By Alison Robertson
A couple of weeks ago in a blog post, I shared with you some research we are doing on the effects of cold stress on soybean susceptibility to seedling pathogens.
Recently a Ph.D. student in my lab, Rashelle Matthiesen, reported that some species of Pythium cause disease at cool (55°F) while others cause disease at warmer temperatures (64°F and/or 73°F) (Plant Disease 100: 583-589).
These experiments are done under controlled environment conditions. I don’t need to remind you that what happens in the field is not controlled.
This morning we started a field experiment in an attempt to validate what we see in the controlled environment conditions. Over the next six weeks we will plant soybean and monitor emergence and seedling disease development. Today was our first date of planting and you can see it was a gorgeous morning in central Iowa. Two years ago, we collected soybeans with Phytophthora root and stem rot from this field. It's a low lying area with heavy clay soils. Consequently, it should be a high risk field for seedling disease.
We will be collecting seedlings from the plots and determining what species of Pythium or Phytophthora are causing the disease. Since we are monitoring soil temperatures at the site, this will enable us to compare our field data with what we see in the lab. In this way, we hope to determine which Pythium and Phytophthora species infect soybean and at what temperature, under field conditions.
Thanks to the soybean check-off, specifically Iowa Soybean Association and the North Central Soybean Research Program, for funding our research.