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Journal and Journal Articles: Recent submissions
Now showing items 1361-1380 of 5157
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Chemical additives enhance the activity of a Bt‐based biopesticide targeting the beet webworm larvae
(2019-09-20)Spoladea recurvalis (Fbr.) (Lepidoptera: Crambidae) larvae can cause up to 100% foliage loss on amaranths during severe outbreaks. The Bacillus thuringiensis Subsp. kurstaki product Halt® is a biologically safe biopesticide recommended for the management of Spodoptera exigua (Hübner) and Plutella xylostella (Linnaeus). Spoladea recurvalis larvae are less susceptible to the product. Thirteen chemical additives to improve the efficacy of a Bt spray for control of S. recurvalis were evaluated in ... -
Integrated pest Management in cocoa agroforest in Southern Cameroon: constraints and overview
(2004)Imports of pesticides have long been subsidised for use in the cocoa agroforests of the humid forest zone of southern Cameroon. With the liberalisation of the cocoa and pesticides sectors and the devaluation of the local currency (CFA franc), farmers are facing fluctuations in the price paid for cocoa and the high cost of farm inputs. Without the support of the extension services, they themselves have developed traditional integrated control methods based on the use of plant extracts mixed with ... -
Impacts of type of fallow and invasion by Chromolaena odorata on weed communities in crop fields in Cameroon
(2004)In the humid forest regions of southern Cameroon in central Africa, sectoral and macroeconomic policy reforms introduced in the late 1980s have led to intensified land use, which in turn has resulted in, among other environmental consequences, shortened fallow systems dominated by the Asteraceae shrub, Chromolaena odorata (L.) King and Robinson, rather than by secondary forest species. A trial was established to determine the effect of shortened fallow duration and invasion by C. odorata on the ... -
Path analysis: a novel approach to determine the contribution of nematode damage to East African highland banana (Musa spp., AAA) yield loss under two crop management practices in Uganda
(2004)Damage caused by plant-parasitic nematodes on East Africa Highland banana cultivar Mbwazirume was evaluated at Sendusu, Central Uganda. Banana plots were either nematode-infested or non-infested and received either continuous heavy mulch or were finger millet (Eleusine coracana) inter-cropped. An infestation with banana weevil, Cosmopolites sordidus, occurred naturally. Suckers detached from third crop cycle harvested plants were indexed for root and corm damage. Nematodes were extracted from the ... -
Nutrient deficiency symptoms in yams (Dioscorea spp.)
(2004)Symptoms of nutritional deficiencies in D. alata and D. rotundata were observed when yam plants were grown in nutrient solutions from which any of the following had been omitted: N, P, K, Ca, Mg, Zn, Fe, B, Mn, Cu and Mo. The symptoms of deficiency of major elements were visible on plants of both species. The omission of Fe, B and Mo produced characteristic symptoms on the leaves of D. rotundata, but D. alata showed symptoms only in response to Fe deficiency. The omission of minor elements led to ... -
Microplot evaluation of the yield reduction potential of Pratylenchus coffeae, Helicotylenchus multicinctus, and Meloidogyne javanica on plantain cv. Apantupa (Musa spp., AABgroup) in Ghana
(2004)The damage potential of the plant-parasitic nematodes Pratylenchus coffeae, Helicotylenchus multicinctus and Meloidogyne javanica, was assessed on plantain (Musa spp., AAB-group) cv. Apantu-pa in microplots in Ghana. Hot water treated suckers, planted in 3 l plastic bags containing sterilised soil, were inoculated 1 month after planting with a single nematode species or a nematode species mixture; controls were not inoculated. The initial single species inocula consisted of 1000 or 10 000 nematodes ... -
Stability of native starch quality parameters, starch extraction, and root dry matter of cassava genotypes in different environments
(2004)Cassava is an important food and cash crop in Malawi. It is also becoming increasingly important for industrial use. The aim of this study was to investigate the native starch quality of different Malawi cassava genotypes. Trials were conducted at Chitedze and Makoka in Malawi in the 2000/01 season. Apart from root dry matter and starch extraction, starch quality parameters considered included protein, moisture and ash contents, pH and whiteness. Various stability measures were used to deal with ... -
Inventaire des especes de mouches des fruits (Diptera tephritidae) infeodees au manguier au Mali et essais de lutte raisonnee
(2004)Au Mali, la production annuelle de mangues est estimée à 100 000 t. Du fait de problèmes structurels et phytosanitaires principalement liés à l'action des mouches des fruits, rarement plus de 1 % de cette production est exporté. L'objectif principal de cette étude a été de mettre au point une lutte raisonnée contre les Tephritidae du manguier au Mali à l'aide de traitements par taches. L'un des préalables a été d'identifier les espèces responsables des dégâts dans les trois zones principales de ... -
Soybean, cowpea, groundnut, and pigeonpea response to soils, rainfall, and cropping season in the forest margins of Cameroon
