Occurrence of Fusarium andiyazi associated with sorghum in Nigeria

Investigations into fungi associated with sorghum grain in Nigeria indicate the occurrence of a newly described fungus, Fusarium andiyazi alongside F. nygamai. These fungi have earlier been reported as F. moniliforme. Our results highlight the need to re-evaluate Fusarium species associated with sorghum in Nigeria.     

Extracellular enzymatic activity of Fusarium section Liseola isolates

Extracellular enzymatic activity of Fusarium species from section Liseola was determined by the Api-Zym^R test, a semiquantitative method for assaying different cellular enzymes. This enzyme testing system was evaluated for possible use as a species identification aid. Twenty-two strains of Fusarium section Liseola were used: 8 of F. moniliforme, 6 of F. proliferatum, 6 of F. subglutinans and 2 of F. anthophilum. The optimal spore concentration was also determined for maximal activity in Api-Zym^R assay. According to our findings, the species showed little difference in Api-Zym^R enzymatic profiles, being not suitable for identification of these species. Only F. subglutinans and F. anthophilum showed a different enzymatic pattern. This revised version was published online in August 2006 with corrections to the Cover Date.     

Occurrence and toxigenicity of shape Fusarium moniliforme from freshly harvested maize ears with special references to fumonisin production in Egypt

Using the seed-plate technique, 18 different isolates of Fusarium moniliforme were isolated on pentachloronitrobenzene (PCNB) agar medium from 18 samples of a local variety of corn collected from locations in Minia Governorate. The isolates of F moniliforme were screened for their ability to produce fumonisins on polished rice grains using the solid state fermentation technique. Based on thin layer chromatographic (TLC) analyses using silica gel plates, 14 of the 18 isolates tested produced FB₁ and FB₂ with R _f (0.17) and (0.24), respectively. Concentration of FB₁ was estimated using high performance liquid chromatography (HPLC). Production of FB₁ by the 14 isolates of F. moniliforme tested ranged from 69 to 4495 ppm indicating that mouldy corn may represent a health hazard to consumers. This revised version was published online in August 2006 with corrections to the Cover Date.     

The distribution ofFusarium species in soils planted to millet and sorghum in Lesotho,Nigeria and Zimbabwe

Samples from soils planted to millet and sorghum from Lesotho, Nigeria, and Zimbabwe were processed and a total of 3,291Fusarium cultures were recovered. Of these 1,296 cultures were isolated from plant debris and 1,995 cultures were recovered from soil dilutions. The most prevalent species recovered wereF. oxysporum (37%),F. equiset (30%),F. solani (14%),F. moniliforme (6%),F. compactum (5%),F. nygamai (4%), andF. chlamydosporum (2%). OtherFusarium species isolated wereF. merismoides, F. polyphialidicum, F. graminearum, F. subglutinans, F. sambucinum, F. longipes, F. semitectum, F. dimerum, F. lateritium, and a group of cultures designated as population A which resembleF. camptoceras. Fusarium equiseti was the predominant species in soil samples from Nigeria and Zimbabwe, whileF. oxysporum was the predominant species recovered from soil from Lesotho.Contribution No. 1881, Fusarium Research Center, Department of Plant Pathology, The Pennsylvania State University.     

A new species of Cryptolepis (Apocynaceae: Periplocoideae) from Kenya and Tanzania, Africa

A new species of Cryptolepis is described from Kenya and Tanzania. It is a tropical forest climber and its unique second corona whorl of deeply cleft lobes distinguishes it from all other Cryptolepis species.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 343–346.     

Identification and genetic diversity of Fusarium sacchari associated with pokkah boeng disease of sugarcane in Northeast Brazil

Isolates from the Fusarium fujikuroi species complex, mainly F. sacchari, have been reported to be the causal agents of pokkah boeng in sugarcane in Brazil. However, inadequate information was available on the occurrence and genetic diversity of F. sacchari in Northeast Brazil, which is a limiting factor on management. Thus, isolates of F. subglutinans sensu lato from sugarcane plants with symptoms of pokkah boeng were evaluated using the sexual cross-fertility to determine species. All the isolates produced black perithecia when they were crossed with the test isolates of F. sacchari. Three weeks after the crossing, the formation of fertile ascospores cirri was observed. Thirty-four isolates were self-sterile hermaphrodites, while 21 were fertile only as males. Five isolates were homothallic. The effective size [N_e(f)] of the population as a function of the frequency of hermaphrodites and female sterile strains was 95.5%. The F. sacchari isolates were separated into four genetic groups independent of geographic location. The mean of polymorphism among all populations was 79%, and the average unbiased genetic diversity (uh) was considered moderate (0.31). This study in addition to confirming that F. sacchari as the main species associated with pokkah boeng in sugarcane in Northeast Brazil, reveals the relationship of mating type and genetic diversity of F. sacchari. The unrestricted gene flow between regions is probably the best explanation for the low geographic correlation. This knowledge will help in the adoption of management measures with fungicides or resistant cultivars.     

