Tar Spot Of Corn: What To Know And New Research

by: Dan Quinn and Darcy Telenko, Purdue University

Due to its relatively recent U.S. discovery and its ability to cause significant production and economic losses, tar spot is often a topic of angst and anxiety amongst corn farmers and agronomists in Indiana. For example, a severely infected field can reach yield losses upwards of 60 bushels per acre! Yield losses are often a result of reduced photosynthetic capacity (green leaf area) of the corn plant during grain fill resulting in poor grain fill, kernel abortion, and reduced kernel weight. In addition, severe infection can reduce corn stalk integrity and cause significant lodging later in the season. Tar spot was first confirmed in northwest Indiana in 2015 and the first significant yield-reducing event of the disease was observed in 2018. Similarly, severe outbreaks and large areas of infection of this disease were observed in Indiana in 2021. Tar spot is caused by the fungus known as Phyllachora maydis and can be identified by small, raised black and circular spots present on corn leaves, stalks, and husks (Figure 1). These black and circular spots are known as fungal fruiting structures called stromata, each of which can produce thousands of spores. Overall, tar spot infection and severity can vary based on environmental conditions, the total amount of the pathogen present in the field, and corn hybrid chosen.

What Conditions Cause Tar Spot? Continue reading

Evaluating the Prevent Plant Option

By: Eric Richer & Chris Bruynis, OSU Extension Educators

Planting progress goes differently every year and in each part of the state. This year is no different in Ohio. Some places got in early and are finished. Others had their ‘normal’ planting progress with ‘normal’ Mother Nature breaks, perhaps with some re-plant needed. And still others have not had ideal conditions all spring to plant.  As such, we have received some recent calls regarding the mechanics and economics of utilizing the Prevent Plant through crop insurance this year in certain parts of the state. First and foremost, we are not crop insurance agents, so speaking with your agent is of utmost importance. In this article, we will walk through an example on the economics of electing Prevent Plant.

In Ohio, once you arrive at the final plant date of June 5 for corn (already passed) and June 20 for soybeans, you basically have 3 options in a corn scenario: Continue reading

Xyway Corn Fungicide Trial

Knox County Xyway Trials

Taking stand counts at our Xyway plot – Great looking field of corn!

 

 

A Special Thanks to Ed & Vicki Piar!!

 

The goal of this study is to determine corn’s response to an at-plant soil application of flutriafol (Xyway™) fungicide. Information from this trial will be used to improve corn disease management recommendations for growers throughout the state.

Vomitoxin Research 2022 – Plot #4

Knox County Vomitoxin Research Station #4 Installed – Thanks to Dr. Pierce Paul and Crew!

A Special Thanks to Braddock Farms – Jim and Susan Braddock!!

 

Fusarium molds that produce DON often develop under wet weather conditions. This particular mold initially enters plants through silks or wounds, and cool, wet conditions during the silking stage promotes spore production, increasing the inoculum load that can potentially infect more plants. Infections by the fungal species F. graminearum result in the development of Gibberella ear and stalk rots. Corn from fields with this disease issue may need to be tested for potential contamination.

The goal of this Statewide research project is to develop a prediction model that will allow producers to take corrective action based upon a weather prediction model to prevent plant infections.

40 of these research stations are scattered throughout West-Central Ohio.

Vomitoxin Research 2022 – Plot #3

Knox County Vomitoxin Research Station #3 Installed – Thanks to Dr. Pierce Paul and Crew!

A Special Thanks to Clark Farms – Tom and Nate Clark!!

 

Fusarium molds that produce DON often develop under wet weather conditions. This particular mold initially enters plants through silks or wounds, and cool, wet conditions during the silking stage promotes spore production, increasing the inoculum load that can potentially infect more plants. Infections by the fungal species F. graminearum result in the development of Gibberella ear and stalk rots. Corn from fields with this disease issue may need to be tested for potential contamination.

The goal of this Statewide research project is to develop a prediction model that will allow producers to take corrective action based upon a weather prediction model to prevent plant infections.

