7/2/2013 - By Matthew Shultz

With scorching hot temperatures across the Eastern U.S., Rhizoctonia tends to become a major problem. Most strains of Rhizoctonia thrive when soil temperatures are between 70-90 degrees F. Infected plants will look as if there is a lack of soil moisture, and often will wilt. Examination of the crown tissue right at the soil line will show the presence of lesions brown to red in color, and over time these lesions will girdle the plant, choking off nutrient and water flow to the canopy.

Rhizoctonia can take on the form of a root rot or stem root in woodies, damping off in herbaceous and bedding plants, and even leaf blights. Growers often have to water more frequently during these hotter months which only helps to promote disease spread. Rhizoctonia can be very difficult to manage once it becomes established in a nursery -- infected soil should be removed immediately. Older plants tend to be more prone to this disease than healthy vigorous ones, and with many nurseries sitting on old plant material, Rhizoctonia maybe prevalent this year.

Rhizoctonia can be controlled using a good spray and drench rotation, using direct sprays at the crown of the plant with Phyton 27, Daconil and Pageant, drench with Hurricane and Medallion, and in outbreak conditions, drench with thiophanate methyl or PCNB. Contact your tech service rep for further spray details.

By Matt Shultz, Horticultural Tech Support Specialist and Sales Representative, Harrell’s LLC.

Reference utilized –http://extension.psu.edu/plant-disease-factsheets/all-fact-sheets/rhizocton