Anthracnose disease of avocado contributes to a huge loss of avocado fruits due to postharvest rot in Kenya. The causal agent of this disease has not been clear but presumed to be Colletotrichum gloeosporioides as reported in other regions where avocado is grown. The fungus mainly infects fruits causing symptoms such as small blackish spots, “pepper spots,” and black spots with raised margin which coalesce as infection progresses. Due to economic losses associated with the disease and emerging information of other species of fungi as causal agents of the disease, this study was aimed at identifying causal agent(s) of the disease. A total of 80 fungal isolates were collected from diseased avocado fruits in Murang'a County, the main avocado growing region in Kenya. Forty-six isolates were morphologically identified as Colletotrichum spp. based on their cultural characteristics, mainly whitish, greyish, and creamish colour and cottony/velvety mycelia on the top side of the culture and greyish cream with concentric zonation on the reverse side. Their spores were straight with rounded end and nonseptate. Thirty-four isolates were identified as Pestalotiopsis spp. based on their cultural characteristics: whitish grey mycelium with black fruiting structure on the upper side and greyish black one on the lower side and septate spores with 3-4 septa and 2 or 3 appendages at one end. Further molecular studies using ITS indicated Colletotrichum gloeosporioides, Colletotrichum boninense, and Pestalotiopsis microspora as the causal agents of anthracnose disease in avocado. However, with this being the first report, there is a need to conduct further studies to establish whether there is coinfection or any interaction thereof.

Sixteen progeny lines of common beans obtained from single crosses made between two parents, GLP2 and KAT B1, were grown in randomized complete block design in a rainout shelter at the Agricultural and Mechanization Research Institute, Machakos, Kenya. e experiment was conducted to study inheritance of traits associated with drought stress adaptation and to establish if significant variation for those traits was existing in order to carry out selection for drought tolerance. e calculated mean values were used to estimate heritability, genetic advance, and correlation study for each trait. Water stress had a significant (p ≤ 0.01) effect on the number of pods per plant, grains per plant, 100-seed weight, and yield per plant. e highest values for genotypic coefficient of variation (36.11%) and phenotypic coefficient of variation (36.70%) were recorded for pods plant -1 under stress condition. Highest broad-sense heritability estimates (96.54%, 94.97%, and 93.16%) coupled with high genetic advance as percent of the mean (22.32%, 34.97%, and 26.32%) were obtained for the number of pods plant − 1 , days to maturity, and yield plant − 1 , respectively, showing that selection of these traits together could lead to yield improvement under stressed conditions. Harvest index showed a significant and positive relationship with biomass aboveground (r � 0.86) and the number of pods plant − 1 (r � 0.86) indicating the possibility of identifying high performing lines of common beans for drought stress environment for further studies on these traits.

No abstract

Colletotrichum gloeosporioides is a serious postharvest pathogen of avocado fruits worldwide. Kenya lacks any registered fungicides for the management of the disease. Nevertheless, farmers commonly use commercially available fungicides such as Bayleton 25WP (Triadimefon 250 g/Kg), Milraz 76WP (Propineb 70% and Cymoxanil 6%), and Copper oxychloride 500WP for disease management. The efficacy of these fungicides against C. gloeosporioides is not known. The purpose of this study was therefore to test the inhibitory effect of these fungicides against 46 C. gloeosporioides isolates from avocado fruits collected from varieties grown at different agroecological zones in Murang'a County, a popular avocado-growing region in Kenya. Mycelial growth rate and sporulation for each isolate were measured in vitro on PDA plates amended with different concentrations of the fungicides. Plates were arranged in a completely randomized design with three replications per treatment. All fungicides were effective in vitro but there were significant differences in sensitivity among isolates. Bayleton had the highest mycelial inhibition followed by Milraz, while copper oxychloride had the lowest mycelial inhibition rates, ranging from 81% to 88%. However, copper oxychloride was more effective in inhibiting sporulation. The inhibitory effect of each fungicide was concentration-dependent, where twice the recommended concentration had the highest inhibitory effect, followed by the recommended concentration. Our results show that the fungicides used by farmers against C. gloeosporioides, the causal agent for anthracnose, are effective. We, however, recommend further field tests in different avocado-growing areas so as to validate their efficacy against various isolates and under different environments.

