Managing for High Yielding, High-Quality, Low-Cost Crops

Daniel Hudson, UVM Extension Agronomist

Feed is, by far, the greatest expense for dairy farms. The 2012 Northeast Dairy Farm Summary published by Yankee Farm Credit showed that on average, feed represented over 37% of total farm expenses, and labor was a distant second at just over 15%. The primary influences that the dairy farmer has over this cost are in the areas of:oesterle chopping

  • Forage yield and quality
  • Crop yield and quality
  • Management of stored feed (preventing losses of quality and quantity between the field and the mouth of the cow).

This is why every farmer benefits from careful management in their cropping system. Land is the farmer’s foundational resource, whether rented or owned. Value is added to the land by growing crops. Value is then added to the crops by running them through the digestive tract of the cow — at least when milk prices are good.

Most dairy farmers would be astonished if they heard a fellow dairy farmer say, “I know that my cows don’t lactate much, limp a lot, and the milk has an extremely high somatic cell count, but I am a crops guy – cows aren’t really my ‘thing.’” What? Unthinkable! If you are not a ‘cow-person,’ hire someone who is! If your cows have fundamental problems, it does not matter how well other things are going.

Interestingly, if a dairy farmer said, “my crop yields are awful, forage quality a perpetual problem, and my feed costs are through the roof,” much less shock would be expressed. I am not saying that dairy farmers are bad at growing crops, but that there are many who could make a lot more money by devoting more attention to the crops. Here are some economically profound facts about crop production in dairy systems:IMG_0211

  1. A tall fescue variety trial conducted at Cornell showed a 30% difference in yield between the high and low yielding cultivars. Choose your forage varieties carefully.
  2. Corn that has its nitrogen needs met can yield twice as much as corn that does not.
  3. The yield of two different corn hybrids of similar maturity can differ by more than 30%.
  4. Under common conditions, grass that had its nitrogen needs met can have protein levels that are 4% higher than in grass that did not. Assuming a 4 ton/ac forage yield, this protein difference would equate to the amount of protein found in 684 pounds of soybean meal, which currently has a value of $163 (CBOT price, more at the farm gate).
  5. Depending on severity, inadequate phosphorus or potassium fertility can reduce crop yields by more than 50%.

    oregon state bunker silo

    From: Oregon State University

All of these facts have implications for risk management (inventory), profitability (grain bill, purchased feed), and efficiency.

Here are some pieces of low-hanging fruit that I believe can help the bottom line of the average dairy farmer in the 2014 cropping season.

  1. As inglorious as it sounds: have your soils tested. Notice that I did not say ‘take soil samples.’ While anybody can learn to properly collect soil samples, it is something that most farmers can and probably should delegate to another competent and trustworthy individual. This is mainly due to the extremely busy schedule that most dairy farmers keep. There are many certified crop advisors (CCA) in Vermont, Massachusetts, Quebec, and New York. Some of them are independent and charge for soil testing services, others work for seed/chemical/fertilizer vendors and may provide the service to their customers. Search online by state and/or expertise. If you search on the website it will be helpful to know that the codes for ‘agronomy’ and ‘soil fertility’ are A1 and U2, respectively ( ).
  2. Manure testing. Failing to regularly and properly test manure is like failing to test the

    from University of Wisconsin Extension

    haylage that goes into your total mixed ration. Similar to making ration, you need to know the nutrient content of each of your soil fertility ‘ingredients’ if you want to reach your crop yield and quality goals.

  3. Knowledge should lead to action: follow the recommendations of your soil test report and account for the nutrients applied in the manure. Just recently a farmer told me that amending the soil in a field that he was renting nearly doubled the yield. I am sure that quality was profoundly affected as well.
  4. Choose corn hybrids and forage varieties with care. Look for independent variety trials that were conducted under conditions similar to your farm. This can be challenging, but variety trials are routinely conducted in Vermont, Wisconsin (corn, forage), Michigan, New York, Ontario (corn, forage), and Minnesota. Conditions vary at each location so it will take some work to narrow down some of the best candidates.
  5. When reseeding perennial forages, include red clover (or alfalfa if your soils are suitable) in the seeding mixture. In pure grass stands between 150 and 200 pounds of actual N over the course of the season is required to optimize yield. In stands that with 40-60% legume, 40-50 pounds of actual N prior to green-up in the spring should optimize forage yield[1].

Cash has been hard to come by for dairy farmers over the past few years, and many have had to make tough choices about where (not) to spend money. Now is a great time to implement these foundational agronomic practices that add value to each acre of land that you manage.

[1] Some recommendations indicate this range to be 20-60% legume.


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Why is barnyardgrass so abundant in Vermont hay fields and pastures this year?

