Agronomy

Ohio Certified Crop Adviser Pre-Exam Preparation

The Certified Crop Adviser (CCA) Exam Training program, delivered by OSU Agronomic Crops Team members, will be available online and in-person to help you prepare for the 2022 CCA exams. An in-person two-day training class will be held on January 12 & 13 from 9 AM to 5 PM each day at the Shelby County Ag Building, 810-820 Fair Rd, Sidney, Ohio 45365. The content is a great basic agronomy course covering information to prepare for the local CCA exam. The cost for this program is $250/person. Registration includes the publications below, lunch both days, and other program materials. Class size is limited to 25, and registration closes on December 20, 2021.

Publications provided with the in-person option:

  • Ohio Agronomy Guide
  • Ohio, Indiana & Illinois Weed Control Guide
  • The Ohio Corn, Soybean, Wheat and Forages Field Guide
  • 2020 Tri-State Fertilizer Recommendations
  • Modern Corn & Soybean Production

Continue reading Ohio Certified Crop Adviser Pre-Exam Preparation →

Fall-Applied Herbicides: Odds and Ends

A commonly asked question about fall herbicides – how late in the fall can herbicides be applied and at what point is it too cold to apply?  We have applied well into December under some very cold conditions and still obtained effective control of winter annuals.  We suggest applying before Thanksgiving and aiming for a stretch of warmer weather if possible, but the effective treatments should work regardless.  Extended periods of freezing weather will cause the perennials to shut down – dandelion, thistle, dock.

We received a lot of questions about annual bluegrass this year, especially regarding difficulty in controlling it in the spring.  Fall is a good time to control this weed.  This will require the addition of glyphosate to whatever herbicide mix is being used. Continue reading Fall-Applied Herbicides: Odds and Ends →

Extended Drydown in Corn

By:  Alex Lindsey OSU Extension

As fall is progressing, crop harvest is also occurring throughout the state. However, many producers are seeing slower than usual drydown in their corn fields this October. This may be in part due to how the weather conditions impacted corn growth and development this year.

In many parts of Ohio in 2020, temperatures were near the long-term average this season. One marked difference though was that precipitation was below normal for much of the season around the state. In the table below, I have shown 2020 weather progression compared to that of 2018 at the Western Agricultural Research Station, specifically highlighting average temperature and accumulated precipitation. Continue reading Extended Drydown in Corn →

Gibberella Ear Rots Showing up in Corn: How to Tell It Apart from Other Ear Rots

By:  Pierce Paul and Felipe Dalla Lana da Silva

Ear rots differ from each other in terms of the damage they cause (their symptoms), the toxins they produce, and the specific conditions under which they develop. GER leads to grain contamination with mycotoxins, including deoxynivalenol (also known as vomitoxin), and is favored by warm, wet, or humid conditions between silk emergence (R1) and early grain development. However, it should be noted that even when conditions are not ideal for GER development, vomitoxin may still accumulate in infected ears.

A good first step for determining whether you have an ear rot problem is to walk fields between dough and black-layer, before plants start drying down, and observe the ears. The husks of affected ears usually appear partially or completely dead (dry and bleached), often with tinges of the color of the mycelium, spores, or spore-bearing structures of fungus causing the disease. Depending on the severity of the disease, the leaf attached to the base of the diseased ear (the ear leaf) may also die and droop, causing affected plants to stick out between healthy plants with normal, green ear leaves. Peel back the husk and examine suspect ears for typical ear rot symptoms. You can count the number of moldy ears out of ever 50 ears examined, at multiple locations across the field to determine the severity of the problem. Continue reading Gibberella Ear Rots Showing up in Corn: How to Tell It Apart from Other Ear Rots →

Late-Season Waterhemp – The Goal is Stopping Seed

By Mark Loux OSU Extension

In our windshield scouting of soybeans this year we have seen a lot of weedfree fields.  This makes sense given the shift toward Xtend, LibertyLink, LLGT27, and Enlist soybeans over the past several years, which provides us with effective POST options for our major weed problems – common and giant ragweed, marestail, and waterhemp (now if we could just get rid of the baggage some of these traits carry).  We are however getting manyreports of late-season waterhemp as it grows through the soybeans and becomes evident.  This also makes sense given that statewide we are in the midst of an overall increase in waterhemp, and continue to move up the curve in terms of number of fields infested and the size of the infestations.  Prevention and management of waterhemp and Palmer amaranth has been one of the primary goals of our state and county educational programs for half a decade or more.  And one of the most important points about waterhemp and Palmer that we try to get across is their capacity for prodigious seed production – 500,000 to upwards of a million seeds per plant – and what this means for their ability to rapidly ramp up populations, infest equipment, etc.

