Purple Corn and Phytophthora

Submitted by Rich Pope

Several people from around Iowa reported answering questions about corn that has developed pronounced purple coloring. For those of you who are or have clients concerned with purpling of corn please visit the corn management webpage: http://www.agronext.iastate.edu/corn/production/management/early/coldstress.html for the article posted on this matter. Extension Plant Pathologist Alison Robertson and her new graduate student Silvina Stewart report that they are collecting samples of phytophthora for use in their research program and ask that if you have suspected phytophthora-infested plants to consider sending them to her lab. This research is to focus efforts in developing phytophthora-resistance based on what races of the pathogen are present. Samples will be race tested, and later this summer or fall they will share with you the races in your submitted samples. Your assistance is completely voluntary!

The message from Dr. Robertson is as follows:

The very wet and warm planting conditions across much of Iowa have been ideal for the development of Phytophthora damping off. Plants infected by Phytophthora have a brown discoloration extending from root up the stem (see photo attached). Alison Robertson’s lab is continuing to assess the diversity of Phytophthora in Iowa. We request your help in this project; we would like to obtain plant samples from suspected Phytophthora-infected plants, as you find them. Please place whole plants with Phytophthora symptoms in an open plastic bag. Include at least part of the root system. Please include information on the location from where the plants were collected (preferably GPS co-ordinates; or township and county). Mail the samples to:

Robertson Lab/Phytophthora Project
Department of Plant Pathology
351 Bessey Hall, Ames, IA 50011-1020