Very little is known on the best way to manage this disease problem. Current research
projects are focused on crop rotation, irrigation management, herbicide interactions,
suppressive cover crops, and varietal tolerance. These types of strategies are
currently used to manage other root rots and they may be useful here.
A common root rot management strategy may include:
Pre-plant:
Plant sweet corn hybrids tolerant of root rot. (Varieties link)
Practice a long crop rotation. Continuous cropping of corn eventually leads
to an increase in soil populations of the pathogens.
Plant corn on well-drained soils or improve drainage. Sub-soiling to a depth
below the plow layer will reduce soil compaction, and improve drainage. Avoid
driving on wet fields.
Post emergence:
Sample field at 6 weeks after emergence. If radicles are severely diseased,
time harvest carefully to avoid loss of quality; harvest earlier rather than
later.
Do not over-water during the first 6 weeks of growth, as root rots are favored
by moist soils.
Effect of Irrigation Scheduling on Root Rot Severity and Yield of Sweet Corn
Ed Peachey, Horticulture
Robin Ludy, Botany and Plant Pathology
Jim Myers, Horticulture
Mary Powelson, Botany and Plant Pathology
Alex Stone, Horticulture
Root rot of sweet corn can significantly reduce yield. The most reliable strategies for root rot management are crop rotation (more than three years out of corn) and planting tolerant varieties. However, growers need other cultural strategies for combating this disease. We learned in a split field trial near Stayton in 2002 that reducing irrigation slightly may reduce root rot severity. We also know that some corn growers moisture-stress their corn for the first half of the season, and as long as there is not a water deficit later in the season when ears are forming, yield does not seem to be adversely affected. However, the impact of a reduction in early-season irrigation on yield in a field of high root rot potential had not been seriously investigated. This was the purpose of three years of research conducted at the OSU Vegetable Research Farm near Corvallis.
We planted sweet corn 'Golden Jubilee' in late June for three years and in the 'low' treatment kept the corn relatively dry until midseason. In the 'high' irrigation treatment, the corn was irrigated at 5-6 days intervals at about 1.3 inches/week. Beginning at midseason both the 'high' and 'low' irrigation plots were irrigated at the same level. In all years, radicle (primary) root rot severity was lower in the 'low' irrigation plots than in the 'high' irrigation plots at midseason. In addition, yield of Jubilee in the 'low' treatment was greater than or equal to the yields in the 'high' irrigation plots. In the 3rd year of the study (2005), sweet corn in the 'low' irrigation treatment yielded as much as 2 t/A more than corn in the 'high' irrigation treatment. Excess early season irrigation of corn not only increases root rot severity but may also decrease yield.
