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Agronomy Notebook



Leaf disease: Management and consideration for 2016

As spring of 2016 approaches, producers across the Eastern Corn Belt will begin to put more thought towards their production plans and management decisions for the upcoming season. One challenge that has affected corn yields in our sales territory over the past few years is foliar disease, especially Northern Corn Leaf Blight. Anyone who attended one of our Winter Agronomy Meetings heard a discussion of what conditions promote diseases (Northern Corn Leaf Blight and Gray Leaf Spot) and possible management options. You might ask, “What are the important management options that will protect yield from leaf diseases?” Below are the answers to that question:

• Select Resistant Hybrids: One very effective way to protect yield potential is to plant varieties that have resistance to leaf disease. Many university publications, including this MSU fact sheet, generally recommend that fungicides are not required for hybrids with strong disease resistance.

• Crop Rotation: It is widely understood that crop rotation is one of the best management practices for mitigating problem diseases.… Continue reading

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Helpful tips for reducing soil erosion

Soil erosion is an annual problem throughout the Eastern Corn Belt. Recent research estimates that farmland across the Corn Belt looses close to four tons of soil per acre each year due to erosion. Additionally, even under the best conditions topsoil buildup is very slow, if it occurs at all. Soil particles can be detached and moved out of a field by both wind and water. Wind can pick up small soil particles, transporting them long distances. Water moving along the ground surface can remove a thin sheet of soil, create small channels, or wash out large gullies.

Soil erosion has a large number of negative effects to both crops and the environment. It is important to use various management practices to protect the soil’s surface and minimize the likelihood of erosion.

 

Factors that contribute to erosion

‪1. Rainfall — soil erosion increases as length or intensity of rainfall increases.… Continue reading

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Palmer amaranth update

During the past few years agronomists and university weed experts have been discussing the potential northern movement of an aggressive weed that can reduce yields and increase costs of weed control. The arrival of Palmer Amaranth, nicknamed “Pigweed on Steroids”, has been confirmed in multiple states across the Eastern Corn Belt. Seed Consultants’ customers and agronomists have already worked together this year to deal with new populations of Palmer that were discovered this spring. Palmer amaranth populations have recently been confirmed in several counties in Indiana, and are present in Michigan, isolated areas of Ohio, and areas of Western Kentucky.

Palmer amaranth is an aggressive plant that thrives in drought, can grow more than two inches a day, is resistant to multiple herbicide modes of action, and produces 100,000 or more seeds per plant. Many populations of this weed are resistant to multiple herbicide modes of action. The key to keeping Palmer Amaranth from establishing itself is implementing management practices to effectively eliminate seed production and hinder its ability to spread.… Continue reading

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Use plot data to make good decisions

As harvest continues across the Eastern Corn Belt, seed companies, universities, and growers will have the chance to compile and analyze data from yield testing. One of the most important decisions a farmer will face all year is deciding what variety to plant and in which field to plant it. To ensure that the best possible decision is made next spring, it is critical to spend some time looking at yield data. While reviewing data is critical, knowing how to determine whether it is accurate and useful is equally important. Below are some tips for using data to make sound planting decisions next spring.

Look for replicated data

Don’t rely on yield results from one strip plot on a farm or from a single plot location. Look for data from randomized tests that are repeated multiple times and across multiple locations. Replications in testing increase the reliability of the data.

For strip plot data, was a “tester” used?… Continue reading

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Tassel ears showing up in fields

While scouting fields this time of year it is common to find a few strange looking ears. Corn is a monecious plant, which means it has separate male (the tassel) and female (the ear) flowers. In some cases, both male and female structures form as a combination in the same plant structure.

“Tassel-ears” often form on the tillers or “suckers” of a corn plant. Corn experts and agronomists believe that tassel ears are the result of some kind of environmental occurrence, however, the exact event that causes their development is unknown. The number of kernels that form on the tassel ear are limited. Without a husk to protect them, these kernels are exposed to environmental conditions and are usually damaged by the time harvest occurs.

