The Study of the Kinetics of Metalaxyl Accumulation and Dissipation in Durian (Durio zibethinus L.) Leaf Using High-Performance Liquid Chromatography (HPLC) Technique

Abstract

Metalaxyl is an effective approach to control Phytophthora palmivora infection in durian plantation. However, inappropriate metalaxyl usage may increase production cost, pathogen with fungicide resistance, and environmental toxicity. This study established and validated a simple and reproducible procedure to measure metalaxyl concentration in the durian leaf using HPLC. Linearity of the detection ranged from 1–100 µg/mL. The limits of detection (LOD) and quantification (LOQ) were 0.27 and 0.91 µg/mL, respectively. The extraction method gave recovery rates ranging from 88% to 103%. Durian seedlings were treated with 4 g/L metalaxyl either by foliar spray or soil drench. The highest metalaxyl accumulation in durian leaf was found between 6–24 h after treatment and persisted above its effective concentration at least 60 days after foliar application. The dissipation pattern fit to a first-order kinetics equation showed a half-life of 16.50 days. Soil drenching led to eight times higher metalaxyl concentrations in plants than foliar spraying and caused plant death within 15 days after application. These results suggest that foliar spraying of 4 g/L metalaxyl or soil drenching at a lower concentration every two months is sufficient in controlling P. palmivora infection in durian seedlings.

Fungicide Dissipation Kinetics and Dietary Exposure Risk Assessment in Squash Fruit and Leaf

“…Regarding the chemical classes, the dissipation half-lives of triazoles were reported to be in the range of 2–12.8 days [ 45 ], which is similar to our results and previous studies. The half-life of metalaxyl was reported to be 2.5 days in Chinese cabbage [ 46 ], 3–3.5 days in cucumber [ 47 ], 4.9 days in grape [ 37 ], and 16.5 days in durian leaf [ 48 ]. The decomposition behavior of pesticides is generally influenced by many factors such as their physicochemical characteristics, formulations, environmental conditions, crop species, and plant growth-based dilution factor [ 29 , 49 , 50 ].…”

Host Range and Control Strategies of Phytophthora palmivora in Southeast Asia Perennial Crops

“…Metalaxyl inhibits fungal RNA synthesis (Drenth & Guest, 2004;Torres-londono, 2016). Metalaxyl can slowly penetrate through the leaf cuticle and into the xylem of a low lipophilic host (Phetkhajone et al, 2021). After penetration, metalaxyl accumulates and is transported upward by the transpiration stream.…”

“…The study also concluded that metalaxyl foliar application at 4g/L is sufficient to control P. palmivora in two months. However, a lower concentration is suggested for soil drenching to treat the root and stem rot disease in durian trees (Phetkhajone et al, 2021). Protectant fungicide, mefenoxam, is a purified active isomer of metalaxyl that can affect mycelium growth and sporulation (Schwinn & Staub, 1995;Ware & Withacre, 2004).…”