By Martin Nagelkirk... Some wheat production areas of the state experienced significant levels of pre-harvest sprouting this season. There is interest in saving some of the grain for use as seed if its viability can be reasonably predicted.

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By Christy Sprague -- Recent rains have brought most field work to a halt. However, as most of us are waiting to get into the field, winter wheat has continued to grow. Knowing what stage your wheat is at is critical when it comes to making decisions on what herbicide to use for weed control.

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By Diane Brown-Rytlewski and Martin Nagelkirk --  The short answer is yes and no. Results were mixed in trials we conducted last year, depending on variety or level of disease present. For the last couple of years, some chemical companies have promoted: 1) the use of a reduced rate of fungicide at the same time that herbicide applications are made to winter wheat, or 2) an application of copper at the same time that herbicide applications are made to winter wheat.

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By Darryl Warncke... Topdress nitrogen (N) studies over the past four years have most often shown topdressing 75 to 80 lbs N per acre to be the most economical N rate. Top yields ranged from 95 to 110 bushels per acre. The amount of nitrogen available for the roots of wheat to take up from green up to the boot stage can have a major effect on tillering, head number and grain yield.

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Darryl Warncke...Planting time fertilization of wheat is very important for phosphorus and potassium nutrition of the crop. Having adequate phosphorus and potassium available for fall growth is important for root system development, winter survival and tillering of the plants in the spring. A 100 bushel per acre wheat crop removes 63 lbs P2O5 and 37 lbs K2O in the grain. And each ton of straw contains 13 lbs P2O5 and 23 lbs K2O. Therefore, a 100 bu/a wheat crop with two tons of straw per acre removed will remove 76 lbs P2O5 and 60 lbs K2O per acre.

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Diane Brown-Rytlewski...As the wheat season is winding down, I thought I’d share a few last disease-related findings as we approach harvest. It seems that Michigan has escaped an epidemic of head scab again this year, and the Penn State Model accurately predicted (mostly low) risk levels. Most areas of the state have reported relatively low occurrence of symptoms in the field. Hopefully, this will translate into low to no levels of DON (vomitoxin) in harvested grain, although visible symptoms aren’t always a clear indicator of levels of DON at harvest.

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Christina DiFonzo...As wheat harvest approaches in Michigan, now is the time to think about storage. Wheat is put into storage under the assumption that its condition will not deteriorate. Insects are one factor that can reduce grain quality and grade during storage by directly feeding on kernels and by reducing test weight. As insects feed, fine matter accumulates in the bin and reduces airflow. This fine dust consists of tiny pieces of wheat, dead insect bits, and caterpillar webbing.

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Christina DiFonzo...Ontario is experiencing a serious armyworm infestation in wheat, the worst infestation in decades, with 20-40 larvae per square foot. In some areas, every wheat field has been treated. Caterpillars are now moving from wheat into corn. Ohio State also reported an armyworm outbreak, especially in northwest Ohio last week, but the wheat has progressed far enough that the problem is passing. Michigan appears to have dodged the worst of this problem.

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Christina DiFonzo...Check wheat fields for armyworm. Reports the week of June 9 range from none to a bunch, with Sanilac County reporting the most consistent populations. It is important to walk into fields to assess populations, because the populations are not consistent from field to field. The caterpillars are still small (1/2 inch), which is ideal for control if populations are over threshold.

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Diane Brown-Rytlewski...Rainy, warm weather one to two weeks in advance of flowering allows development of inoculum, and sets the stage for infection of wheat during flowering by fusarium head blight (FHB). Until last weekend, the weather in much of Michigan was too dry and cool to provide optimum conditions for the FHB fungus to sporulate. We now have favorable weather for FHB and the risk level increases the longer that those weather conditions continue.

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Bruce MacKellar and Lyndon Kelley...Raising wheat or other small grains on irrigated land has not been a common practice in southwest Michigan. However, with high wheat prices and the expansion of production of short season vegetable crops in the area, many producers are trying double cropping on irrigated wheat fields. Late spring to early summer soil moisture deficits can dramatically reduce small grain yield potential on our non-irrigated loamy sand to sandy loam soils.

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Diane Brown-Rytlewski...The season has been cool and dry so far – too much so for most foliar diseases. For the low levels of foliar disease we have had, fungicides are not needed. Even though weather is expected to warm over the next week, but there still isn’t much rain in the forecast. Wheat is at flag leaf to boot stage in much of the state. Now is a good time to scout for foliar diseases. Take the time to scout your fields for foliar diseases and determine whether disease thresholds have been reached before making the decision to apply a fungicide.

