Comparative studies on virulence, genetic variability and mycotoxin production among isolates of fusarium species infecting wheat

Isolates of Fusarium species isolated mainly from wheat in Germany and Kenya were
investigated for variation in mycotoxin production, virulence and PCR-based DNA
characteristics. The isolates were tested for mycotoxin production on wheat ears and in culture
while differences in virulence was tested on wheat ears and seedlings in pot and field
experiments. Genetic variation was determined by random amplified polymorphic DNA
(RAPD-PCR). Wheat varieties from Kenya were also tested for their susceptibility to

Diallel analysis of turcicum leaf blight resistance in Kenyan maize lines

Exserohilum turcicum is a major constraint to maize production in the humid highlands of sub-Saharan
Africa. To develop efficient cultivars, the gene action involved and genetic stability across target
ecologies must be understood. A half diallel study of 12 inbred lines was conducted to assess the types
of gene action involved in turcicum resistance and genetic stability across 5 locations in central and
western Kenya. Both additive and non-additive gene effects were important and highly dependent on

Effects of Early and Late Harvest on Agronomic Performance and Stability of Late Blight Resistant (R-gene Free) Potato Genotypes

Late blight is an important constraint to potato production and genotype resistance is an effective disease control mesure. Ten late
blight resistant potato genotypes (R-gene free) were assessed for yield performance and stability at early (90 days) and late harvest
(120 days) at two locations in Kenya during two years. Significant differences (
P
<
0.05) in area under disease progress curves
(AUDPC) were detected among potato genotypes. Resistant genotypes free of R-genes had significantly (
P
<

Relationship Between Incidence of Late Blight Tuber Rot, Foliage Blight Control and the Effect of Weather and Soil Variables

The relationship of late blight disease, tuber blight and the effects of weather and soil variables were determined at 2 distinct environments of New York and Kenya during 1999 to 2001. In well replicated field experiments at the two sites where A2 (US8 clone) and A1 (US1 clone) respectively are dominant, foliar and tuber blight development, climatic and soil variables were quantified during three cropping seasons. Variation in tuber blight in New York and Kenya was detected.

Development of Tuber Blight (Phytophthora infestans) on Potato Cultivars Based on In Vitro Assays and Field Evaluations

Tuber blight may result from infection of wounded or unwounded potato tubers
exposed to sporangia from foliar blight, soil, or blighted tubers. However, there are
limited data on the prediction of tuber blight in field or storage environment based on in
vitro assays. To assess this relationship, potato cultivars with foliar blight resistance (Rgenes)
and general resistance were evaluated for tuber blight incited by Phytophthora
infestans (US-1) based on wound-induced and unwounded tuber inoculations. Surface

Relationship between late blight [Phytophthora infestans] of potato on tuber and foliage, as affected by the disease severity on foliage, cultivar resistance, and atmospheric and soil variables

Potato tuber blight, caused by Phytophthora infestans, is an important component of the late blight pathosystem. Although the dynamics of tuber blight on potato (Solanum tuberosum) cultivars have been evaluated, the effects of climatic and soil variables on tuber blight incidence have not been adequately quantified. Field experiments were conducted at two distinct environments: in New York (1998–1999) using the A2 mating type (US-8 clonal lineage), and in Kenya (2000–2001) using the A1 mating type (US-1 clonal lineage).

Efficacy of phosphoric acid and stinging nettle extract in the management of late blight of potato

Late blight of potato caused by P. infestans is the major disease constraint to potato
production in Kenya. Knowledge on sensitivity of late blight pathogen (Phytopthora
infestans) to metalaxyl and different fungicide and evaluation of alternative fungicides is
important for effective management of late blight. Studies were carried out at two sites in
Kenya to evaluate the efficacy of phosphoric acid and stinging nettle compared to other
commonly used fungicides, Ridomil and Dithane M45 in the management of potato late

Reaction of Potato Cultivars to Natural Infestation of Late Blight Caused by Phytophthora infestans in Kenya

The late blight resistance and yield characteristics of 32 potato genotypes were studied at KARI-Tigoni between 2006 and 2007 under natural late blight inoculums pressure. Foliar late blight resistance was assessed on the basis of area under disease progress curve (AUDPC) whereas the relative area under disease progress curve (RAUDPC) was used to classify the genotypes into five late blight resistance groupings (resistant, moderately resistant, intermediate, moderately susceptible and susceptible). Tuber yields for individual cultivars ranged from 5.87 to 60.70 t/ha.

Recent developments in managing tuber blight of potato (Solanum tuberosum) caused by Phytophthora infestans

Tuber blight, caused by Phytophthora infestans, occurs wherever potato (Solanum tuberosum) is cultivated and accounts for significant losses under field and storage conditions. After decades of research in late blight, there has been substantial progress, but numerous challenges remain for the management of tuber blight. The tuber blight disease components comprising of infection pathways, tuber resistance, cultivar interactions, pathogen transmission, and survival on tubers are highlighted in this article.

Diversity in Mycotoxins and fungal species infecting wheat in Nakuru District, Kenya

Mycotoxin contamination of wheat kernels and diversity of fungal pathogens were monitored in a survey of 26 fields in Nakuru district, Kenya, in 2006. Sampling was performed twice; at mid-anthesis in July for leaves, stems and spikelets and at harvest in September for spikelets and kernels. Kernels were analysed for the occurrence of 32 mycotoxins using a high performance liquid chromatography – electrospray tandem mass spectrometry (LC-ESI-MS/MS) method. Fungi were isolated from surface-sterilized tissues and differentiated morphologically to the genus level.

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