Tomato root colonization by fluorescent-tagged pathogenic and protective strains of Fusarium oxysporum in hydroponic culture differs from root colonization in soil

The colonization process of tomato roots inoculated separately or/and simultaneously by a pathogenic Fusarium oxysporum f. sp. lycopersici strain Fol8 and the protective F. oxysporum strain Fo47, genetically tagged with the red and green fluorescent protein genes, respectively, was studied in a hydroponic culture. Plants were coinoculated with Fol8 and Fo47 at two conidial concentration ratios of 1/1 and 1/100, in which biological control was not effective or effective, respectively. First observation of fungi on root was possible 48 h after inoculation at a high inoculum level and 5 days post inoculation at the lower concentration of inoculum. The pattern of root colonization was similar for both strains with the initial development of hyphal network on the upper part of taproot, followed by the growth of hyphae towards the elongation zone, lateral roots and root apices. Finally, the whole elongation zone and root apex were invaded by both strains but no specific infection sites were observed. When coinoculated, both strains could grow very closely or even at the same spot on the root surface. At the nonprotective ratio, Fol8 was the successful colonizer, but application of Fo47 at a concentration 100 times >Fol8 delayed vessel colonization by the pathogen.     

Nursery treatments with resistant inducers,soil amendments and biocontrol agents for the management of the Fusarium wilt of lettuce under glasshouse and field conditions

Lettuce Fusarium wilt, caused by Fusarium oxysporum f. sp. lactucae, represents a major problem in most lettuce production areas worldwide. In the present study, a number of resistance inducers, organic amendments and biocontrol agents were applied in a preventative way, in experimental and commercial situations, to soils artificially or naturally infested with race 1 of the pathogen, and to moderately susceptible lettuce cultivars. Potassium phosphite, acibenzolar‐S‐methyl, green composts, and Bacillus subtilis Qst713, Trichoderma asperellum + Trichoderma gamsii, and Pseudomonas strains achieved the most consistent disease control under the experimental conditions. Moreover, potassium phosphite, green compost, B. subtilis Qst713 and T. asperellum + T. gamsii, also showed a positive effect on plant development. In general, the results of the different treatments in naturally infested soil were similar to those observed in glasshouse trials under artificial inoculation. Potassium phosphite provided a consistent disease reduction (48%–62% in artificially infested soil and 60%–75% in naturally infested soil). The effects of adding 10% compost to a peat growing medium in the nursery, followed by a soil mixing application when lettuce was transplanted, significantly reduced the severity of Fusarium wilt (50%–59% efficacy) and increased fresh biomass production. Compost enrichment with Trichoderma TW2 generally further increased its efficacy. When tested under field conditions, the commercially available Trichoderma spp. and B. subtilis, together with experimental strains of Pseudomonas and Trichoderma spp., applied at the nursery level, provided a disease reduction of 30%–78%. Early application of the different control measures under nursery conditions and at lettuce transplant is noteworthy because it was carried out at a more localized level, with reduced amounts of products. Their use in practice should be integrated with other control strategies.     

Description of four new species in the hard coral genus Acropora Oken, 1815 (Scleractinia: Astrocoeniina: Acroporidae) from south-east Africa

Four new species in the hermatypic scleractinian coral genus Acropora art described from southeast Africa. Two species, A. natalensis sp. nov. and A. mossambica sp. nov. , occur in both South Africa and Mozambique. Two species, A. sordiensis sp. nov. , and A. branchi sp. nov. , are only known from northern Natal in South Africa. A. branchi sp. nov. and A. mossambica sp. nov. are intertidal species and were collected from permanent tidal pools. A. sordiensis sp. nov. and A. natalensis sp. nov. are strictly subtidal species.     

Crossing maize with sorghum,Tripsacum and millet: the products and their level of development following pollination

Summary Maize was crossed with sorghum, Tripsacum and millet with the aim of introgressing desirable alien characteristics into maize. The products of crosses were analyzed as to their level of differentiation following pollination; their further development on artificial culture medium was compared. In spite of a stimulation rate close to 5%, no evidence of hybridization between maize and sorghum or millet could be obtained. The plants recovered proved to be of maternal origin. However, with an appreciable frequency, stimulation leading to hypertrophic growth of nucellar tissue was observed. This phenomenon is bound to pollination, never occurring in non-pollinated ears. In crosses involving Tripsacum, more than 140 true hybrids were isolated. The influence of the genotypes used as well as factors such as climatic conditions or in vitro techniques are discussed. Except for one haploid maize plant, all the plants recovered proved to be classical hybrids, most of them showing the expected complement of chromosomes from each parent (10 + 36 chromosomes), a few others being slightly hyperploid (2n = 47 to 50 chromosomes). No non-classical hybrids constituted by a nonreduced female gamete and a reduced male gamete were obtained.     

