Traditionally a problem disease in the western Corn Belt, Goss’s wilt is now prevalent across the Corn Belt and spreading into Canada. Once corn plants are infected, yield potential can be reduced by up to 50 percent. There are no effective chemical control measures for Goss’s wilt. The best way to limit spread of the disease is by selecting hybrids with strong Goss’s wilt tolerance. This bulletin provides information about Goss’s wilt and tolerance ratings for Mycogen® brand corn hybrid families. The ratings are the result of 2011-15 field trials conducted in Illinois, Iowa, Minnesota, Nebraska, South Dakota and Wyoming.

DISEASE INFORMATION
Goss’s wilt is caused by the bacterium Clavibacter michiganensis subsp. nebraskensis. It overwinters in infected corn residue, primarily found on or near the soil surface. Inoculum in the infected residue primarily spreads by wind and splashing rain. To a minor degree, Goss’s wilt also can survive in seed. To infect a corn plant, the bacterium needs an entry point or wound, which is generally caused by heavy rainstorms, hail, wind, blowing sand or mechanical damage. Humid, wet weather is another risk factor because moist or wet leaves are conducive to the spread of disease.

Corn hybrid selection and fertility planning are key in alkaline, or high pH, soils. High-pH soils reduce the availability of plant nutrients, including zinc, iron and phosphorus. Interveinal yellow stripes on middle to upper leaves are signs of iron deficiency, while white stripes on young leaves are characteristic of zinc deficiency. Dark green or purple coloring of lower leaves indicates phosphorus deficiencies.

Crop injury can occur from pre- or post-emergence corn herbicide application. It usually occurs due to poor application timing, improper application rate, carryover from the previous year’s application or leftover residual in the spray tanks, lines and filters. Fortunately, yield loss, in most cases, is minimal. Be aware of herbicide injury symptoms and ways to prevent them.

The key to a successful growing season is advanced preparation. Early hybrid selection and ordering helps to give the best hybrid selection and maximize the yield potential on your farm. Agronomist Jon Erickson offers seven steps on selecting the right grain corn hybrids for your acres.

With so many Bt trait offerings on the market today, it can be challenging to determine which package best fits your farm. Each package contains different combinations of traits with different levels of effectiveness against specific pests. Understanding best management practices is critical to ensuring control options for years to come.

A successful harvest depends not only on crop conditions but also on properly functioning equipment. While you can’t eliminate all harvest losses, you can identify the source and adjust harvest equipment for optimum performance.

Fertilizer programs should begin with accurate soil testing. Growers who can self-sample reduce costs and better understand their soil situations. Review best practices so your samples lead to more reliable results and more educated management decisions.

Contrary to some studies, dry matter losses after blacklayer are not overwhelming. Still, growers should carefully manage their corn harvest timing to minimize loss altogether.

A corn rootworm (CRW) beetle infestation can decimate corn yield. They have a keen ability to adapt to control strategies, which makes vigilant scouting and management a priority. Regions with heavy continuous corn acres can harbor high CRW populations. However, rotation-resistant beetles and extended diapause beetles contribute to increased populations, even with a rotation in place. With careful monitoring, a timely insecticide application can manage CRW pressure and mitigate damage the following year.

Grain corn ear molds can lead to yield loss at harvest. If mycotoxins are present, grain may be toxic to animals and ultimately unusable. It’s important to understand environmental conditions that lead to diseases and how those diseases affect grain.

Factors that stress corn throughout the growing season can lead to stalk rots, which can lead to yield loss due to premature plant death or lodging. Understanding stalk rots risk factors and management practices are critical.

Corn growers often mistakenly correlate test weight (TW) to yield. Understand why the two measures are only marginally related.

Traditionally a problem disease in the western Corn Belt, Goss’s wilt is now prevalent across the Corn Belt and spreading into Canada. Once corn plants are infected, yield potential can be reduced by up to 50 percent. There are no effective chemical control measures for Goss’s wilt. The best way to limit spread of the disease is by selecting hybrids with strong Goss’s wilt tolerance.