According to Bob Nielsen from Purdue University, “The male and female reproductive organs of a corn plant are contained in physically separate unisexual flowers (a flowering habit called “monoecious” for you trivia fans.) The tassel represents the male flower on a corn plant, while the ear shoots represent the female flowers.… Continue reading

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Assessing fields after a roller coaster 2015

The growing season of 2015 has turned out to be a roller coaster ride of moisture stress (both too much and too little), disease pressure, and curiosity in the mind of the grower as to what’s really out there in terms of yield.

We started 2015 with an abundance of rainfall across the state from north to south, causing late planting dates in some areas and prevented planting claims in others. Depending on which field you are standing in, yield potential seems to range from very good to very poor. Near record yields appear to be anticipated in parts of the southern Ohio area, as well as pockets of central Ohio, whereas dismal yields from drowned areas and flooding appear as you look north.

As corn plants neared reproductive stages, northern corn leaf blight and gray leaf spot could be found in most of the state. Growers that applied fungicides to help prevent infection are now happy that they had done so.… Continue reading

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Standability a concern this harvest season

As crops approach maturity and harvest begins, standability could become a concern in some corn fields.

Corn fields across the Eastern Corn Belt have experienced various environmental factors that create stress conditions for the plant and as a result, stalk rots could become an issue late in the season. Ohio State University Bulletin 802 states: “The severity of stalk rot is confounded by plant stress. In general, the greater the stress the plant endures, the greater the severity of stalk rot. This has been demonstrated very well with plant nutrition. Plants with excessively high levels of nitrogen or with an imbalance between nitrogen and potassium are very susceptible to stalk rot. Plants stressed by drought (especially late season drought), foliage disease, or insect injury generally have more stalk rot.”

Many corn fields have experienced nitrogen loss, leaf disease, and insect damage this year. Some areas of the Eastern Corn Belt have experienced dry conditions late in the season as well.… Continue reading

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Stress during grain fill

Rains during June and July set new records in some areas of the Cornbelt this year, causing weak root development, nitrogen loss and even affected pollination in some fields with poor ear-tip fills. Leaf diseases like Northern Corn Leaf Blight and Gray Leaf Spot were rampant in some areas causing additional stress on the corn crop. Some of the effects of this stressful environment on grain-fill are indicated below:

• After pollination, we need 50-60 days depending on the relative maturity of the hybrid, for the grain-filled period. This is when the plants’ primary focus is to fully develop the kernels.

• If there is severe heat or moisture stress during the grain-fill period, the plants start to cannibalize their leaves and stalks to fulfill the growing needs of their progeny, the seeds or grain.

• Plants, like animals, don’t want to produce runts. So, if there is stress during the grain-fill period, the plants start to abort the youngest kernels causing tip die-backs so that the remaining kernels can fully develop.… Continue reading

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Do cover crops reduce leaf diseases?

Five years ago a lot of the ground was left bare during winter without any cover crops. Recent surveys have indicated that the number of farmers using cover crops in the Corn Belt states is increasing every year.

Many benefits of cover crops have been reported but a major advantage has not been emphasized. While scouting corn fields during the last three years, I have noticed fewer disease lesions of fungal diseases like Northern Corn Leaf Blight (NCLB) and Gray Leaf Spot (GLS) in fields following cover crops than those following corn or even soybeans. The disease lesions were more prevalent even on fields where corn was grown two years ago in a corn-beans rotation.

I scouted some corn fields near Batesville, Indiana in the last three years and saw several fields with NCLB and GLS where cover crops were not used. However, less than 20 miles away where Marshall Alford has been using cover crops for many years, I had hard time finding any disease lesions on hybrids with exactly the same genetics.… Continue reading

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Factors for Phosphorus loss from land to surface water

Most of us have reduced fertilizer inputs as crop prices have gone down and this is documented by reduced phosphorus fertilizer sales. But still, I am often asked about issues of phosphorus from an agriculture and water quality standpoint, “Is rate the only concern?”

Rate, and more appropriately soil test level, is important from a water quality standpoint. If we are at a soil test level that does not require any fertilizer application, perhaps 35% of our fields, then risk of loss is reduced to whatever background levels are coming from the soil. If the soil test is in an agronomic range (15-40 ppm Bray P1), water concentration of Total P in runoff is 0.5 ppm or less. If soil test levels are four to five times agronomic levels, however we can see this produce a runoff concentration of 1 ppm or more.

