Dealing with the Weather and Unharvested Crops

Source: Penn State Extension (Edited)

WHAT A FALL!!!  According to the November 26 Crop Weather Report, approximately 14% of corn and 10% of beans still in the field.  The average moisture content of corn harvested last week was 17 percent and the average for soybeans was 16 percent, how big of a concern is this?

The weather continues to be unpredictable and give challenges to operators with grain and crops still in the field. Snow and ice over the last couple weeks have just been the latest in a long list of hurdles that growers have had to overcome this season. With some careful thought and planning you can still have a successfully harvest.

Having corn in the field now can be a double-edged sword. The longer it stays out, the dryer the corn will be when harvested, thus decreasing your drying costs. However, there is a higher risk of yield loss the longer the corn stays unharvested. Research on winter corn drydown showed that over a five-year span, corn grain would lose roughly 40% of its moisture between the months of October and December, when left in the field. The tradeoff is that we cannot anticipate the weather. The same study found that a single year yield decreased by 45% and another year decreased by only 5%.

Another concern of unharvested corn could be disease and mold. When discussing disease and mold, snow and ice pose no more danger to your crop than rain does. A positive of this situation is that the lower temperatures could have a limiting effect on pathogens’ ability to incubate or develop. A drawback of having laying snow is an increased opportunity for lodging. This year we have already seen a lot of lodging due to stem rots and adding snow to the mix may increase this risk. The risk of lodging is even further increased when coupled with winter winds and snow and ice to come. The takeaway is that disease and mold issues should not be your largest concern right now.

If you have a large amount of stock rot and lodging, harvesting as soon as possible will be best for a successful harvest. If your corn crop has lodged, one thing to remember is that this is not a usual harvest. Special consideration and care must be taken to get acceptable yields, which means slowing down and using caution. A few other options you have for getting a better harvestable yield are combining in the opposite direction, or “against the grain.” This will allow the head to get under the crop and lift it up. Another option is to use a corn reel. A corn reel is a specialized piece of equipment that mounts on the top of your corn head and uses rotating hooks to lift the corn and allow the head to get under the lodged crop.

The last concern is compaction and rutting of fields … Who Doesn’t Have Compaction Issues This Year??  Compaction will linger for years and will require attention to avoid problems with next year’s crop.

 

Stalk Quality Concerns

Source: Dr.’s Peter Thomison, Pierce Paul, OSU

Poor stalk quality is being observed and reported in Ohio corn fields. One of the primary causes of this problem is stalk rot. Corn stalk rot, and consequently, lodging, are the results of several different but interrelated factors. The actual disease, stalk rot, is caused by one or more of several fungi capable of colonizing and disintegrating of the inner tissues of the stalk. The most common members of the stalk rot complex are Gibberella zeaeColletotrichum graminicolaStenocarpella maydis and members of the genus Fusarium.

The extent to which these fungi infect and cause stalk rot depends on the health of the plant. In general, severely stressed plants (due to foliar diseases, insects, or weather) are more greatly affected by stalk rot than stress-free plants. The stalk rot fungi typically survive in corn residue on the soil surface and invade the base of the corn stalk either directly or through wounds made by corn borers, hail, or mechanical injury. Occasionally, fungal invasion occurs at nodes above ground or behind the leaf sheath. The plant tissue is usually resistant to fungal colonization up to silking, after which the fungus spreads from the roots to the stalks. When diseased stalks are split, the pith is usually discolored and shows signs of disintegration. As the pith disintegrates, it separates from the rind and the stalk becomes a hollow tube-like structure. Destruction of the internal stalk tissue by fungi predisposes the plant to lodging.

Nothing can be done about stalk rots at this stage; however, growers can minimize yield and quality losses associated with lodging by harvesting fields with stalk rot problems as early as possible. Scout fields early for visual symptoms of stalk rot and use the “squeeze test” to assess the potential for lodging. Since stalk rots affect stalk integrity, one or more of the inner nodes can easily be compressed when the stalk is squeezed between the thumb and the forefinger. The “push” test is another way to predict lodging. Push the stalks at the ear level, 6 to 8 inches from the vertical. If the stalk breaks between the ear and the lowest node, stalk rot is usually present. To minimize stalk rot damage, harvest promptly after physiological maturity. Harvest delays will increase the risk of stalk lodging and grain yield losses and slowdown the harvest operation. Since the level of stalk rot varies from field to field and hybrids vary in their stalk strength and susceptibility to stalk rot, each field should be scouted separately.

Seed Quality Issues in Soybeans

Let’s face it – we’ve had historic rains in parts of Ohio during 2018 and we are now observing many late season issues that come with this.  Seed quality is one of them and the symptoms or warning signs that there could be issues are on the stems.  The stems in some fields are heavily colonized with a mix of disease pathogens that cause Anthracnose, Cercospora, and pod and stem blight (Figure 1).  The bottom line is that all of these diseases can be better managed with higher levels of resistance but ultimately during 2018 – we had a perfect storm, lower levels of resistance combined with higher than normal rainfall conditions and add in the presence of a new insect pest, stink bugs.  Below I’ve outlined the general conditions of the crop and for each disease, the distinguishing characteristics.

Figure 1

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Tips for Harvest and Planning for the 2019 Field Season

Source: Dr. Anne Dorrance, OSU (edited)

Based on my trip across the state on Saturday, it is clear harvest has started.  A couple of things to keep track of as the combines run across the fields:

  • Make note of those low yield spots in soybeans to soil sample for soybean cyst nematode levels.
  • Did you leave unsprayed strips?  Harvest each of these first separately.  Yield is not even throughout a field so comparisons to the average of these unsprayed strips are a more accurate measure of what the baseline level of yield is within a field.  This is the number to compare yields for any treatments.
    • Note: the outside borders of the field are usually not comparable since these have additional secondary factors such as shade from trees, compaction, old fence rows etc. which can impact yield.
  • Fields with Sclerotinia should be harvested last. Yes, seed quality will continue to decline but this will avoid contaminating equipment with sclerotia which can then be introduced into more fields.  There are limited fields with this pathogen, and this approach will help keep it that way.
  • Fields with stink bug injury, generally moldy due to Phomopsis etc.: harvest those ASAP and get the seed dried down.  Phomopsis will continue to colonize pods from openings on those pods caused by insect feeding and then colonize the neighboring seeds.  This fungus that causes Phomopsis seed decay as well as other seed decay fungi tend to be a bit slow growing.  If the seed can be harvested, and dried down it will prevent further growth. It has also been noted that on a seed germination test in the fall, germs will be lower, but the seed where only the outside is colonized, not the germ, the fungus will die under out winter conditions (if the storage is dry) and then the germ will improve over the winter for Phomopsis seed decay.
  • While you are also harvesting make note of the varieties that did well on your farms. Not every soybean variety is meant for our wet poorly drained soils. We’ve had lots of reports and observed shallow root systems, extensive root rot, as well as Phytophthora stem rot and sudden death syndrome during 2018. In fields where diseases developed in 2018, pay attention to the resistance on these and other diseases for 2019. 
    • Remember, every company uses a different rating system, read the fine print to be sure that you understand what resistance actually means for those varieties. Is 1 dead or is it the best?

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 …