Sorghum diseases prevalent in Ghana.

Field survey, screening trials and laboratory investigation were used to determine the prevalence of sorghum diseases in the major sorghum-growing climatic zones (Sudan, northern and southern Guinea savanna). Farmers\' fields were surveyed in 1997. Ten sorghum entries were evaluated under natural field conditions in 1997 and 1998 at Damongo for their reaction to foliar and panicle diseases while seed samples of field-harvested sorghum were assessed for fungal infection using the blotter method. Two main types of sorghum, viz. the early-maturing, brown-seeded, guinea or guinea-caudatum type and the late-maturing, photoperiod-sensitive, white-seeded, guinea or guinea-caudatum type were found in the sorghum-growing areas. The survey showed that sorghum was cultivated under a range of cropping systems in all possible crop mixtures. Grey leaf spot (Cercospora sorghi), oval leaf spot (Ramulispora sorghicola), zonate leaf spot (Gloeocercospora sorghi) and covered smut (Sporisorium sorghi) were prevalent in all the sorghumgrowing areas. Other diseases recorded were leaf blight (Exserohilum turcicum), sooty stripe (Ramulispora sorghi), grain mould (caused by a complex group of fungi), long smut (Sporisorium ehrenbergii), head smut (Sporisorium reiliana), rust (Puccinia purpurea) and rough leaf spot (Ascochyta sorghi). Anthracnose (Colletotrichum graminicola) occurred infrequently across the regions. Striga hermonthica was more prevalent in the two Upper regions than in the Northern Region. The sorghum entries varied considerably in their susceptibility to the field diseases, with severity mean scores ranging from 2.5 to 3.6. Eight species of fungi were recorded from seed samples. The occurrence of these varied with the sorghum entries, with the genera Fusarium and Phoma dominating, followed by Curvularia. Enquete sur le terrain, essais de depistage et investigation de laboratoire etaient faites pour determiner la prevalence de maladies de sorgho dans les zones climatiques principales (soudano-savane et savane guineenne du nord et du sud) cultivant le sorgho. L\'enquete etait menee en 1997 aux champs d\'agriculteurs. Dix varietes cultivees de sorgho etaient evaluees sous les conditions naturelles au champ en 1997 et 1998 a Damongo pour leur reactions aux maladies foliaires et aux maladies de panicules alors que les echantillons de graine de sorgho moissonnee de champ etaient evalues pour infection fongique en employant la methode de buvard. Deux types principaux de sorgho a savoir la maturation tot: graine-brune, guinee ou le type caudatum guineen et la maturation tardive: sensible a la photoperiode, graine-blanche, guinee ou le type caudatum guineen etaient rencontres dans les zones cultivant le sorgho. L\'enquete revelait que le sorgho est cultive sous les systemes de culture divers dans toutes les associations des cultures possibles. La tache a feuille grise (Cercospora sorghi), la tache a feuille ovale (Ramulispora sorghicola), la tache a feuille zonee (Gloeocercospora sorghi) et le couvert de charbon des cereales (Sporisorium sorghi) etaient en prevalence dans toutes les zones cultivant le sorgho. D\'autres maladies observees etaient la rouille des feuilles (Exserohilum turcicum) la rayure de suie (Ramulispora sorghi) la moisissure de grain (causee par un groupe complexe de fongus), le charbon long des cereales (Sporisorium ehrenbergii), le charbon de tete (Sporisorium reiliana), la rouille (Puccinia purpurea) et la tache a feuille rugueuse (Ascochyta sorghi). Anthracnose (Colletotrichum graminicola) se produit peu souvent a travers les regions. Striga hermonthica etait la plus en prevalence dans les deux Hautes regions que dans la Region du Nord. Les varietes cultivees de sorgho variaient considerablement en leur predisposition aux maladies du champ avec les resultats moyens de severite variant entre 2.5 et 3.6. Huit especes de fongus etaient observees d\'ehantillons de graine. L\'apparition de ceux-ci variait avec les genres Fusarium et Phoma dominant, suivi par Curvularia. Ghana Journal of Agricultural Science Vol. 40 (2) 2008: pp. 119-126