Inorganic copper (Cu) fungicides and bactericides are widely used to control disease in fruit and vegetable crops and has led to widespread accumulation of the metal in soil beyond regulatory thresholds. We aimed to elucidate the impacts of Cu on soil health within cherry orchard soils in New Zealand, focusing on three biological indicators: earthworm behaviour, soil respiration, and plant growth. We sampled soils from four blocks of different ages within a single orchard, varying in amounts of accumulated soil Cu (7-263 mg kg^-1) but also in Soil Organic Matter (SOM) content (3-10 %). Experimental work was designed to isolate the impacts of both Cu and SOM on three critical biological descriptors: earthworm behaviour, soil respiration and root growth. Soils were amended to standardise both variables in laboratory and glasshouse experiments. The results demonstrated a pronounced inhibition of soil respiration and root development, as well as adverse effects on earthworm behaviour, with increasing Cu concentrations. SOM played a mitigating role, reducing the bioavailability and toxicity of Cu to soil organisms. However, the buffering capacity of SOM is limited and long-term reliance on SOM to mitigate Cu toxicity is not sustainable. Currently Cu continues to accumulate in most orchard soils. This study highlights the importance of assessing Cu bioavailability and soil health in the context of orchard management.

Copper (Cu)-based fungicides are widely used in agriculture, but excessive Cu accumulation in soils can pose risks to crop performance, particularly in perennial fruit crops like apples. This study evaluated the physiological responses of three apple varieties—Braeburn, Fuji, and Cripps Pink—under Cu concentrations ranging from 0 to 20 mg Cu kg⁻¹ using a callus media system. Key traits including the callus growth, fresh and dry weight, copper accumulation, tolerance index (TI), and bioaccumulation factor (BCF) were assessed. The results revealed that high Cu concentrations significantly inhibited the callus growth and biomass. Braeburn’s growth was notably reduced to 0.27 times the control at 15 mg Cu kg⁻¹, and Fuji showed no growth at concentrations above 10 mg Cu kg⁻¹. Cripps Pink displayed greater tolerance, maintaining growth even at 20 mg Cu kg⁻¹. Copper accumulation peaked in Fuji at 4200 mg kg⁻¹ at 20 mg Cu kg⁻¹, while Cripps Pink’s BCF peaked at 120 under 15 mg Cu kg⁻¹. The TI for Cripps Pink consistently exceeded 100% across all Cu levels, contrasting with Fuji’s TI, which dropped significantly at 15 mg Cu kg⁻¹. These findings suggest that maintaining soil Cu levels below critical thresholds is essential to preserve varietal performance and inform Cu management practices in apple cultivation.

Copper (Cu)-based fungicides are widely used in agriculture, but excessive Cu accumulation in soils threatens crop performance, particularly in perennial fruit crops like apples. This study investigated the effects of varying Cu concentrations on the physiological responses of three apple varieties—Braeburn, Fuji, and Cripps Pink—using a callus-media system. Callus cultures were exposed to Cu concentrations ranging from 0 to 20 mg Cu kg⁻¹ to assess traits such as growth, fresh and dry weight, copper accumulation, and bioconcentration factor (BCF). Results revealed that media Cu concentration had a stronger effect than variety on most traits, especially above 10 mg Cu kg⁻¹, where copper stress reduced genetic variability. At lower Cu concentrations, varietal differences were more apparent, with Cripps Pink showing greater copper tolerance. These findings suggest that high Cu levels suppress varietal differences, leading to a uniform stress response. This study provides valuable insights into copper toxicity in apple varieties and highlights the need to maintain soil Cu levels below critical thresholds to preserve varietal performance, with potential implications for soil-plant systems.

Soo-Jin Lee, Jae-Hyun Ryu, Geun-Ho Kwak, Lak-Yeong Choi, Dasom Jeon, Meejeong Park, Kyung-Do Lee. Korean J. Remote Sens. 2025;41:717-26. https://doi.org/10.7780/kjrs.2025.41.5.2

Ho-Yong Ahn, Jeonghwan Kim, Tae-Myung Kim, Dasom Jeon, Kyung-Do Lee, Jae-Hyun Ryu. Korean J. Remote Sens. 2025;41:1251-8. https://doi.org/10.7780/kjrs.2025.41.6.22