(2004)Yields of groundnut, the traditional grain legume grown in central and southern Cameroon and in much of the humid zone of Central Africa, are generally low. Other food legumes may provide alternatives to groundnut. On-farm experiments examined the relative yields of up to 15 pigeonpea, 10 groundnut, 7 soybean, and 4 cowpea varieties over three growing seasons in four to six rural communities. Soil analytical values and rainfall data from all seasons were used as covariates in the analysis of ... -
Infestation and damage by Clavigralla tomentosicollis and Anoplocnemis curvipes (Hemiptera: Coreidae) in cowpea plants with modified leaf structure and pods in different positions relative to the canopy
(2004)Potted cowpea, Vigna unguiculata (L.) Walp., plants were used to determine the effects of defoliation and pod position relative to the leaf canopy on infestation and damage by the coreid pod-bugs Clavigralla tomentosicollis Stål and Anoplocnemis curvipes (F.). Temperature measurements were taken within and outside the canopy to determine whether there was a correlation to seed damage. Seed damage decreased significantly with increasing defoliation in plants infested with C. tomentosicollis; an ... -
Using farmer knowledge to combat low productive spots in an irrigated rice scheme in Burkina Faso
(2004)In the oldest sections of Burkina Faso's largest irrigation scheme in the Sourou Valley (13° 10′ N, 03° 30′W) rice (Oryza sativa L.) yields dropped from about 5 to 6 t ha−1 in the early 1990s, shortly after establishment of the scheme, to 2 to 4 t ha−1 from 1995 onwards. Farmers blamed this yield decline on the appearance of 2 to 20 m diameter low productive spots. According to farmers and field measurements, the low productive spots decreased yields by 25–50 per cent. The low productive spots are ... -
Effect of metalaxyl on incidence of pearl millet downy mildew disease in northern Nigeria
(2004)Pearl millet downy mildew (DM) incidence, severity and yield losses of two pearl millet varieties (local and improved) due to the disease were determined in the field. Significant differences in the disease incidence and severity were recorded in the plots sown with metalaxyl-treated seeds and those sown with non-treated seeds, indicating the efficacy of the fungicide on the fungus. Yield losses due to non-treatment of seeds with metalaxyl was 40.88 and 45.39% in a local variety and 43.00 and ... -
Soybean yield determinants and response to rhizobial inoculation in an onfarm trial in the northern Guinea savanna of Nigeria
(2004)The response of two soybean varieties (Samsoy-2 and improved variety TGx 1448-2E) to Bradyrhizobium inoculation in the northern Guinea savanna of Nigeria was tested in a researcher-managed on-farm trial. There were variations in soybean yields between and within farmers fields. Data obtained from 24 farmers fields were analysed in a mixed model analysis of variance whereby the variance of the random component was estimated using Gausian restricted maximum likelihood. Five major soil components ... -
Differences in the growth stages of Erysiphe pisi on cultivars of field pea (Pisum sativum L.)
(2004)The infection process of Erysiphe pisi on field pea cvs. ‘Highlight’ and ‘Tara’ carrying resistance gene erl, line ‘JI2480’ carrying resistance gene er2, and susceptible cv. ‘Radley’ (Er) was studied at 20 °C in controlled conditions. The growth stages of E. pisi were observed on these cultivars with an environmental scanning electron microscope and a light microscope. No significant differences in the number of conidia with appressoria within 12 h of incubation and in the shape of the appressoria ... -
Effects of potassium deficiency, drought, and weevils on banana yield and economic performance in Mbarara, Uganda
(2004)This paper reports results from a 6-year long-term fertilizer X banana weevil trial for highland banana in Mbarara, Uganda. The objective of the study was to quantify the effect of mineral fertiliser (100 kg N, 50 kg P, and 100 kg K ha -1 yr-1) on crop and economic performance and weevil pest status. Soil and foliar analyses, and visual observations (i.e. yellowing of leaves) revealed that potassium deficiency was the major soil fertility constraint and a function of slope. Topsoil (0-15 cm) ... -
Life table study of Sitotroga cerealella (Lepidoptera: Gelichiidae), a strain from West Africa
(2004)Life table studies for the Angoumois grain moth, Sitotroga cerealella (Olivier), a pest on stored maize, Zea mays L., in West Africa, were conducted as part of the expansion of a mathematical simulation model that has been developed for two pests of stored maize. The effects of four temperatures (20, 25, 30, and 35°C) and two relative humidity levels (44 and 80%) on developmental time, age-specific survivorship and fecundity, sex ratio, and intrinsic rate of natural increase (rm) of S. cerealella ... -
Sources of resistance to cowpea bacterial blight disease in Nigeria
(2004)The development of resistant crop varieties depends on the reliability of the method of screening for resistance. One of the techniques widely used in evaluating field resistance is the field screening method. However, most cowpea varieties regarded as having field resistance are often found to be susceptible in farmers’ fields, where the inoculum density can be higher. This study rescreened 96 cowpea varieties, evaluated earlier in breeders’ fields as resistant to Xanthomonas campestris pv. ...
