Showing papers in "International Journal of Pest Management in 1997"
TL;DR: Development of eggs and immature stages inside grain kernels was completely inhibited by eugenol treatment, and Eugenol was also highly repellent to the four beetle species tested with overall repellency in the range of 80- 100%.
Abstract: Toxicity and protectant potential of eugenol against Sitophilus granarius, Sitophilus zeamais, Tribolium castaneum and Prostephanus truncatus was investigated in the laboratory using contact toxicity, grain treatment and repellency assays. Eugenol applied topically, impregnated on filter papers, whole grains or glass pebbles was highly toxic to all the four species. Beetle mortality was dosage-dependent. Eugenol was more effective on grain than on filter paper discs since the lowest dosage of 1 mul/kg of grain killed all the beetles within 24 h. The effectiveness of eugenol was significantly reduced by the length of storage after application. For grains bioassayed after 10 days of storage following treatment mortality decresed to less than 30% even with the highest dose of 10mul/kg. Eugenol was also highly repellent to the four beetle species tested with overall repellency in the range of 80- 100%. Development of eggs and immature stages inside grain kernels was completely inhibited by eugenol treatment.
217 citations
TL;DR: The aim of this paper is to determine the extent to which wild vertebrates are perceived to damage crops, and to identify factors that help predict farmers' vulnerability to these animals.
Abstract: The aim of this paper is to determine the extent to which wild vertebrates are perceived to damage crops, and to identify factors that help predict farmers' vulnerability to these animals. Data were collected using questionnaires and informal interviews in a farming community in western Uganda. Approximately 70% of farmers interviewed are wholly dependent on agriculture for their subsistence, either as farmers and/or as seasonal agricultural labourers. Farmers consider crop-raiding by wild animals, particularly baboons and pigs, to be a major source of crop losses. Susceptibility to crop-raiding is influenced by a number of factors including proximity of fields to forest boundary and types of crops grown. The farmers' expressed fear of baboons and pigs may truly reflect the scale of damage these animals can cause, or it may be influenced by baboons' and pigs' perceived ability to harm or even kill humans.
203 citations
TL;DR: To increase yields and reduce crop losses, agricultural development programmes have been launched andsidized pesticides were made easily available and have been a major factor in disrupting traditional pest management practices.
Abstract: Most farmers in sub-Saharan Africa are resource-poor in terms of access to natural resources, credit, information and external inputs. In traditional cropping systems, crop protection is based on a combination of techniques to constrain pest development: IPM 'avant la lettre'. Resource-poor farmers are experimenters and inventors, who learn and generate their own technology. Their agricultural practices are often very well adapted to the agro-ecological and socio-economic conditions, and farming systems are flexible and responsive to all kinds ofrisks, including those ofpests. These low-externalinput systems often operate near the optimum, but generally do not produce high yields. To increase yields and reduce crop losses, agricultural development programmes have been launched. Subsidized pesticides were made easily available and have been a major factor in disrupting traditional pest management practices. The technology transfer model has been used, based on results of formal research which did not take ...
102 citations
TL;DR: Oil efficacy was compared to an organophosphate pesticide and an insect growth regulator, and all providedsimilarly effective control of psyllaanymphs, but control ofeggs was not achieved by any of the treatments as application of sprays was not correctly timed.
Abstract: The efficacyof petroleumspray oil against citrus psylla was tested in Guangzhou, China. As the oil concentration increased from 0◊ 25% to 1◊ 0% there was a linear decrease in the number of psylla of each stage present on foliar shoots after 8 days. When psylla infested shoots were sprayed with equivalent oil concentrations, survival was significantly different between oil treatments. Psylla survival was also stage-dependent, with 1st± 2nd instars being the most susceptible and eggs being the most tolerant to oil. Oil efficacy was compared to an organophosphate pesticide and an insect growth regulator, and all providedsimilarlyeffectivecontrolofpsyllanymphs. Controlofeggs was not achievedby any of the treatments as application of sprays was not correctly timed.
