Current status of Colletotrichum capsici strains, causal agents of Brown blotch disease of cowpea in Burkina Faso

Brown blotch disease, caused by Colletotrichum capsici, is an important disease of cowpea with a significant yield losses ranging from 42 to 100% in West Africa. In this study, a specific polymerase chain reaction (PCR) primer set CC1F1/CcapR was used to characterize and to study the phylogenetic relationship of thirty eight strains of Colletotrichum species. This primer set is capable of amplifying only C. capsici from different fungal structures and provide a powerful tool for C. capsici detection in brown blotch disease in cowpea. Phylogenetic analysis from neighbor-joining (NJ) showed a high genetic variability in the rDNA-ITS region of the isolates. The isolates formed four groups or clusters on the basis of specific fragment analysis. Groups I, II, and III consist of strains containing specific region length of twenty one nucleotides and were considered as variant 1 of C. capsici. Group IV was a heterogeneous and consists of variants 1, 2, 3, and 4 of C. capsici.Keywords: Cultivars, internal transcribed spacer (ITS) sequence, Colletotrichum specie

Effect of sorghum seed treatment in Burkina Faso varies with baseline crop performance and geographical location

Sorghum [Sorghum bicolor (L.) Moench] is a major subsistence crop throughout the region of Sahel. With the exception of seeds and labour, no agricultural inputs are in general used in sorghum production since the grain is of a relatively low commercial value and the risk of losing the crop to drought, flooding, etc. is substantial. A meta-analysis of 118 field experiments was carried out to identify conditions in which two protective seed treatments could support a yield increase of sorghum in Burkina Faso. The two treatments were: i) treatment with the pesticide Calthio C (thiram and chlorpyrifos) and ii) treatment with an aqueous extract from the plant clipta alba. Both treatments were found to produce a yield increase (Medians: Calthio C +199 kg ha-1, P<2x10-9; E. alba +90.5 kg ha-1 P<4x10-4). A strong relative effect of Calthio C on yield (+36%) was found for field experiments with a low baseline yield. A strong relative effect of E. alba extract on yield (+22%) was found for experiments with a low baseline of emergence. ANOVA of the 118 field tests showed that baseline crop performance (yield and emergence) and the effect of seed treatments were strongly linked to geographical location (twelve different villages included). Roots from sorghum in the village showing the strongest effect of both seed treatments (>40% yield increase) were found to carry a comparatively high load of the infectious ascomycetes: Fusarium equiseti, Macrophomina phaseolina and Curvularia lunata.Key Words: Curvularia lunata, Fusarium equiseti, Macrophomina phaseolina, Sorghum bicolo

In vitro Antifungal Activity of Various Local Plant Extracts in the Control of Phoma sorghina (Sacc.) Boerema et al. and Colletotrichum graminicola (Ces.) Wilson, as Sorghum Seed Mold Pathogen in Burkina Faso

The use of phytosanitary products is becoming increasingly restricted, due to their high cost, as well as the unavailability of certain products on the local market and their damaging effects on the environment and health. These different reasons motivated the search for alternative solutions to the use of synthetic pesticides. On this basis, we took on the task of evaluating the anti-fungal effectiveness of aqueous plant extracts from Balanites aegyptiaca, Cymbopogon citratus, Cassia occidentalis and Portulaca oleracea. These extracts, at 30% concentration, were obtained after different maceration periods (6, 12, 24 and 48 hours) and tested in vitro against Colletotrichum graminicola and Phoma sorghina. The effect of the extracts on the mycelium growth of various fungi, when evaluated 10 days after incubation (DAI), shows that extracts of C. citratus, B. aegyptiaca, P. oleracea and C. occidentalis inhibit the growth of C. graminicola by 100%, 65%, 43% and 38%, respectively. The extract of C. citratus prevents the development of C. graminicola, regardless of the maceration period. This extract produces a greater inhibitory effect than the fungicide Calthio DS (20% Lindane and 25% Thirame). Compared to P. sorghina, inhibition percentages of 100, 72 and 16 were recorded for extracts of C. citratus, P. oleracea and C. occidentalis. However, extracts of C. citratus (macerated for 24 and 48 hours) and extract of P. oleracea (macerated for 48 hours) were more effective than the other extracts

