Allen County Crop Scouting Update – Late July

Clint Schroeder – OSU Extension

As both corn and soybeans have entered the reproductive phase of the crop cycle it is an important time to be scouting for disease and insect issues. One of the most important parts of integrated pest management (IPM) is crop scouting. When done properly it can help farmers obtain higher yields and increased profit per acre. When heading to the field don’t forget your copy of the Corn, Soybean, Wheat, and Forages Field Guide to help determine identification and threshold levels for each disease or pest. The field guide can be purchased at the extension office if you do not already have a copy.

Corn

OSU Extension conducts weekly monitoring of Western Bean Cutworm (WBC) pheromone traps throughout the state and published the data in the weekly in the C.O.R.N. Newsletter. Those results can be found here. Trap numbers have remained low for Allen County, but there has been an uptick in surrounding counties. Now is the time to scout for egg masses on the upper leaves. Select 20 consecutive plants in 5 locations of the field. If over 5% of those plants have egg masses an insecticide application is warranted. Continue reading

Does Tillering Impact Corn Yield?

By Peter Thomison-OSU Extension

This year I’ve seen more tillering in corn than normal, and there have been enquiries about the impact of tillers on crop growth. When farmers see extensive tillering in their corn hybrids they often express concern that the tillering will have a detrimental effect of crop performance (tillers will “suck” nutrients from the main plant and thereby reduce yields). As a result, tillers are often referred to a “suckers”. However, research has shown that tillers usually have little influence on grain yields and what effects they do have are generally beneficial.


Tillers are lateral branches that form at below ground nodes. Although tiller buds form at each below ground node, the number of tillers that develop is determined by plant population and spacing, soil fertility, early season growing conditions, and the genetic background of the hybrid. Many hybrids will take advantage of available soil nutrients and moisture by forming one or more tillers where stands are thin in the row or at the ends of rows. Tillers are most likely to develop when soil fertility and moisture supplies are ample during the first few weeks of the growing season. They are usually visible by the 6-leaf stage of development. Hybrids with a strong tillering trait may form one or more tillers on every plant even at relatively high populations if the environment is favorable early in the growing season.

A number of studies have been conducted to determine relationships between tillers and the main plant. Defoliation experiments in the 1930’s revealed that defoliated plants that had tillers yielded nearly twice as much grain as defoliated plants that had no tillers. These results suggested that there was a connection between the tiller and the main plant that allowed sugars produced in the tiller leaves to be moved to the ears of the main plants.

More recent studies have found that there is little movement of plant sugars between the main plant and tillers before tasselling. However, after silking and during grain fill, substantial amounts of plant sugars may move from earless tillers to ears on the main plant. When there are ears on both the tiller and the main plant, little movement of plant sugars occurs. The main plant and tillers act independently, each receiving sugars from their own leaves. The nubbin ears, that tillers may produce, therefore have no impact on the ear development of the main plant as was once thought.

If a particular hybrid shows excellent yield potential and also produces extensive tillering under some growing conditions, it should not be avoided. However, excessive tillering may indicate problems with stand density and distribution. If tillering is associated with row gaps and less than optimal plant populations, these are the conditions which need to be corrected to ensure optimal yields rather than selection of the hybrid.

Tillering can also be caused by diseases such as “crazy top” and Stewart’s bacterial wilt (which are also associated with other symptoms). Such tillering is a disease symptom and not beneficial to plant performance. Severe weather conditions ( i.e. hail, frost, and flooding injury) that destroy or damage the growing point can also result in tiller development and non-productive plants.

Livestock and Grain Producers: Dealing with Vomitoxin and Zearalenone

Vomitoxin in the 2020 corn crop continues to plague both livestock and grain producers. Livestock producers are trying to decide how best to manage corn and corn by-products with high levels of vomitoxin, and those who grow corn are trying to decide how best to avoid vomitoxin contamination in 2021.

In the 15 minute video below, OSU Extension Educations John Barker, Rob Leeds, and Jacci Smith discuss where and why this year’s vomitoxin issues originated, considerations for avoiding problems in coming years, how it impacts livestock, and what’s involved in testing grain for vomitoxin.

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

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

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

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

Help OSU Extension Document the Yield Impacts of the 2019 Planting Delays

By: CFAES Ag Crisis Taskforce

Normal planting dates for Ohio range from mid-April to the end of May. This season was quite different when planting for both crops was delayed until late May and stretched into June and even July across many parts of Ohio. We found ourselves grasping for any information we could find including 1) how much of an effect late planting dates would have on yield, and 2) what, if anything, we should change in management of these late planted crops. The historical planting date information we did have was somewhat helpful, but we did not have any data on what could happen when planting is delayed into the second half of June nor July. Continue reading

Corn Ear Rots: Identification, Quantification and Testing for Mycotoxins

By Pierce Paul OSU Extension

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. So, a good way to determine whether you do have a major ear rot problem this year is to quantify the disease in your field and get suspect samples tested for mycotoxins. And the best way to tell the difference among the ear rots is to know the types of symptoms they produce.