40 of these research stations are scattered throughout West-Central Ohio.

Vomitoxin Research 2022 – Plot #2

Knox County Vomitoxin Research Station #2 Installed – Thanks to Dr. Pierce Paul and Crew!

 

A Special Thanks to David and Emily Mitchem!!

 

Fusarium molds that produce DON often develop under wet weather conditions. This particular mold initially enters plants through silks or wounds, and cool, wet conditions during the silking stage promotes spore production, increasing the inoculum load that can potentially infect more plants. Infections by the fungal species F. graminearum result in the development of Gibberella ear and stalk rots. Corn from fields with this disease issue may need to be tested for potential contamination.

The goal of this Statewide research project is to develop a prediction model that will allow producers to take corrective action based upon a weather prediction model to prevent plant infections.

40 of these research stations are scattered throughout West-Central Ohio.

Vomitoxin Research 2022 – Plot #1

Knox County Vomitoxin Research Station #1 Installed – Thanks to Dr. Pierce Paul and Crew!

 

A Special Thanks to Sassafras Hill Farms – Nate McKee and Skyler Epler!!

 

Fusarium molds that produce DON often develop under wet weather conditions. This particular mold initially enters plants through silks or wounds, and cool, wet conditions during the silking stage promotes spore production, increasing the inoculum load that can potentially infect more plants. Infections by the fungal species F. graminearum result in the development of Gibberella ear and stalk rots. Corn from fields with this disease issue may need to be tested for potential contamination.

The goal of this Statewide research project is to develop a prediction model that will allow producers to take corrective action based upon a weather prediction model to prevent plant infections.

40 of these research stations are scattered throughout West-Central Ohio.

Rainfast Intervals, Spray Additives, and Crop Size for Postemergence Corn Herbicides

Mother nature is finally cooperating, allowing us to get some corn and beans in the ground.  Later this summer it will be time for postemergence herbicide applications.  The table below from the “2022 Weed Control Guide” lists important information on rainfast intervals, spray additives and crop size  for corn postemergence applications.

 

 

Click on each page to print a camera ready copy

 

Alternative spring burndown/postemergence strategies when herbicides are in short supply

by: Dr Mark Loux, OSU

There is a lot of speculation about herbicide shortages for the 2022 growing season, and some products are apparently getting more expensive and/or scarce now. This will affect herbicide buying and weed management decisions for the 2022 season. The two main active ingredients that we’re hearing about right now are glyphosate (Roundup, others) and glufosinate (Liberty, others), for which prices have increased substantially. There will likely be limited supplies of other pesticide active ingredients as well, but in the short term, a shortage of these two active ingredients poses some major challenges for corn and soybean production. The purpose of this article is to discuss ways to minimize the impact of herbicide shortages, primarily glyphosate, on corn and soybean production. As you search for alternatives to these two herbicides and others, the weed control guides and technical guides produced by University Extension and industry are an important tool for planning weed management programs and herbicide purchases.

Some guiding principles based on our experience that may help with decisions, especially where glyphosate will not be in all applications:

  1. Spring tillage is an option to replace herbicide burndown. Can cause long-term compaction problems if tilled when too wet. Waiting until weeds are large makes tillage less effective. Weeds that survive tillage will be difficult to control with POST herbicides. In other words, till when soil conditions are fit and before weeds are huge.
  1. Where it’s only possible to use glyphosate once, it may be needed most in the burndown. Saflufenacil can be added for enhanced control of rye and ryegrass, and marestail. ACCase herbicides (e.g. clethodim, quizalifop) can then be used for POST grass control in soybeans. Glufosinate, Enlist Duo, or XtendiMax/Engenia can be used for many broadleaf weeds, especially the glyphosate-resistant ones. Where residual herbicides are omitted, or do not provide enough control, we would expect POST treatments to struggle more in the absence of glyphosate with weeds such as lambsquarters. So use residuals. Glyphosate is still more than just a grass herbicide.

Continue reading