68 citations
TL;DR: Averaged over the three years of the study, predator numbers in the intercrops were highest in sorghum and lowest in wheat, suggesting that it would be a better winter intercrop than wheat for enhancing predator numbers.
Abstract: Relay intercropping winter and spring strip crops with cotton was used to conserve and enhance the numbers of predators of the cotton aphid ( Aphis gossypii Glover) in 1992, 1993 and 1994 in northern Texas, USA. Numbers of aphids and aphid predators in cotton isolated from other crops were compared with numbers where canola, wheat, sorghum (strip intercrops) and cotton were planted adjacent to each other and overlapped temporally. Aphid and predator populations were also monitored in the intercrop. The intercrops acted as a reservoir for predators during the non-cotton season; these intercrops 'relayed' aphid predators from canola and wheat in the winter to sorghum in the spring and finally to cotton in the summer. Averaged over the three years ofthe study, predator numbers in the intercrops were highest in sorghum and lowest in wheat. In all years, canola had higher predator numbers than wheat, suggesting that it would be a better winter intercrop than wheat for enhancing predator numbers. Average aphid ...
66 citations
TL;DR: Green mirid adults have a distinct preference for Lucerne over cotton but in the absence of lucerne the female will not oviposition, indicating that the cotton industry currently relies on broad spectrum insecticides for the control of Helicoverpa spp.
Abstract: The green mirid, Creontiades dilutus (Stal) is one of the most serious early-season pests of cotton in Australia. The cotton industry currently relies on broad spectrum insecticides for the control of Helicoverpa spp., butthis disrupts biological controlofother major cotton pests. Field experiments to evaluate the use oflucerne, Medicago sativa L., in the management of green mirids on cotton were conducted under mesh house free/no choice and commercial farm conditions at Norwood near Moree, and at Auscott and the Australian Cotton Research Institute atNarrabri in NewSouth Wales from 1992 - 94. In the mesh cage choice tests and under field conditions, lucerne was preferred over cotton by C. dilutus adults for oviposition. However, with no-choice tests, oviposition on lucerne and cotton and also the survival of mirid nymphs on these plants were not significantly different. This indicates that green mirid adults have a distinct preference for lucerne over cotton but in the absence of lucerne the female will ...
57 citations
TL;DR: The effect of native vegetation on the distribution of the green ant, Oecophylla smaragdina, and the main insect pests in cashew, Anacardium occidentale, plantations in tropical northern Australia was studied by field surveys and by observations.
Abstract: The effect of native vegetation on the distribution of the green ant, Oecophylla smaragdina, and the main insect pests in cashew, Anacardium occidentale, plantations in tropical northern Australia was studied by field surveys and by observations. O. smaragdina was an efficient predator and the most abundant ant species in cashew plantations. Infestations of the main insect pests in the trees lacking ant nests were significantly higher than in those with ant nests. Although O. smaragdina were abundant on a wider range of native tree species, they preferred Acacia aulacocarpa and Planchonia careya, and they also thrived on cashew trees after dispersing into cashew plantations. In cashew plantations, O. smaragdina preferentially colonized trees with thick canopies irrespective of tree height. Fierce fights between O. smaragdina colonies were a major factor responsible for changes in population sizes, colonization and distribution of O. smaragdina in cashew plantations. The availability of preferred native tr...
51 citations
TL;DR: There was considerable variation in both disease incidence and virus distribution in the different crop habitats within and between seasons.
Abstract: Enzyme-linked immunosorbent assay (ELISA) was used to detectviruses in649 cowpea leafsamples collectedfrom115 fields during a 3-year survey carried out from 1991 to 1993 throughout all agroecological zones in Nigeria. Six viruses, cowpea aphid-borne mosaic potyvirus (CAMV), blackeye cowpea mosaic potyvirus (BICMV), southern bean mosaic sobemovirus (SBMV), cowpea mottle carmovirus (CMoV), cowpea (yellow) mosaic comovirus (CpMV) and the cowpea strain of cucumbermosaic cucumovirus (CMV-CS)were detectedin 390 outofthe 649 samples assayed. There was considerable variation in both disease incidence and virus distribution in the different crop habitats within and between seasons. Thus, while SBMV had the highest incidence (27.4%) and was the most prevalent (66.7% in 1991, CAMV had the highest incidences (11.3% and 28.8%, respectively) and was the most prevalent 33% and 68%, respectively) in 1992 and 1993. CpMV and CMoV remained consistently moderate both in incidence and prevalence throughout the duration of the...
