Early Yellowing Soybeans

Source: Dr Anne Dorrance, OSU Extension

Sudden Death Syndrome

Soybeans across the state range from ready to harvest to still flowering.  But in some fields, the yellowing was limited to pockets – some was sudden death syndrome or brown stem rot, charcoal rot, Phytophthora stem rot, and soybean cyst nematode.  There are some other early yellowing situations that we are still working on an accurate diagnosis, but yellowing in these cases may be linked to fertility issues and/or related to late flooding injury.  I think in 2018 we’ve observed just about everything, and it was all dependent on where in the state the soybeans were grown, how much rain occurred and when that rain fell, as well as the variety.  It did seem that we had calls on the same variety from multiple regions.

The heat this past weekend is also going to move the crop fairly fast. So if you haven’t driven by the earliest planted fields – this is the week to do so.  Sudden death syndrome is very widespread – but in most fields, it is limited to a scattering of plants throughout the wet areas.  The plants were not severely affected as most of the fields I visited were holding their leaves and not defoliating as quickly as I have observed for the most susceptible varieties. Late season Phytophthora stem rot is also present – in this disease, the plant wilts, holds its leaves and develops a brown canker that extends from the base of the plant up the stem.  Charcoal rot can also cause early yellowing or dying, and these symptoms were present last week in several areas of the state.  To distinguish this from other diseases, cut open the tap root and look for the black dots embedded in the tissue and lower stem.  When populations of soybean cyst nematode are high, plants will also mature earlier.  For cyst, you can dig up the plants, shake the soil off and see the small white pearls (females) on the roots.  Often we need a microscope as the cyst will turn tan to brown and becomes hard to see.

This round of late season scouting is important for variety selection, improving fertility applications for the fall, and prioritizing which fields to sample for soybean cyst nematode.  Let’s just hope the weather cools so we can get out of the trucks and walk into the fields!

Seeing Yellow Spots in Your Soybeans that aren’t Normal Plant Maturity … Check Your Potassium Levels.

Soybean fields are beginning to mature very rapidly.  For the past several weeks “yellow areas” have been showing up in many fields throughout the Knox County.  One possible explination could be potassium (K) deficiency.

Late season K deficiency is usually found on leaves near the top of the plant.  These symptoms typically occur in areas of the field where K fertility values are low however, this symptomology can sometimes be found in fields with adequate K levels during dry periods in a growing season.   Additionally these symptoms can appear later in the growing season after a significant rain following an extended dry period.

Picture 2. Sudden Death Syndrome

Sometimes K deficiency is confused with Sudden Death Syndrome (SDS) symptomology.  Picture 2 shows SDS symptoms. The presence of the green veins is the key identifying characteristic for SDS.  The veins on the leaves will remain green while the leaf tissue between the veins will turn yellow and then brown.

 

Picture 3. Potassium Deficiency

 

Picture 3 shows soybean with K deficiency.  The leaf discoloration starts on the outer edge of the leaf and moves inward, including leaf veins.

 

 

 

Ear Rots of Corn: Telling them Apart

by: Pierce Paul, Felipe Dalla Lana da Silva, OSU Extension, (edited)

Over the last few weeks, we have received samples with at least four different types of ear rots – Diplodia, Gibberella, Fusarium, and Trichoderma. Of these, Diplodia ear rot seems to be the most prevalent. 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.  Most are favored by wet, humid conditions during silk emergence (R1) and just prior to harvest. But they vary in their temperature requirements, with most being restricted my excessively warm conditions such as the 90+ F forecasted for the next several days. However, it should be noted that even when conditions are not optimum for ear rot development, mycotoxins may 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.

(A) DIPLODIA EAR ROT – This is one of the most common ear diseases of corn in Ohio. The most characteristic symptom and the easiest way to tell Diplodia ear rot apart from other ear diseases such as Gibberella and Fusarium ear rots is the presence of white mycelium of the fungus growing over and between kernels, usually starting from the base of the ear. Under highly favorable weather conditions, entire ears may become colonized, turn grayish-brown in color and lightweight (mummified), with kernels, cobs, and ear leaves that are rotted and soft. Rotted kernels may germinate prematurely, particularly if the ears remain upright after physiological maturity. Corn is most susceptible to infection at and up to three weeks after R1. Wet conditions and moderate temperatures during this period favor infection and disease development, and the disease tends to be most severe in no-till or reduce-till fields of corn planted after corn. The greatest impact of this disease is grain yield and quality reduction. Mycotoxins have not been associated with this disease in US, although animals often refuse to consume moldy grain.