Recently applied P is subject to loss based on the timing, source and placement during the nutrient application.… Continue reading

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Productivity issues for your 2015 corn crop

Yellow corn and soybeans have been widespread the first part of July in most of Ohio. Since May 1,

many parts of Ohio have received at least three to four inches above the five-year average. Growing Degree Days (GDD’s) for the same period have accumulated 1,300 to 1,400 units, which is 200 to 300 GDD’s ahead of normal. We use the GDD’s to track the overall progress of corn development. I like to consult the numbers weekly to track the progress of rainfall and temperature in the state. You can also track these at the Ohio page for the National Agricultural Statistics Service: http://www.nass.usda.gov/Statistics_by_State/Ohio/Publications/Crop_Progress_&_Condition/index.asp

Another great service for tracking rainfall comes from The Climate Corporation. Climate Basic is a free service that will send you e-mail alerts when rainfall is detected at your farm. The nice feature of Climate Basic is that it will send you alerts daily on a field-specific report.… Continue reading

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Fungicide economics

Mother Nature has been too generous with moisture this year in most of the Corn Belt states. It has hurt some crops but has been conducive to the development for diseases like Northern Corn Leaf Blight and Gray Leaf Spot. Some of the early planted corn has already been sprayed with foliar fungicides. Late planted corn is starting to pollinate. I have seen a lot of these two diseases during the last two weeks especially on corn after corn ground and have been asked by some farmers if these fungicides applications are economical at the current prices. Some of the guidelines for economic thresholds are given below:

• Corn needs to be protected from leaf diseases mostly during the grain-fill period. Depending on relative maturity of the hybrid, 45 to 55 days, are needed from pollination to physiological maturity or Black Layer.

• We need to protect leaves above the ears which produce most of the grain yield.… Continue reading

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Oxygen a vital nutrient for corn

There are many things in life that we take for granted, such as the sun rising in the east and setting in the west, April 15 being tax day and a salesman showing up just before you were wanting to leave early for the day! There are also some things in the world of crop production we take for granted — it will be hot in August and the weather forecast modules are always wrong after we mow hay.

Crop nutrients can be taken for granted as well, with oxygen being one of those. Growers spend considerable amount of time talking and managing nutrients such as N, P and K (and if we are in a really risky group we may whisper the words boron and zinc). But to bring up oxygen at the coffee shop as a vital nutrient we should manage — that will reward you with the bill.… Continue reading

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Is your corn N deficient?

June 2015 has been a very wet month in most of the Corn Belt setting new records in many places. Some of the corn fields I have visited recently are showing N-deficiency symptoms. Nitrogen is one of the most important elements needed by all green plants for chlorophyll production and for photosynthesis. Urgent action is needed in some fields to save this crop.

• If lower leaves of your corn crop are getting yellowish, starting in mid-rib and moving towards edges, there is a good chance it is a sign of N-deficiency.

• Should you apply additional nitrogen? It depends on how, when and how much nitrogen you have already applied? Did you apply it in the fall and use a nitrogen stabilizer? What form of nitrogen did you use? Do you generally sidedress?

• Some people have suggested soil testing before sidedressing. Well, that may be OK if you had plenty of time, but in my opinion, these tests during the growing season are not reliable, especially with lot of rains we have experienced in June this year.… Continue reading

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Stress during ear development affects corn yield

Understanding how corn ears respond to stress can help determine what stress was present, when the stress occurred, and how to mitigate the stress in the future.

Environmental stresses during any of four ear development stages significantly affect the number and weight of harvestable kernels. The four critical stages are: (1) when the corn ear is setting the maximum number of kernel rows around the ear (approximately V7), (2) when the ear is establishing the maximum number of ovules along the length of the ear (just before pollination), (3) when the maximum number of ovules are pollinated to form kernels (at pollination), and (4) when the ear sets maximum kernel size during the latter portion of grain fill (approximately R3 to R5).