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Diane Brown-Rytlewski...Disease-wise, it has been pretty quiet so far this season. I diagnosed leaf rust on one sample of Caledonia white wheat from Oceana County this week. It was on only the lowest leaves, and appeared as if it may have overwintered. There was plenty of snow cover this winter to protect the rust fungus. It had not started to move up the leaves, and no fungicide application was needed. A little powdery mildew is beginning to appear now low on the plants in early planted fields that are particularly lush-growing, but so far it has stayed low in the canopy.

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Darryl Warncke...Manganese (Mn) is one of the more challenging micronutrients to manage and is the one most likely to be deficient on many field crops. MSU Extension bulletin E-486 is an excellent resource for information on manganese and the other secondary and micronutrients. The field crops most likely to show Mn deficiency are dry beans, soybeans, sugarbeet, wheat and oats.

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Diane Brown-Rytlewski...In Michigan, we have a lot of people to thank for helping make the Section 3 label for tebuconazole (Folicur) happen this spring. Tebuconazole, also known as Folicur, has been given a full Section 3 label by the Environmental Protection Agency for use on wheat and barley. Michigan received a state label for Folicur yesterday. We should thank Lois Rossi, Director of the Registration Division at the Office of Pesticide, Programs for EPA with her efforts to work with us to resolve the barriers that have held up registration of Folicur for the past 11 years.

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Diane Brown-Rytlewski...Much of the wheat in the state is at Feeke’s 5 (full tillering ) to Feeke’s 7 (second node). However, wheat in some Ingham county fields is already at Feeke’s 8 (flag leaf emergence).

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Diane Brown-Rytlewski...Two models have been developed to serve as decision aids for growers to determine whether an application of fungicide should be made to control Fusarium head blight (FHB). The Penn State Model and the Ontario DONcast model are described in this article. Through research funded by Project GREEEN in 2006-2007, both the Penn State and DONcast models were validated in Michigan using weather information and collecting field data from grower locations and research plots.

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Dennis Stein and Diane Brown-Rytlewski...Along with record prices expected for wheat, there has been a high degree of interest in fungicides to control Fusarium head blight and decrease DON levels. In the last Field CAT Alert, we discussed instances where a fungicide application could either be cost effective or result in inadequate return to growers. A partial budget worksheet has been prepared to help you calculate the cost of applying a fungicide and the potential benefits of an application to determine whether a fungicide application will be economical in your situation.

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Christy Sprague...Of all the crops grown in Michigan, winter wheat has typically been the crop that has not been intensively managed. However with higher wheat prices, growers are looking at more intensive management to maximize yield. Where weeds are present, herbicide applications to control both winter and summer annuals is one management practice that may improve yield at the end of the season.

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Martin Nagelkirk...Throughout much of the state, there has been concern over the layer of ice (ice sheeting) that blanketed some of this year’s wheat crop, particularly during early March. Ice sheeting can threaten wheat’s survival by limiting oxygen and, therefore, limiting respiration. It causes the build up of potentially toxic levels of carbon dioxide, ethylene and methanol. Flooding also limits oxygen, so the adverse affect of flooding and ice sheeting can be cumulative.

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Diane Brown-Rytlewski...The difference between what will potentially be paid for food grade wheat versus wheat that can only be used for feed is much higher this year than in past years, prompting growers to look at ways that they can maximize both quality and yield, including the use of fungicides.

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Diane Brown-Rytlewski...With the current prices for wheat, there is interest in looking at all options to increase yield. The use of including early season fungicide applications and their possible contributions to yield has been a hot topic for discussion lately. However, it’s important to remember that fungicides work mainly to protect the yield potential that is already present.

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Fred Springborn...With wheat prices at historic highs, there is much enthusiasm about planting wheat this fall. Here are a few tips and reminders to help you maximize the yield potential of your wheat crop. Plant clean high quality wheat seed. Laboratory testing for germination is a good assurance of the viability of the seed. Seed that has been field inspected during its growing year helps to ensure its varietal purity and that it is free of seed-borne disease.

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Darryl Warncke...With the enthusiasm for producing ethanol from corn and biodiesel from soybeans, wheat has become the forgotten field crop. However, including wheat in a corn-soybean rotation can provide some real benefits for the quality and productive of the soil. The price of wheat makes it an economically attractive crop as well. In the 1990’s, Dick Harwood did considerable research evaluating the effects of wheat in rotation with corn and soybeans. Including wheat in the rotation was found to increase corn yields by at least 10 percent.

