Sorghum head bug infestation and mould infection on the grain quality of sorghum in northern Ghana

Abstract

Sorghum (Sorghum bicolor) panicle is reported to be attacked by a myriad of insect pest species, whose infestation predisposes the grains to fungal infection, thereby compromising their quality. A complex of bugs has been reported to infest sorghum, thereby affecting quality of grains in West Africa. The objective of this study was to investigate the effect of head bug (Eurystylus oldi (POPPIUS) infestation and mould infection on sorghum grain quality. An experiment consisting of eight sorghum breeding lines (two parental checks and six F8 derivatives), was carried out in fields at three Agro-ecological Zones (Nyankpala, Damongo and Manga) in Northern Ghana. Results showed that damage caused by head bug populations per panicle were not significant (P>0.05). Head bug damage was, however, found to be highly correlated with panicle grain mould ratings (PGMR) at all three locations. This points to the significant roles head bug damage plays in fungal infection of sorghum grains. The derivatives, on the other hand, suffered less PGMR than the compact headed Kapaala, across the three locations. The three dominant fungi isolated at Manga and Nyankpala included those of the genera Curvularia sp. (31.6 and 31.4%, respectively), Fusarium sp. (22.3 and 27.6%, respectively) and Thielaviopsis sp. (20.3 and 20.9%, respectively). At Damongo, Fusarium sp. (29.6%), Curvularia sp. (23.6%) and Mucor sp. (17.2%) were dominant. Grain quality, in terms of head bug and mould damage ratings, showed the following lines emerging superior at Manga (SARSORG-MRG-2011-3, SARSORG-SBG-2011-5 and SARSORG-SRG-2011-6), at Damongo (SARSORG-TRG-2011-1, SARSORG-SBG-2011-5 and SARSORG-MBG-2011-4) and at Nyankpala (SARSORG-MBG-2011-4, SARSORG-MRG-2011-3 and SARSORG-TRG-2011-1) and; thus suggest they may possess some desirable traits for which they could be selected for further improvement.

Key Words: Curvularia, Eurystylus oldi, Sorghum bicolor