Towards the identification of new sources of resistance to stem borer pests of maize in Ghana: Preliminary findings and matters arising

2020

English

Ensuring that the production of maize keeps pace with increasing demand requires that yield reducing factors such as infestation by lepidopteran stem borers are curbed. One of the ways to achieve this is through screening of maize germplasm to identify and promote the use of new sources of stem borer resistance for crop improvement. This study evaluated the susceptibility of 34 maize accessions to stem borer infestation at Bunso. Data on stem borer incidence was collected at the vegetative, flowering (tasseling) and post-flowering stages. The proportion of borer infested plants increased progressively from three weeks after germination (WAG) to plant maturity. Differences in the levels of infestation between accessions from three WAG to the late vegetative stage were not significant (P > 0.05). At harvest, however, significant differences (P < 0.001) in the level of stem borer infestation were observed between maize accessions. It was observed further that the percentage of infested maize plants was positively correlated (r = 0.791) with the number of internodes damaged per plant and negatively correlated with the number of days to 50 % flowering (r = -0.62). The number of stem borer larvae recovered per maize stem was positively correlated with the number of exit holes per stem (r = 0.740). Defining what stem borer damage parameters to include in an insect resistant maize breeding programme is vital to the success of such programmes. The implications of the findings of this study, which can be regarded as baseline, to the identification of sources of resistance to current and emerging lepidopteran pests of maize are discussed.

Kotey, D. A; Siamey, J.; Egbadzor, K. F.; Bissah, M. N.