Mobility of oxathiapiprolin in and between tomato plants

BACKGROUND: Oxathiapiprolin (OXPT; FRAC code 49) is a new piperidinyl‐thiazole isooxazoline anti‐oomycete fungicide that targets oxysterol‐binding proteins. The fungicide is known to translocate acropetally from root to shoot to protect plants against fungal attack. RESULTS: OXPT is ambimobile. It can also translocate basipetally from shoot to root. OXPT exhibits an unprecedented capacity for trans‐plant protection. When two tomato plants are grown in one pot, and one is treated with OXPT (on the stem, leaves or apex), while the other plant and soil surface are adequately covered, both plants become protected against late blight caused by Phytophthora infestans. CONCLUSION: Trans‐plant systemic protection induced by OXPT involves translocation of the fungicide from the shoot of the treated plant to its root, exudation into the soil and uptake by the root of the neighboring untreated plant to protect it against the disease. Liquid chromatography–tandem mass spectrometry analyses confirmed the occurrence of OXPT in root exudates of OXPT‐treated tomato plants in quantities sufficient to protect detached tomato leaves and intact plants against P. infestans. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.