ASHS 2025 Conference

Plant nutrient acquisition and responses to different fertilization programs in fruit orchards oftentimes depend on many biotic or abiotic factors or a combination of both, including tree or orchard age and nutrient source. This study aims to evaluate the effect of topically applied, slow-release source of essential nutrients from mulch mixed with poultry litter (PLM) or without (M) and fast-release growers’ standard rate of mineral fertilizer on an eight-year-old replanted orchard containing ‘Juneprince’ and ‘Scarletprince’ peach trees in South Carolina. Soil health indicators such as soil moisture and nutritional status, and tree health parameters, including yield and fruit quality (specifically on the incidence of diseases and physiological disorders), were evaluated over two years. The results showed that soil organic matter and cation exchange capacity were significantly higher in PLM across both years of this study when compared with other treatments. Both PLM and M treatments had higher moisture retention than the grower’s standard. However, yields between the two cultivars used in this study varied considerably in response to treatment and years. Yield of ‘Juneprince’ trees treated with GS was significantly higher in the first year of this study when compared with PLM and M but did not significantly differ in the second year. In contrast, yield of ‘Scarletprince’ trees treated with PLM and M were consistently higher numerically when compared with GS in both years. PLM significantly reduced bacterial spot incidence and severity in both cultivars across the study years. This result suggested that amending the soil through surface covering with mulch mixed with poultry litter provides the nutritional requirement, increases yield and significantly lower disease pressure and improves the quality of the marketable fruit in a mature orchard.