Seasonal Effect on the Yield, Incidence and Damage by Some Pests of Jute Mallow (Corchorus olitorius L.) in Nsukka

Abstract

Objective: This study investigated the seasonal effects on the yield, incidence, and insect damage of jute mallow (Corchorus olitorius L.) in Nsukka. The experiment aimed to identify the specific pests associated with different planting cycles and assess how seasonal variations influence crop growth and vulnerability to infestation.

Method: The experiment compared early- and late-planting seasons to assess variation in growth and pest pressure. Data were collected on various parameters, including leaf number, stem girth, flowering rate, and specific indicators of insect damage, such as leaf perforations and the total number of pests per plant. Observations were recorded at 4, 6, and 8 weeks after planting (WAP) to determine significant interactions between season and crop variety.

Result: The results identified Acrea terpsicore (leafworms) and Podagrica spp. (flea beetles) as the primary early-season pests, while Zonocerus variegatus (variegated grasshopper) dominated the late season. Early-season crops produced significantly more leaves at 8 WAP and wider stem girths at 6 and 8 WAP. However, these early crops also suffered significantly higher damage, characterised by more leaf perforations at 4 and 8 WAP, more non-perforation leaf damage at 4, 6, and 8 WAP, and a higher percentage of damage incidence at 6 and 8 WAP compared to late-season plantings.

Conclusion: The study concludes that while the early season favours growth parameters such as leaf production and stem width, it also experiences substantially higher pest pressure and damage incidence. Significant interactions between season and variety regarding flowering, leaf count, and perforation levels suggest that variety selection must be tailored to the specific planting season. These findings provide a basis for developing season-specific pest management strategies for jute mallow cultivation in the Nsukka region.