A new strategy for durable control of late blight in potato by a single soil application of an oxathiapiprolin mixture in early season.

Yigal Cohen,Avia E Rubin,Vijay Kumar

doi:10.1371/journal.pone.0238148

Abstract

Root treatment with oxathiapiprolin, benthiavalicarb or their mixture Zorvec-Endavia [ZE (3+7, w/w)] was shown to provide prolonged systemic protection against foliar oomycete pathogens attacking cucumber, tomato and basil. Here we report that these fungicides can effectively protect potato plants against late blight when applied to the soil in which such potato plants are grown. In two field experiments, performed in 2019 and 2020, potato plants grown in 64 L containers were treated with a soil drench of oxathiapiprolin, benthiavalicarb or ZE at 12.5, 25 or 50 mg ai/five plants in a container. Artificial inoculations with Phytophthora infestans revealed that such treated plants were protected against late blight in a dose-dependent manner all along the season. Interestingly, oxathiapiprolin persisted in the treated soil for at least 139 days, providing systemic protection against late blight to the following potato crops grown in that treated soils. Potato plants grown in loess soil in the field were either sprayed or drenched with ZE. Plants treated via the soil were significantly better protected against late blight compared to the plants treated by a spray. The data demonstrate a new strategy for season-long protection of potato against late blight by a single soil application of ZE. The systemic nature of oxathiapiprolin and benthiavalicarb composing ZE assures the translocation to the foliage of two fungicides with different modes of action. This shall minimize the risk of developing resistance against either fungicide in the treated crops.

Highlights

Late blight caused by the oomycete Phytophthora infestans (Mont.) De Barry is a devastating disease of potato and tomato world-wide
In a recent study [3] we demonstrated that a single application of oxathiapiprolin, benthiavalicarb, or their mixture (3+7, w/w) to the root system of nursery plants grown in multi-cell trays provided prolonged systemic protection against late blight and downy mildews in growth chambers and in the field
At 25 days after soil drench, plants in all containers were spray inoculated in situ with sporangial suspension of P. infestans isolate 164

Summary

Introduction

Late blight caused by the oomycete Phytophthora infestans (Mont.) De Barry is a devastating disease of potato and tomato world-wide. Oxathiapiprolin (OXPT) is a new piperidinyl thiazole isoxazoline fungicide (FRAC code U15) that targets the oxysterol binding proteins in oomycete cells [1]. It is extremely active against plant pathogenic oomycetes except Pythium (see literature cited by [2]). It inhibits zoospore release, zoospore motility, cystospore germination and direct germination of sporangia.

Methods

Results

Conclusion