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Kurt Thelen...Manganese deficiency is the most common crop micronutrient problem in Michigan, particularly in soybeans and wheat. The availability of manganese to the plant generally decreases as soil pH levels increase. Consequently, soybeans grown in the calcareous soils of Michigan’s Thumb area and in the lake-bed soils in Michigan’s Southeast Lower Peninsula, historically have been found to be deficient in manganese.

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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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Jim Kells and David Hillger...The primary benefit of pre-harvest herbicide application in small grains is in aiding harvest. This treatment will not increase yield. However, there are several negative aspects of a pre-harvest application including: the damage to the small grain caused by driving over the field with the application equipment and potential off-target injury. Therefore, this practice is generally not recommended.

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Diane Brown-Rytlewski...There have been a couple of reports in Michigan of wheat with a red or yellow discoloration beginning at the flag leaf tip and progressing toward the base of the leaf. There is no stunting of the heads and minimal stunting of the plants. These leaf discoloration symptoms, along with stunted heads, stunted plants and flag leaves remaining in an upright position, are classic symptoms of barley yellow dwarf virus, an aphid transmitted virus.

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Diane Brown-Rytlewski...Powdery mildew is the only wheat foliar disease showing up with any regularity this season, and the amounts of it are quite variable. On susceptible or highly susceptible varieties, there is a substantial amount of mildew. With rain and humid weather along with cooler temperatures forecast for the next few days, conditions may be favorable for powdery mildew to come up out of the lower canopy where the temperatures have been cooler and more humid and climb up on the flag leaves and heads.

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Christina DiFonzo...This week there are reports of sprays going on for aphid infestations in wheat. Commercial companies are promoting intensive wheat management in Michigan, including managing fertility, weeds, diseases and insects. It is rare to have an aphid population in wheat in Michigan that merits spraying.

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Ron Gehl...Many stands of winter wheat in the state have taken a good beating this spring due to early growth followed by a mid-April cold spell. The variable weather affecting wheat growth has also prompted the appearance of manganese (Mn) deficiency in some fields. Manganese deficiency is the most common micronutrient problem in Michigan, and wheat is highly responsive to Mn. Manganese exists in many forms in the soil, most of which are unavailable to the growing crop.

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Diane Brown-Rytlewski...The North Central Regional Committee on Management of Small Grain Diseases has developed the following information on fungicide efficacy for control of certain foliar diseases of wheat for use by the grain production industry in the United States. Efficacy ratings for each fungicide listed in the following table were determined by field testing the materials over multiple years and locations by the members of the committee.

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Diane Brown-Rytlewski, Willie Kirk and Martin Nagelkirk...Recent freezing temperatures in Michigan caused some injury to wheat foliage. Injury is showing up as tip burn, and in low areas of fields as more extensive browning of leaves. The wheat should recover with little impact on yield. However, be watchful for diseases this spring, as the stress caused by freeze injury may cause wheat to be somewhat more susceptible to foliar diseases.

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Diane Brown-Rytlewski...For the second year, I will be providing Michigan-specific commentary about weather conditions, wheat diseases and wheat developmental stages for the Penn State Fusarium head blight (FHB) model website. The Michigan Agricultural Weather Station Network (MAWN) weather station locations (48) have been added to the model website, providing significantly increased coverage for the state.

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Diane Brown-Rytlewski, Willie Kirk and Martin Nagelkirk...The most important leaf diseases of wheat in Michigan include powdery mildew, Stagonospora leaf and glume blotch, Septoria leaf blotch, and leaf rust. Depending on conditions, a serious level of any one of these fungal diseases can cause a significant yield loss. Part 1 of this article on wheat foliar diseases covers powdery mildew, Septoria leaf blotch, and Stagonospora leaf and glume blotch.

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Darryl Warncke...Winter wheat response to topdress application of nitrogen may vary from year to year. Nitrogen response studies were conducted for three years at the MSU Agronomy Farm on a Capac loam, south of the main campus. Some of the variability in response is related to soil moisture status as it affects N availability, and to N source. In 2004, “Hopewell” soft red winter wheat responded well to nitrogen applied just prior to green-up (Table 1).

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Martin Nagelkirk...An estimate of the yield potential of individual wheat fields during early spring is an important basis for management decisions. Plant density, along with considerations for production factors, can be useful in establishing a reasonable approximation.