51 citations
TL;DR: A brief chronological history of the management of Plutella xylotsella L. in the Cameron Highlands to date is presented, including recent evidence for resistance to selective insecticides, and the urgent need for resistance management strategies is discussed.
Abstract: A brief chronological history of the management of Plutella xylotsella L. in the Cameron Highlands to date is presented, including recent evidence for resistance to selective insecticides (Bacillus thuringiensis-based products and abamectin), and the urgent need for resistance management strategies is discussed. Field studies on parasitism of P. xylostella on two host plant species (Brassica oleracea var. capitata and B. pekinensis) by three key parasitoids (Diadegma semiclausum Helle n, Diadromus collaris Gravenhorst and Cotesia plutellae Kurdjumov) are described and show distinct species-specific trends. In particular, Plutella xylostella outbreaks occurred most commonly on B. pekinensis, a crop which appeared less attractive to D. semiclausum (in terms of searching efficiency, the superior endolarval parasitoid) than to Cotesia plutellae. The possible involvement of induction and genetic (co-evolutionary) mechanisms in the observed species-specific differences is discussed together with suggestions for...
50 citations
TL;DR: Application of supplementary foods to attract, retain and conserve beneficial arthropods in crop systems has been used for several years on crop plants to enhance biological control of pests and predatory insects failed to respond consistently or clearly to either sucrose or a protein supplement spray used in Envirofeast B.
Abstract: Application of supplementary foods to attract, retain and conserve beneficial arthropods in crop systems has been used for several years on crop plants to enhance biological control of pests. The responses of predatory insects of Helicoverpa spp. to sugar and to a mixture of petroleum oil and Kelgum and newly developed food products, Envirofeast and Envirofeast B, were investigated at a commercial, irrigated cotton farm at Auscott in Narrabri in New South Wales from 1992- 94. Individual plots received 8 fortnightly applications of each substance dissolved in water and were compared with a synthetic insecticide-treated and an unsprayed plot. Adult Coccinellidae, Melyridae, Lygaeidae, Nabidae and Chrysopidae responded more positively and numbers increased more throughout the study on plots sprayed with Envirofeast A than all other treatments. In the present of Envirofeast A the predatory insects failed to respond consistently or clearly to either sucrose or a protein supplement spray used in Envirofeast B. ...
49 citations
TL;DR: In field trials, treatments of hot pepper with various nitrogen application rates between 0 and 500 kg N/ha were combined with mulch treatments in factorial trials carried out under tropicallowland conditions, and negative correlations between nitrogen levels in leaves and incidence of blossom mould and thrips were found.
Abstract: In field trials, treatments of hot pepper with various nitrogen application rates between 0 and 500 kg N/ha were combined with mulch treatments in factorialtrials carried out under tropicallowland conditions. Nutrient levels of leaves and fruits were analysed. Crop performance was monitored as plant height, branching and fruiting time, and crop health as incidence and severity of pests and diseases. Crop production was measured as yield of healthy fruits, mean weight of healthy fruits, and mid-harvesttime. In potexperiments in a growth chamber, effects of nitrogen application rates on severity of Cercospora leaf spot were studied. Nitrogen fertilization improved plant growth, but did not influence fruiting time. Increasing nitrogen application rates increased Cercospora leaf spot in growth chamber trials, and Cercospora leaf spot and anthracnose fruit rot in field trials. Negative correlations between nitrogen levels in leaves and incidence of blossom mould and thrips were found. Moderate nitrogen applica...