This bulletin provides information about Goss’s wilt and tolerance ratings for Mycogen® brand corn hybrid families. The ratings are the result of 2011-14 field trials conducted in Illinois, Iowa, Minnesota, Nebraska, South Dakota and Wyoming.


DISEASE INFORMATION
Goss’s wilt is caused by the bacterium Clavibacter michiganensis subsp. nebraskensis. It overwinters in infected corn residue, primarily found on or near the soil surface. Inoculum in the infected residue primarily spreads by wind and splashing rain. To a minor degree, Goss’s wilt also can survive in seed.

To infect a corn plant, the bacterium needs an entry point or wound, which is generally caused by heavy rain storms, hail, wind, blowing sand or mechanical damage. Humid, wet weather is another risk factor because moist or wet leaves are conducive to the spread of disease.


IDENTIFYING GOSS’S WILT
Scouting is important because infection can occur at any point during the growing season. Infested seedlings show systemic wilting, stunting and a variety of leaf symptoms.

More-mature plants demonstrate the foliar leaf blight version of the disease. The first signs of infection are dark green to black, oblong spots that are water-soaked with a greasy look that appear parallel to leaf veins. Streaks of freckles within the lesions are a distinctive feature of Goss’s wilt. Droplets of bacterial exudate ooze from the freckles, leaving a crystalline substance that glistens in direct sunlight. The spots coalesce as they enlarge, forming long lesions with wavy edges. As the lesions age, they turn tan and can blight much of the leaf. Systematically infected plants have discolored (orange) vascular tissue and likely slimy stalk rot.

Key Symptoms:
• Freckles in lesions
• Crystalline deposits
• Droplets of exudate

Commonly confused with:
• Drought damage
• Heat stress or sun scalding
• Other leaf blights


CONTROLLING GOSS'S WILT
Because Goss’s wilt is a bacterial disease, it cannot be treated with fungicides. The best method of control is planting hybrids with strong Goss’s wilt tolerance. Tables 1 through 4 demonstrate the wide range of tolerance in hybrids.

Growers can limit the spread of Goss’s wilt to uninfected fields by selecting tolerant hybrids, harvesting infected fields last and thoroughly cleaning harvest equipment. Destroying infected crop residue will lower the amount of bacteria present. This is most effective when done immediately after harvest. In most situations, rotating to a nonhost crop, such as soybeans, dry beans, sugarbeets or alfalfa, is a more viable option. Last, manage irrigation to reduce humidity in the field during the growing season.

Talk to your Mycogen Seeds sales representative or customer agronomist to learn more about managing Goss’s wilt on your corn acres.

As corn’s fifth micronutrient, boron is often an afterthought. Boron’s impact is most felt when it’s not available. Deficiencies or a complete absence of boron can cause stalks to become barren, ears to twist and yield to suffer. Monitor your crop for these symptoms and take action if a deficiency is determined to be present.

Cover crops planted after harvest can improve and maintain soil quality in today’s intensive corn-soybean rotations. Understand how different types of cover crops recover unused nutrients, retain soil moisture, suppress weeds and break up compaction.

It is a common belief that high heat and humidity are ideal for corn growth. In reality, high temperatures, especially high nighttime temperatures, can reduce corn yield potential by increasing respiration.

Utilizing winter cover crops for hay and corn production allows you to realize soil conservation benefits while increasing dry matter production per acre. Proper cover crop management in the spring can ensure the subsequent corn crop is successful, as well.

Zipper ears, or ears with missing kernel rows, are a result of stress during pollination or grain fill. Ears affected by zippering have kernels that developed poorly or more slowly than other kernels or have ovules that aborted shortly after pollination. It’s important to understand how and why zipper ears occur and how to minimize their occurrence in the future.

Between the V3 and V5 growth stages, corn transitions from deriving energy directly from the seed to acquiring energy from sunlight through photosynthesis. Visual appearances during these stages offer clues to overall plant health.

Stand establishment depends not only on the success or failure of germination but also on early season stresses. If you notice early stand problems, carefully examine damaged seedlings to discover clues to the likely causes.

By properly identifying the various developmental stages in early season corn growth, producers can make well-informed decisions on replanting, applying herbicides, managing insects and more. Make sure to understand what to look for and how to differentiate the stages.

