3-Chloro-5-trifluoromethylpyridine-2-carboxylic acid, a Metabolite of the Fungicide Fluopyram, Causes Growth Disorder in Vitis vinifera.

The aim of this study was to investigate the effect of 3-chloro-5-trifluoromethylpyridine-2-carboxylic acid (PCA), a metabolite of the fungicide fluopyram, on grapevine. During spring and summer 2015, grapevine growth disorders were observed in several countries in Europe. An unprecedented herbicide-like damage was diagnosed on leaves and flowers, causing significant loss of harvest. This study proposes PCA as the causing agent of the observed growth disorders. PCA was shown to cause leaf epinasty, impaired berry development that leads to crop loss, and root growth anomalies in Vitis vinifera similar to auxin herbicides in a dose-dependent manner. Using both field trials and greenhouse experiments, the present study provides first evidence for a link between the application of fluopyram in vineyards 2014, the formation of PCA, and the emergence of growth anomalies in 2015. Our data could be useful to optimize dosage, application time point, and other conditions for an application of fluopyram without phytotoxic effects.

Droplets deposition pattern from a prototype of a fixed spraying system in a sloping vineyard.

In Italy high-quality vines are sometimes grown in small fields with slope steeper than 5-10%, where an air-blast sprayer is impractical so spray-gun application of pesticides is used, a technique that is very costly and labour intensive, and that causes high pesticide exposure of the operators. A possible alternative is the use of a fixed spraying system, and the first researches are in progress in Italy. A fixed spraying system prototype was built in a vineyard at Laimburg Research Centre with an upper line with micro-sprinkler and a lower line with cooler-type nozzles, and a trial was performed with the aim of measuring the deposition pattern of droplets on the row and between rows with water sensitive papers, also in comparison with a precise low-drift air-blast sprayer. Results show that with the fixed spraying system the treated crop row accounts for 38-44% of total deposition, that about 85-88% of sprayed solution falls on the sprayed row and on the closest right and left adjacent inter-rows, and that at 4 m from the spraying line the spray drift was <0.1%. This highlights that a fixed spraying system has the potential to apply plant protection products without generating drift problems, with a field performance similar to a low-drift sprayer, becoming an opportunity for vineyards on very steep slopes.