Preliminary Studies on Fungal Species Associated with Guava Fruit Drop Disease and Possible Management

Abstract

Four phytopathogenic fungi i.e., Alternaria alternata, Lasiodiplodia theobromae, Fusarium semitectum and Pestalotiapsidii, were isolated from the dropped guava fruits collected from different orchards located at Beheira Governorate during 2013 and 2014 growing seasons. Disease incidence recorded higher percentages during 2013 than that of 2014 season. Pathogenicity of the isolated fungi was carried out on apparently healthy guava fruits, attached to its branches, collected from 15-year-old trees. Data show that maximum disease intensity was occurred on either petioles and/or fruits inoculated with mixture of fungal pathogens. These results indict that guava fruit drop might be a fungal disease complex when caused by certain phytopathogenic fungi. Four fungicides, i.e. Kemazed, Homai, Vacomil plus and Topas,were in vitro evaluated for their efficacies against the isolated pathogenic fungi. Moreover, the efficacy of four compounds i.e., hydrogen peroxide, potassium sorbate, potassium bicarbonate and calcium chelate, was in vitro evaluated as alternative control means against the growth of tested pathogenic fungi. In this concern, hydrogen peroxide and potassium bicarbonate recorded the highest performance against the tested fungi.Under natural field infection, chemical control trails cleared that the efficiency of Homai 80% WP and Kemazed 50% WP reached 69.0 and 78.8%, respectively, as compared to the check treatment. It is worth to note that the concerned disease could be controlled by applying either of Homai 80% or Kemazed 50% at the rate of 70 g/100 l water.