Assessment of tolerance for reducing yield losses in field pea caused by Aphanomyces root rot

Abstract

Conner, R. L., Chang, K. F., Hwang, S. F., Warkentin, T. D. and McRae, K. B. 2013. Assessment of tolerance for reducing yield losses in field pea caused by Aphanomyces root rot. Can. J. Plant Sci. 93: 473–482. Aphanomyces root rot, caused by Aphanomyces euteiches Drechs., is a serious disease of peas (Pisum sativum) that can severely reduce seed yield, and few effective control measures are available. The development of pea cultivars with tolerance or partial resistance to Aphanomyces root rot is generally considered to be one of the best options to reduce yield loss. A 4-yr field study was conducted at disease-free sites and at an Aphanomyces root rot site to compare the responses of cultivars and lines in the presence and absence of Aphanomyces root rot, identify breeding lines with tolerance and to evaluate the effects of tolerance on plant growth, disease severity and yield. At the Aphanomyces root rot site, a second test was established in which the phosphite fungicide Phostrol™ was applied as a soil drench treatment to the pea cultivars and lines. Aphanomyces root rot reduced seedling emergence, biomass production and yield in the susceptible pea genotypes. However, line 00-2067 consistently produced relatively high yields at all the field sites. At the Aphanomyces root rot site, yield was closely associated with plant vigour and shoot weight. Small, but significant, differences (P<0.05) in disease severity were observed between susceptible cultivars and tolerant lines indicating that the lines producing high yields at the Aphanomyces root rot site are tolerant rather than partially resistant. The root/shoot weight ratio was very low in the tolerant lines, indicating that even though their root systems were reduced and severely damaged by root rot, they were still able to produce high yields under favourable conditions for the disease. Drench application of the fungicide Phostrol™ did not significantly reduce root rot severity or improve the performance of any of the pea cultivars or lines.

Detection of interactions between the pea root rot pathogens Aphanomyces euteiches and Fusarium spp. using a multiplex qPCR assay

“…The composition of root pathogen populations can differ between the root, stem and crown tissues of P. sativum (Esmaeili Taheri et al ., ). Aphanomyces euteiches invades the cortical cells of its host, eventually leading to sloughing of the cortex while the vascular cylinder remains intact (Conner et al ., ). Decay and ‘pinching’ of the epicotyl is a diagnostic feature of ARR, but cortical degradation is typically present throughout the entire root system.…”

“…However, its high prevalence in the latter two provinces indicates that it was probably present for many years prior to detection. Aphanomyces root rot (ARR) is characterized by honey‐coloured lesions on the root cortical tissues that can progress to cause complete destruction of the cortex, resulting in severe stunting, chlorosis and premature death (Gaulin et al ., ; Conner et al ., ). Yield losses of up to 60% and 80% have been reported in field pea as a result of FRR and ARR, respectively (Chang et al ., ; Gaulin et al ., ), and complete loss due to root rot disease has been observed in severely affected fields in Alberta and Saskatchewan (S. Chatterton, unpublished data).…”

Economics of pulse crop frequency and sequence in a wheat‐based rotation

“…Despite these benefits cropping pulses at an intensive level in rotations could also lead to the build‐up of pathogens in the soil (Bainard et al., 2017). For example, a high frequent cropping of field pea on the same land has been shown to increase the likelihood that a crop will fail as a result of Aphanomyces root rot (Conner, Chang, Hwang, Warkentin, & McRae, 2013). Farmers must therefore strike a balance between PC and cereal crops to maximize their benefits without cropping too intensely.…”

“…Farmers must therefore strike a balance between PC and cereal crops to maximize their benefits without cropping too intensely. The disease severity can be reduced by designating the crop rotation cycle length with proper crop sequence to break the life cycle of pathogens (Conner et al., 2013). For example, root rot complex is a disease caused by A. euteiches , a highly specialized pathogen that affects a number of PC especially pea and lentil under favorable conditions (Harvey & Hagedorn, 1979; Hossain, Bergkvist, Berglund, Mårtensson, & Persson, 2012; Moussart et al., 2013).…”

Isolation, identification, and assessment of soil bacteria as biocontrol agents of pea root rot caused by Aphanomyces euteiches

“…Loss of plant productivity can reach up to 100% in soils heavily infested with the pathogen (Gaulin et al 2007). Options for management are limited, as resistant pea cultivars presently do not exist (Conner et al 2013;Lavaud et al 2015). Monitoring pathogen inoculum levels in field soils and crop rotations can help farmers avoid crop losses.…”