Diversity of putatively toxigenic Aspergillus species in maize and soil samples in an aflatoxicosis hotspot in Eastern Kenya

Salano, Elsie Nyangweso; Obonyo, Meshack; Toroitich, Faith Jebet; Odhiambo, Benard Omondi; Aman, Bonaventure Omondi

doi:10.5897/ajmr2015.7645

Cited by 14 publications

(4 citation statements)

References 31 publications

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“…Frequency of isolation was assessed as the number of times every isolate has appeared per site sampled. As described by; (Benard et al, 2013) using the following equation;…”

Section: Assessment Of Diversity and Frequency Of Isolationmentioning

confidence: 99%

Symptomatology and Identification of Major Fungal Pathogens of Pyrethrum (Chrysanthemum cinareriifolium) in Kenya

2024

JBAH

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Fungal pathogens are major biotic constraints in almost all pyrethrum producing zones in the world. Due to limited information, this study was designed to document on symptomatology and diversity of major fungal pathogens of pyrethrum in Kenya. Stratified random sampling technique was applied during a field sampling in major production zones of Nakuru County where agro ecological zones were considered as strata and on each stratum, biased sampling was used to sample pyrethrum tissues showing symptoms of fungal infections. Disease symptoms on these samples were described based on the findings of earlier scholars. The samples were taken to University of Eldoret Plant Pathology Laboratory for fungal isolation, morphological studies and identification. Surface sterilized samples were cultured on PDA media and incubated at 25 o C -27 o C for seven days after which the actively growing fungal mycelia were sub cultured to obtain pure isolates on a freshly prepared PDA and incubated at alternating 12 hours of light and darkness to induce sporulation. A light microscope was used at X1000 magnification to assess micro characteristics while Color charts were used to describe macro characteristics of isolates and laboratory manuals, journals and reference books were used to confirm the actual identities of each isolate. Frequency of occurrence was assessed based on sites as well. Three major diseases were described in both sites; Bud disease, crown rot disease and pyrethrum wilt disease. A total of ten diverse pure isolates belonging to six different genera were obtained from the samples analyzed and from these isolates, genus Fusarium was the most abundant with four different species namely F. oxysporum, F. solani, F. graminearium and F. avenaceum. Followed closely by the genus Alternaria with three species isolated and they include Alternaria solani, Alternaria alternata and Alternaria tenuissima. Other identified fungi were Rhizoctonia solani, Phoma spp and Sclerotinia minor. It is evident that a wide range of fungal pathogens are responsible for low pyrethrum yield and pyrethrum quality in Kenya thus the need to exploit effective management strategies.

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“…Frequency of isolation was assessed as the number of times every isolate has appeared per site sampled. As described by; (Benard et al, 2013) using the following equation;…”

Section: Assessment Of Diversity and Frequency Of Isolationmentioning

confidence: 99%

Symptomatology and Identification of Major Fungal Pathogens of Pyrethrum (Chrysanthemum cinareriifolium) in Kenya

2024

JBAH

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“…Three strains of Aspergillus avus and three strains of Fusarium sp. were obtained from the Mycotoxin Research Laboratory at Egerton University, Nakuru Kenya (Elsie et al 2016). These fungal strains had originally been isolated from contaminated soils and stored as pure cultures in Potato Dextrose Agar (PDA) at 25°C.…”

Section: Fungal Strains and Inoculamentioning

confidence: 99%

Insecticides influence colonization and toxin accumulation by Aspergillus and Fusarium in orange and white maize flour varying in susceptibility to mycotoxigenic fungal pathogens

Ochieno

Nekesa

Naluyange

et al. 2023

Preprint

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Mycotoxigenic Aspergillus and Fusarium species that contaminate cereal crops with aflatoxins and fumonisins are a major threat to food security, human and animal health. Cases of mycotoxin contamination have been on the rise globally, with causes of such surges raising research interests. We conducted factorial experiments in the laboratory to test the hypothesis that some recently produced improved maize varieties that are not purposively bred for resistance to storage insect pests and mycotoxigenic fungi, require protection by synthetic insecticides, which in turn serve as nutrient sources to mycotoxigenic fungi, leading to invasive growth and enhanced toxin production by fungi, especially in conditions of high moisture. Flour from the improved white maize variety Western 505 that is not purposively bred for resistance to storage insect pests and mycotoxigenic fungi had the highest level of colonisation by A. flavus (6,633 CFU g-1) and Fusarium sp. (10,870 CFU g-1) with consequent elevated concentrations of aflatoxin (203 ppb) and fumonisin (2.23 ppm); while flour from the local yellow maize variety Spindi exhibited the least colonisation and mycotoxin production by A. flavus (4,133 CFU g-1) and Fusarium sp. (6,145 CFU g-1) with the local white Rachar being intermediate, at high moisture conditions. The synthetic insecticides Super Blue Cross (BC) and Actellic Super (AS) promoted growth and mycotoxin production by A. flavus and Fusarium sp.; while Ash promoted growth of A. flavus and Fusarium sp., but suppressed mycotoxin production by the two mycotoxigenic fungi (Aflatoxin and Fumonisin: control=114 ppb and 1.46 ppm; Ash=114 ppb and 1.46 ppm; AS=270 ppb and 2.31 ppm; BC=320 ppb and 3.55 ppm). It is concluded that flours from the local yellow Spindi and local white Rachar maize varieties are less susceptible to infection and mycotoxin contamination by A. flavus and Fusarium sp. compared to the improved white maize variety WH505, which accumulates higher levels of the mycotoxigenic fungi and their toxins, especially when treated with the synthetic insecticides Super Blue Cross and Actellic® Super that act as fungal nutrient sources under high moisture conditions. The implications of these findings are further discussed in the context of some relevant policies.

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“…parasiticus . For example, studies in Kenya showed that the density of A. flavus in soil was higher than that of A. parasiticus (Benard et al, 2013;Elsie et al, 2016). This is the opposite with the Zambian scenario ((Kachapulula et al, 2017b); Figure 3), which has a different climate and is at higher latitude than Kenya.…”

Section: Comparison Of Soil and Maize Community Structuresmentioning

confidence: 96%

“…Soil is the main reservoir for Flavi . Flavi communities on crops and in soil have been explored before Elsie et al, 2016;Thathana et al, 2017). Considering that soil is a niche for mycotoxigenic Flavi that may infect crops growing on those soils, Aspergillus biocontrol agents (non-aflatoxin producing isolates of Aspergillus flavus) are generally applied to the soil, to outcompete mycotoxigenic strains after transfer to the crop.…”

Section: Supplemental Materialsmentioning

confidence: 99%

On the fungal contamination dynamics in maize : towards competitive exclusion to control mycotoxins

Katati

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Diversity of putatively toxigenic Aspergillus species in maize and soil samples in an aflatoxicosis hotspot in Eastern Kenya

Cited by 14 publications

References 31 publications

Symptomatology and Identification of Major Fungal Pathogens of Pyrethrum (Chrysanthemum cinareriifolium) in Kenya

Symptomatology and Identification of Major Fungal Pathogens of Pyrethrum (Chrysanthemum cinareriifolium) in Kenya

Insecticides influence colonization and toxin accumulation by Aspergillus and Fusarium in orange and white maize flour varying in susceptibility to mycotoxigenic fungal pathogens

On the fungal contamination dynamics in maize : towards competitive exclusion to control mycotoxins

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