Flowering Waterhemp

The bottom line here is that it’s essential to scout fields this time of the season and kill or remove plants that could produce seed.  Allowing even a few plants to produce seed means an increased population for the next year or two at least.  Running harvest equipment through planst loaded with seed is a primary mechanism of spread from field to field.  Plants can survive into late season because they emerged after herbicide treatments, or survived an improperly timed and less than effective POST treatment.  These plants should produce less seed than plants allowed to grow full season without interruption.  It’s also possible given waterhemp’s propensity to become resistant to any herbicide used against it, that the survivors are resistant to whatever POST herbicide was used.  Resistance to glyphosate, ALS, and PPO inhibitors is widespread in Ohio, and we expect the development of resistance to dicamba, 2,4-D, and glufosinate will occur given their intensity of use (which is why the current period of clean fields makes us nervous).  The only way to ensure that resistance does not develop is to follow herbicide programs with later season scouting and removal of plants to prevent seed. Continue reading Late-Season Waterhemp – The Goal is Stopping Seed →

Looking for soybean fields with late season waterhemp

By Mark Loux OSU Extension

OSU weed scientists and ag engineers are looking for soybean fields that have populations of waterhemp or Palmer amaranth surviving into July and August (after all control with herbicides has been attempted).  We have a project involving the use of a drone to identify these weeds in mid to late season when they are evident above the soybean canopy.  We need fields with more than just a few surviving plants.  Populations consisting of a few good patches up though a disaster are fine.  Contact Mark Loux – loux.1@osu.edu, 614-395-2440.  Thanks in advance for your help.

Distribution of Waterhemp and Palmer Amaranth in Ohio

By: Mark Loux and Bruce Ackley, OSU Extension

The maps that accompany this article show our current knowledge of waterhemp and Palmer amaranth distribution in Ohio.  These are based on information from a survey of OSU Extension County Educators, along with information we had from samples submitted, direct contacts, etc. We still consider any new introductions of Palmer amaranth to be from an external source (brought in from outside Ohio) – hay or feed, infested equipment, CRP/cover/wildlife seedings.  Palmer is not really spreading around the state, and as the map shows, we have had a number of introductions that were immediately remediated.  The number of counties where an infestation(s) is being managed is still low, and within those counties, the outbreak occurs in only a few fields still.  Waterhemp is much more widespread in Ohio and is spreading rapidly within the state from existing infestations to new areas via equipment, water, animals, etc.  We do not have Ag Educators in all counties, and even where we do, infestations can occur without us knowing about them.  Feel free to contact us with new information to update the maps. Continue reading Distribution of Waterhemp and Palmer Amaranth in Ohio →

How does flooding affect soybean germination?

By Michael Staton, Michigan State University Extension

The recent heavy rains have created flooded conditions in many areas of Michigan and producers need to understand how the standing water will affect their soybean fields. There is a lot of information available regarding the effects of flooded or saturated soils on emerged soybeans and this information is summarized in the Michigan State University Extension article, “Assessing water damage to emerged soybeans.”

Photo by Paul Gross, MSU Extension.

There is less information about how flooding affects the germination of recently planted soybean seed. A 2001 journal article, “Flooding and temperature effects on soybean germination,” by Wuebker et al. is a commonly cited reference on this topic. The research was conducted in a growth chamber so that temperature, timing of the flooding and the duration of the flooding could be controlled and varied. The researchers looked at two temperatures, 59 and 77 degrees Fahrenheit, three timings, one, two and three days after imbibition (seed swell or 12 hours after planting) and five durations of flooding ranging from 1 hour to 48 hours.

Temperature effects

The researchers found that overall, flooding adversely affected germination more severely at 59 F than at 77 F. This was true regardless of the duration of the flooding. They also showed that damage was reduced by warmer soil temperatures when the flooding occurred one to two days after imbibition. At 59 F, flooded conditions lasting for only 1 hour reduced germination rates by 22%. Continue reading How does flooding affect soybean germination? →

Heat Unit Accumulation and Corn Emergence

By Peter Thomison OSU Extension

There have been reports of slow corn emergence in some areas and that corn planted more than two weeks ago is not yet emerging. Is this cause for concern? Not necessarily. Corn requires about 100 growing degrees days (GDDs) to emerge (emergence requirements can vary from 90 to 150 GDDs). To determine daily GDD accumulation, calculate the average daily temperature (high + low)/2 and subtract the base temperature which is 50 degrees F for corn. If the daily low temperature is above 50 degrees, and the high is 86 or less, then this calculation is performed using actual temperatures. If the low temperature is less than 50 degrees, use 50 degrees as the low in the formula. Similarly, if the high temperature is above 86 degrees, use 86 degrees in the formula. The high cutoff temperature (86 degrees F) is used because growth rates of corn do not increase above 86 degrees F. Growth at the low temperature cutoff (50 degrees F) is already near zero, so it does not continue to slow as temperatures drop further.

Continue reading Heat Unit Accumulation and Corn Emergence →

Choosing The Right Nitrogen Rate For Corn Is Important To Profitability

By: Jim Camberato and Bob Nielsen Purdue University

Although nitrogen (N) fertilizer can be costly, it is needed to optimize profit in Indiana cornfields. Applying too little N reduces profit by reducing grain yield. Too much N does not return value and can also damage the environment.

Results from 167 field-scale N response trials conducted over more than 10 years underpin current region-based N recommendations. These data-driven N recommendations replaced the old yield-goal based system1, which was proven ineffective. Current recommendations represent the N rate for maximum profit over the long-term, but differences in soil type, management, and weather can result in lower or higher N requirements in any given situation. Rainfall after N application will primarily determine the efficiency of applied N2, with excessive rainfall causing higher N loss and greater need for fertilizer N.  Although N applied prior to planting this season has not been subject to conditions promoting N loss in most areas of Indiana, N loss can occur season-long, particularly prior to the V8 growth stage when corn N uptake and water use are relatively low. Continue reading Choosing The Right Nitrogen Rate For Corn Is Important To Profitability →