It is hard to believe that the “dog days” of August are nearing. Overall our crops look as good as one can hope for on a year like this.

There are certainly many areas of the state that do not look as good as we do as a whole. I encourage producers to get out and scout their fields for disease, insects and escaped weed control.

One item of concern reported by Anne Dorrance, Ohio State Plant Pathologist is the presence of Corn rust.

According to Dorrance, Ohio corn producers are reporting more rust on corn this year, and are concerned that it might be southern rust, the rarer but more damaging of the two major rust diseases that affect corn in state.

Based on the fact that they both produce rusty looking pustules on the leaves, producers may actually be confusing common rust with southern rust, especially when they are not occurring side-by-side on the same leaf.

Check fields and observe the weather before making an application. As it becomes warm and dry, typical of summers in Ohio, the development and spread of common rust slow down considerably or stop. For southern rust, however, fungicides may be warranted and economically beneficial if timed correctly (as soon as the first few pustules are observed).

A couple differences between the two rusts is for common rust the rust postule color is brownish to cinnamon-brown and can be found on both the upper and lower surface of the leaves and commonly only found on the leaves.

For southern rust the postule color is more reddish orange and is found predominantly on the upper leaf surfaces but can also be found on the stems and husks.

Since common rust is rarely ever an economic concern in this part of the world, no extensive research has been done to determine damage, fungicide application, or any other thresholds in Ohio. Dorrance notes that if the hybrid is susceptible and conditions seem favorable, you can use the guidelines below for gray leaf spot (GLS) and northern corn leaf blight (NCLB) as a guide, with the understanding that they were not developed for rust.

The biology of common and southern rust is vastly different from that of GLS, NCLB, and Eye Spot.

Scout fields just prior to tassel emergence, and examine plants for disease symptoms. A foliar fungicide application should be considered under the following situations:

Susceptible hybrids: If disease symptoms are present on the third leaf below the ear or higher on 50% of the plants examined.

Intermediate hybrids: If disease symptoms are present on the third leaf below the ear or higher on 50% of the plants examined, AND the field is in an area with a history of foliar disease problems, and growing and weather conditions favor the disease in question.

Resistant hybrids: Fungicide applications generally are not recommended.

Mark your calendars for the upcoming Southwest Ohio Corn Growers & Fayette Co. Agronomy Field Day set for Tuesday, Aug. 15 from 9:30 a.m. to 3 p.m. at the Fayette county farm, 2770 SR 38, Washington Court House.

Topics and speakers will include:

• Spray Drift and Spray Nozzle Selections — Erdal Ozkan, The Ohio State University

• Follow-up for 2018 Farm Bill Listening Session — Jed Bower, Ohio Corn and Wheat Growers

• Corn Seeding Rates and Emergence — John Fulton, The Ohio State University

• Corn Ear Rot, Diagnostic Demonstration — Paul Pierce, The Ohio State University

• Using On-Farm Research to Make Adaptive Nitrogen Decisions – Elizabeth Hawkins, The Ohio State University

• Cover Crops for Pollinators — Denise Ellsworth, The Ohio State University

• Ohio Corn and Wheat Growers Association Update

• Programs available to plant Pollinator Strips — Katie Maust, USDA Farm Service Agency and Will Newman, Pheasants Forever

All-day events will include:

• Corn and soybean show plots

• Two $500 gift certificates drawing for Ohio Corn Grower Members

• Trade show

• Plane rides from FCA Flight Training, $30/person for a 30-minute flight (must register at 740-335-2430, payment in cash or check made to FCA Flight Training)

• Health screenings in the morning (please fast prior for blood testing)

• CCA sredits and private pesticide re-certification credits offered

For more information contact Tony Nye at (937) 382 – 0901 or at nye.1osu.edu.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for 29 years, currently serving Clinton County and the Miami Valley EERA.