Seven new species and two new subspecies of Sclerocypris SARS, 1924 from Africa,with new records of some other Megalocypridinids (Crustacea,Ostracoda)

Sclerocypris dayae n.sp., S. dedeckkeri n.sp., S. dumonti n.sp., S. zelaznyi n.sp. and S. zelaznyi etoshensis n.ssp. are described from South — West Africa (Namibia). S. exserta makarikarensis n.ssp. originates from the endorheic pan system Makarikari in Botswana. S. woutersi n.sp. was described from Lake Albert where it is quite common. S. virungensis n.sp. is known from the Virunga National Park, south of Lake Edward (Zaire). The latter two species are closely related and from part of the flabella-species group. S. longisetosa n.sp., described from a marsh near Kisumu (Kenya), is an enigmatic species, holding an isolated position in the genus due to an aberrant T1.Present address: Rijksuniversiteit Gent, Laboratorium voor ecologie der dieren, zoögeografte en natuurbehoud (Institute for Ecology), K. L. Ledeganckstraat 35, B9000 Gent, Belgium.     

Effects of method of straw disposal and depth of cultivation on populations of Fusarium spp. in soil and on brown foot rot in continuous winter wheat

Soil samples (0–10 cm depth) taken from plots of continuous winter wheat at intervals between January 1993 and July 1996 were dilution-plated on PCNB agar to identify and enumerate colony-forming units (cfus) of Fusarium spp. Cfus of the main wheat pathogen, F. culmorum, were more numerous in soil from plots that were shallow-cultivated to 10 cm after each harvest than in those that were ploughed. They were also usually more numerous in plots in which straw had been chopped and incorporated (by shallow cultivation or ploughing) than in those in which straw had been burnt. Increasing amounts of straw tended to increase the number of cfus. Deeper sampling (15–25 cm) showed that ploughing resulted in a more even, but diluted, distribution of cfus down the soil profile. Populations of some commonly found species that are not pathogenic on wheat {F. oxysporum, F. equiseti, F. flocciferum and F. merismoides) were sometimes also affected by straw disposal or cultivation treatments. Alternative methods of estimating population densities (baiting soil with wheat kernels or wheat seedlings, or plating-out straw fragments) showed generally similar effects of treatments on populations of F. culmorum; the relative merits of the methods are considered. Large differences in population densities of all species occurred within and between seasons. The smallest populations were found in January 1995 but, in the case of F. culmorum, they increased to relatively large numbers in July 1995. The summer of 1995 was warm and dry and especially favourable for development of fusarium foot rot. Severe disease occurred only in this year and was less frequent after ploughing than after tine-cultivation but more frequent after straw burning than after straw incorporation. The implications of these observations for understanding the role of propagules of F. culmorum in soil as inoculum for foot rot are discussed.     

A review of the alderfly genus Leptosialis Esben-Petersen (Megaloptera, Sialidae) with description of a new species from South Africa

The monotypic South African alderfly genus Leptosialis Esben-Petersen, 1920 is reviewed and Leptosialis africana Esben-Petersen, 1920 is redescribed. In the process a new species of alderfly Leptosialis necopinatasp. n. from the Eastern Cape and KwaZulu-Natal provinces of South Africa is recognised and described. Within Sialidae the new species most closely resembles Leptosialis africana. A key to the two species of Leptosialis using both adult and larval characters is provided.     

The in vitro effect of gossypol and its interaction with salts on conidial germination and viability of Fusarium oxysporum sp. vasinfectum isolates

AIMS: To assess the effect of different concentrations of gossypol (0, 2, 4, 10 and 20 mg l(-1)) in combination with NaCl and Na(2)SO(4) (20 mS cm(-1)) on the conidial germination and viability of Fusarium oxysporum f.sp. vasinfectum (Fov). METHODS AND RESULTS: A multinomial logistic model was developed to estimate the germination probability of Fov. The inhibitory effect was markedly evident at the two highest concentrations of gossypol; it varied among the isolates tested and with time, and it was attenuated by the presence of sodium salts. The inhibition was temporary as the germination probability increased after 8 h. Fluorescent staining revealed that gossypol either killed the conidia or retarded the elongation of the germ tubes. CONCLUSION: Fov showed the ability to overcome gossypol inhibition over time, and the inhibitory effect is reduced under saline conditions. Differential responses among Fov isolates to the presence of gossypol suggest that gossypol tolerance is genetically determined in the pathogen. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that selecting for high plant gossypol cultivars would have minimal effect on the overall Fov resistance of cotton. A new statistical model was developed to explore the statistical significance of plant-pathogen interactions.     