If your central Corn Belt fields have been damaged by heavy rain, hail, pests or poor emergence, you may consider replanting.

Many farmers feel it is a greater agronomic benefit to apply nitrogen (N) in the spring rather than in the fall, because it coincides with the nitrogen needs of the corn crop. With this thought, a key question of many growers is, “Is a spring nitrogen stabilizer application still needed?”

Northern corn rootworm (NCRW) is one of the most damaging corn pests in North America. Because the NCRW typically has a one-year life cycle, rotating corn with another crop has been a successful management strategy. Unfortunately, some populations of NCRW have successfully adapted to a corn soybean rotation and now have a two-year life cycle. This is called extended diapause because the eggs remain dormant in the soil for almost two years before hatching.

Maximizing yield starts with correct planting, and correct planting starts with adjusting the planter to the proper settings. Carefully check planting equipment before you hit the field this spring.

Planting is arguably the most important time in crop production. Your crop has its maximum yield potential on the day it’s planted. Crop success or failure depends on your ability to control planting factors. Whether it is your first season or your 51st, it’s worthwhile to revisit planting fundamentals.

Producers who plant insect-traited corn are required to manage refuges to preserve Bt technology. With so many trait options, following refuge management guidelines has become more complicated. SmartStax^® Refuge Advanced^® available in Mycogen^® brand hybrids simplifies achieving higher whole-farm yield potential by making refuge management easier. Refuge Advanced ensures refuge compliance in the Corn Belt¹ with a blend of 95 percent SmartStax seeds and 5 percent non-insect-traited refuge seeds in one bag.

Growers can protect their investment in Roundup Ready^® crops and maximize yield potential through the use of a residual herbicide, such as SureStart^®II or Sonic^®. SureStart delivers consistent, broad-spectrum weed control during early stages of corn growth and offers application flexibility. Sonic provides broad-spectrum foundation control of tough broadleaf weeds to reduce competition for emerging soybeans.

Nitrogen (N) can be lost from the soil between application and crop uptake. By managing applications, you can maximize yield by making sure N is available when corn plants need it most.

Like a house with a poorly prepared foundation, corn plants with rootless corn syndrome (or floppy corn syndrome) between the V3 and V8 growth stage can topple at any moment, leading to stunted growth and even plant death. What causes this phenomenon and how can plants survive?

Early season seedling damage can significantly reduce yield. Scout cornfields regularly and diagnose problems before economic losses occur.

Planting larger seeds creates challenges. Growers should follow some basic management tips.

Extensive university research illustrates that corn planted in a twin-row configuration can have a significant yield advantage versus a single-row crop. Several factors support this conclusion.

Flooding affects fields differently based on a variety of factors. Manage flooded corn to minimize damage and ensure optimum plant health and yields.

Utilizing winter cover crops for hay and silage production allows you to realize soil conservation benefits while increasing dry matter production per acre. Proper cover crop management in the spring can ensure the subsequent corn crop is successful, as well.

Planting corn at the appropriate population can help maximize the crop’s yield potential. Specific populations can vary by geography so it is important to consider management practices, ear type, row width and other environmental factors.

Palmer amaranth is a resilient weed with increasing herbicide resistance and territorial expansion that could harm your crops. Through identification and precaution, you can maintain your plant health and yield potentials.

The optimum time to select corn hybrids for the next season is often in the fall, shortly after harvest is complete and your observations from harvest are still fresh in your mind or can be reviewed in your records. Additionally, early ordering often can help ensure availability of hybrids and seed sizes that best fit your farming practices.

Harvesting corn for silage leaves little plant residue on the ground to help control water runoff and soil erosion. A cover crop either interseeded before or planted immediately after silage harvest will help protect the soil from wind and heavy rains. An established cover crop also helps improve soil structure and uptake of nutrients.

It can be difficult to schedule irrigation, herbicide application and harvest if you don’t have a good handle on corn maturity. Identifying the milkline and blacklayer will help gauge the stage of corn growth and estimate physiological maturity.