By Daniel Hudson, UVM Extension Agronomist

This year many farmers are wondering why barnyardgrass is present in unusual abundance in their hay fields and pastures.  This annual warm-season grass weed is physically similar to Japanese millet and is found throughout the world.  In North America it is found from Mexico to Alaska.  This discussion will cover:

  • Forage quality and palatability questions and concerns
  • Factors that contributed to the problem in 2013
  • Crop management implications

Physical description

The tallest plants in this picture (aside from trees) are barnyardgrass

The tallest plants in this picture (aside from trees) are barnyardgrass

Depending on growing conditions and the time of germination, mature barnyardgrass plants may be between 1 and 6.5 feet tall.  Larger plants with more dense tillering (thick clumps with many shoots) can be expected in areas of very high fertility and/or less frequent harvest.  Stems are coarse and may range from 0.15 to 0.5 inches in diameter.  Leaves are between 4 and 12 inches long, up to 0.6 inches wide, green in color and occasionally have a reddish hue.  Seed heads have a sparse panicle arrangement (i.e., shaped like a ‘Charlie Brown Christmas tree’), generally have between four and seven lateral branches, and may be reddish-purple and/or green in color.  Branches of the seedhead range from 0.75 to 2.5 inches long and have bristly seeds densely packed along the length.  Roots are dense and fibrous.

First things first: what about the forage quality and palatability?  In absolute terms, barnyardgrass is not very palatable as a pasture forage except in the vegetative stage.  As with most weeds, barnyardgrass wastes no time moving from the vegetative IMG_0427stages to the reproductive stage.  If low to moderate amounts of barnyardgrass are present in a perennial hay field that is harvested for haylage, palatability of the ensiled product will almost certainly not be affected.  Research published by Marten and Andersen (1975) compared the forage quality and palatability characteristics of 12 pasture weeds to oats.  At the time the oats were at the early-head stage, the barnyardgrass was still vegetative, and their forage quality parameters compare as follows:





CP %

Ca %

P %

K %

Mg %

Barnyardgrass 81 30 3.0 21 0.8 0.4 4.2 0.6
Oats 71 34 3.6 19 0.4 0.4 2.9 0.3

*Data from 1973

The point here is not that barnyardgrass is a superior forage species compared to oats or anything else, but to demonstrate that barnyardgrass will not harm the forage quality parameters listed above if harvested or grazed at a vegetative stage.   As with all grasses, if barnyardgrass  is allowed to progress to the reproductive stage the forage quality will suffer greatly.

The researchers in this study used sheep to measure palatability of the various weeds: barnyardgrass was palatable, common ragweed was sometimes unpalatable, and wild mustard was unpalatable.  The researchers also tested for alkaloids, compounds which are grazing dairy heiferknown to reduce palatability; none were found in any of the grasses tested.  The data from the mineral analysis was used to calculate Ca/P ratios, which can indicate if that feedstuff may predispose cows to milk fever.  The K/(Ca + Mg) ratios were calculated to determine if any of the forages might be prone to induce grass tetany to grazing livestock.   The ratios for barnyardgrass suggest that it is unlikely to induce milk fever or grass tetany.  Finally, the nitrate levels were checked for all species in the study.  Forages with nitrate levels above 0.35% can induce nitrate toxicity, and some have suggested that barnyardgrass might occasionally have this problem.  In this study, however, barnyardgrass had 0.09% nitrates, while oats had 0.10%.  Nitrate toxicity is much more likely to occur in barnyardgrass and other forages in drought situations.

Why is barnyardgrass so abundant this year?  As with most weed problems that happen suddenly over a wide geographic area, the cause is environmental.

Interacting factors likely included:

  • Dry weather until the last week of May likely delayed nitrogen mineralization which reduced the vigor of early-season forage growth.  This left more nitrogen in the soil than would ordinarily be there in early-June.  This delayed release held back early growth of the pasture grasses yet coincided nicely with the early growth-stages of barnyardgrass seedlings.
  • Record precipitation in late-May through June set the stage nicely for germination and rapid growth of barnyardgrass, which thrives in extremely wet soils, especially if nitrogen is abundant.
  • Warm-season grasses like barnyardgrass and corn like hot weather.  The temperatures in July and August favored rapid growth of warm-season plants.

For some farms, one or two of this year’s hay cuttings happened on wet soils.  In some cases, this led to compaction, which favored retention of surface water and reduced competition from the established perennial plants.  Some farmers may notice strips of barnyardgrass oriented in the same direction that the field is harvested.

Could my management practices have made this problem worse?  Maybe a little.  Given the many multifactorial decisions that need to be made each year, most IMG_0235farmers have to choose between the ‘lesser of two evils’ several times per year.  In this case the choice for many was between taking the first cutting when soils were still somewhat wet during a two day break in the rainy weather as opposed to delaying harvest until soil conditions improved.  In many cases, delaying the harvest would be the greater of the evils given the inevitable loss of forage quality that would affect the bottom-line for the rest of the year.  In pasture settings, barnyardgrass always has a competitive advantage around watering areas due to higher levels of compaction, abundant nutrients, moisture, and destruction (i.e., reduced competition) of the perennial pasture plants.  Given the geographic scope of the problem in the state, it is safe to say that fields with certain types of soils probably would have ended up with barnyardgrass this year under many management scenarios.