(B) GIBBERELLA EAR ROT – When natural early-season infections occur via the silk, Gibberella ear rot typically develops as white to pink mold covering the tip to the upper half of the ear. However, infections may also occur at the base of the ear, causing the whitish-pink diseased kernels to develop from the base of the ear upwards. This is particularly true if ears dry down in an upright position and it rains during the weeks leading up to harvest. The Gibberella ear rot fungus may also infect via wounds made by birds or insects, which leads to the mold developing wherever the damage occurs. When severe, Gibberella ear rot is a major concern because the fungus produces several mycotoxins, including deoxynivalenol (vomitoxin), that are harmful to livestock. Once the ear is infected by the fungus, these mycotoxins may be present even if no visual symptoms of the disease are detected. Hogs are particularly sensitive to vomitoxin. Therefore the FDA advisory level for vomitoxin in corn to be fed to hogs is 5 ppm and this is not to exceed 20% of the diet.

(C) FUSARIUM EAR ROT – Fusarium ear rot is especially common in fields with bird or insect damage to the ears. Affected ears usually have individual diseased kernels scattered over the ear or in small clusters (associated with insect damage) among healthy-looking kernels. The fungus appears as a whitish mold and infected kernels sometimes develop a brownish discoloration with light-colored streaks (called starburst). Several different Fusarium species are associated with Fusarium ear rot, some of which produce toxins called Fumonisins. Horses are particularly sensitive to Fumonisins, but cattle and sheep are relatively insensitive.

(D) 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.

Farm Science Review Agronomy College is September 11th

by: Harold Watters, OSU Extension

The FSR Agronomy College is held in partnership between the Ohio AgriBusiness Association & OSU Extension. The event is designed to educate agronomists, Certified Crop Advisers, custom applicators and farmers on current agronomy issues. The full-day event features time with OSU Extension staff in the field in the agronomy plots on the east side of the Farm Science Review grounds. Breakout sessions will feature topics including a weed management update, weed and crop screen, variable rate soybean seeding, an update to the Tri-State Fertilizer Recommendations, the new Ohio Phosphorus Index, and some how we will squeeze in even more. CCA and pesticide application credits available to those attending.

Date: September 11, 2018

Location: Farm Science Review – Molly Caren Agricultural Center, London, OH

Time: Check-in begins at 8:30 a.m.; sessions begin at 9 a.m. and concludes at 4:00 p.m.

Cost: $120 Registration: Click here to register for the event. (or try this link:http://oaba.net/aws/OABA/pt/sd/calendar/67757/_PARENT/layout_details/false)

Contact: Janice Welsheimer at 614-326-7520 or by email: jwelsheimer@oaba.net

Or for additional information, Harold Watters, 937-604-2415 or by email: watters.35@osu.edu

Frogeye Leaf Spot

by: Anne Dorrence, OSU Extension

Only Susceptible Varieties are Prone to Diseases and May Require a Fungicide Application.

From the scouting reports from the county educators and crop consultants – most of the soybeans in the state are very healthy with no disease symptoms.  However, as the news reports have indicated, there are a few varieties in a few locations that have higher incidence of frogeye leaf spot than we are accustomed to seeing at this growth stage – mid R2 – flowering in Ohio.  Most of the reports to date are along and south of route 70, which based on the past 12 years is where frogeye is the most common.  When this disease occurs this early in the season, where it can be readily observed, this is a big problem and should be addressed right away with a fungicide soon and a second application at 14-21 days later depending on if disease continues to develop and if environmental conditions (cool nights, fogs, heavy dews, rains) continue.  Table 1. Lists the fungicides that have very good activity towards frogeye leaf spot based on University trials around the country (thank you land grant university soybean pathologists in NCERA-137). Note that on this list there are no solo strobilurin fungicides, as we have detected strains of the fungus, Cercospora sojina, that are resistant to this class of fungicides in the state.

Click here to Read More …

Knox County Crop Conditions

Perfect time to grow corn

by: Chuck Martin, Mount Vernon News

 

The right weather at the right time, along with the right management by farmers, and the crops will respond.

That, essentially, is what has happened with the corn crop so far this year, said Knox County Ohio State University Extension Educator John Barker.

“There was a time, early, when there was a little concern about planting because it was so wet,” he said, “but most of the fields got planted and with the combination of heat and moisture, the corn just took off.”

Some fields were even tasseling out by July 4.

“That’s what we want to see,” said Barker. “The old adage of corn needing to be “knee high by the Fourth of July” is from a time when corn was often not planted as early.

“At one time many farmers didn’t think about planting until May 1, now they expect to be done by May 1.”

Click to read more …

Foliar Fungicide Use in Corn

by: Pierce Paul, OSU Extension

Foliar diseases, especially Gray Leaf Spot (GLS), are beginning to show up in some corn fields. This is not at all surprising, given that the crop was planted relatively late and it has been wet and humid in some areas. GLS is favored by humid conditions, particularly if temperatures are between 70 and 90 F. Foliar diseases of corn are generally a concern when they develop early and progress up the plant before grain fill is complete. This is especially true when the hybrid is susceptible. In most years, GLS and NCLB usually develop late or remain restricted to the lower leaves. However, if it continues to rain and stays humid, this will likely not be the case this year.

