Abstract Detail

Host/Plant Pathogen Interactions and Plant Health Management

Dalton, Jill [1], Gossen, Bruce [2], Al-Daoud, Fadi [3], McDonald, Mary Ruth [1], Pageau, Denis [4].

Decline in the concentration of resting spores of Plasmodiophora brassicae and the effect of crop rotation following a susceptible crop.

The concentration of resting spores of Plasmodiophora brassicae Woronin in soil increases rapidly when susceptible crops are grown in short rotation. Some of these spores survive for many years, but the rate of decline is unknown. There may be a practical advantage to a 2- to 3-yr break between susceptible canola (Brassica napus L.) and a clubroot-resistant cultivar. The objective of this research was to determine the concentration of resting spores following different durations of crop rotation including susceptible canola. Small blocks in a naturally-infested field at Normandin, Québec, have been in cropping rotations that included clubroot-susceptible canola in rotation with barley, field pea and fallow treatments. Resting spore populations in soil were quantified after continuous canola and break intervals of 1, 2, 3, 5, and 6 years between canola crops, using a multiplex qPCR protocol. The concentration of resting spores in soil declined over time as the length of break from the susceptible canola crop increased. Regression analysis indicated a quadratic relationship of y = 1E + 07e^-0.759x . R²=0.65. Compared to continuous canola (1.3 x 10⁸ spores g^-1 soil), resting spore concentration declined by 96% after a 1-yr break, 99% after a 2-yr break, but then declined very slowly after a 3-, 5-, and 6-yr break (<1%).These results support a previous report. In general, large numbers of resting spores die or disappear in the first 2 years after a susceptible crop, then remain at a relatively constant, low concentration following longer rotations out of canola.

1 - University of Guelph, Plant Agriculture, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada
2 - Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK, S7N 0X2, Canada
3 - University of Guelph, Department of Plant Agriculture, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
4 - Agriculture and Agri-Food Canada, Research farm, 1468 St-Cyrille street, Normandin, QC, G8M4K3, Canada

Keywords:
Clubroot
crop rotation
plant diseases
Brassica napus
Plasmodiophora brassicae
integrated pest management.

Presentation Type: Oral Paper:Papers for Topics
Session: 65
Location: Salon 9/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 10:15 AM
Number: 65001
Abstract ID:1054
Candidate for Awards:CPS Best Student Presentation Awards