Ned Birkey...With USDA predicting a corn yield for Michigan of 146 bushels per acre, many Michigan farmers will probably be interested in conducting preliminary yield assessments of their corn fields. Fields planted in late May and June are more likely to be affected by dry weather. In upcoming weeks, corn growers with drought stressed fields may want to predict grain yields prior to harvest in order to help with marketing and harvest plans.

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By Tim Boring...The cool, wet conditions we have experienced this spring have created ideal conditions for nutrient deficiencies to arise in corn fields. On June 12, corn at the V2-V3 stage in a field east of Reese on M-81 was found to be displaying severe purpling, most pronounced on the lower leaves.

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By Darryl Warncke... There have been a number of reports of nutrient deficiencies in corn. Many of these are likely the result of the cool, wet soil conditions that the young corn plants have experienced. These conditions have resulted in slow root growth which results in limited nutrient uptake. Purple coloration of the leaves is frequently associated with inadequate phosphorus uptake.

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By Wes Everman... It has come to my attention that Yukon herbicide, a premix of halosulfuron and dicamba, was inadvertently left out of A-434 Weed Control Guide for Field Crops and the herbicide update earlier this spring. I wanted to give some information on Yukon for those interested in using it this season.

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By Kurt Thelen... The extreme wet weather this planting season has delayed corn planting relative to past years across much of the state. As discussed in an earlier message, it is important to exercise patience when deciding when to restart field operations following periods of rain. Jumping the gun and compacting soils has the potential to be more detrimental to crop yield and profits compared to delaying planting a few more days.

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By Darryl Warncke... Nitrate testing of soil is an excellent and inexpensive way of evaluating the available nitrogen (N) status of your soil. Michigan State University research and demonstration studies have shown that many farmers could reduce their N fertilizer application rate on corn without risk of reducing yields if they used the nitrate soil test.

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By Wesley Everman... It’s that time of year again where we are all trying to get as much corn planted as we can before the next rain. This year weather has played a major role in planting, and rain has kept many of us out of the field. Preemergence herbicides should be applied as soon after planting as possible because delayed application increases the risk of poor herbicide performance, especially for grass control.

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By Chris DiFonzo and Christy Sprague -- In the April 16 Field CAT Alert, I provided detailed information about Bt traits in the article “Keeping Corn Stacks Straight.” Every season there are more transgenic traits and stacks, and new brand names to add to the confusion. Below is a top-ten list of things you can do to avoid mistakes at planting and help diagnose field problems later in the season.

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By Fred Warner -- As if soybean growers didn’t have enough to worry about with soybean cyst nematodes, aphids, rust and the lousy economy, along comes another potential issue. To qualify right up front, this problem is far less severe than the economy because it addresses another nematode and we all know nematodes rank just under the economy.

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By Christina DiFonzo... As planting season begins, it is important to understand the myriad of options available in transgenic corn. Not only are there more traits and more stacks, but there are new brand names that may be confusing. Over the last several years, I have seen an increasing number of field problems and complaints originating with mistakes in use of traits.

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An MSU timing study on post emergent weed control showed that 95 percent of weed control or better can be achieved when weeds are 9 inches tall, but yields were reduced 25 bushels per acre. (Everman et al., 2008)

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The University of Minnesota Crop eNews published a couple resourceful articles recently. Below you will find brief summaries and links to the articles on the web.

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Darryl Warncke...The nitrate nitrogen concentration in the lower portion of the corn stalk at the time grain black layer is formed is a good indicator of the nitrogen status the crop experienced throughout the growing season. When used over a number of years the stalk nitrate test can help identify N efficient fields and/or management systems, thus enabling fine tuning of N inputs.

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Darryl Warncke...This summer I received calls from several farmers indicating that they were seeing signs of N deficiency on the lower leaves of corn, even though they had applied what should have been adequate nitrogen. Some of these situations involved the application of partially composted dried poultry manure. In some cases similar N management programs were being used on adjacent fields or different fields of a farm. In some fields the corn was growing well, but in other fields with a similar N program the corn was “firing” or showing signs of N deficiency.

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Lowell Gentry and Sieglinde Snapp...Soil organic matter (SOM) plays a critical role in fertility, water holding capacity, aggregate stability, tilth, and overall soil quality. It has been estimated that 50 percent of the SOM of most soils was lost in the first 100 years after the agricultural conversion of prairies and savannahs. A major goal of the USDA/NRCS has been to decrease soil erosion through practices such as reduced tillage, contour farming, grassed waterways, and buffer strips.

