Abstract:
Strawberry production and consumption is experiencing significant growth in Kenya and globally due to its increasing use in the food processing industry. The fungus Botrytis cinerea is a major pathogen causing Grey mould in strawberry and can cause a significant economic loss of fruits both in the field and in storage. The pathogen is controlled using synthetic fungicides, but new strains develop resistance very fast making it difficult to control. Therefore, there is a need for alternative methods of control using biological agents that are environmentally friendly and not harmful to human beings. This study was designed to contribute towards improved strawberry production in Kenya through reduced Botrytis cinerea incidence using Tithonia diversifolia (T. diversifolia) extracts and Trichoderma asperellum (T. asperellum). Two experiments were conducted at the Horticulture Research Field, Egerton University. The factorial experiments were laid out in a Randomized Complete Block Design with three replications. There were two factors i.e T. diversifolia and T. asperellum. Tithonia diversifolia was applied at four concentrations (0mL/L, 250mL/L, 500mL/L, and 750mL/L) while T. asperellum was applied at three levels (0mL, 40mL and 80mL per 20 liters of water). Data were collected on; growth, Botrytis cinerea incidence and severity, fruit yield, and fruit quality. T. diversifolia and T. asperellum influenced growth and yield of strawberry fruits. A Combination of T. diversifolia at 750mL and T. asperellum at 80mL produced the highest number of leaves (58.83) while control produced the least (43.63). T. diversifolia and T. asperellum influenced Botrytis cinerea incidence and severity in strawberry fruits. There was a decrease in disease incidence at T. asperellum 80mL and T. diversifolia 750mL (16.49%) compared to control (85.27%). A combination of T. asperellum and T.diversifolia reduced disease severity by recording the lowest percent (12.07%) compared to control (89.04%). Different concentrations of T. diversifolia and T asperellum had significant p≤0.05 effects on strawberry fruit yield where T. diversiofolia at 750 mL and T. asperellum at 80mL produced the highest yields (199.5g per plant) compared to control(53.9 g per plant). Total soluble solids was highest in fruits treated with T. diversiofolia at 750 mL and T. asperellum at 80mL (13.28 brix) compared to control (7.97 brix). Ascorbic acid content was highest in fruits treated with T. diversiofolia at 750 mL and T. asperellum at 80mL (55.12mg/100g) compared to control (38.75mg/100mg). Based on the results, T. diversifolia and T. asperellum significantly (p≤0.05) influenced disease incidence and severity, growth and Fruit yield of strawberry. Consequently, T. diversifolia at 750mL and T. asperellum at 80mL are recommended for use in strawberry production.
