Skip to main content


  • Phytophthora

    Phytophthora root rot (PRR), caused by Phytophthora sojae, is a considerable threat to soybean production in Iowa, particularly in wet summers. Currently, PRR is primarily managed by planting soybean varieties with genes that confer resistance (Rps genes) to P. sojae. The effectiveness of a resistance gene relies on its ability to recognize the pathogen’s corresponding avirulence gene (Avr).

  • Field trial evaluating teh effect of cereal rye termination timing on seedling disease, corn growth and yield.

    Cover crops may provide numerous ecosystem services: they retain residual soil nitrate (NO3--N), reduce soil erosion, increase soil organic matter, sequester carbon (C), and improve general soil health. Cereal rye (CR) is by far the most dominant cover crop grown in field crop production systems in Iowa because it easily establishes, overwinters well, and thus can produce large amounts of spring biomass. However, there are negative tradeoffs associated with CR cover crops, including the potential to reduce corn yields (‘yield drag’). We are working with colleagues in the Dept. of Agronomy and USDA-ARS, to understand the factors play a role in yield drag. We have shown seedling disease and allelopathy likely play a role.

  • Foliar fungicides

    Foliar fungicides have traditionally not been used in commercial corn because they have seldom been profitable. However, the use of foliar fungicides in hybrid corn production has increased dramatically in the past four years, primarily because of higher grain prices and physiological, yield-enhancing effects that are claimed by the agrochemical industry but are not related to reduced disease.

  • Phytophthora damping off

    To optimize yield potential, soybean farmers in Iowa are planting earlier in the growing season. Together with reduced tillage practices, this often means that seed germinate in cold, wet soils and are at risk for seed rot and damping off due to soil borne pathogens such as Pythium spp., Phytophthora sojaeFusarium spp.