The first yield component determined by a corn plant is the development of ovule rows on the ear, which begins at about the V7 growth stage. Each ovule row will eventually divide to produce a pair of rows.… Continue reading

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Flooding effects on corn

Recent rains have caused a lot of ponding in low lying areas of the fields. What effects would ponding or flooding have on corn plants? Below are some facts:

• Under flooded conditions plants can’t breathe and survive for long. Flooding interrupts the breathing and photosynthetic processes of plants. Obviously, plants which are completely covered by water are at higher risk than those which are partially submerged.

• Oxygen in the soil also gets depleted within 48 hours of flooding and the plant growth functions like nutrient absorption is affected.

• Duration of ponding or flooding is critical. Cooler temperatures after flooding will help the survival of the young plants. Warmer temperatures above 75-80 degrees F following flooding can kill the plants.

• Corn plants which are partially submerged may continue breathing, photosynthesizing and living. Obviously, the longer they are under water, the lower their survival rate.

• Plants older than V6 stage survive better because the growing point is above ground after this stage.… Continue reading

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Seedling blights of corn

We like growers to plant their corn early, however, we want them to wait until the ground is ready and soil temperatures are 50 degrees and above. When you have a lot of area to cover, you have to plant when the weather will let you. But this can create opportunities for disease organisms and insects to attack the newly emerging plants. This year after planting, it turned cold and the seedling blights had their chance to invade. There have been several reports of seedling root-rot in corn fields. Some of the causes for seedling blights are as follows:

• Seedling diseases are favored by wet and cool soil conditions (50-55 F) after planting. Corn planted early or in no-till ground is more susceptible to these diseases. Recent cool and wet periods were ideal for the pathogens that cause seedling blights.

• The disease organisms that infect corn seedlings are species of Pythium, Fusarium and Rhizoctonia.… Continue reading

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Watch fields for black cutworms

Black Cutworm moths are starting to arrive in the Corn Belt with the recent weather fronts moving from southwest and we need to be ready with the rescue treatments, if necessary. We need to learn about their habits and what to look for while scouting. Some of the important points are as follows:

• Black cutworms can’t survive the winters in the Midwest. They fly south before the winter arrives.

• Every spring, moths come back with spring storms and lay eggs on grasses and weeds like mustards, chickweed or even winter wheat.

• From egg hatching to becoming adults it takes 40-50 days depending on temperatures. Even though cooler temperatures earlier may have killed some of the moths, warmer temperatures that followed increased the speed up their development and more will come. Some cutting activity has already been observed in Southern Illinois.

• Corn and soybeans are not their favorite hosts.… Continue reading

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Corn plant development

Much of the corn crop has been planted in the Corn Belt but establishing a good plant stand is most important for getting good yields. The seedling stage is the most critical phase in the life of a corn plant. The young stage of every organism is critical for development and productivity of the adults. If we understand how our crops grow, we can do a better job of meeting the needs of our crops and improve yields. Let’s look at what happens as the young corn plants develop.

• V1 to V2:  It takes 110-120 Growing Degrees for corn seedling emergence. The seedlings emerge when coleoptile, the spear-like leaf pierces thru the ground. First and second leaves develop six to seven days after the seedlings emerge.

• The first roots start to supply water and nutrients to the young seedlings. Roots are very small and banded fertilizer close to the roots at this stage should be very helpful in stimulating early growth.… Continue reading

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Tips for managing a late spring

As winter begins to wind down and the first warm spell of the year arrives in March, many growers are most likely anxious to get into the field. However, ideal weather for spring field work may not be right around the corner. As of the beginning of March, 88% of the Great Lakes were still covered with ice and extended forecasts were calling for colder than normal weather to last into April. Should these predictions be correct, Ohio’s farmers may be looking at a slow start to spring in addition to many other challenges.

One area of concern some producers may have after experiencing harsh winter weather is the current condition of winter wheat stands. Are they sufficient to produce a profitable wheat crop? According an article in a 2014 C.O.R.N. Newsletter written by Laura Lindsey, Ed Lentz, Pierce Paul, “Fields should not be evaluated until completely green from warmer temperatures for at least 10 to 14 days.… Continue reading

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