Wet and/or humid conditions can lead to black, sooty molds in cornfields at harvest. Sooty molds are species of secondary saprophytic fungi — microorganisms that feed on dead plant material. The presence of these molds can create excessive amounts of black dust when harvesting affected cornfields.

Dry summers and relentless pests increase your corn crop’s susceptibility to aflatoxins, which are harmful to livestock. Reduce your exposure with effective management.

Early frost at harvest can lead to high or uneven moisture, low test weights and increased foreign material. Careful planning and management of drying and storage can help maintain yield.

Many factors contribute to how early frost in the fall will affect corn harvest and the expenses associated with drying and storage. Damage severity will depend on the stage of the crop, the duration of freezing temperatures and subsequent plant damage.

Corn rootworm is one of the most damaging pests in the Corn Belt. Don't let corn rootworm rob your yields. Scout for the pest by digging for larvae. Jeff Housman, Mycogen Seeds customer agronomist, walks through how to do root digs to find corn rootworm to evaluate the damage in your fields.

Corn aphids are becoming a common pest for corn growers, as populations can develop in massive numbers. Aphids are problematic during tasseling and can colonize corn later in the summer, with populations building to striking levels, threatening yield potential.

Heavy wind and rain late in the growing season can dramatically affect corn. Flooding, downed plants and disease are just a few of the potential management challenges related to extreme weather. Consider your options for recovering as much value as possible and take precautions when storing and feeding damaged corn.

A high rate of black cutworm (BCW) moth catches, green fields and late planting dates are the perfect recipe for significant damage from black cutworm. Damage can range from very little to almost 100 percent stand loss. To give late-planted corn the best yield potential, make controlling this pest a high priority.

Planting corn at the proper depth helps to ensure proper germination and development, allows for optimum seed-to-soil contact, leads to more uniform emergence and helps achieve top yield potential.

When corn planting is delayed due to inclement weather and poor field conditions, you can still take advantage of the compressed growing season and achieve reasonable yield results by adjusting your hybrid selection and managing cropping activities with later planting dates.

When corn planting is delayed due to inclement weather and poor field conditions, you can still take advantage of the compressed growing season and achieve reasonable yield results by adjusting your hybrid selection and managing cropping activities with later planting dates.

In areas of the Corn Belt, frost and variable soil temperatures can place corn under significant stress after planting.

If your cornfields have been damaged by heavy rain, hail, pests or poor emergence, you may consider replanting.

Greensnap occurs when wind causes corn stalk breakage. This yield-robbing phenomenon is most prevalent in the central and western Corn Belt, where high winds are common. Corn is most susceptible to greensnap during the five- to eight-leaf stages and again from the 12th-leaf stage to one week after silking. During these rapid growth stages, lignin is not deposited into the new cells, leaving them brittle and vulnerable.

An accurate soil map is important when efficiently managing fields and soil fertility levels. Grid sampling is an effective soil sampling method to use when fields have a high number of soil types or textures, and when previous cropping and management practices have changed or are unknown.

A bacterial disease that has been prevalent in areas of the western Corn Belt for decades, Goss’s wilt has expanded to additional areas of the central and eastern Corn Belt in recent years. If infections occur early in the season, during key crop development times, yield potential can be reduced by up to 50 percent.

Demand for higher grain yields are helping to reinforce the importance of healthy, robust corn crops. Using a starter fertilizer can increase early plant growth, nutrient uptake and yield potential, as well as improve overall plant health. What is the best approach to applying a starter fertilizer?

Since the adoption of corn hybrids with biotechnology traits, growers have continued to see more consistent 200-bushel-plus corn crops in past seasons. However, increased yields have created the challenge of dealing with increased levels of residue when planting next year’s crop.

Warm, moist conditions from July to September can cause increased disease incidence in corn. Recent studies have show potential economic benefits from foliar fungicide applications. Fungicide treatments can give protective or curative benefits for corn diseases such as: gray leaf spot, common rust, eyespot and antracnose. These diseases can limit photosynthesis due to tissue death. Loss of leaf tissue also may result in grain production loss or harvest loss due to weakened stalk strength and harvestability issues.

