated Nematode Pest Control Strategy In Cassava (Manihot Esculenta Crantz) Production

ABSTRACT

These studies on evaluation of cassava cultivars and intercropping with legumes as an

integrated nematode control strategy in cassava production were carried out as

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greenhouse/microplot and field experiments. Of the 200 cultivars screened for resistance

to Meloidogyne spp., only 76 survived and from this lot only 3 lines 77/227, TMS30572

and 73/222, showed any resistance while 7 others namely NR8082, 75.668, 73/238

(Egbenegbe), 73/295, 73/118, 75740(Panya), 82/00661 and 73295B were tolerant. All the

other cultivars tested were susceptible. The second experiment, to determine the

economic threshold level of the root-knot nematode M. javanica populations on two

cassava varieties, showed that, with the exception of the control plants, the root-knot

nematode damage was obtained at all levels of the inoculum used and the root-knot

nematode populations had no significant effect on the aerial growth parameters like leaf

and stake weights. The two cassava varieties differed significantly in the final nematode

population in their roots. The economic threshold level was identified as an initial density

of 500eggs/plant. The lower pest values obtained for TMS30572 with increase in

inoculum density further confirmed it to be resistant to M. javanica.

Intercropping four cassava varieties with four legume types in microplots revealed that

nematode at both levels used, (0 and 1,000 eggs/plant) had no significant effect on

growth and yield of the cassava but amongst sole and legume-intercropped cassava

cultivars, significant differences were obtained. The feeder roots and stake/stem weights

of the sole cassava varieties were significantly higher (p>0.05) than their intercropped

mixtures with legumes. The highest tuber yield values were observed for NR8083 planted

sole (630g/plant) followed by TMS30572 intercropped with bambaranut (537g/plant).

Nematode-treated plants were significantly affected when they were destructively

sampled for damage symptoms on the cassava. Though no significant effect was

observed on yield, the significant nematode damage effects on the cassava indicate that

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the root-knot nematodes affect the outward appearance, the shelf life and storability of

the cassava products. The productivity of the legumes under cassava was significantly

different (p