Organic farming systems are gaining popularity as agronomically and environmentally sound soil management strategies with potential to enhance soil microbial diversity and fertility, environmental quality and sustainable crop production. This work aimed at understanding the effect of organic and conventional farming on the diversity of soybean nodulating bradyrhizobia species. Field trapping of indigenous soybean Bradyrhizobium was done by planting promiscuous soybeans varieties SB16 and SC squire as well as non-promiscuous Gazelle in three organic and three conventional farms in Tharaka-Nithi County of Kenya. After 45 days of growth, 108 nodule isolates were obtained from the soybean nodules and placed into 13 groups based on their morphological characteristics. Genetic diversity was done by polymerase chain reaction (PCR) targeting 16S rDNA gene using universal primers P5-R and P3-F and sequencing was carried out using the same primer. High morphological and genetic diversity of the nodule isolates was observed in organic farms as opposed to conventional farms. There was little or no genetic differentiation between the nodule isolates from the different farms with the highest molecular variation (91.12%) being partitioned within populations as opposed to among populations (8.88%). All the isolates were identified as bradyrhizobia with close evolutionary ties with Bradyrhizobium japonicum and Bradyrhizobium yuanminense. Organic farming systems favor the proliferation of bradyrhizobia species and therefore a suitable environmentally friendly alternative for enhancing soybean production.

In tea (Camellia sinensis) water stress generally affects the content of various plant secondary metabolites including catechins. The objective of the study was to evaluate the effects of different soil moisture content on the catechin levels of various tea clones. We found out that variation of soil water content and accumulation of catechins were strongly correlated. The experiment was conducted in an open field with the drought tolerant clones namely; SFS150, TRFK 303/577, and drought susceptible clones; TRFK 6/8, TRFK 12/9, TRFK 301/4, TRFK 31/11, S15/10, TRFK 7/9, TRFK 31/8, and BBK 35. During the cold and wet periods, the effect of plant water content on catechin level was not clearly expressed. However, significant clone × soil water content interactions (p≤ 0.05) were observed for all clones during the dry and hot periods. This observation indicated that declining plant water content (PWC) due to soil moisture stress reduced catechin levels. It was concluded that variation of catechin in various tea clones over different soil water content could be of great significance in evaluating water stress tolerance ability of tea clones.

Globally, organic farming and bradyrhizobia inoculation are gaining popularity as agronomically and environmentally sound soil management strategies with great potential to alleviate declining soil fertility, maintain environmental quality and enhance soybean production. However, the role of bradyrhizobia in organic farming system is poorly understood. Field experiment was conducted to evaluate the effects of bradyrhizobia inoculation and organic farming on growth parameters and yield quality of soybean varieties: SC squire, SB19 and Gazelle. The experimental treatments included native bradyrhizobia, commercial Bradyrhizobium japonicum, mixture of native + commercial bradyrhizobia and uninoculated control. The experimental design was a split-split plot, with three replications. The results demonstrated significant improvement in soybean nodule dry weight (NDW), shoot dry weight (SDW) and seed dry weight (SEDW) following bradyrhizobia inoculation. Remarkably, organic farming significantly out-performed conventional systems in nodulation, SDW and SEDW. Moreover, seed nutrient content differed depending on farming system; where nitrogen, phosphorus, potassium and organic carbon were higher in organic farming. Soybean varieties differed significantly on SDW, NDW and SEDW; where SC squire performed better than SB19 and Gazelle. The results demonstrate the importance of organic farming and bradyrhizobia inoculation in enhancing soil fertility, yield production and quality, a key step towards sustainable food production.

Abstract Introduction: Staphylococcus aureus is a major foodborne pathogen that poses a serious threat to public health. Indiscriminate use of antibiotics increases evolution of antibiotic resistant strains. This study aimed to determine the presence of Staphylococcus aureus in milk and milk products and their antimicrobial susceptibility patterns. Methods: A total of 334 samples were collected for analysis in the laboratories. To determine antimicrobial susceptibility patterns, selected antibiotics from different classes were used: Penicillin G, Erythromycin, Vancomycin, Chloramphenicol, Tetracycline, Gentamycin, Methicillin, and Ciprofloxacin. Results: The presence of S. aureus in milk and milk products was found occurring in 21.56% of all the samples. In raw milk analyzed, 64.81% of samples were contaminated by Staphylococcus aureus, 20.54% in pasteurized milk, 10.71% in yogurt, and 3.57% in ice cream. All isolates were found to be 100 % sensitive to Tetracycline, Ciprofloxacin, Erythromycin, and Methicillin. Infrequent sensitivity was found in Gentamicin and Vancomycin. Resistance to Penicillin G was occasionally observed across the different sources of milk and milk products. Resistance to Gentamicin (42 %) and Vancomycin (11 %) was seldom observed in isolates, hence occurring in yogurt samples only. Conclusion and Recommendation: The research hypothesis was rejected based on the presence of pathogenic Staphylococcus aureus across the different samples analyzed. It is recommended that Tetracycline, Ciprofloxacin, Methicillin, and Erythromycin antibiotics should be used for the treatment of Staphylococcus aureus infections based on the susceptibility test outcome.