EFFECTS OF SOIL COMPACTION, TEMPERATURE, AND MOISTURE ON THE DEVELOPMENT OF THE FUSARIUM ROOT-ROT COMPLEX OF PEA IN SOUTHWESTERN ONTARIO

The pea root rot complex (Fusarium spp.) is known to be affected by co mpaction, temperature, and moisture of the soils. This paper reports t he effects of these factors on root rot severity and pea (Pisum sativu m) growth tested in a controlled environment, using a Fusarium-infeste d soil collected from a field with a severe root rot history. For each factor, several increments were used. The results showed that in a co ntrolled environment, an increase in soil bulk density due to compacti on significantly increased root rot incidence and disease severity, an d drastically reduced the fresh weight of pea plants. Stepwise increas es in soil temperature from 10 to 30-degrees-C resulted in increases i n estimated root rot severity and foliar symptom expression. Pea plant s grown in soil moisture at 75% of field capacity had significantly lo wer Fusarium root rot incidence and severity than those grown in soil at 100%, 50% or 25% of field capacity. Pea plants subjected to tempora ry flooding exhibited an increased root rot incidence and severity as the duration of flooding increased from 1 to 5 d.