TL;DR: Yield loss studies showed that insect pests can contribute to over 50% yield reduction under field conditions, and head feeders and stem borers were regarded as important pests of millet.
Abstract: Studies were conducted between 1994 and 1995 in the northern savanna zone of Ghana on farmers' perceptions of insect pests ofmillet using a checklistin semi-structured interviews. Such information is essential for priority setting and also for the generation oftechnologies that meet farmer aspirations and are thus likely to be adopted by them. Farmers identified millet insects and diseases as the second most important production constraint after low soil fertility. Head feeders and stem borers were regarded as important pests of millet. Farmers generally relied on natural control for field pests but in storage, sundrying infested produce was mentioned as a control measure adopted by many farmers. Yield loss studies showed that insect pests can contribute to over 50% yield reduction under field conditions.
TL;DR: Results showed that at the time when H. pernicialis caused serious damage to a tree without O. smaragdina nests, a tree with a constant ant population was only slightly damaged, and the damage level never exceeded the control level, and it appears that 6- 10% damage level can be regarded as a control threshold.
Abstract: Helopeltis pernicialis damage to a cashew crop was very serious in each of two years, resulting in no harvest unless the trees were protected either by pesticides or biological control agents. A control threshold was determined by a combination of the net income from increased yield and the frequency of insecticide use. A damage level of 1- 5% achieved the highest net profit. A damage level of 6- 10% resulted in yield that was over 73% of the yield of the 1- 5% damage level, but required one third less pesticide application. Therefore, it appears that 6- 10% damage level can be regarded as a control threshold for H. pernicialis . The pre-flowering flush appeared to be the most appropriate time to carry out the monitoring and spray programme to control H. pernicialis . Preliminary results showed that at the time when H. pernicialis caused serious damage to a tree without O. smaragdina nests, a tree with a constant ant population was only slightly damaged, andthe damage level never exceeded the control thre...
TL;DR: Diffusates from the majority of forest trees, herbs and shrubs showed an inhibitory effect against strain XC-100 of the bacterium, and were significantly more effective in reducing the number of lesions on detached leaves and fruits, thus exhibiting protective as well as curative actions.
Abstract: Two hundred and eight diffusates from various plants such as forest trees, herbs, shrubs, fruit trees, spices, vegetables, food legumes, fodder, oil seed, fibre crops, cereals and ornamentals were evaluated through agar diffusion assay to determine their inhibitory action, if any, against Xanthomonas campestris pv. citri . Diffusates from the majority of forest trees, herbs and shrubs showed an inhibitory effect against strain XC-100 of the bacterium. Diffusates from various parts of Phyllanthus emblica, Acacia nilotica, Sapindus mukorossi and Terminalia chebula, which exhibited an inhibition zone measuring 4.83 6.00 mm at 50 g l-1 concentration, appeared to be the most effective. These diffusates showed an inhibitory effect even at a concentration of 1.25 g l-1. These diffusates at concentrations of 50, 20 and 10 g l-1 < were significantly ( P 0.01) more effective in reducing the number of lesions on detached leaves and fruits, thus exhibiting protective as well as curative actions. Diffusates from highe...
TL;DR: Parasitism resulting from release of adults was higher than that resulting from Trichogramma spp.
Abstract: This study was carried out in cotton fields in Lambayeque, Peru to investigate dispersal and parasitism by Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae), an egg parasitoid of Heliothis virescens (Fab) (Lepidoptera: Noctuidae) Experiments were conducted in a cotton crop 38 to 55 days old, in plots of 625 m2 The release of T pretiosum adults was done at two densities: 160 000 and 320 000 parasitoids/ha Two release strategies were used: (1) one day prior to adult emergence (pupae), and (2) adults one day post-emergence and fed on honey Parasitoids released as pupae achieved low parasitism Parasitism resulting from release ofadults was higher than that resulting from Trichogramma spp present in the crop prior to parasitoid release There was no difference between parasitism upwind and downwind of the release point at points along a transect for 10 m, except in the case of pupae released at a density of 160 000 parasitoids/ha which showed lower upwind parasitism Parasitism of eggs foun
TL;DR: Trials were undertaken in Tanzania to examine the residual efficacy of spray applications of insecticide mixtures as protectants of shelled maize grain against infestation by Prostephanus truncatus (Horn) and Sitophilus species.