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Diane Brown-Rytlewski...This year, there have been higher than usual amounts of common corn rust showing up, as weather conditions were conducive for the disease early on. The fungus spreads by airborne spores traveling on wind currents and storms from the South, and does not overwinter in Michigan. Common rust rarely causes economical loss in field corn, as most hybrids have adequate resistance. Unless there are other foliar diseases present, such as gray leaf spot or northern corn leaf blight, it isn’t usually an economic proposition to apply a foliar fungicide.

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Kurt Thelen...Corn grain yield determination involves the continuous interaction of genetic, climatic, soil, plant pest, and nutrient factors present for a specific growing season. Michigan has a wide range of soil types and in most years, a high degree of variability in rainfall and pest patterns. This variability in weather and production potential makes forecasting state-wide yields a difficult proposition at best.

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Diane Brown-Rytlewski...High market prices for both corn and soybeans this year are once again tempting growers to consider applying fungicides in the absence of disease. Whether or not a yield increase will result continues to be a topic of many lunch counter discussions, and among plant pathologists.

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Christina DiFonzo...For those of you in the northwest part of the state, I have received multiple reports of armyworm in both corn and alfalfa fields, and visited a big infestation personally in Mason County. Judging by the time of the year, this is second generation armyworm. In some cases, the caterpillars are moving out of alfalfa and into corn. I assume these are alfalfa/grass fields, since the grass component is attractive for egg-laying.

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Dale Mutch...On Wednesday, July 2, near Charlotte, Michigan, located in the central part of the state, there was a terrible hail storm that devastated soybean and corn fields. These pictures show a field of plants with no foliage on them. Throughout my 28 years with MSU Extension, I have never seen damage this severe from hail. At the MSU W. K. Kellogg Biological Station we were hit by hail, however, nothing in comparison to these fields near Charlotte.

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Diane Brown-Rytlewski...Recent bouts of hail have caused severe damage to some fields, not so much to others. There have been continuing questions about whether hail-damaged corn can benefit from fungicide application to either help it recover or protect it from stalk rots and other diseases that enter through wounds. Fungicides do not control stalk rots, smuts, or bacterial diseases such as Stewart’s disease.

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Diane Brown-Rytlewski...There have been some questions about whether or not fungicides can be of benefit in reducing foliar disease and improving yield when applied to corn after hail damage. A study to simulate hail damage in corn and the effects of fungicide application at tassel emergence was conducted at the University of Illinois last year by Dr. Carl Bradley, plant pathologist in the Department of Crop Sciences.

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Jackie Smith and Steven Gower...Several corn samples have been submitted to the lab over the past few days infected with anthracnose leaf blight. All samples have come from fields where corn was grown last season.

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Darryl Warncke...Following the past couple of weeks of variable rainfall, many corn fields are showing light yellow areas. Where rainfall was heavy the soil has been compacted and the surface crusted. Some of the yellow areas are associated with lower areas in fields where nitrogen was lost by leaching and denitrification.

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Wes Everman...I ran across some information the other day concerning stressed corn following glyphosate applications this spring, and thought I would make it available in case it impacts anyone in the state.

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Kurt Thelen...Last week’s heavy rains have resulted in isolated areas of severe ponding in parts of the state. This problem has left growers struggling with the question of whether or not to replant water damaged stands. The replant decision is further complicated by the fact that we are now nearing the end of the viable planting season window for corn and soybean.

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Wes Everman...Corn growers in potato growing regions will be looking to control volunteer potatoes where potatoes were grown in 2007. It is important to control volunteer potatoes to preserve corn yield, however, it is as important to control volunteer potatoes to manage pests that can be a problem if potato is in rotation for next year. There are a few different options that will provide suppression of volunteer potato and significantly reduce the number of daughter tubers per plant; however, there currently are no herbicides available that will completely control volunteer potato.

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Darryl Warncke...Nitrate testing of soil is an excellent and inexpensive way of evaluating the available nitrogen (N) status of your soil. Nitrogen available in the soil is nitrogen that does not need to be purchased. Michigan State University research and demonstration studies have shown that many farmers could reduce their N fertilizer application rate on corn without risk of reducing yields if they used the nitrate soil test. Nitrate testing also helps to prevent over-use of N fertilizers.

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Kurt Thelen...It appears that most of Michigan’s emerging corn and soybean crop has made it through the recent cold snap in fairly good shape. Regional reports from MSU Extension educators located in the primary corn and soybean growing areas indicated overnight temperatures in the low 30s, and upper 20s the past week. Most of the state did not quite reach the critical 28°F threshold and avoided significant frost injury.

