Grain Protectant Effects of Selected Weeds (Senna Occidentalis and Setaria Palmifolia) on Cowpea (Vigna Unguiculata (L.) Walp) Varieties

The search for effective and non-hazardous method of controlling insect and fungal pests of cowpea seeds during storage is currently trending in order to achieve food security. This research was carried out in the Crop Protection Laboratory of University of Abuja in 2021. The aim was to evaluate the effectiveness of Senna occidentalis (SO@0.5g/1g per 3 seeds) and Setaria palmifolia (SP@0.5g/1g per 3 seeds) powdered leaf extracts as protectants against Callosobrachus maculatus and fungal pathogens of cowpea seeds during storage.  An invitro experiment was set up in a CRD structure consisting of three cowpea varieties, two test plants at two different levels (0.5g and 1g) while two chemical protectants: Dress Force powder (5g) and Fluconazole tablet (50mg) per kg of seed were used as positive controls. Analysis of insect mortality within 24 hours showed that all treatments had similar insecticidal effects (F=1.05; P=0. 441) and varieties were equally susceptible to insect infestation. Dress Force pesticide had the highest mortality (77.8%) followed Sp@1g (50.0%). At 72 hours, insect mortality differed significantly among treatments (F=33.5; P<0.05). SO@1g was the most improved treatments having recorded 97.3% insect mortality after Dress Force (100.0%). Fungicidal effects of extracts showed that all treatments (chemical and plant extracts) suppressed the growth of Aspergillus niger, Fusarium and Penicillium in SAMPEA 19 seeds. All treatments inhibited the growth of only A. niger in SAMPEA-15 treated seeds; while only chemical treatments (Dress Force and Fluconazole) suppressed the growth of all fungal species in FUAMPEA-1 treated seeds. The optimal time for fungal inhibition among treatments was observed with 24 hours of exposure using A.niger as a reference point.  Dress Force had the highest zone of inhibition (7.4mm) followed by Fluconazole (3.53mm) and SO@1g (1.37mm) while the least inhibition was observed in S. palmifolia (0.23mm). This study has confirmed that the two test plants had insecticidal and fungicidal properties that could be used in the preservation of cowpea seeds during storage. However, S.occidentalis performed better than S. palmifolia. It may be exploited in the manufacture of protectants subject to further improvement. This would be a cheaper and safer source of making preservatives than the use hazardous chemicals.