Abstract: Trials were undertaken in Tanzania to examine the residual efficacy of spray applications of insecticide mixtures as protectants of shelled maize grain against infestation by Prostephanus truncatus (Horn) and Sitophilus species. Application of 0 .5 mg/kg deltamethrin, applied with either 8 mg/kg pirimiphos-methyl or 8 mg/kg chlorpyrifosmethyl, provided complete protection for at least nine months against both types of pest, regardless of whether the maize was stored in galvanized steel bins or jute bag stacks.
TL;DR: This study shows the effectiveness, economic benefit and environmental sustainability of biological control of Kariba weed under Zimbabwean conditions.
Abstract: We assessed the feasibility, practicability and economics of biological control of Kariba weed ( Salvinia molesta ) in Zimbabwe. The weed has become an important aquatic weed in inland water impoundments in Zimbabwe, and is detrimental to irrigation, both domestic livestock water supply, fisheries and the environment in general. During 1992- 95, attempts were made to control Kariba weed using a biocontrol agent ( Cyrtobagous salviniae : Curculionidae) on two dams comprising 16 ha in Tengwe commercial farming area in northwest Zimbabwe. The effectiveness of biological control of Kariba weed was apparent within four months of release of the weevil agent and 99% control of weed was obtained within two years. The benefit, cost ratio of biological control as compared to chemical control, was 1 :10.6 over a four year period. This study shows the effectiveness, economic benefit and environmental sustainability of biological control of Kariba weed under Zimbabwean conditions.
TL;DR: Great intensity of maize/bean intercropping was negatively related to yield loss for both crops, and insectpests were more important than disease pests.
Abstract: Pestyield loss in maize and beans in the Kenya highlands is studied using farmer elicited information. Total losses due to pests in maize and beans were estimated at 57 and 42%, respectively. As a group, insectpests were more important than disease pests. Regression methods were used to test the relationship between crop yield loss and short- and long-term pest control practices. For maize, the short-term control, use of certified seed, was positively associated with yield loss, while labour availability was negatively associated. Seeding rate and use of fertilizer and manure were not significant. For beans, fertilizer use resulted in a lower yield loss while random sowing methods resulted in a higher loss. Labour, manure use and cultivar sown were not significant. Greater intensity of maize/bean intercropping was negatively related to yield loss for both crops.
TL;DR: The current distribution and economic importance of leaf spots, web blotch, rust, gray mould, pod rots, blackhull, Sclerotinia blight, stem rot, seedling diseases, aflatoxin contamination, rosette, groundnut streak necrosis, pod nematode, and pod scab nematodes diseases, and various options for their management are briefly reviewed.
Abstract: Groundnut is an important food and cash crop in the Southern African Development Community (SADC) region, and is grown largely by smallholder farmers under low input conditions. Constraints are many and varied, both between and within the member states, but diseases are generally regarded as major constraints to groundnut production throughout the region. A large number of fungal, viral, nematode, and bacterial diseases of groundnut have been reported. Most of the diseases are widespread, but only a few of them are economically important on a regional basis. In this paper, the current distribution and economic importance of leaf spots, web blotch, rust, gray mould, pod rots, blackhull, Sclerotinia blight, stem rot, seedling diseases, aflatoxin contamination, rosette, groundnut streak necrosis, pod nematode, and pod scab nematode diseases, and various options (chemical control, host-plant resistance and cultural practices) for their management, are briefly reviewed. Future research needs on groundnut diseases in the region are discussed.
TL;DR: Monthly plantings of the rice variety Bouake 189 were made under lowland irrigated conditions, to obtain information on the phenological and seasonal occurrence of pests and diseases on the West African Rice Development Association (WARDA) research farm near Bouake, Cote d'Ivoire.
