Evaluation of Dazitol for the management of nematodes in carrots

Project Code BPR13-050

Project Lead

Mary Ruth McDonald  University of Guelph

Tristan Jobin  Agriculture and Agri-Food Canada

Objective

To develop efficacy and crop tolerance data in support of a regulatory submission for Dazitol for the management of nematodes in carrots

Summary of Results

Background

Nematodes are a serious problem for carrot production, especially in muck soils, in most carrot growing regions in Canada. There are few products available, and as a result during the annual Biopesticides Priority Setting Workshop in March 2012, nematodes in carrots were selected as a priority issue by Canadian growers.

Dazitol™ (mustard oil and oleoresin of capsicum), a broad spectrum, soil applied pesticide developed by Champon Millennium Chemicals, Incorporated, was identified as a potential solution. Dazitol™ is registered in the United States for control of nematodes and other pests on various crops including carrots.

Approaches

Four trials were conducted to evaluate Dazitol™ for the management of nematodes in carrot fields: 2 in 2013 in Ontario (ON), and 1 each in ON and Quebec (QC) in 2014.

The ON trial fields were naturally infested by nematodes, Root lesion nematode (Pratylenchus sp.), pin nematode (Pratylenchus sp.), and stunt nematode (Tylenchorhynchus sp.), while the plots used in QC were inoculated with Root lesion nematode (Pratylenchus penetrans) and Northern root knot nematode (Meloidogyne hapla) in advance of the trial. Dazitol™ was injected at 23-25 centimeters (cm) below the surface at 60 Litres per hectare (L/ha) using a shank injection unit. Pic Plus and Vydate were included as the commercial standards in ON and QC, respectively, and each treatment was assessed in 4 replications. Soil samples taken during the course of the trial were used to determine nematode counts, and carrots were assessed for nematode damage at harvest. Both of these parameters contributed to the evaluation of product efficacy.

Results

The efficacy of Dazitol™ was variable within and among trials. One of the Ontario trials showed that the Dazitol™ treatment numerically reduced both stunt and root lesion nematode counts in soil by greater than 85 percent (%) in 2013, while carrot damage in the treated plots was the same as in the untreated control. In the other two ON trials, however, Dazitol™ significantly reduced both incidence of nematode damage to carrots (by approximately 61% in 2013 and 70% in 2014) and also damage severity (by 62% in 2013), resulting in increases in marketable carrot yield by 16.2 and 22% in 2013 and 2014, respectively.

Although Root lesion nematode and Northern root knot nematode were introduced successfully into carrot plots in QC, Dazitol™ was not effective in reducing nematode counts or carrot damage in the QC trial. No phytotoxicity was observed in any of the trials.

It appeared that most of nematode damage to carrots occurred within the first four weeks after seeding. Nematode populations later in the season have less effect on yield or quality of carrots. However, the results of these trials revealed a lack of correlation between carrot damage and nematode density, possibly the result of the use of an insufficiently powerful technique to detect nematodes in soil samples.

The availability of a more sensitive technique for the detection of nematode pest species in agricultural soils would improve the evaluation of potential control products, and would also be of use for growers’ planting and pest management decision making.

Data generated within this project is included in a regulatory submission for registration of Dazitol™ in Canada.

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