Variation and distribution of total mercury in water, sediment and soil from northern Lake Victoria, East Africa

Lake Victoria, the world's largest tropical freshwater lake, is an important resource, ecologically and economically. THg distribution in the northern parts of the lake are not well known, so to answer this gap, patterns in total mercury (THg) in water, soil and two dated sediment cores from northern Lake Victoria were determined. Water THg concentrations ranged from 0.7 to 5.8 ng/L, and there were no apparent differences observed between Napoleon and Winam Gulfs. Two precipitation samples had Hg concentrations of 7 and 31 ng/L. Surface soil samples collected from various agricultural sites around Jinja, Napoleon Gulf, have THg concentrations between 12.7 and 48.4 ng/g dry weight; they were correlated with organic carbon, total phosphorus and % clay. A near-shore core taken in Itome Bay in Napoleon Gulf, and an offshore core collected from the deepest part of the lake had similar THg concentrations and profiles (78 to 458 ng/g dry weight). The increase in THg concentration in the profiles of both cores began around 1960 and peaked around 1980. The similar sedimentary THg profiles and fluxes in the cores suggest that the THg sources to L. Victoria are primarily atmospheric, with some erosion inputs, and that equatorial African ecosystems are not exempt from the global increase in baseline THg concentrations.     

Amphibians and squamates from the middle Eocene of Namibia,with comments on pre-Miocene anurans from Africa

Three middle Eocene localities (Silica North, Silica South, Black Crow) recently discovered in Namibia have produced terrestrial faunas that rank among the few known from the period of insulation of Africa (Aptian-early Miocene). Collectively, the three localities have yielded anuran amphibians (one pipid frog, the earliest assemblage [three taxa] of ranoid frogs in Africa, one indeterminate family) and squamate reptiles (an amphisbaenian ‘lizard’, a snake that likely represents a colubroid, and two indeterminate ‘lizards’). These Eocene faunas suggest that ranoids, colubroids and African pipids are autochthonous to Africa. However, whereas pipids are vicariants inherited from West Gondwana, ranoids and colubroids (if really autochthonous) originated in Africa from unknown stems. Silica North and Silica South correspond to aquatic environments, permanent fresh water being present in the first locality; the environment of Black Crow was drier.     

Importance of spittle bugs, Locris rubens (Erichson) and Poophilus costalis (Walker) on sorghum in West and Central Africa, with emphasis on Nigeria

Locris rubens (Erichson) (Cercopidae: Homoptera) and Poophilus costalis (Walker) (Aphrophoridae: Homoptera) are endemic pests of sorghum (Sorghum bicolor (L.) Moench) in Nigeria and some other countries in West and Central Africa. Other hosts are maize, pearl millet, rice, sugarcane, and grasses. On sorghum, L. rubens lays eggs in the epidermis of the leaf sheath. There are five nymphal instars and development from egg to adult takes about 33 days. Both species of spittle bugs feed on all growth stages and all parts of sorghum, including the panicle. Feeding symptoms include yellow leaf blotching. Severe infestations often kill young leaves and plants. Under artificial infestation in cages, the severity of damage and associated symptoms as well as grain yield loss increased with an increase in the population density of spittle bugs. Infestation by 15 pairs of adult L. rubens     

Baseline sensitivity of Fusarium graminearum from wheat fields in Henan,China, to metconazole and analysis of cross resistance with carbendazim and phenamacril

The filamentous plant pathogenic fungus Fusarium graminearum is one of the most important pathogens causing Fusarium head blight (FHB) in wheat in the Henan Province of China. Metconazole is among the demethylation inhibitor (DMI) fungicides with a higher inhibitory activity on the mycelial growth of F. graminearum. In 2016 and 2017, 119 single spore isolates of F. graminearum, prior to being exposed to metconazole, were recovered from 52 wheat fields near 11 cities in Henan Province. The inhibitory activity of metconazole on the mycelia of the Henan F. graminearum population was determined, and EC₅₀ values were calculated. The range of EC₅₀ values of the Henan F. graminearum population to metconazole was 0.0103 to 0.0775 μg/ml with an average EC₅₀ value of 0.0293 ± 0.0114 μg/ml. The sensitivity frequency distribution curve presented a single peak in a narrow range. No cross-resistance was found between the DMI fungicide metconazole and the benzimidazole fungicide carbendazim or the cyanoacrylate fungicide phenamacril. Therefore, these sensitivity data could be used as the baseline of F. graminearum susceptibility to metconazole in the Henan Province and provide the basis for monitoring metconazole resistance in this area.     

Distribution and population dynamics of Porphyra (Bangiales, Rhodophyta) in the southern Western Cape, South Africa

Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed. This revised version was published online in August 2006 with corrections to the Cover Date.