Abstract: Monthly plantings of the rice variety Bouake 189 were made under lowland irrigated conditions, to obtain information on the phenological and seasonal occurrence of pests and diseases on the West African Rice Development Association (WARDA) research farm near Bouake, Cote d'Ivoire. Regular sampling of insect pests and observations on rice yellow mottle virus (RYMV) disease infection throughout the year provided information on the occurrence of RYMV and potential insect vectors. RYMV incidence and grain yields varied depending on planting date, and for a given planting date, varied from one year to another. There was no evidence that RYMV incidence increases in successive seasons under continuous cropping. There was no significant correlation between RYMV incidence and either rainfall or wind speed. Leaf feeding damage by the beetle vector of RYMV, Trichispa sericea Guerin-Meneville (Coleoptera: Chrysomelidae), and percentage RYMV infected plants were severe in the July and August plantings in 1993, but whe...
TL;DR: Although pictograms did enhance the accessibility of safety information on the labels, some users found them to be confusing and the effect of pictograms in improving the effectiveness of the communication ofsafety information to users was incomplete.
Abstract: This experiment was designed to test whether warning labels on agricultural pesticide containers could be better understood by users if pictograms illustrating appropriate safety precautions were added to existing labels containing text only. Labels with added pictograms were perceived by pesticide users as significantly easier to obtain information from than labels containing text only. However, the effect of pictograms in improving the effectiveness ofthe communication of safety information to users was incomplete. When pictograms were added to labels they were associated with a significant increase in the proportion of users nominating correct safety precautions for storing the pesticides, butnotfor mixing or applying them. Addition of pictograms to labels did notsignificantly altersubjects'perceptions ofthe danger of the pesticide to the user. Although pictograms did enhance the accessibility of safety information on the labels, some users found them to be confusing. Pictogram systems need to be impro...
TL;DR: Results show that post-repellent treatment with methiocarb suppressed rice consumption in male Red-winged Blackbirds, whether the repellent was alone or combined with a visual (red dye) and/or volatile (methylpyrazine) cue.
Abstract: Red-winged Blackbirds ( Agelaius phoeniceus ) cause substantial damage to a variety of crops throughout North America. Nonlethal methods for controlling damage are generally ineffective, and environmental and cost concerns have limited the availability of chemical repellents such as methiocarb. One means of potentially lowering the effective application rate of methiocarb and similar aversive compounds is by combining the treatment with sensory cues. We tested groups ( n = 4) of male Red-winged Blackbirds in a series of 4-day feeding trials using brown rice treated with 0.025% (g/g) methiocarb, five times less than the previously established effective bird repellent rate. Each methiocarb treatment suppressed rice consumption, whether the repellent was alone or combined with a visual (red dye) and/or volatile (methylpyrazine) cue. When rice treated with just the sensory cues was subsequently presented, the red dye, but not the methylpyrazine, continued to deter feeding on rice. These results show that post...
TL;DR: Information gathered from informal interviews and questionnaires to groups of men in local communities, together with observations made over exploratory transects, were used to appraise the nature of agriculture- wildlife conflicts and the perceptions of indigenous people in a Sahelian wetland about vertebrate pests.
Abstract: Information gathered from informal interviews and questionnaires to groups of men in local communities, together with observations made over exploratory transects, were used to appraise the nature of agriculture- wildlife conflicts and the perceptions of indigenous people in a Sahelian wetland about vertebrate pests Twenty-one taxa of birds were reported as important as occasional pests of rice, millet, sorghum, wheat, cowpeas, tomatoes, peppers, and guava Nine mammalian taxa were listed Mammals also were perceived to produce losses in groundnuts, maize, and cassava The relative effects of these animals on community livelihood or quality of life varied from 36% (pests), 28% (source of food), 16% (folklore and naturopathy), 12% (seasonal calender), to 8% (aesthetic) These people, many at subsistence levels, said they would tolerate 5% loss (six communities), 10% (eight), 15% (two), 20% (five), one each would tolerate up to 30 35% loss, and two reported 50% tolerable-loss levels Many techniques to red
TL;DR: Eight viruses were identified infecting bambara goundnut in farmer's fields in Nigeria and the importance of these viruses to the crop is discussed and details on their ecology and geographical distribution are given.