Will it show up again?  The seeds that produced the plants we see this year were already in the soil. References to research done on the subject of barnyardgrass seed viability in the soil suggest that most of the seed in the soil seed bank loses viability within three years, but some may survive 13 years or more.  Given that barnyardgrass is a prolific seed producer (it can produce 2,000 pounds of seed/ac in a severe infestation) it is reasonable to assume that past infestations made significant contributions to the soil seed bank and that we will probably see it again.

How can this weed be managed in the future?  Knowledge about the particular characteristics of a weed can help the manager make decisions about how to manage it in the future.  Barnyardgrass:

  • is a warm-season annual grass.  It will not be a factor for a timely first cutting, but the plants will grow rapidly thereafter.
  • seed production will be heaviest in August and September.  Plants will keep attempting to produce seed until cooler temperatures inhibit regrowth.
  • favors rich, moist soils and grows well in poorly drained soils.
  • is not tolerant of shading by other plants
  • thrives when nutrient (particularly nitrogen) levels are high in the soil
  • seeds float; moving water is a major mode of seed dispersal.
  • can be removed from corn and legume fields with herbicides, but there are no labeled herbicides that will remove it from a grass hay field or pasture.


While barnyardgrass is not something that anyone would intentionally plant in their pastures and hayfields, the impact on haylage quality will be minimal unless infestations IMG_0224are very heavy; in a few cases the impact on forage quality may even be positive.  To minimize future problems, endeavor to harvest fields before the barnyardgrass produces viable seed.  Promoting dense and vigorous growth of your perennial forage species will increase your chances of out-competing barnyardgrass, which is quite intolerant of shade.   In pastures, degraded areas will probably continue to favor barnyardgrass until management is changed to so that compaction and physical damage to the perennial forages is corrected.  In certain situations where barnyardgrass is a major problem, rotating the field to corn will give the crop manager the option to use herbicides.


Esser, L. L. Index of species information: Echinochola crus-galli.  From Fire Effects Information System. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory.  Online:  Accessed: September 2013.

Lanini, W. T., and B.A. Wertz.  Weed Identification 12: Barnyardgrass.  Penn State Extension.  Online:  Accessed:  September 2013.

Marten, G. C., and R. N. Andersen.  1975.  Forage nutritive value and palatability of 12 common annual weeds.  Crop Sci. (Vol. 15): 821-827. Online:  Accessed: September 2013.

Mitich, L.  Intriguing world of weeds: barnyardgrass.  Weed Sci. Soc. Amer.  Online:  Accessed: September 2013.

Sprague, C.  E-434: 2013 weed control guide.  Michigan State University.  Online:  Accessed: September 2013.

Weiss, W.P. and Shockey, W. L. Nitrate toxicity in drought-stressed plants.  West Virginia University Extension Service.  Online:  Accessed: September 2013.

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Does Your Corn Have Northern Corn Leaf Blight?

By Daniel Hudson, University of Vermont Extension Agronomist

silage corn affected by northern corn leaf blight (NCLB)

Silage corn affected by northern corn leaf blight (NCLB)

The silver lining of most disasters is that they are often accompanied by opportunities to learn something new or at least be reminded of something already known.  The down side is that disasters are often very expensive in the short-term.  The disaster of the day is northern corn leaf blight (NCLB), a fungal disease that in some circumstances can decimate corn yield and silage quality.  Northern corn leaf blight has been observed at varying levels of severity in Vermont for the past several years.  This year some fields along the Connecticut River (and probably elsewhere) will probably suffer 30% yield losses from this disease.  Much of this loss will result from poor grain fill stemming from the reduction of photosynthetic area on the affected leaves, which will also have implications for silage quality.

IMG_0096.JPG (2)

Cigar-shaped lesions on the leaves of a plant infected by northern corn leaf blight.

Northern corn leaf blight is most easily recognized by the ½ – 1” wide by 1-7” long ‘cigar-shaped’ lesions that form on the leaves.  In severe infestations, the lesions can be  prolific enough that they eventually join at the edges and may turn the entire leaf a grayish brown color.  The earlier this foliar disease occurs in the growing season, the greater the yield (and quality) impact will be.  Yield losses can be as high as 50% if the disease becomes established prior to tasseling.  To make matters worse, fields with severe infestations are often more susceptible to stalk rot. The NCLB inoculum can be deposited on the growing crop from distant fields via rain or wind, but infection will be more severe if inoculum is present in the field.