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Kurt Thelen...The cool, early May temperatures have resulted in significant variability in corn emergence across fields. Ideally, we would like to see all corn plants emerge simultaneously to minimize plant to plant competitive advantages and maximize yield potential. Under marginal conditions of cool weather within field spatial variability conditions are exacerbated. Areas with darker soils and more well drained soils warm up quicker and, conversely, poorly drained areas and areas with heavy residue take longer to warm up.

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Christina DiFonzo...In the last Field CAT Alert, I noted the presence of Asiatic garden beetle grubs in many fields in St. Joseph County. In the next few weeks as corn and soybean emerges, the first indications of grub damage will be apparent. Grubs, the larvae of scarab beetles, are a growing concern in field crops in Michigan and surrounding states. Early in the season, grubs feed on germinating seeds and small plants, reducing plant stand.

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Wes Everman...Although many people have rotated corn to soybeans or other crops this year, if you are planting corn following corn there are several weed management issues to consider. Herbicide inputs are a greater concern in a continuous corn system when compared to growing corn in rotation with another crop. This is due primarily to increased crop residue levels as well as weed escapes from the previous year.

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Christina DiFonzo...Avitec seed treatment is available through a Section 18 for corn in Michigan (as well as Wisconsin and Minnesota). The Section 18 is specifically to reduce crane damage to newly planted field and sweet corn. Legal protection of cranes has resulted in growing populations, thus crop damage from sandhill cranes has risen over the last several decades. Harassment methods are time consuming and often do not work, simply driving birds to neighboring fields.

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Wes Everman...Preemergence herbicides should be applied as soon after planting as possible because delayed application increases the risk of poor herbicide performance, especially for grass control. However, there can be challenges for herbicide application following planting, such as high winds and rainfall. Therefore, it is likely there will be situations where corn has emerged before preemergence herbicides have been applied.

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Kurt Thelen...Recent popular press articles have blamed U.S. agricultural ethanol production on causing global warming, primarily due to the indirect effect of causing deforestation of tropical rain forests. This type of narrowly focused, indirect analysis is fraught with error, lacking in science, and ultimately leads to poor policy. In fact, with an indirect analysis narrowly focused on environmental effects, we would conclude that things like public education, baseball and hospitals are all bad ideas since they too contribute to global warming.

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Darryl Warncke...The change from recommending nitrogen (N) based on expected yield to recommending N based on economic return is quite significant. To adapt to this change will take time and some on-farm N rate evaluation by farmers to become comfortable with these new recommendations. In making this change, farmers may want to use the higher recommended amount in the “Maximum Return to N (MRTN)” range in Table 1.

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Darryl Warncke...Nitrogen plays a significant role in the growth, development and yield of corn. From the mid-1900s until present time, supplemental inputs of nitrogen through various nitrogen sources, especially legumes and manufactured nitrogen fertilizers, have contributed greatly to improvement in corn yields in Michigan.

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Christy Sprague and Wesley Everman...The 2008 Weed Control Guide for Field Crops, Extension Bulletin E-434 is now available online at http://www.msuweeds.com/publications/2008_weed_guide/. It is also available in print at the MSU Extension Bulletin office by calling (517)353-6740 or your county Extension office.

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Diane Brown-Rytlewski...Last fall, an epidemic of Stewart’s disease occurred with foliar symptoms showing up on many field corn varieties in numerous locations across the state (figure 1). Stewart’s disease is caused by the bacterium, Pantoea stewartii, and transmitted to corn by the corn flea beetle when it feeds on foliage and deposits its bacteria-laden feces in the feeding wounds. The flea beetle overwinters as an adult in ground litter and harbors the bacterium in its gut.

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Kurt Thelen...Although recent rains brought relief to some areas of the state, areas of droughty conditions still remain. In a recent article, we discussed the potential corn grain yield loss associated with dry soil conditions. This information is summarized in Table 1.

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Diane Brown-Rytlewski...Some growers may be contemplating the use of foliar fungicides on hybrid corn this season, due to higher market prices for corn, marketing of fungicide products, or concern over increased disease risk from planting corn-on-corn. Growers may have similar thoughts of applying foliar fungicides to soybeans due to higher market prices.

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Christina DiFonzo...Corn rootworm adults are emerging in southern and central Michigan. Now is the time, particularly in the southern tier of counties, to assess corn for corn rootworm larval damage. I have already observed lodging in one of my research fields on the MSU campus. However, even corn that isn’t lodged may have significant root damage – the only way to tell is by digging and washing roots. Note that in southwest Michigan, rotated as well as continuous corn should be checked due to the presence of corn rootworm variant.

