Cultural, Morphological and Biochemical Identification of Xanthomonas Spp the Causative Agent of Bacteria Leaf Spot in Tomatoes in Wanguru, Mwea, Kirinyaga County, Kenya

Abstract

Bacteria diseases are major constraints in commercial agriculture. Bacteria diseases have continuously caused huge loss to both conventional and organic farming systems globally. Bacteria leaf spot is a tomato disease of concern whose management remains a challenge across the globe. The pathogen Xanthomonas campestris pv vesicatoria the causative agent of leaf spot in tomato has been isolated and positively identified in many countries to enable control. In Kenya, tomato farmers have experienced losses associated with bacterial diseases despite using available control strategies. Application of control mechanisms by majority of farmers heavily rely on symptoms on plants other than laboratory facts on pathogen identification. As such wrong chemicals have been applied which have led to development of resistance due to pathogen evolution. Scientific identification of pathogen is necessary to enable application of accurate and effective management strategy. Nonetheless, this has scarcely been done for tomato bacteria diseases in Kenya. The objective of this study was to isolate and identify bacteria leaf spot pathogen of tomato from Wanguru area in Mwea, Kirinyaga county in Kenya using nutrient agar, differential staining and selected biochemical methods. A total of ten tomato heavily infected leaves were selected randomly from different farms. The colonies were generally yellow on the surface of nutrient agar. Results of differential staining showed gram negative rods while biochemical tests slightly varied. Based on totality of cultural, morphological and biochemical tests results, we concluded that Xanthomonas campestris pv vesicatoria is responsible for leaf spot tomato disease in Wanguru. However, we recommend the inclusion of molecular tool for proper identification.