Fungicide Efficacy for Control of Corn Diseases

Jul 19, 2021

By Pierce Paul and Stephanie Karhoff

Many corn fields in Ohio are rapidly approaching silking (R1), and foliar diseases such as Gray leaf spot have been observed where the environment has been conducive to disease development, prompting growers to consider fungicide applications. The information below was developed by the Corn Disease Working Group (CDWG) as part of the Crop Protection Network. The Crop Protection Network is a a multi-state and international collaboration of university and provincial extension specialists, and public and private professionals who provide unbiased, research-based information to farmers and agricultural personnel.

The CDWG developed ratings for how well fungicides control major corn diseases in the United States. The CDWG determined efficacy ratings for each fungicide listed in the table below by field testing the materials over multiple years and locations. Ratings are based on the product’s level of disease control and does not necessarily reflect yield increases obtained from product application. A product’s efficacy depends upon proper application timing, rate, and application method as determined by the product label and overall disease level in the field at the time of application. Differences in efficacy among each fungicide product were determined by directly comparing products in field tests using a single application of the labeled rate. The table includes marketed products available that have been tested over multiple years and locations. The table is not intended to be a list of all labeled products. Additional fungicides are labeled for disease on corn, including contact fungicides such as chlorothalonil. Other fungicides may be available for diseases not listed in the table, including Diplodia, Gibberella and Fusarium ear rots. Many products have specific use restrictions about the amount of active ingredient that can be applied within a period of time or the amount of sequential applications that can occur. Read and follow all use restrictions prior to applying any fungicide.

Source : osu.edu

Video: Wheat Yields in USA and China Threatened by Heat Waves Breaking Enzymes

A new peer reviewed study looks at the generally unrecognized risk of heat waves surpassing the threshold for enzyme damage in wheat.

Most studies that look at crop failure in the main food growing regions (breadbaskets of the planet) look at temperatures and droughts in the historical records to assess present day risk. Since the climate system has changed, these historical based risk analysis studies underestimate the present-day risks.

What this new research study does is generate an ensemble of plausible scenarios for the present climate in terms of temperatures and precipitation, and looks at how many of these plausible scenarios exceed the enzyme-breaking temperature of 32.8 C for wheat, and exceed the high stress yield reducing temperature of 27.8 C for wheat. Also, the study considers the possibility of a compounded failure with heat waves in both regions simultaneously, this greatly reducing global wheat supply and causing severe shortages.

Results show that the likelihood (risk) of wheat crop failure with a one-in-hundred likelihood in 1981 has in today’s climate become increased by 16x in the USA winter wheat crop (to one-in-six) and by 6x in northeast China (to one-in-sixteen).

The risks determined in this new paper are much greater than that obtained in previous work that determines risk by analyzing historical climate patterns.

Clearly, since the climate system is rapidly changing, we cannot assume stationarity and calculate risk probabilities like we did traditionally before.

We are essentially on a new planet, with a new climate regime, and have to understand that everything is different now.