The influence of plant injury on development of Mycosphaerella pinodes in field pea

Abstract

Plants of field pea, Pisum sativum ‘AC Tamor’, were mechanically injured by sandblasting and inoculated with Mycosphaerella pinodes immediately after this pretreatment and 1, 2, 4, and 8 days later under controlled conditions. A negative linear relationship was observed between disease severity, measured as the area under the disease progress curve over a period of 17 days, and the time elapsed between injury and inoculation. Control plants, without injury, were inoculated parallel to the injured plants and did not show this response. Inoculation up to 24 h after injury resulted in significantly higher disease severity than inoculation after that period or inoculation of control plants, suggesting that injury facilitates infection of the pea plant by M. pinodes prior to the formation of callus. In field experiments, differences between injury and control treatments of nine field pea genotypes (cultivars and germplasm accessions) were apparent only a few weeks after inoculation. Disease severity in the second half of the cropping season that was characterized by above-average precipitation was similar in all treatments. This indicates that plant injury plays a minor role in the establishment and development of M. pinodes when conditions are conducive to an epidemic outbreak of the disease. Spore production was monitored with simple spore traps in plots with and without injury treatment and did not show any difference in spore numbers.

Keywords:

• Mycosphaerella pinodes
• field pea
• Pisum sativum
• mechanical plant injury
• pathogen development