Efficacy of Certain Essential Oils, Copper Oxide, Copper Oxide Nanoparticle, Imazalil and Bacillus subtilis to Control Fruit Rot of Avocado

Abstract

Disease incidence and disease severity of avocado fruit rot were assessed on cv. Hass and cv. Fuerte during 2019 and 2020 growing seasons. The highest percentages of disease incidence and disease severity were recorded in cv. fuerte in the market at El-Qanater El-Khayria, Qaliobia Governorate. On the other hand, the lowest percentages of disease incidence and disease severity were recorded in cv. Hass in the field at El- Rahawy, Giza Governorate during the two growing seasons. Four different fungi, i.e., Colletotrichum gloeosporioides, Lasiodiplodia theobromae, Fusarium moniliforme and Penicillium expansum were isolated from the naturally infected avocado fruits in the surveyed regions. Pathogenicity tests showed that the maximum percentage of disease severity on cv. Hass and cv. Fuerte resulted from infection by L. theobromae, followed by C. gloeosporioides, while the lowest percentage of disease severity was incited byP. expansum. The efficacy of alternative products namely essential oils of Lemongrass (Cymbopogon citratus L.), Rosemary (Rosmarinus officinalis L.) and Thyme (Thymus vulgaris L.) and Serenade ASO (Bacillus subtilis QST713) was evaluated in in vitro and in vivo as well as under field conditions for controlling fruit rot of avocado comparing with Imazalil, Copper oxide and Copper oxide nanoparticles. Complete inhibition of colony growth and protection from fruit rot was recorded with essential oils and Copper oxide at concentration of 3 ml or g/L of each. Meanwhile, the same effect was recorded at concentration of 1 ml/ L in case of Imazalil, Copper oxide nanoparticles and Serenade ASO. However, under field conditions, Copper oxide nanoparticles and Imazalil gave the highest efficacy for controlling avocado fruit rot disease, followed by Serenade ASO, Copper oxide and Thyme, while the lowest efficacy was recorded when trees sprayed with Lemongrass and Rosemary, respectively. The results indicated that avocado fruit rot disease could be controlled using suitable concentration of the tested treatments.