Corn grain farmers have had NCLB on their radar for a long time because the pathogen overwinters in the abundant corn residue which is characteristic of that cropping system.  Corn silage systems typically have fewer problems with NCLB because of the scarcity of residue remaining after harvest.

Will this disease be a problem every year?  Probably not, but the potential for economic loss is large enough that local farmers should seriously consider selecting resistant cultivars, especially in fields with the primary risk factors.  The fields with the greatest risk of developing NCLB are those that have:

  • a recent history of NCLB
  • characteristics that favor extended leaf wetness (6 – 18 hours per day).  For example, river bottoms with frequent fog, sheltered areas with reduced air movement, shade.
  • infrequent crop rotation
  • no-till or reduced tillage
  • much corn residue remaining after harvest
  • weather conditions includes frequent rain, cloud cover, high humidity, and mild temperatures (64-81⁰F)
IMG_0101.JPG (2)

This 97-day corn hybrid has a NCLB resistance rating of ’4′ (a rating of ’9′ indicates the highest level of resistance)

Be aware that the scales used to rate disease resistance may vary among seed companies.  Pioneer and Mycogen, for example, have a scale of 1-9, with a rating of 9 indicating excellent resistance; DeKalb’s scale is opposite, and a rating of 9 indicates poor resistance.  The variety planted in a local river-bottom field with a severe NCLB infestation had a rating of ‘4’ on the Pioneer/Mycogen scale.

IMG_0102.JPG (2)

This 106-day hybrid was planted in the adjacent field and had a NCLB resistance rating of ’6′ (a rating of ’9′ indicates the highest level of resistance). The difference in condition between the fields is probably only partially due to genetics.

There are two forms of NCLB resistance that exist in commercial cultivars: partial and race-specific.  The ‘partial’ resistance gives the plants some degree of resistance to all races of NCLB.  In areas where NCLB is a common problem, producers and their seed representatives can work together to choose hybrids that are resistant to the local NCLB race that is known to be most problematic.  Yellow lesions often still appear on resistant varieties, but they are small and do not result in the production of spores.

Other management options include crop rotation and fungicides. Scouting for NCLB should occur just prior to tassel emergence.  If the disease is beginning to develop at that stage and the forecast and other risk factors indicate that an infestation is likely to occur, a fungicide application may reduce the impact of the disease.  When warranted, the greatest economic returns will be realized when fungicides are applied between tasseling and early silking.  There are no established economic thresholds for fungicide applications in corn.  In conventional tillage systems, rotation away from corn for one year greatly reduces the likelihood that NCLB will develop in the subsequent corn crop.  In no-till systems, a two-year break is advisable.

Northern corn leaf blight can be easily confused with other diseases such as Stewart’s bacterial wilt and Diplodia leaf streak.  Contact your local Extension agronomist or Certified Crop Advisor for assistance with a diagnosis.

Daniel Hudson can be contacted by e-mail at or by phone: 802-751-8307.


Darby, H.  Northern Corn Leaf Blight.  Online:  University of Vermont Extension.  Accessed September 2013.

Dillon, P. Northern Corn Leaf Blight (NCLB).  Online:  University of Kentucky Extension. Accessed September 2013.

Lipps, P.E., and D. Mills.  Extension Fact Sheet: Northern Corn Leaf Blight.  Online:  Ohio State University Extension. Accessed September 2013.

Wise, K. Diseases of Corn: Northern Corn Leaf Blight.  Online:  Purdue University Extension. Accessed September 2013.

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Can foliar diseases in forage grasses cause economic losses for livestock producers?

By Daniel Hudson, UVM Extension Agronomist

late blight on ripe tomato. From Cornell University

Most garden enthusiasts are familiar with fungal diseases in fruit and vegetable crops. These diseases can induce a range of experiences from mild gardener irritation to complete crop loss.  Late blight in tomatoes, powdery mildew in squash, leaf spot, phytophthora , and pythium, just to name a few.  The most frustrating diseases are those that spoil the quality of the product just before it is ready to harvest!  Spores for most plant pathogens can be found almost everywhere those plants grow!  Given the right conditions, they can devastate a crop.  While some species and varieties of plants have varying degrees of resistance to certain pathogens, no plant is entirely immune.

Fungal infection of fruit and vegetables can render a crop completely unmarketable, a fact that looms large in the minds of producers.  In field crops and forages, however, fungal pathogens often do not prevent harvest or marketing, but often compromise yield and quality in ways that are not immediately evident.  Until recently I had the impression that foliar disease on forages was not a ranking concern among livestock farmers or hay producers.  This is why I was very surprised when I recently heard a farmer state that mid-summer grass diseases (foliar) are the most significant agronomic problem on his farm!

What are these diseases?