Comparative response of a day-neutral and photoperiod-sensitive sorghum to delayed sowing or transplanting

(African Crop Science Journal, 1997 5(3): 259-266

Biological Control of Witch Weed in Fields of Burkina Faso Using Isolates of Fusarium oxysporum

Fifteen Fusarium oxysporum isolates from diseased parasitic weeds ( Striga hermonthica plants) were evaluated over two years (1997-98) to identify the most effective isolates for the control of the parasite in infested sorghum fields in Burkina Faso. In both years the fungus was found to reduce Striga infection in sorghum by 50% although no significant differences were found among the 15 isolates in this respect. In 1997, Striga emergence was delayed by 10 days and the 47% reduction in Striga biomass is attributed to the effects of fungal isolates, whereas in 1998, Fusarium reduced emerged Striga densities by 45%. However, there is need for improved bioherbicide formulations and delivery systems to enhance the potential role of biological control for integrated management of the parasite in Burkina Faso.Quinze Fusarium oxysporum isolés des mauvaises herbes (plante de Striga hermonthica ) étaient évalués pour une période de plus de deux ans (1997-1998) pour identifier les isolés les plus efficaces pour le contrôle de parasites dans les champs de sorgho infectés au Burkina Faso. Pour les deux ans les champignons avaient significativement réduis les infections dues au Striga par 50% même si les quinze isolés n'étaient pas significativement différents. En 1997, l'émergence du striga avait retardé de 10 jours et le 47% réduction de la biomasse du Striga était attribuée aux isolés de champignons, alors qu'en 1998, Fusarium avait réduit la densité du Striga émergeant par 45%. Cependant, il y a nécessité d'améliorer formulation des bio-herbicides et du système de livraison pour augmenter le rôle potentiel du contrôle biologique pour une gestion intégrée de parasites au Burkina Faso

Biological Control Of Witch Weed In Fields Of Burkina Faso Using Isolates Of Fusarium oxysporum

Fifteen Fusarium oxysporum isolates from diseased parasitic weeds (Striga hermonthica plants) were evaluated over two years (1997-98) to identify the most effective isolates for the control of the parasite in infested sorghum fields in Burkina Faso. In both years the fungus was found to reduce Striga infection in sorghum by 50% although no significant differences were found among the 15 isolates in this respect. In 1997, Striga emergence was delayed by 10 days and the 47% reduction in Striga biomass is attributed to the effects of fungal isolates, whereas in 1998, Fusarium reduced emerged Striga densities by 45%. However, there is need for improved bioherbicide formulations and delivery systems to enhance the potential role of biological control for integrated management of the parasite in Burkina Faso. Key Words: Biological control, Fusarium oxysporum, Sorghum bicolor, Striga hermonthica RESUME Quinze Fusarium oxysporum isolés des mauvaises herbes (plante de Striga hermonthica) étaient évalués pour une période de plus de deux ans (1997-1998) pour identifier les isolés les plus efficaces pour le contrôle de parasites dans les champs de sorgho infectés au Burkina Faso. Pour les deux ans les champignons avaient significativement réduis les infections dues au Striga par 50% même si les quinze isolés n\'étaient pas significativement différents. En 1997, l\'émergence du striga avait retardé de 10 jours et le 47% réduction de la biomasse du Striga était attribuée aux isolés de champignons, alors qu\'en 1998, Fusarium avait réduit la densité du Striga émergeant par 45%. Cependant, il y a nécessité d\'améliorer formulation des bio-herbicides et du système de livraison pour augmenter le rôle potentiel du contrôle biologique pour une gestion intégrée de parasites au Burkina Faso. Mots Clés: Contrôle biologique, Fusarium oxysporum, Sorghum bicolor, Striga hermonthica African Crop Science Journal Vol. 13 (1) 2005: 41-4