Efficacy of a Surfactant (ORO-79) in Various Rates with the Presence and Absence of Lime to Manage Clubroot on Canola- 2020

Objective: To determine the efficacy of a surfactant (ORO-79) in various rates in the presence and the absence of lime to manage clubroot on canola.

Methods: The surfactant ORO-79 was tested in different application rates to manage clubroot under the influence of lime and without lime. The experiment was laid out under field conditions in a split-plot arrangement (where the main plots are lime and without lime; and the subplots are treatments). The trial was replicated four times. The field has natural soil population of P. brassicae of 5.5 million resting spores/g of soil. Different rates of the surfactant ORO-79, were compared with treatments of the non-treated check. A combination treatment of the fungicide Ranman® and ORO-79 was a new surfactant ORO-09 (Table 1). The treatment of lime was incorporated at a depth of 4-6 inches a week before planting, and the treatments of surfactant were applied right before planting in the form of soil drench. A susceptible canola cultivar to clubroot ‘Invigor L233P’ was planted at a depth of a half inch. Lime was acquired from the Langdon land fill station (a by-product of lime sludge from the Langdon water plant). The trial was planted in the first week of June and evaluated the first week of August (exactly 60 days after planting) at growth stage BBCH-65. 

Rating scale: Clubroot rating scale: 0 = no galling, 1 = a few small galls (small galls on less than 1/3 of roots), 2 = moderate galling (small to medium-sized galls on 1/3 to 2/3 of roots), 3 = severe galling (medium to large-sized galls on more than 2/3 of roots) was used for disease rating of incidence and severity. A Clubroot Disease Index (CRDI) has been calculated using the incidence and severity data of clubroot obtained. 

Table 1: List of treatments in main plots and sub-plots that were tested in the trial.

Table 2: The effect of ORO-79 at various rates on the mean clubroot disease index (CRDI) ratings.

* indicates significance at P < 0.05; “ns” is non-significant at P < 0.05

Results: Different rates of ORO-79, ORO-09 and Ranman + ORO-79 had similar effects in managing the clubroot under field conditions (Table 2) and the treatments were significant when compared with the non-treated check. The two-way interaction among main plots (lime and without lime) and sub plots (different treatments) did not have a significant effect at p < 0.05, indicating there was no added advantage on combination treatments of lime + surfactant to control clubroot.

Acknowledgments: Funding from the ORO Agri and Northern Canola Growers Association and thanks to all the product suppliers. Special thanks to Interns Jacob Kram (NDSU), Ben Girodat and Vivek Muddana.