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Biopesticides are derivatives of plants, microorganisms and insects. Substances from plants and animals have been used to manage diseases in crops, animals and humans. Reliance on nature to heal nature is a practise for many people around the world. Use of natural products was overtaken by synthetic chemicals due to their efficacy, reliability and quick knock down effect. However, synthetic pesticides have become a health hazards for humans and environment due to their toxicity and pollution. Biopesticides are potential alternatives to synthetic pesticides. Sources of biopesticides are readily available, easily biodegradable, exhibit various modes of action, are less expensive and have low toxicity to humans and non-target organisms. Neem, pyrethrum, cotton and tobacco are known sources of botanical pesticides and have already been commercialized. Other sources of botanical pesticides include garlic, euphorbia, citrus, pepper among others. Species of Trichoderma, Bacillus, Pseudomonas, Beauveria have been commercialized as microbial pesticides. Biopesticides are however faced with challenges of formulation, registration, commercialization, acceptance and adoption. This paper describes several aspects of biopesticide development, including but not limited to, their sources, production, formulation, commercialization, efficacy and role in sustainable agriculture.

Kenya is one of the leading exporters of snap beans (Phaseolus vulgaris) to Europe, but the export volume has remained below potential mainly due to failure to meet the market quality standards. The quality concerns include the presence of regulated and quarantine pests, pesticide residues, harmful organisms, and noncompliance with the technical standards. These challenges call for the development of alternative approaches in overcoming the phytosanitary and quality challenges in the export of snap beans and other fresh vegetables. These may include integrated pest management (IPM) approaches that incorporate non synthetic chemical options, such as diversified cropping systems, plant and microbial-based pesticides, varieties with multiple disease and pest resistance, insecticidal soaps, pheromones and kairomones, entomopathogens and predators. These approaches, coupled with capacity-building and adherence to the set quality standards, will improve compliance with export market requirements. The aim of this paper is to increase knowledge on implementing good practices across the value chain of fresh vegetables that would lead to improved quality and thereby meeting institutional requirements for the export market. The novelty of the current review is using snap beans as a model vegetable to discuss the challenges that must be mitigated for the quest of achieving high quality and increased volume of fresh export products. Whilst many of the publications have focused on alternatives to synthetic pesticides in addressing MRLs in fresh vegetable exports, there is a disconnect between research and industry in achieving chemical residue and pest free export vegetables. This review describes the phytosanitary and technical challenges faced by smallholder farmers in accessing export markets, evaluates the phytosanitary and quality requirements by the niche markets, and explores the strategies that could be used to enhance compliance to the institutional and market requirements for fresh vegetables.

Indiscriminate use of synthetic pesticides has resulted in loss of access to niche markets due to presence of chemical residues in fresh vegetable produce. There is need for safe alternatives to synthetic pesticides in management of pests and diseases in horticultural production. The objective of this study was to evaluate effectiveness of plant extracts in suppressing growth of plant pathogenic fungi in vitro. Mature plant tissue samples were finely blended, extracted with 95% (v/v) ethanol and the extracts were concentrated by evaporation under vacuum at 60 0 C to remove the ethanol. Antifungal activity of the extracts was tested by incorporating the extract into the culture media onto which fungal pathogens were then cultured. Sensitivity of the fungal pathogens was determined by measuring the pathogen colony radial growth of the treatments compared to controls. Extracts from different plants varied in activity, with turmeric extracts being the most active. Turmeric extracts inhibited fungal colony radial growth by 30 to 73 % while mint was the least active. Alternaria solani was the most susceptible pathogen while Pythium ultimum was the most sensitive to extracts from all the plants evaluated. Fusarium oxysporum f. sp. lycopersici was tolerant to most of the plant extracts tested. Sensitivity of all the pathogens tested was found to decrease with the age of the cultures. The study showed that plants extracts contain compounds that inhibit growth of plant pathogenic fungi. Such compounds could be exploited as biopesticides to manage plant diseases thereby reducing the chemical residues in horticultural production.

The horticultural sector is a key contributor to Kenya’s gross domestic product through the export of fresh-cut flowers, fruits and vegetables to various niche markets. It employs over 350,000 people, while about six million depend on it. However, the sector is constrained by the strict technical and phytosanitary quality requirements set by the export markets. The phytosanitary concerns include the presence of pests and microbial contaminants, while the presence of chemical residues constitute the major technical challenge. These constraints cause the interception and rejection of produce at the export destinations. The fresh produce should be free of quarantine and regulated non-quarantine pests, pest damage, pesticides above the stipulated maximum residue levels (MRLs) and phytosanitary certification. This review discusses the following four-tiered approach to compliance with phytosanitary and pesticide residue requirements: (i) use of alternative pest management approaches, including biocontrol options, cultural and physical practices; (ii) collaboration among regulatory agencies, institutions, producers and regional countries in the enforcement of standards; (iii) investment in research and the adoption of innovative technologies; (iv) awareness creation and training of actors along the fresh vegetable value chain. It is envisaged that this approach will contribute to sustainable fresh vegetable value chains, leading to improved access to export markets, and increased export volumes and income to smallholder farmers and other actors in the fresh vegetable value chain.

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