Soil acidity is one of the primary fertility issues that can limit crop growth. High levels of acid can reduce nutrient availability, restrict root growth and increase the toxicity of some elements. Soil acidification occurs naturally as the result of rainfall, plant growth, breakdown of organic matter and the application of ammonia fertilizers. Applying lime reduces soil acidity and is a source of calcium (Ca) and magnesium (Mg).

Slug damage in corn and soybeans has increased with the adoption of no-till and minimum-till practices. Because rescue treatment options are limited, growers should take steps to prevent slug damage.

Increased use of reduced tillage and no-till production practices has increased gray leaf spot occurrence. Caused by a fungus, the disease leads to leaf tissue loss, resulting in a decrease in plant sugars and decreased grain production. Potential yield losses range from 5 percent to 40 percent.

Strip-till is a conservation system that uses minimum tillage. It combines the soil-drying and warming benefits of conventional tillage with the soil-protection advantages of no-till by disturbing only the soil that will contain the seed row. Strip-till rows are usually about 8 to 10 inches wide. Because special equipment is required for this type of tillage, understanding what is needed for a strip-till system can help you determine if it’s the right practice for your fields.

Crop harvest removes valuable nutrients from the soil. Understanding the amount of nutrients removed is crucial to understanding how to fertilize for the highest yield potential next season. With high input costs, it can be tempting to skimp on nutrients to save cost. Over time, however, this approach can reduce yield potential and profitability.

Several methods provide growers with a reasonable estimate of corn hybrids’ relative maturity, but differences among rating systems sometimes confuse growers. Are you familiar with each method?

The brown marmorated stink bug (BMSB) is an invasive species that is causing economic damage to fruit, vegetable and agronomic crops in the Mid-Atlantic states. The insect now is expanding its range westward across the Corn Belt.

Poor nitrogen (N) application methods or application timing could result in a shortage of available N to meet your corn crop’s needs next season. Understanding proper N application methods can help maximize N efficiency on your operation.

Fair weather along with an early harvest provides conditions conducive for growers to fall-apply manure to their fields. Before applying manure, review your nutrient management plan to determine the appropriate amounts of nutrients needed to improve success in selected fields.

Difficult-to-control and herbicide-resistant weeds are major issues facing crop farmers. Troublesome weeds sometimes get a head start by popping up in the fall. Although tillage can take care of problem weeds, it isn’t always preferred or even possible. A well-timed fall herbicide application can prevent weeds from getting a head start and save time during the busy spring season.

The final application of irrigation water can help corn reach peak yield potential. Manage your crops with effective and responsible use of water resources.

Southern rust is a common threat to corn crops across the southern United States. The disease damages crops in the Corn Belt only about once every five years, but when it does yields may be cut by more than 40 percent.

Hailstorms regularly strike growing corn fields. But not all damage is created equal. Know how to accurately assess yield loss.

Glyphosate-tolerant corn and soybean systems have become commonplace. But more than a decade after the introduction of glyphosate-tolerant crops, weed control has again become a major problem in nearly every crop-producing state. Many weeds have become more difficult to control and herbicide application rates have spiked. Learn to effectively balance your management approach.

Mastering foliar fertilizer application methods and timing help maximize your crop’s efficiency. Follow these guidelines for proper foliar fertilizer application.

Corn nematodes are plant parasites that exist in every field to some degree. Yield loss varies by nematode species and their populations. Collecting and submitting samples for plant parasitic nematode analysis is the only way to evaluate your exposure.

Nutrient deficiency symptoms are not always caused by a lack of nutrients in the soil. Other factors can be to blame, such as poor root development, unfavorable soil conditions or weather. Plant tissue sampling helps identify the problem and determine corrective action.

Grasshopper population levels are highest during hot, dry summers. Active scouting and applying appropriate crop management practices can help guard your crop from damage.

Applying a portion of your crop’s nitrogen (N) requirement with irrigation water is a best management practice to reduce nitrate leaching in coarse soils. New irrigation technology systems have made the process of chemigating easier.

When low temperatures or frost injure young corn plants, you may wonder if these plants will recover. Carefully weigh your options and don’t make any quick replanting decisions. The key to assessing corn seedling viability is to find and observe the growing point.