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Kurt Thelen...To date, the 2007 growing season in Michigan can be characterized as widely variable in terms of rainfall. Some parts of the state have experienced near ideal precipitation levels while others remain quite dry. Inadequate moisture during any period of growth can result in reduced grain yield. Nutrient availability, uptake and transport are impaired without sufficient water. Plants weakened by stress are also more susceptible to disease and insects.

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Ron Gehl...Manganese deficiency is the most common micronutrient issue found in Michigan row crop production. Soybeans and wheat are the two field crops most likely to develop manganese deficiency, although deficiency may also be found in corn and sugar beets. Manganese deficiency appears as yellowing between the leaf veins (interveinal chlorosis) of corn, soybeans, and sugar beets, and as yellow-green striping in wheat (see photos).

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Kurt Thelen...There have been a number of reports of purple-colored corn seedlings this year. These symptoms are not unusual for Michigan, but have been particularly prevalent this year. There are several factors that contribute to the purple color, but the main culprit is likely restricted root growth. The April rains and early season planting delays may have caused some growers to “jump the gun” and begin planting before field moisture conditions were optimal.

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Kurt Thelen...Reports of climate change, global warming and greenhouse gas emissions have been all over the news lately. What does this have to do with agriculture? After many decades of being pointed to as a source of environmental issues, field crop agriculture is being looked to as one of the solutions to global climate change. The basis for this environmental remediation affect is corn’s and other crops’ tremendous potential to remove carbon dioxide (CO2), a major greenhouse gas, from the atmosphere.

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David Hillger...For several years, MSU has demonstrated the importance of timely herbicide applications to prevent the loss of yield in corn. We have shown that it is necessary to control weeds before they reach 4 inches of growth to prevent measurable yield reduction. Two-pass herbicide applications (preemergence followed by postemergence or two postemergence) or timely single postemergence applications with residual control, are most effective at preserving yield and maximizing gross margin.

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Christy Sprague...Volunteer potatoes may be a problem this year in corn fields where potatoes were grown in 2006. Not only is it important to control volunteer potatoes to preserve corn yield, but controlling volunteer potatoes is critical for the management of potato pests, such as late blight disease that can be a problem if potato is next year’s rotational crop.

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Bruce Mackellar...We have had at least one instance this spring in St. Joseph County where white grubs have caused enough stand reduction to cause re-planting of a corn field. The grower’s seeding population was around 26,000 seeds per acre and the stand in areas affected in the field was reduced to around 9,000 plants per acre. The previous crop was a grass-alfalfa mixed hay.

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David Hillger and Jim Kells...There can be many challenges for herbicide application following planting, such as high winds and rainfall. Therefore, it is likely there will be situations where corn has emerged before preemergence herbicides have been applied. In fields with emerged corn and no herbicide applied, growers have two primary options: to use an herbicide program typically applied before emergence; or switch to a total postemergence strategy. There are several possible herbicide programs with each strategy.

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Ron Gehl...The recent decreases in atmospheric S deposition, increases in corn yields, and relatively early corn planting dates have prompted grower and industry interest in the use of S-containing starter fertilizer sources for corn. Six S-starter study locations were evaluated in Michigan in 2005 and 2006, including two sites per year on MSU research farms and the remaining four on producer fields. Sites were located on coarse-textured soils with a minimum or no-till cropping system.

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David Hillger and Christy Sprague...Since the release of the 2007 Weed Control Guide for Field Crops, several new herbicides have been registered for the 2007 growing season in corn and soybean.  Following is information on some of the new products you will hear about this season.  New registrations or label changes that occurred prior to publishing the Weed Control Guide can be found in the previous article, Updates from 2007 Weed Control Guide for Field Crop.

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Ned Birkey...Lots of economic and agronomic factors are affecting Monroe County and area farmers’ decision regarding crop rotation and sequence for 2007 and perhaps into 2008 and even 2009. The corn marketplace has been telling farmers that it needs 10 million more acres, at trend yields, to provide enough supply for projected demand. Higher corn prices, relative to soybeans and wheat, means that farmers are generally going to plant more acres to corn this year.

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Ron Gehl...The recent increases in N fertilizer costs have driven renewed interest in evaluating producer N management practices for corn. Current Michigan N recommendations for corn are based on response data collected in the 1980’s. Since that time, advancements in corn genetics, insect and weed management and production practices have affected corn yield response to N. Efficient use of N fertilizer for corn production is essential to maximizing economic return for the producer and minimizing adverse effects on groundwater quality and emission of greenhouse gases.