Stripe rust. Picture from: Oregon State University

While some species and varieties are resistant to some fungal pathogens, all grasses and legumes are susceptible to some diseases.  For example, there are at least 30 fungal diseases that can affect orchardgrass.  Depending on the time of year, the primary ones we see are rusts (caused by species of Puccinia fungi), scald (species of Rhynchosporium), and leafspot/blotch (species of Drechslera).  All of these diseases are favored by prolonged periods of leaf wetness.

What are fungal pathogens really after?

Fungal pathogens ‘want’ to reproduce; to do this, they need a source of energy.  Fungal pathogens specialize in accessing the carbohydrates in the tissue of certain classes of plants but are ineffective at exploiting other types of plants.  As in the case of communicable diseases among people, there are certain conditions that favor the development of disease in plants.  In forage crops, fungal foliar disease is likely to develop if:

soil test report

soil test report showing potassium deficiency

  • the plant has been stressed by drought, nutrient deficiency, insect damage, another disease, or lack of sunshine.  Potassium deficiency is often connected with increased susceptibility to foliar disease.
  • the leaves of the plant are wet for prolonged periods of time.  This time of year the dew sets early, nights are getting longer, and the grass is wet late into the morning.  Heavy forage stands reduce air movement, which causes the leaves lower in the canopy to stay wet longer.  Prolonged leaf wetness allows pathogens more time per day to penetrate plant defenses.
  • there is a lot of inoculum around.  In perennial forage stands, there is a lot of inoculum (spores) around in the soil and decaying plant material.
  • the plants are over-mature.  Plants will prioritize sending mobile nutrients to parts of the plant that have more access to sunlight.  Lack of photosynthesis deeper in the canopy and self-induced nutrient deficiencies accompany senescence (death) of lower leaves.  As this happens, these leaves are often colonized by plant pathogens.

Is foliar disease really an economic problem for farmers in the Northeast? 

Yes, but is difficult to estimate the size of the problem in the region or on a particular farm.  While foliar diseases on grasses may not be the biggest agronomic problem for every farmer in the Northeast, it can affect an individual farm in important ways, several of which are interrelated:

  • Reduced forage quality

    Leafspot (drechslera spp.). Picture by Daniel Hudson, University of Vermont Extension.

    • Fungi are after the total nonstructural carbohydrates (TNC) in the plant.  In affected tissue, much of the TNC and proteins that are not consumed by the fungi will be consumed by opportunistic microbes.
    • USDA laboratory research published in 1978 found that orchardgrass plants that had been inoculated with the pathogen that causes stem rust had TNC levels that were 36% lower than uninoculated plants.  The report also suggested that the nonstructural carbohydrates from infected areas of the leaf are essentially gone.

      the rust colored patches are fungal uredia (fruiting bodies) on wheat. Source: USDA-APHIS

    • Other research shows that fiber digestibility below fungal uredia (the visible spore-producing areas on the leaf) are not digested in the rumen.
    • Higher fiber levels: losing nonstructural carbohydrates increases the proportion of fiber in the harvested product. Because ruminant feed intake is determined (limited) by fiber levels, livestock can eat fewer pounds of that higher-fiber product per day.
    • Reduced palatability
      • Refused pasture: this is what most graziers notice.  It is not uncommon for animals to refuse a large percentage of grass tissue in a pasture when it is diseased.  Reduced NSCs change the taste and smell of the forage, and there may be a bad taste besides associated with the spores or byproducts of microbial metabolism.

        photo by Daniel Hudson, UVM Extension

        Leaf scald (caused by Rhynchosporium spp.). Picture by Daniel Hudson, UVM Extension

      • Sorting hay: livestock will often sort or reduce intake of dry hay that had foliar disease prior to harvest.  Have you ever noticed many tan/brown blades of grass in an otherwise green bale of second cut hay?  They are likely the result of foliar disease.
      • Yield losses
        • Lost nonstructural carbohydrates results in total dry matter yield
        • Plants that are weakened by disease this year are more likely to be winter-killed or injured, which will reduce forage yield next year.

          A cow with low body condition score. Picture from Virginia Tech.

These problems are economically harmful to livestock producers.  Forage in the pasture that is rejected by the cows will not help the calves grow or the cows lactate.  Refused pasture forage translates to fewer animal grazing days per acre.  Dry hay that your livestock sort out rather than swallowing is a direct economic loss.  Hay or haylage with significant foliar disease prior to harvest will have lower NSC and higher fiber levels, which reduces intake and performance.  The only way to completely compensate for this is by feeding more grain.  If a farmer chooses not to compensate for the lower forage quality, animal performance will be compromised: slower growth, lower levels of  lactation, and/or loss of body condition.

If this is such a problem, why is it almost never discussed?

We are not collectively more aware of the costs associated with foliar diseases in forages because the the crops and livestock do not die outright, there is no bad smell associated with it, and it is not as visibly dramatic as many agronomic problems.  We are frustrated with poor performance, refused pasture, and the costs of supplementation, but often do not acknowledge the role that foliar disease can play in the process.

