Incidence and distribution of head and loose smuts of sorghum (s. Bicolor l. Moench) in the Nigerian Sudan savanna

In this study, field surveys were conducted (between October to November) in the 2008 and the same period in the 2009 agricultural years to determine the incidence, prevalence and severity of head and loose smuts of sorghum in the Sudan savanna agro-ecological zone of Nigeria. The surveys were conducted in three states, namely; Kano, Katsina and Jigawa states representing the Sudan savanna region during which farmers’ fields were surveyed every 15-20 km on a road network. Disease incidence was obtained from a random sample of 100 plants each from three fields in an “X” or “W” pattern across each farm. Results of the study revealed that both head and loose smuts occurred in both years and in more than 84% of the fields surveyed. Incidence of both loose and head smuts varied significantly (P=0.05) between years and locations probably because of the variability of the pathogens and the little differences in climatic factors of the two years. The incidence of loose and head smuts in 2008 was 8.33% and 3.33%, respectively but both diseases were more prevalent and severe in Kano and Katsina states than Jigawa state. In 2009 on the other hand, head smut incidence was relatively higher averaging 5.00% compared to loose smut with mean incidence of 3.00%. However, prevalence and severity of the two diseases were still higher in Kano and Katsina states compared to jigawa state. It appeared that the incidence of the two smuts varied with the year, location and sorghum variety. The severity of the two smuts was generally low but taken together, could result into serious financial loss to farmers. So efforts should be made to find means of minimizing these losses

Advances in research on cowpea Striga and Alectra

The parasitic weeds, Alectra vogelii Benth., and Striga gesnerioides (Wild.) Vatke, have become major yield-reducing factors in cowpea. Currently, Striga is more prevalent in the Sudan savanna and Sahelian regions and Alectra in the northern Guinea savanna and southern Sudan savanna regions of West Africa, as well as in East and southern Africa. However, both are fast spreading beyond these limits. Therefore, concerted efforts are being made to develop cowpea varieties resistant to Striga and Alectra, as well as other control measures to minimize yield losses. Systematic research on Striga started in Burkina Faso and on Alectra in Botswana in the early 1980s, which subsequently evolved into a collaborative research effort involving IITA, the Semi-Arid Food Grain Research and Development (SAFGRAD) project, the Natural Resources Institute (NRI). Long Ashton Station (UK), and various national programs. This has led to the identification of several sources of resistance to Striga and Alectra and the development of resistant varieties, as well as systematic studies on strain variation and integrated control. Progress is reviewed

Effect of intra row spacing on the incidence and severity of pearl millet downy mildew and grain yield

The effect of seven intra row spacing (10, 20, 30, 40, 50, 60, 70 cm) on the incidence and severity of downy mildew of pearl millet and yield components of a local pearl millet variety (Zango) were studied under field conditions in 2002 and 2003 at Samaru, Nigeria. Intra row spacing did not have significant effect on the incidence and severity of the disease but significantly increased plant height, panicle length and weight, 1000-grain weight and grain yield

Breeding for resistance to Striga and Alectra in cowpea

An outline is given of the progress made in a systematic breeding programme set up in Nigeria to develop improved cowpea cultivars with combined resistance to Striga gesnerioides and Alectra vogelii along with multiple disease and insect resistance. Several sources of resistance to both parasitic weeds have been identified. Of these, B301, a land race from Botswana has shown complete resistance to S. gesnerioides and A. vogelii. This was crossed with a susceptible cultivar, IT84S-2246-4, which is resistant to aphids, bruchids, thrips and 10 diseases and has a high yield potential. The F1 plants were back-crossed with cv. IT84S-2246-4 and segregating populations were screened for resistance to S. gesnerioides, A. vogelii and various insects and diseases. Several F6 breeding lines have now been developed which look very similar to cv. IT84S-2246-4, with combined resistance to S. gesnerioides, A. vogelii, aphids, bruchids, thrips and a variety of diseases Parasitic plantstriga gesnerioidesplant breedingweedsalectravigna unguiculataplant genetic

In-Vitro Whole-Seedling Assay For Evaluating Non-Host Crop Plant Induction Of Germination Of Witch Weed Seeds