Abstract: Eight viruses were identified infecting bambara goundnut in farmer's fields in Nigeria: cowpea aphid-borne mosaic potyvirus, blackeye cowpea mosaic potyvirus, peanut mottle potyvirus, cowpea mottle carmovirus, cowpea mosaic comovirus (cowpea yellow mosaic virus), cowpea mild mottle carlavirus, cucumber mosaic cucumovirus and southern bean mosaic sobemovirus. The importance of these viruses to the crop is discussed and details on their ecology and geographical distribution are given.
TL;DR: Assessment of the effects of fertilizer application on the bionomics and population dynamics of cowpea aphid, Alphis craccivora Koch, and on the growth and yield ofcowpea, Vigna unguiculata (L.) Walp found significant differences in crop growth rate between infested and uninfested ICV-1 plants.
Abstract: Field and greenhouse studies were conducted in 1990 and 1991, to assess the effects of fertilizer application on the bionomics and population dynamics of cowpea aphid, Alphis craccivora Koch, and on the growth and yield of cowpea, Vigna unguiculata (L.) Walp. Five fertilizer regimes were applied to seedlings of aphid-resistant (cv. ICV12) and aphid-susceptible (cv. ICV-1) cowpeas. Treatments consisted of: NH4NO3 at 40 kg/ha, P2O5 at 20 and 60 kg/ha, NH4NO3 at 40 kg/ha plus P2O5 at 60 kg/ha, and no fertilizer. Test plants were initially infested with five adult apterae or were left uninfested. Treatments were maintained for 22 days. Response variables recorded included extended leaf heights (cm), aphid counts and crop growth rate (g/dm2 land area/ day). At harvest, pods per plant and seeds per pod were also recorded. ANOVA indicated significant differences in crop growth rate between infested and uninfested ICV-1 plants, and also between infested plants of ICV-1 and ICV-12; except for the 20 and 60 kg/ha P...
TL;DR: Oospore density in the soil was highly correlated with disease incidence at 90 days after sowing indicating the important role of oospores in disease epidemiology, and soil organic C content, pH(H2O) and loam fraction showed significant correlations with Disease incidence.
Abstract: The constraints upon pearl millet ( Pennisetum glaucum (L.) R. Br.) cultivation were investigated in four regions in southwest Niger. Drought and low soil fertility constitute the principal problems according to farmers. Pearl millet downy mildew ( Sclerospora graminicola (Sacc.) Schroet.) is one of the possible biotic constraints. Its occurrence and epidemiology were studied in two regions in southwest Niger with different mean annual rainfalls. Disease incidence ranged from 7.6% to 42.0% in the area with highest rainfall and from 0% to 16.4% in the drier region. Disease severity ranged from 4.3% to 24.8% and from 0% to 8.5%, respectively, in the two regions, which gave a good indication of estimated crop loss. Oospore density in the soil was highly correlated with disease incidence at 90 days after sowing ( r = 0.83, 18df) indicating the important role of oospores in disease epidemiology. Soil organic C content, pH(H2O) and loam fraction showed significant correlations with disease incidence ( r = 0.70,...
TL;DR: This study reports observations of Striga infestations in 21 locations consisting of 12 research stations, 7 commercial farms and 2 small-scale farms in five countries of West and Central Africa between 1982 and 1994, suggesting that the results obtained suggests that the continuous cropping of maize and high N application reducedStriga infestation significantly within five years.