How can foliar disease problems be reduced in my forages?

Spreading poultry manure on pasture. Picture from University of Georgia.

  1. Address soil fertility problems.  Soil test reports will reveal if you have nutrient deficiencies.  Alleviating potassium deficiencies in particular will make plants less susceptible to fungal attack.  Keep in mind that the first cutting removes the vast majority of the potassium for the season.  If potassium levels are marginal in the spring, they will likely be critically low for subsequent cuttings that year and that can make disease problems worse in mid- to late-summer.
  2. Consider whether shortening your harvest interval might be appropriate, especially in conditions that favor the development of disease.  If you compare regrowth from a recently harvested hay field with a more mature regrowth, you will notice that older leaf tissue is more susceptible to infection by some of the most significant pathogens.  Timely harvest will often improve quality and remove potential inoculum.
  3. While it may not be practical in many cases, crop rotation can reduce the amount of inoculum in the soil for a short period of time.

    Ryegrass susceptible to crown rust (left) next to ryegrass resistant to crown rust (right). Picture from:

  4. Learn to identify which diseases are plaguing your forages.  When you are reseeding, seek out plant varieties that are resistant to those diseases.  Seed companies usually indicate what diseases their varieties have resistance against.  Some university variety trials also rate disease resistance.
  5. Alfalfa and clover do not share many diseases with grass.  While it will not entirely stop the spread of disease in the stand, inclusion of these and other legumes in your pasture and hay fields may reduce the spread of inoculum by providing a physical impediment against the spread of spores from one grass plant to another.
  6. In pastures, graze the regrowth when it is ready – not after you have finally caught up with the part of the pasture that initially got away from you earlier in the grazing season.   Allowing the plants to get too large increases the likelihood of fungal infection.
  7. If you are ever trying to decide whether to take that last cutting that looks ‘almost big enough to harvest’, keep in mind that grass thatch from an unharvested hay field will be a source of inoculum the next year.  This fact alone is not enough to justify harvesting marginal-yield last cutting, but it is a factor that should be considered.
  8. If you notice that foliar disease is a problem for a particular species on certain soil types, think about what might be causing that plant to be stressed and whether you should plant different species on those soils.
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Be Careful When Considering ‘Fertilizer Enhancers’

By Daniel Hudson, UVM Agronomist

Some timely, serious, and even controversial questions have recently been raised about the efficacy and safety of various “fertilizer enhancers.”  Urease inhibitors are one such product, and they are a relevant subject for those who are planning on applying sidedress nitrogen to corn fields in the next few days.  The purpose here is not to promote a particular brand of urease inhibitor, but to strongly discourage farmers from expending resources on products that are not effective.  As it turns out, only two products are mentioned in this discussion.

A quick review for context:

‘Urease’ is an enzyme that is present in microbes, plants, and throughout the soil.  As the name suggests, urease functions to break down urea; the byproducts of the reaction are ammonia and carbon dioxide.  If urea or UAN (a mixture of urea and ammonium nitrate) fertilizer is applied to the soil surface and not quickly followed by enough rain to move it into the soil, MUCH of it can be lost by volatilization through the activity of urease.  Heat, soil moisture, and wind all promote volatilization.

If the urease molecules local to the droplet or granule of fertilizer are inhibited, these volatilization losses can be reduced.  At least one product that claims to be a urease inhibitor has been proven to work; at least one has been shown not to work as claimed.  A product that does not work costs you more than just the cost of the product – the urea portion of the fertilizer is still unprotected and vulnerable to volatilization losses.

What the research says…

Getting to the point, I will focus on only two products for which urease inhibiting claims are made.  Other products may exist. The trade names of these products are NutriSphere-N® and Agrotain Ultra®.  While this is certainly not an exhaustive review of the subject, the studies mentioned are representative of the conversation in the literature from independent researchers.

Research done at Cornell  concludes that the active ingredient of Agrotain® (NBPT) does effectively function as a urease inhibitor while the active ingredient of NutriSphere-N® does not.  After studying in the laboratory and in wheat and rice systems, researchers from ND, MS, and AR concluded that NutriSphere-N® “. . . has no urea volatilization inhibiting properties at recommended rates . . .” The one source of consistent positive yield results (of which I am aware) from NutriSphere-N® comes from a former faculty member from Kansas State University.  On pages 5 and 6 of a document called Nitrogen Extenders and Additives for Field Crops, those findings are described as ‘curious’ in light of the body of contradictory evidence.

Finally, a concern has been raised about the possibility that one of the ingredients of an Agrotain® product could pass through cows and into the milk supply.  This concern is based on a situation in New Zealand where an ingredient from one Agrotain® product (Agrotain Plus®) was found in dried milk products. The ingredient of concern, a nitrification inhibitor abbreviated ‘DCD’, is found in Agrotain Plus® but not in other Agrotain® products such as Agrotain Ultra® or ADII® (‘Agrotain® Dry’).  Again Agrotain Ultra® and ADII® contain the appropriate urease inhibitors to use with sidedress nitrogen on corn in the Northeast; they do not contain DCD and have not been found to pass through to the milk.