Legume-cereal rotation can reduce density of witch weed ( Striga hermonthica ) seeds in soil. However, legume species and cultivars vary greatly in ability to stimulate germination of S. hermonthica seeds of same or different populations, hence the need for simple method for routine characterisation of these species and cultivars for germination of the parasite seeds. A simple and inexpensive technique, In-vitro whole-seedling assay; was developed and tested for screening non-host crops for ability to stimulate germination of S. hermonthica seeds. In order to compare this new technique with the well established 'cut-root assay', sixteen legume cultivars, comprising of seven cowpea ( Vigna unguiculata ), six soybean ( Glycine max ), and three groundnut ( Arachis hypogea ), in addition to maize ( Zea mays L.) hybrids 8338-1 and 9022-13 (used as checks) were screened against three S. hermonthica populations. The new technique was at least as efficacious as the cut-root assay in detecting differences in ability of cultivars of legume crop species to stimulate germination of S. hermonthica seeds. There was less variability in the results obtained in different experimental runs with the new technique, compared with those obtained with the cut root method. The new technique is considered simpler and requires less time, labour and materials. The results obtained for the different legume cultivars screened also suggest that large scale screening of groundnut cultivars for suicidal germination of Striga would be worthwhile in the development of control strategies for the parasite in the region.La rotation de légumes et de céréales peut réduire la densité de graines de Striga hermonthica dans le sol. Cependant, les espèces et les variétés de légumes varient largement en capacité pour stimuler la germination de graines du S. hermonthica des mêmes ou différentes populations. De là, la nécessité d'élaborer des méthodes simples de caractérisation de routine des espèces et variétés de germination de parasites des graines. Une technique simple et moins coûteuse, l'essai complet de semi in vitro, était développée et testée pour le dépistage des plantes non hôtes pour leurs aptitudes a stimuler la germination des graines de S. hermonthica. Dans le but de comparer cette nouvelle technique avec celle établie d'essai de coupe de racine, seize variétés de légumes, comprenant sept de niébé ( Vigna unguiculata ), six de sorgho ( Glycine max ), et trois d'arachide ( Arachis hypogea ), en plus du maïs ( Zea mays L.), les hybrides 8338-1 et 9022-13 (utilisées comme contrôles) étaient évalués contre trois populations de S. hermonthica. La nouvelle technique était au moins efficace comme celle de l'essai de racines coupées dans la détection des différences en capacités des variétés des légumes d'espèces de plantes pour stimuler la germination des graines de S. hermonthica. Il y avait une faible variabilité dans les résultants obtenus dans les différentes expériences faites avec la nouvelle technique comparés avec ceux obtenus avec la méthode de coupe de racine. La nouvelle méthode est considérée simple et demande moins de temps, de travail et matériels. Les résultants obtenus pour les différentes variétés de légumes évaluées suggèrent aussi qu'une grande échelle d'évaluation des variétés d'arachide pour la germination désespérée de Striga serait utile dans le développement des stratégies de contrôle de parasites dans la région

Recent advances in research on cowpea diseases

Cowpea diseases induced by various pathogenic groups (fungi, bacteria, viruses, nematodes, and parasitic flowering plants) constitute one of the most important constraints to cowpea production in all agroecological zones where the crop is grown. This paper presents an overview of the major research findings on cowpea diseases since the 1995 World Cowpea Conference. The focal points include con sideration of the present state of scientific knowledge of these diseases with special emphasis on new information on etiology, biology, distribution, epidemiology, economic significance, and integrated disease management options. Knowledge gaps that should be bridged through research to minimize losses from these diseases are highlighted wherever necessary

Field evaluation of improved cowpea lines for resistance to bacterial blight, virus and striga under natural infestation in the West African savannas

The average productivity of cowpea in the existing traditional systems is low due to a complex of biotic and abiotic stresses. The biotic factors include insect pests, parasitic plants, and viral, fungal and bacterial diseases. Concerted efforts are being made to develop improved cowpea varieties with combined resistance to these constraints. Twenty five cowpea lines including two local land-races were grown at three locations in the first year (2002) and at six locations in the second year (2003) in Nigeria and Niger for field screening for resistance to Bacterial blight. Many of the improved varieties had significantly higher grain and fodder yields than the local checks. There was genotype x environment interactions for grain and fodder yields. About 44% of the varieties tested were resistant to bacterial blight while 20% showed moderate resistance and others were susceptible. Bacterial blight was more important in the Sahel, and several improved cowpea breeding lines, IT98K-506-1, IT97K-1113-7, IT97K- 1069-6, IT97K-1092-2, IT97K-1069-5, IT98K-131-2 and IT97K-568-18 produced higher grain and fodder yields than the other varieties and showed combined resistance to the disease. These varieties should therefore be evaluated on-farm for onward release to farmers where there seed types meet the farmers preferred seed type other wise they can be used as parent lines as source of important genes for resistant to the diseases and high grain and fodder yields