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The severity of cassava bacterial blight at two sites in the forest-savanna transition (FST) and dry savanna (DS) zones of West Africa were studied by assessing the effects of: (i) shift of planting date; (ii) potassium fertilizer application and mulching; (iii) intercropping cassava with sorghum or cowpea vs. cassava monoculture; and (iv) the combination of these measures. Disease severity of bacterial blight in two genotypes was generally reduced by 20–60% by late planting, without a negative effect on cassava root yield, in monocropping systems in most treatments in the FST zone (reduction in four treatments, and increase in two treatments, out of 19) and the DS zone (two of eight treatments in 1 year). Late planting led to crop failure in the DS zone in the second year. Intercropping cassava with sorghum reduced bacterial blight severity significantly, up to 80% at normal (all treatments) and late planting time (three out of six treatments) in the FST zone, and in some treatments (four out of seven) at normal planting in the DS zone. Intercropping of cassava with cowpea in the DS zone also reduced disease severity. Cassava-sorghum intercropping generally had no effect on root yield compared with cassava monocropping at both planting times in the FST zone and provided an additional harvest of the intercrop, while yield was affected by intercropping in the DS zone at late, and in some treatments (three out of seven) at normal, planting time. Mulching and potassium treatment had no effect on disease severity, but increased or decreased root yield in some treatments in both sites. Analysis of combined data showed that cropping system, year, site, and site combined with planting date were the highest significant determinants of variation in bacterial blight development. 相似文献
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Valerien Zinsou Kerstin Wydra Bonaventure Ahohuendo Lukas Schreiber 《Euphytica》2006,149(1-2):189-198
Summary To elucidate the role of leaf surface structures as first barriers to confer resistance to bacterial blight, leaf stomata and their occlusion with leaf waxes were studied in cassava genotypes. For the first time, cassava leaf waxes were quantitatively and qualitatively analysed. Comparing the susceptible and resistant standard genotypes BEN86052 and TMS30572, respectively, the total quantity of triterpenes was significantly higher in the resistant genotype, grown in three ecozones of Benin. In cuticular leaf waxes of seven cassava genotypes the triterpenes beta amyrins, epi-taraxerol, taraxerone and taraxerol were dominant constituents across genotypes, and alkanes (C25-C33) and acids (C30 and C32) occurred in minor concentrations. Comparing seven genotypes, no clear relation between resistance or ecozones and total quantities of the major wax constituents was observed. Only the highly resistant genotype TMS30572 showed high triterpene levels irrespective of ecozone. Scanning electron-microscopy revealed a regular distribution of waxes at the abaxial leaf surface, covering and occluding stomatal pores of susceptible and resistant genotypes, while on the adaxial leaf surface waxes were in form of crystalloids and did not occlude the stomata. The number of stomata on the abaxial surfaces was about 7–11 fold higher than on the adaxial surfaces, where stomata were located along the midrib and major veins. No significant differences in stomata number were observed between genotypes varying in resistance to bacterial blight. It is suggested, that stomata on the adaxial surface might be portals of entry for the bacteria. 相似文献
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Leonard A. C. Afouda Regina Kotchofa Razack Sare Valerien Zinsou Stephane Winter 《Phytoparasitica》2013,41(3):271-276
In surveys conducted in 2011 and 2012 to identify the viruses causing diseases on pepper and tomato in the department of Alibori in northern Benin, 451 samples of pepper and tomato were analyzed by ELISA using 11 specific antibodies. The highest virus incidence among the surveyed districts was recorded on pepper in Malanville (56.18%), followed by Karimama (39.32%). The most frequently found viruses were Pepper veinal mottle virus (PVMV), Cucumber mosaic virus (CMV), and Potato virus Y-necrotic (PVY-n), accounting respectively for 22.39%, 21.73% and 15.96% of the collected samples. Tomato yellow leaf curl virus (TYLCV) was detected in only 2.43% of the samples, whereas Alfalfa mosaic virus (AMV), Chilli veinal mottle virus (ChiVMV), Tomato mosaic virus (ToMV) and Tomato spotted wilt virus (TSWV) were not detected in any of the samples tested. Double and triple infections involving different virus combinations were found, respectively, in 14.86% and 4% of the samples. Five plant species (Euphorbia hirta Linnaeus, Moringa oleifera Lam, Leucas martinicencis (Jacquin) R. Brown, Combretum micranthum G. Don, Abelmoschus esculentus L. Moench.) out of 30 samples belonging to 13 botanical families, collected within or nearby tomato and pepper fields, were found infected with PVMV, PVY-n, and CMV. Control measures to reduce the impact of viruses on pepper and tomato production are discussed. This is the first report of viruses infecting pepper and tomato in Benin. 相似文献
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Hounzangbe-Adote Zinsou FE Hounpke V Moutairou K Hoste H 《Tropical animal health and production》2005,37(3):205-214