Disclaimer: the purpose of this article is not for UVM or myself to promote the Agrotain® brand.  The active ingredient found in Agrotain® (known as NBPT) is the only commercially available product in the U.S. that has been shown to actually function as a urease inhibitor.  As far as I know, there are no other brands of fertilizer enhancers that have NBPT as an ingredient.

More information:

Agrotain® labels:

NutriSphere-N® label:

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Corn Nitrogen Update

By Daniel Hudson, UVM Extension Agronomist

It is no secret that many of the corn fields are nitrogen deficient right now – mostly due to leaching. The result is that many farmers will be applying more sidedress nitrogen than usual, and many who typically rely entirely on manure will need to sidedress in order to attain the full yield potential of their corn crop.

Here are some thoughts to consider as you are thinking about sidedressing nitrogen on your corn next week.

  • Most of the pre-sidedress nitrate test (PSNT) results are coming back very low, indicating that a considerable amount of nitrogen fertilizer is needed in order to optimize crop yield. While I am sure some fields need no sidedress N, all of the recommendations that I have seen have ranged from 50 to 130 pounds of sidedress N per acre. That does not mean that you have a similar problem in your field. You cannot know if you have a problem or how severe the problem is unless you check. Using the PSNT is a good place to start. If you think it is too late for the PSNT, please contact me and we can consider some other strategies to come up with a recommendation.
  • While it is convenient to have urea and ammonium nitrate (UAN) applied by a custom operator, it is one of the more expensive forms of sidedress N. Keep in mind that the nitrate is subject to leaching immediately and the urea fraction is subject to volatilization losses. This time of year, including a urease inhibitor with UAN is a good idea. Using streamer bars or drop nozzles is advisable.
  •  If you are sidedressing your corn with urea, it is a very good idea to use a urase inhibitor unless you KNOW that it is going to rain a lot (at least 0.5 inches) within a day or two. With damp soils, sunny weather, and high temperatures, it would be very easy to have volatilization losses exceeding 25% in a matter of days. In these conditions, using a urease inhibitor such as Agrotain® is likely to be a profitable decision. [This is not an endorsement of the Agrotain® brand by myself or UVM.]
  • For those who applied urea before planting or before emergence, do not assume that the N from that product is still in the soil. In one case that I am aware of, urea was applied at 200 lb/ac near planting time. When the soil nitrate and ammonium levels were recently checked, the report indicated that most (if not all) of than nitrogen was lost.
  • When using urea for sidedressing your corn, it is a good idea to wait until the leaves are dry. Wet leaves will cause more of the urea granules to stick to the plant tissue and cause burning. If you expect a lot of rain in the next few days, that is even better.
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Wireworms in Your Corn?

By Daniel Hudson, University of Vermont Extension Agronomist

It clearly too late to take preemptive action against wireworms for this year.  If you suffered insect damage to your corn this spring, it is a good time to identify the culprit and make plans to avoid it next year.

Vermont corn field with massive wireworm damage + some cutworm damage

Vermont corn field with massive wireworm damage + some cutworm damage

Last year at least one farmer I know made the decision to replant all or part of a field due to damage caused by wireworms.  In this case, the corn had been planted using no-till equipment but was developing very slowly due to the local growing conditions.  Eventually, the farmer noticed that many of the plants were dying outright.  Upon closer inspection we discovered feeding patterns at the base of the corn seedling that are characteristic of wireworms.

What are wireworms?  Wireworms are the larval form of the ‘click beetle.’  This insect pest has a life cycle that varies in length from two to seven years, depending environmental factors.  The larvae are hard-bodied, range in length from 0.25 to 1.5 inches long, and range in color from white at the youngest stage to a rusty-orange color at the later stages.  A field with wireworm problems will typically have wireworms at many or all stages of development in a given year.

photo from Virginia Tech.

Where is wireworm damage likely to occur?                                                    Wireworms are attracted to germinating seeds and decomposing plant material.  In fields that have recently been in rotation with a perennial forage crop, wireworm populations will be higher.  Fields and certain areas within fields  are at a higher risk from wireworms if they are weedy, wet, have high organic matter, are narrow (i.e., field edges are relatively close), or have a recent history of perennial sod or cover crops.  Due to the lack of physical disruption of the larvae, no-till fields are also at a higher risk than conventionally tilled fields.

What does wireworm damage look like? Wireworms feed below the soil surface and will attack seeds before, during, and after germination.  After emergence, the most visible damage occurs at the base of the plant where the IMG_1657wireworm seems to target the growing point.  Until V6 the growing point of corn is at or below the soil surface and therefore vulnerable to the wireworm and other pests.  After this stage, the risk of yield-damaging wireworm damage seems to diminish rapidly.