Due to wide variations in planting dates, weather conditions, and hybrid maturities, the corn crop is at growth stages ranging from emergence to tassel across the state. Now is the time to start scouting those early-planted fields for foliar diseases, especially those planted with susceptible hybrids in an area with a history of foliar diseases or in a continuous-corn, no-till fields. Those are the fields most likely to benefit from a fungicide application. Use hybrid susceptibility, weather conditions, field history, and current disease level as guides when making a decision to apply a fungicide.

Click to Read More

 

Young Corn with Wet Feet: What Can We Expect?

by: Alexander Lindsey, Peter Thomison, Steve Culman, OSU Extension

Around the state, there are many corn fields with young plants with standing water due to the intense storms that have passed through. But what are the long-term effects of standing water on emerged corn? Preliminary data from two locations in Ohio in 2017 suggests that as long as a sidedress N application can be made following the waterlogging, yield loss may be minimal if the waterlogged conditions lasted 4 days or less.

Waterlogging can affect yield in two main ways: 1) damage to the plant physiologically, and 2) N loss through denitrification or leaching. The presence of standing water in the field can affect corn yield by inhibiting growth and restricting ear development (which occurs during vegetative stages). Standing water also reduces the amount of oxygen in the soil, which can cause nitrate in the soil to be converted to forms that are unavailable for plant uptake and may be lost to the environment. Trials in Ohio conducted in 2017 suggest that corn can survive waterlogged conditions for 4 days or less in the early vegetative stages (V4-5) with minimal impact on yield if a sidedress application can be made after the soil has dried. However, if a sidedress application cannot be made on corn waterlogged for 4 days or more, a yield penalty of 13 to 45% was observed. When waterlogging extended to 6 days even with a sidedress N application, a reduction in yield of 9-33% was observed compared to corn flooded for 4 days or less. These results are consistent with past research (10-50% yield loss if flooded longer than 2 days), but will be repeated in 2018 for validation.

Continue reading

CONSERVATION TILLAGE CONFERENCE: NEW TOPICS FOR CHANGING AG

by Mark Badertscher

So what is the relationship between healthy soils and healthy water? How can you manage inputs and planting date for high economic corn yields? Which soils should respond to sulfur applications? What are some opportunities and considerations with subsurface placement of nutrients? How can you build soil health and organic matter with cover crops and no-till? How can you use economics in the choice between growing corn and soybeans? What will the revised P index look like? How can you get started in honey bees, barley, or hops production? What are some methods to manage invasive plants around the farm?

These are all questions you might have asked yourself, but have struggled to find an answer. This year’s Conservation Tillage Conference (CTC) has the answers to these questions and many more. The McIntosh Center at Ohio Northern University will once again be the location were about 60 presenters, several agribusiness exhibitors, and approximately 900 participants will come together March 6th and 7th in Ada, Ohio. Attend this year’s conference to add value to your operation by learning new ideas and technologies to expand your agronomic crops knowledge.

A general session with well-known author David Montgomery from the University of Washington discussing “From Dirt to Regenerating our Soils” will officially open this year’s conference. Corn University, Nutrient Management, Precision Ag & Digital Technologies, Healthy Soils for Healthy Water, Regenerative Ag, and Healthy Foods from Healthy Soils are the sessions that make up day one.

On the second day, conference participants will be able to choose from Soybean School, Water Quality Research and BMPs, Alternative Crops, Pest Management of the Atypical Pests: Slugs, voles and more, Healthy Soils for Healthy Waters Precision Nutrient Management, and Healthy Water. In addition, there will be an EPA required dicamba training on both days of this year’s Conservation Tillage Conference provided for pesticide applicators in attendance. To register for one of these Monsanto-provided dicamba application requirements training events, go to: www.roundupreadyxtend.com/training.

Find out what experts from OSU Extension, OARDC, USDA, and SWCD are learning from the latest research about the timely topics that affect today’s farmers, crop consultants, and agribusiness professionals who are out in the field working together to produce crops in an efficient and environmentally responsible manner. Certified Crop Adviser (CCA) and Certified Livestock Manager (CLM) credits will be available to those who attend. Visit ctc.osu.edu and make plans to participate in this year’s Conservation Tillage Conference by February 24 to take advantage of early registration rates.

 

eFields Report Now Available

eFields represents an Ohio State University program dedicated to advancing production agriculture through the use of field-scale research. This program utilizes modern technologies and information to conduct on-farm studies with an educational and demonstration component used to help farmers and their advisors understand how new practices and techniques can improve farm efficiency and profitability. The program is also dedicated to delivering timely and relevant, data-driven, actionable information. Current projects are focused on precision nutrient management strategies and technologies to improve efficiency of fertilizer placement, enable on-farm evaluation, automate machine functionality, enhance placement of pesticides and seed, and to develop analytical tools for digital agriculture.

 The results from Knox County Seeding Trials are included on page 86.  The entire report can be downloaded at https://fabe.osu.edu/programs/eFields