Effect of residue type and burial depth on survival of Mycosphaerella pinodes in Manitoba

Abstract

Survival of Mycosphaerella pinodes in leaf and stem residues placed at 0, 5, and 10 cm below the soil surface was examined at Morden and Winnipeg, Manitoba, from October 1999 to October 2000. Survival was measured as production of spores from residue and pathogenicity of residue washings on the susceptible field pea cultivar 'AC Tamor'. Spore production on the residues decreased over the 12-month sample-retrieval period, regardless of residue type and burial depth. Spores were rarely produced from residues after 11 months at Morden and 9 months at Winnipeg. In general, more spores were produced on leaf residues than on stem residues. No or few lesions developed from residue washings after 9 months for leaf residue and 8 months for stem residue at both locations. Residues on the soil surface had greater spore production and subsequently produced greater disease severities on pea plants inoculated with residue washings than those of the buried residues. There was no statistical difference in spore production and disease severity produced by residue washings between residues buried 5 and 10 cm deep.

Keywords:

• mycosphaerella blight
• Mycosphaerella pinodes
• field pea
• Pisum sativum
• survival