Poster Presentation Science Protecting Plant Health 2017

Biofumigation potential of Brassica crops to control Rhizoctonia solani infection of potato (#345)

Le P Thanh 1 , Richard E Falloon 2 , Hayley J Ridgway 1 , Eirian E Jones 1
  1. Lincoln University, Lincoln 7647, Canterbury, New Zealand
  2. The New Zealand Institute for Plant & Food Research Limited, Lincoln 7608, Canterbury, New Zealand

Biofumigation using Brassica crops has been used for the management of soilborne diseases caused by Rhizoctonia solani. However, to date, there is limited evidence for the efficacy of biofumigation for controlling R. solani on potato under New Zealand growing conditions. In this study, the three selected Brassica crops ‘Caliente’ mustard (Ca), brown mustard (Bm) and ‘Nemat’ arugula (Ne) were assessed for control of R. solani infection of potato under shadehouse conditions using soil from a field with a history of R. solani disease. Seven treatments were set up, comprising Ca, Bm, Ne, allyl isothiocyanate (allyl ITC) and fungicide (azoxystrobin for soil treatment and pencycuron for seed treatment) applied to R. solani inoculated field soil, and a positive (untreated R. solani inoculated field soil) and nil (uninoculated field soil) control. Brassica crops were grown in planting bags for 55 days, then macerated and incorporated into the soil by hand, watered and allowed to decompose for four weeks before potato (cv. ‘Russet Burbank’) planting. Stem, stolon and root diseases caused by R. solani were evaluated at five weeks after planting. Ca, Ne and the fungicide treatments significantly reduced stem canker severity (50-58%) relative to the positive control, followed by Bm (34%). Ca significantly decreased stolon disease severity by 56% compared with the positive control treatment, but was significantly lower than the fungicide treatment (77%). Allyl ITC had no significant effect on stem and stolon canker levels compared with the positive control. The nil control had the lowest stem and stolon canker severity levels (3.9 and 7.8%, respectively) compared with other treatments. There were no significant differences in the level of root disease between treatments (0.73-1.11 disease scale). These preliminary results indicate that selected Brassica crops, particularly Ca, have the potential to control R. solani infection of potato.