Abstract: Striga species (witchweed) are considered the greatest biological constraint upon food crop production in sub-Saharan Africa. Erratic field infestation is known to be one of the major bottlenecks to achieving progress in Striga research worldwide. This study reports observations of Striga infestations in 21 locations consisting of 12 research stations, 7 commercial farms and 2 small-scale farms in five countries of West and Central Africa. The observations were carried out for a period of two to five years between 1982 and 1994. Eighteen locations included S. hermonthica, two S. aspera and one S. asiatica . The results obtained from these observations suggests that the > continuous cropping of maize and high N application ( 120 kg ha-1) reduced Striga infestation significantly within five years. Only artificial > inoculation with a large quantity of Striga seed ( 3000 germinable < seeds per maize plant), low N application ( 30 kg ha-1) and ridge slowing sustained high Striga infestation. Apparently, low N...
TL;DR: The sweetpotato butterfly ( Acraea acerata Hew.) is an important defoliating insect pest in Eastern Africa and control strategies such as handpicking, chemical control, host-plant resistance, cultural control and biological control are discussed.
Abstract: The sweetpotato butterfly ( Acraea acerata Hew.) is an important defoliating insect pest of sweetpotato in Eastern Africa. Data on distribution, biology and yield loss are presented. Control strategies such as handpicking, chemical control, host-plant resistance, cultural control and biological control are discussed.
TL;DR: Suet-eating birds, primarily downy woodpeckers ( Picoides pubescens Linnaeus), were repelled by treated suet at all concentrations compared with untreated suet, and damage to wood siding on untreated and TP-40-treated boxes was similar in both years.
Abstract: We evaluated the effectiveness of ReJex-iT TM TP-40, containing 40% methyl anthranilate (MA) for deterring woodpeckers from food and from damaging wood sidings of buildings. During December 1993-February 1994 we conducted three 2-week trials at four sites using six pairs of feeders containing untreated or TP-40-treated suet (5.0, 2.5, or 1.25% g/g). We then placed 10 (1995) and four (1996) pairs (1 each TP-40-treated and control) of boxes with wood siding containing untreated suet at seven and four sites with known woodpecker activity for 2-3 weeks to assess damage to the siding. We also applied TP-40 to woodpecker-damaged wood siding of 14 residential buildings during 1994-1996. Suet-eating birds, primarily downy woodpeckers (Picoides pubescens Linnaeus), were repelled (P<0.01) by treated suet at all concentrations compared with untreated suet. By contrast, damage (primarily by downy woodpeckers) to wood siding on untreated and TP-40-treated boxes was similar (P≥ 0.32) in both years. Also, 5 of 10 buildings treated with TP-40 received woodpecker damage in areas treated previously. We conclude that TP-40 deters woodpeckers from food but does not reduce Woodpecker damage to wood siding. This difference in repellency is likely to have been a consequence of rapid degradation of TP-40 from siding (49% in 3 days) and the fact that woodpeckers do not ingest wood, which minimized their exposure to TP-40. We conclude that chemical repellents will generally be ineffective in reducing woodpecker damage to wood, and that other techniques including exclusion, frightening devices, and alternate forms of wood siding (e.g. wood composites) should be developed.
TL;DR: In 1994 and 1995 the insect growth regulator Triflumuron ('Alsystin') was tested on Schistocerca gregaria in Mauritania and it was shown that barrier treatments caused mortality rates of up to 80% after 5 to 15 days and topical application, especially using motorized blowsprayers on roosting areas, achieved over 90% in 3 to 7 days.
Abstract: In 1994 and 1995 the insect growth regulator Triflumuron ('Alsystin') was tested on Schistocerca gregaria in Mauritania. In these trials two different methods ofapplication were used: barrier applications and roosting place treatments. Based on measurements of population densities, it was shown that barrier treatments caused mortality rates of up to 80% after 5 to 15 days. Even 25 days after barrier applications a mortality rate of 70% was achieved. Hence, these treatments are well suited for preventive control measures in recession areas and for the protection of smaller cultivated areas in large vegetation areas which cannot be totally blanket-treated. With topical application, especially using motorized blowsprayers on roosting areas, a mortality rate of over 90% was achieved in 3 to 7 days. Therefore, Triflumuron acts as a feeding poison and as a contact poison as well. This method is also suitable for acute invasions. Moreover, since the products are only applied at specific points, one advantage is ...