Foliar anthracnose, caused by Colletotrichum sublineolum, is a major disease of sorghum in Nigeria. Pathogenic diversity was studied among foliar isolates of C. sublineolum collected from sorghum cultivars in farmers ®elds in the Sahel, Sudan, northern Guinea and southern Guinea zones of Nigeria during the 1997 crop season. For the study a total of 50 isolates were identi®ed based on typical symptom types and cultural characteristics. On the basis of growth in culture and morphological characteristics, the isolates were classi®ed into nine morphological groups (MGs). Pathogenicity tests were done on a set of known sorghum differential lines by inoculating pot-grown seedlings in a greenhouse. On the basis of disease reaction and disease severity scores on the differential lines, the 50 isolates were classi®ed into seven pathogenic groups (PGs). Sixteen representative isolates of the MGs and the PGs were further evaluated for virulence and aggressiveness on the differential lines and were classi®ed into ®ve distinct groups using the centroid method of cluster analysis. The existence of ®ve races of C. sublineolum in major sorghum growing zones of Nigeria is suggested.

Hassan M.A., Chindo P.S., Marley P.S., Alegbejo M.D. (2010) and sawdust (SD), for the management of root knot nematodes, Meloidogyne spp., on tomato. Organic wastes were applied at the rate of 15, 30 and 45 metric tons per hectare. Furadan (3G) was applied at the rate of 16, 32 and 64 kg/ha and non-amended plots served as control. The experiment was laid out in randomized complete block design (RCBD). Four weeks old tomato seedlings (cv. Roma VF) susceptible to root knot nematodes were transplanted at a number of eight seedlings per plot of 2 m × 1 m with 45 cm spacing between stands. Fertiliser application, weeding, irrigation and other practices were done as recommended. The results showed that RD treatment gave the significantly (P = 0.05) highest reduction in the nematode population compared to nonamended treatment. It resulted in a significant (P = 0.05) increase in the yield of tomato by 17-100% for RD, 13-84% for SD and 21-63% for RH.

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ABSTRACT. Anthracnose caused by Colletotrichum graminicola remains the most important foliar disease of sorghum in West and Central Africa. This paper describes the advances made in sorghum anthracnose research that has led to a better understanding of pathogenic and genotypic diversity, epidemiology and important disease management strategies. We further highlight how understanding pathogen diversity interplays with the major sustainable anthracnose management strategies such as the use of host plant resistance and crop residue management within the region.

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