TRICHODERMA EAR ROT – Abundant thick greenish mold growing on and between the kernels make Trichoderma ear rot very easy to distinguish from Diplodia, Fusarium, and Gibberella ear rots. However, other greenish ear rots such as Cladosporium, Penicillium and Aspergillus may sometimes be mistaken for Trichoderma ear rot. Like several of the other ear rots, diseased ears are commonly associated with bird, insect, or other types of damage. Another very characteristic feature of Trichoderma ear rots is sprouting (premature germination of the grain on the ear in the field). Although some species of Trichoderma may produce mycotoxins, these toxins are usually not found in Trichoderma-affected ears under our growing conditions.

DIPLODIA EAR ROT – Diplodia causes a thick white mass of mold to grow on the ear, usually initiating from the base of the ear and growing toward the tip. Eventually the white mold changes to a grayish-brown growth and infected kernels appear glued to the husk. Infected ears are usually lightweight and of poor nutritional value. When infections occur early, the entire ear may become moldy. When infections occur late, only a fine web of fungal growth appears on and between the kernels.

Continue reading

Converting Wet Corn Weight to Dry Corn Weight

By: R.L. (Bob) Nielsen Purdue University

Corn is often harvested at grain moisture contents higher than the 15% moisture typically desired by grain buyers. Wetter grain obviously weighs more than drier grain and so grain buyers will “shrink” the weight of “wet” grain (greater than 15% moisture) to the equivalent weight of “dry” grain (15% moisture) and then divide that weight by 56 to calculate the market bushels of grain they will purchase from the grower.

The two sources of weight loss due to mechanical drying are 1) the weight of the moisture (water) removed by the drying process and 2) the anticipated weight loss resulting from the loss of dry matter that occurs during the grain drying and handling processes (e.g., broken kernels, fines, foreign materials). An exact value for the handling loss, sometimes called “invisible shrink”, is difficult to predict and can vary significantly from one grain buyer to another. For a lengthier discussion on grain weight shrinkage due to mechanical drying, see Hicks & Cloud, 1991.

The simple weight loss due to the removal of grain moisture represents the greatest percentage of the total grain weight shrinkage due to drying and is easily calculated using a handheld calculator or a smartphone calculator app. In general terms, you first convert the “wet” weight (greater than 15% moisture) to absolute dry weight (0% moisture). Then you convert the absolute dry weight back to a market-standard “dry” weight at 15% grain moisture.

Concept:

  1. The initial percent dry matter content depends on the initial grain moisture content. For example, if the initial grain moisture content is 20%, then the initial percent dry matter content is 80% (e.g., 100% – 20%).
  2. If the desired ending grain moisture content is 15% (the typical market standard), then the desired ending percent dry matter content is 85% (100% – 15%).
  3. Multiply the weight of the “wet” grain by the initial percent dry matter content, then divide the result by the desired ending percent dry matter content.

Example:

  1. 100,000 lbs of grain at 20% moisture = 80,000 lbs of absolute dry matter (i.e., 100,000 x 0.80).
  2. 80,000 lbs of absolute dry matter = 94,118 lbs of grain at 15% moisture (i.e., 80,000 / 0.85).
  3. 94,118 lbs of grain at 15% moisture = 1681 bu of grain at 15% moisture (i.e., 94,118 / 56).

One take-home reminder from this little exercise is the fact that the grain trade allows you to sell water in the form of grain moisture… up to a maximum market-standard 15% grain moisture content (or 14% for long term storage). Take advantage of this fact and maximize your “sellable” grain weight by delivering corn grain to the elevator at moisture levels no lower than 15% moisture content. In other words, if you deliver corn to the elevator at grain moisture contents lower than 15%, you will be paid for fewer bushels than you otherwise could be paid for.

Related reading

Hicks, D.R. and H.A. Cloud. 1991. Calculating Grain Weight Shrinkage in Corn Due to Mechanical Drying. National Corn Handbook Publication NCH-61. https://www.extension.purdue.edu/extmedia/nch/nch-61.html [URL accessed Sep 2019]

Nielsen, RL (Bob). 2018. Corn Grain Test Weight. Corny News Network, Purdue Extension. http://www.kingcorn.org/news/timeless/TestWeight.html [URL accessed Sep 2018]

Pryor, Randy, Paul Jasa, & Jenny Rees. 2017. Plan Harvest to Deliver Soybeans at the Optimum Moisture. Cropwatch, Univ Nebraska Extension. http://cropwatch.unl.edu/2017/plan-harvest-deliver-soybean-optimum-moisture [URL accessed Sep 2019]