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Ron Gehl...Questions have started coming in as late regarding N management for corn this year. While corn prices are high relative to this time last year, the recent increases in N fertilizer prices will add significant costs to production. Costs for urea and UAN have climbed to equivalents of over $0.50 per pound of actual N, so implementing efficient N management practices will be key again this year for maximizing economic returns.

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Darryl Warncke...As corn grain has or soon will reach black layer, corn growers should consider using the stalk nitrate test to evaluate their nitrogen management program. Even though the stalk nitrate test is post-mortem (end-of-season) it can be useful for long-term adjustment of N management practices. The nitrate N concentration in the lower portion of the corn stalk at the time grain black layer is formed is a good indicator of the nitrogen status the crop experienced throughout the growing season.

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Willie Kirk, Diane Brown-Rytlewski, Jan Byrne, Beth Bishop and Chris DiFonzo...Stewart’s disease of corn has been reported in several field corn fields in Saginaw and Allegan counties so far this summer. The disease has also been confirmed in Clinton and Gratiot. So far we do not how extensive this disease is in Michigan.

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Kurt Thelen...At what point in the growing season is corn grain yield determined? Well, of course it involves the continuous interaction of genetic, climatic, soil, plant pest and nutrient factors present for a specific growing season. However, from a crop management standpoint, it is helpful to characterize the most critical stages of development in the life of a corn plant with respect to determining final grain yield.

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George Rehm with Ron Gehl...This time of the year we often receive questions regarding foliar fertilization of row crops. Past research has shown that nutrient deficiencies can sometimes be corrected with foliar applications, resulting in a positive yield response. But in areas where there are no obvious deficiencies, can foliar nutrient applications increase crop yields? Results of nationwide studies have shown mixed results. Even where yield increases have been observed, the level of yield increase often does not offset the cost of the fertilizer and application.

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Steven Gower...A seed corn sample submitted to the lab this week from St. Joseph County, Michigan, had symptoms indicative of fomesafen (Flexstar/Reflex) carryover. We are in the process of testing for fomesafen residue in the soil.

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Jim Kells, Kathrin Schirmacher and David Hillger...There are several herbicide options for postemergence weed control in corn. The best choice for any given field depends on the specific situation. Three of the critical factors to consider when selecting a postemergence herbicide in corn are:

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Kurt Thelen...A number of calls have come in regarding discolored corn plants with one grower remarking “I’ve never seen corn turn so many colors before.” These symptoms are not unusual for Michigan but have been particularly prevalent this year. The pale yellow color is symptomatic of low photosynthetic activity and general nutrient stress experienced by the plant. Similarly, poor root growth can result in purple-colored corn. The main culprit is the recent cool, wet weather experienced across Michigan this spring.

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Kathrin Schirmacher, Dave Hillger and Jim Kells...There have been several questions about the possibility of failed preemergence herbicide applications and the likelihood of annual grass weed escapes, particularly more difficult to control weeds such as large crabgrass. Emerged large crabgrass is difficult to control in conventional systems with smooth crabgrass being even harder to control.

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Kurt Thelen...The heavy rains have continued and have resulted in isolated areas of severe ponding in parts of the state. This problem has left growers struggling with the question of whether or not to replant water damaged stands and how to manage fields that have yet to be planted.

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Jim Kells, Kathrin Schirmacher and David Hillger...There can be many challenges for herbicide application following planting such as high winds and rainfall. Therefore, it is likely there will be situations where corn has emerged before preemergence herbicides have been applied.

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Mike Staton...Farmers planting Bt rootworm corn (YieldGuard Rootworm and Herculex RW) in 2006 are required to plant a refuge area within each field or in an adjacent field. The refuge area should be planted to non-Bt corn and cover at least 20% of the acreage in the field. The purpose of the refuge area is to prevent or significantly delay rootworm resistance to Bt. Some rootworm larvae will survive after feeding on the roots of Bt rootworm corn.

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Christina DiFonzo...The EPA has approved a Section 18 application for Avitec, a non-lethal crane repellent, on corn in Wisconsin, Minnesota, and Michigan. The Section 18 was developed by Eileen Cullen at the University of Wisconsin and the Wisconsin Department of Ag, Trade and Consumer Protection, in conjunction with many other agencies and groups. The Section 18 was supported by the several Audubon Society chapters as well as the International Crane Foundation.

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