Infections of the gastrointestinal tract with parasitic nematodes, and particularly Haemonchus contortus, represent one of the main pathological constraints on the breeding of small ruminants in tropical countries. Owing to the constant development of anthelmintic resistance in worm populations, alternative control methods are being evaluated, including an assessment of the value of the traditional plants. The effect of the consumption of Fagara leaves on sheep infected with gastrointestinal nematodes was therefore measured both under controlled conditions and in a field survey. In sheep experimentally infected with 2500 third-stage larvae of H. contortus, a three-day administration of Fagara was associated with a decrease in egg excretion and a significant reduction in the fertility of female worms, without changes in the worm number. A reduction in egg output was also confirmed from the results obtained of a survey or naturally infected sheep performed in smallholder farms. This survey also indicated that the repeated consumption of small amounts of Fagara leaves was more effective than a single three-day administration. Results of both studies suggest that Fagara leaves might be an alternative option to chemotherapy to modulate the epidemiology of H. contortus in tropical countries. 相似文献
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Valerien?Zinsou Kerstin?WydraEmail author Bonaventure?Ahohuendo Bernhard?Hau 《European journal of plant pathology / European Foundation for Plant Pathology》2005,111(3):217-233
Thirty-seven cassava genotypes from Benin, including advanced breeding lines, were tested for their reaction to bacterial blight in the forest–savanna transition, wet savanna and dry savanna zones of Benin. Sixteen genotypes were repeated in 12 environments. In year 1998, genotypes RB92164, RB92022, TMS30572, BEN86004, RB92033 and Dangbo2, and in year 2000, genotypes RB92202, RB92151, RB92132 and TMS30572 were resistant in one ecozone. Among the more resistant genotypes, CAP94030, BEN86040, RB89509, RB92132 and TMS30572 showed low interaction across environments and were most stable in disease reaction. Ten genotypes were classified as high yielding across environments. Among the more resistant group of genotypes, only TMS30572 and RB89509 were high yielding, with RB89509 being unstable in yield across environments. Selection of genotypes proved reliable only after artificial inoculation. Comparing environments, artificially inoculated treatments in the wet savanna zone and in the forest–savanna transition zone with stable high symptom severity proved most suitable for screening of genotypes, while the wet savanna zone with low natural infection in year 1998 was suitable for production of propagation material, and the site in the dry savanna zone with natural infection in year 1998 was the best environment for cassava production. The correlation between disease severity and root yield was significant only for the non-inoculated treatment in the dry savanna zone in year 2000 (R = –0.58), but not in any other environment. Among the 37 genotypes tested, several genotypes can be recommended to farmers in specific ecozones, and genotype TMS30572 revealed as relatively stable in disease resistance and in high yield across ecozones. 相似文献
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ABSTRACT Cassava suffers from bacterial blight attack in all growing regions. Control by resistance is unstable due to high genotype-environment interactions. Identifying genes for resistance to African strains of Xanthomonas axonopodis pv. manihotis can support breeding efforts. Five F(1) cassava genotypes deriving from the male parent 'CM2177-2' and the female parent 'TMS30572' were used to produce 111 individuals by backcrossing to the female parent. In all, 16 genotypes among the mapping population were resistant to stem inoculation by four strains of X. axonopodis pv. manihotis from different locations in Africa, and 19 groups with differential reactions to the four strains were identified, suggesting that the strains represent different pathotypes. Four genotypes were resistant to leaf inoculation, and three were resistant to both stem and leaf inoculations. Genotypes with susceptible, moderately resistant, and resistant reactions after leaf and stem inoculation partly differed in their reactions on leaves and stems. Based on the genetic map of cassava, single-markeranalysis of disease severity after stem-puncture inoculation was performed. Eleven markers were identified, explaining between 16 and 33.3% of phenotypic variance of area under disease progress curve. Five markers on three and one linkage groups from the female- and male-derived framework of family CM8820, respectively, seem to be weakly associated with resistance to four strains of X. axonopodis pv. manihotis. Based on the segregation of alleles from the female of family CM8873, one marker was significantly associated with resistance to two X. axonopodis pv. manihotis strains, GSPB2506 and GSPB2511, whereas five markers were not linked to any linkage group. The quantitative trait loci (QTL) mapping results also suggest that the four African strains belong to four different pathotypes. The identified pathotypes should be useful for screening for resistance, and the QTL and markers will support breeding for resistance. 相似文献
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