How can it be prevented?  Wireworm problems are more common in fields that have had a sod or cover crops recently and in no-till situations. Tillage significantly disturbs the larvae and is the only means of control in organic systems.  Problems can be reduced in organic systems by avoiding early planting. While germinating corn seeds are at risk, corn seedlings that emerge and just ‘sit there’ during cool/wet/cloudy conditions are very vulnerable to wireworm damage and secondary pathogens that capitalize on damage caused by them.

Using slightly higher seeding populations is another way to partially offset the impact of wireworm damage.  The effectiveness of this strategy will be somewhat mitigated by the fact that wireworm damage tends to be patchy within a field rather than evenly distributed throughout.

There are few if any predators, parasitoids known to be strategically useful for controlling wireworms and none of the Bt traits used against corn rootworm provide any control of wireworms.  Some research in potato production suggests that there may be some entomopathogenic nematodes that play a role in controlling wireworms.

What are some management options?

Most conventional corn seed is purchased pre-treated with Cruiser or Poncho insecticide.  These insecticides provide protection to the seed from direct insect contact and systemic protection to the plant from insects that may feed on them.  In some years when farmers plant early and/or the growing season otherwise starts slowly, the insecticidal treatment can run out (due to decomposition or dilution) and the plants can again become vulnerable to attack.  The first picture (above) is from a Central Vermont farm that had a severe infestation of wireworms early in the 2012 growing season.  The damage to the field was extensive enough that the farmer decided to replant the field.

Control options


first page of Cruiser 5FS label. From

After the field is planted, there is nothing that can be done to treat wireworm problems.  If you have crop damage due to wireworms this year, it is important to understand why so that you can take appropriate management steps for next year in that and other fields.


first page of Poncho label. From

Most non-organic corn seed comes pretreated with some formulation of Cruiser  (thiamethoxam) or Poncho  (clothianidin) insecticides, both of which are neonicotinoid insecticides and are effective against wireworms.  A high rate of these seed-applied insecticides is 1.25 mg/seed, which equates to about 1.54 ounces per acre; the low rate is 20% of that amount.  These products are systemic, which means that the compound is taken into the plant tissue and susceptible species of insects that try to eat the plant will be eliminated if it is within the window of control (one to three weeks after crop emergence).  This class of compounds is neurotoxic to susceptible insects and works against target pests by binding to nicotinic acetylcholine receptors; These products have comparatively low toxicity in mammals, which is why it has they have been so favored in recent years.

Other options for controlling wireworms (and certain other insect pests) in non-organic systems include row-applied pyrethroid or organophosphate insecticides.  Major downsides compared to seed-applied options for these products include:

  1. More exposure of non-target insects
  2. More direct handling of pesticides in forms that are likely to increase human exposure.
  3. Generally less convenient

But there is some controversy!

Image from David Cappaert, Michigan State University,

While neonicotinoid insecticides are widely used, they have become very controversial since concerns have been raised about their impact on bees and a possible connection to colony collapse disorder (CCD).  The magnitude of the concern has become more obvious in April 2013 when the EU has banned the use of neonicitinoid for two years while they reexamine the evidence.  Depending on the source, the disagreement and uncertainty seems to surround:

  1. Whether neonicitinoids are harmful to bees in the concentrations at which bees are likely to be exposed and in ways that bees are likely to be exposed.
  2. Whether doses that are sub-lethal (in the short term) have deleterious effects on bees in the mid- and long-term that would affect the viability of the individual bee or the hive.
  3. Whether these pesticides impact bees in ways that are not typically expected that may be otherwise contributing to CCD.

Resources Used

Gray, M. 2010.  Secondary corn insects: how significant is the threat?  The Bulletin. No. 3,  Article 1.  University of Illinois Extension.  Online:

Johnson, G. 2009.  Wireworms and wireworm management in crops.  University of Delaware Extension, Kent County.  Online:

Kuhar, T.P., Doughty, H. B., Speese, J., and S. Reiter.  2009.  Wireworm pest management in potatoes.  Virginia Cooperative Extension.   Online:

Ratcliffe, S.T., Gray, M.E., Steffey, K. L.  Wireworms.  In Integrated Pest Magement.  University of Illinois Extension.  Online:

Stewart, J., and Krupke, C. 2013.  Corn growers should assess wireworm risk prior to planting.  Purdue Agriculture News.  Online:

Szczepaniec, A. 2013.  Scouting for wireworms in corn.  In iGrow (SDSU).  Online:

Van Duyn, J.  2005.  Organic Insect Pest Management: Field Corn.  In Organic Field Crop Production and Marketing in North Carolina.  North Carolina State University.  Online:

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