A Global Survey on Diseases and Pests in Oilseed Rape—Current Challenges and Innovative Strategies of Control

Abstract

The introduction of high-yielding and hybrid cultivars and the opening of new markets in the food and feed sector have steadily increased rapeseed production since the 1980s in the main production regions, Canada, Europe, China, India, and Australia. Since the 1990s, however, the average growth rate of yields has declined in Europe and Australia, which has been associated with a less effective control of biotic stresses. A global survey including the knowledge of 22 experts from 10 countries revealed a total of 16 diseases, 37 insect pests, several species of nematodes, and slugs currently affecting rapeseed production globally. A ranking of the top 10 most important biotic stresses in the four global regions where Brassica napus is grown (Canada, China, Europe, Australia) indicated an increase in several important stresses and distinct regional differences in the priority of prevailing diseases and pests. A stronger overlap exists among diseases, with Sclerotinia stem rot, Phoma stem canker, and clubroot occurring in all the four global regions on the top 10 list, while the range of prevailing insect pests was more diverse among the regions, with no top 10 insect playing an equally important role worldwide. Management options are substantially broader in disease than in pest control, making the latter the larger challenge. Since common integrated pest management (IPM) tools such as crop rotation, soil management, resistant cultivars or biocontrol are ineffective or not available, insect control largely relies on insecticides. Increasing restrictions on insecticide use, particularly in Europe, and losses in insecticide efficacy threaten the profitability of oilseed rape production and its role as an important break crop in cereal dominated cropping systems. Since the survival time of insects in the absence of their main host is relatively short (<1 year), a regional synchronization of cropping schemes resulting in one or more years without the crop could lead to a substantial disruption of regional insect populations. If rotation schemes were implemented on the landscape instead the farm level, by coordination among growers in zones covering the range distances of insect pests, an efficient and chemical low management strategy could be established and enable a more sustainable rapeseed production in the future.

Influence of Soil-Borne Inoculum of Plasmodiophora brassicae Measured by qPCR on Disease Severity of Clubroot-Resistant Cultivars of Winter Oilseed Rape (Brassica napus L.)

“…High temperatures in the 2018 season (e.g., 30-37 • C at Kumla) also affected evaporation, and therefore yield differences due to clubroot was probably strongly masked (Table S1), as experienced by others [3]. Yield in the clubroot-resistant cultivars at Kumla in 2018 was only 10% higher than for the susceptible Cultivar mix, despite severe clubroot infection (Table 1), compared with 35% at Simrishamn and 55% at Tomelilla.…”

“…In the main Swedish production areas, the acreage of winter OSR has increased from 90 to 94% of total oilseed rape acreage since 2015. However, increasing outbreaks of plant diseases that survive in the soil as resting spores or resting bodies, such as clubroot, Sclerotinia stem rot, and Verticillium wilt, have also been reported recently in Sweden and globally [3].…”

Local Duplication of TIR-NBS-LRR Gene Marks Clubroot Resistance in Brassica napus cv. Tosca

“…Many important crops cultivated worldwide, including oilseed rape (Brassica napus), belong to the Brassicaceae (Dixon, 2007). Clubroot disease has been becoming a global problem of increasing economic impact in cruciferous crops and has been ranked under the top 10 most significant worldwide threats to oilseed rape production (Dixon, 2009;Zheng et al, 2020). An infection of oilseed rape was shown to cause up to 60% loss of yield at relatively low spore densities, and total yield failure at a higher pathogen pressure (Strehlow et al, 2015).…”

Epidemiology, Genetics and Resistance of Alternaria Blight in Oilseed Brassica

“…Rapeseed-mustard dominates the total oilseed production after soybean globally [1]. Alternaria blight is one of the major biotic threats that drastically reduces oilseed production all over the world including Australia, Europe, China and Canada [2]. Alternaria blight is a recalcitrant disease caused by the Alternaria species primarily A. brassicae and A. brassicicola, of which A. brassicae is the most deadly [3][4].…”