Abstract: Twig blight disease of bayberry is the most important disease in bayberry industry at present. In this study, the effects of three bio-organic fertilizers, chicken manure, sheep manure and earthworm manure, on the disease control and tree vigor recovery were studied. The results showed that the control effect of three bio-organic fertilizers on twig blight disease was 35.2%-49.6%. The contents of nitrogen, potassium, iron, copper, zinc, calcium and manganese in leaves of three bio-organic fertilizer treatments were higher than those of the control. The content of organic matter and soil elements such as nitrogen, phosphorus, potassium, sulfur, boron, zinc and copper were higher than those of the control. Plant shoot diameter, leaf length, chlorophyll content and photosynthetic rate were 15.0%-24.5%, 4.3%-12.7%, 1.4%-6.5%, 40.2%-81.3% higher than those of the control, respectively. The contents of soluble solids, vitamin C and total sugar were increased by 10.2%-19.0%, 0.3%-23.9%, 3.3%-11.2% respectively and titratable acid was decreased by 2.2%-22.0% compared with the control. In summary, bio-organic fertilizer could reduce the occurrence of bayberry twig blight disease, promote the plant growth and restore the tree vigor of bayberry, and improve fruit quality. It was suggested that appropriate amount of bio-organic fertilizer should be applied as base fertilizer in bayberry production.

Key words: twig blight disease of bayberry, bio-organic fertilizer, control efficiency, recovery of tree vigor