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Jim Kells and Kathrin Schirmacher...Annual weed densities are very high in wheat stubble this year. These weeds must be managed soon in order to prevent seed production. Several effective options are available for management of annual weeds in wheat stubble. However, these practices must be implemented before seed production to avoid significant additions of seeds to the weed seed bank.

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Diane Brown-Rytlewski...Wheat is being harvested in the state with harvest approaching 80% completion in some of the southern areas of the state to around 25% in many other areas. So far, there have not been any reports of high levels of vomitoxin. In the next Field Crop CAT Alert, we’ll have an update of what has been reported.

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Diane Brown-Rytlewski...There have been reports across the state of scattered occurrences of white heads in wheat fields, but so far, serious outbreaks of head scab have not been reported. Likewise, there have been reports of leaf rust throughout the state. Stagnospora leaf and glume blotch (Stagnospora nodorum, formerly known as Septoria leaf and glume blotch) is appearing in a few fields in the central areas of the state.

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Diane Brown-Rytlewski and Willie Kirk...Wheat streak mosaic virus was confirmed on the white wheat variety Caledonia at a research plot in Williamston, Michigan last week. A sample was sent to an outside lab that specializes in virus testing.

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Diane Brown-Rytlewski...Leaf rust (Puccinia recondita f.s. tritici) was found in several wheat fields near Holland, Michigan this week. (see photos) When rust severity is high, as it was in these locations, one of the most noticeable symptoms for anyone walking the field is that their hands or clothing become covered with a powdery orange dust from the spores. There can be substantial differences among wheat varieties in their levels of resistance to leaf rust.

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Diane Brown-Rytlewski...According to the Penn State model, risk is high to moderate along the western edge of the state. Hot, humid weather over the last few days has accelerated flowering. In addition to estimating risk based on the seven days of weather prior to flowering, the Penn State model provides risk estimates based on weather forecasts.

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Steven Gower and Martin Nagelkirk...Wheat submitted to the lab this week in the boot stage of growth showed a pattern of drift and specific symptoms characteristic of glyphosate injury. The wheat was stunted with discolored and often collapsed flag leaves. Specific leaf symptoms included interveinal yellowing, bleaching and/or reddening near the base of the flag leaf. (see photos)

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Diane Brown-Rytlewski and Willie Kirk...Up to this point, risk of head scab throughout the state has been generally low, but growers should watch the weather. Wheat is entering the critical growth stages that are important for head scab infection. In the southwest and southeast parts of the state; wheat is heading and some is beginning to flower. In other parts of the state, wheat is in the boot stage or beginning to head out. Up to this point, wheat development has in Michigan been slow.

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Diane Brown-Rytlewski and Willie Kirk...During visits to wheat fields in the Thumb area, southwest Michigan (Van Buren and Berrien counties) and plots near the MSU campus, we found powdery mildew at varying levels of severity. On some highly resistant varieties, there was little more than a trace of mildew, while susceptible varieties nearby ranged from moderate to severe. Now is the time (flag leaf to boot stage) to scout your wheat fields for powdery mildew, if you haven’t done so already.

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Diane Brown-Rytlewski and Willie Kirk...Last week, we covered the Penn State Model used to forecast the risk of an epidemic of Fusarium head blight (FHB). The DONcast model was developed at the University of Guelph (Ridgetown campus) in Ontario, Canada, and is widely used by Canadian wheat growers. There are about 500 locations for data collection in the Ontario Weather Network (OWN), which owns and operates the DONcast model and others including BEETcast and TOMcast. The DONcast model uses Zadok’s stages of wheat growth instead of the Feeke’s scale.

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Diane Brown-Rytlewski and Willie Kirk...Wheat growth in some areas of the state is at flag leaf or fast approaching it. The flag leaf is responsible for 60 to 70% of the photosynthate needed for grain development. With Wednesday’s heavy rainfall (May 10), forecasts of additional precipitation for the next few days and resulting high humidity, it’s probably a good time to mention powdery mildew. A powdery white growth of mold on the leaves is symptomatic of powdery mildew.

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Christina DiFonzo...Extension educators, especially in southern Michigan, report vast areas of fields infested with low growing weeds. This type of situation sets up a cutworm problem. Cutworms have come north and are present in fields in Indiana. Females prefer to lay eggs in weedy areas of fields, and larvae can move over to corn when the weeds are killed.

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Darryl Warncke...There have been few reports of manganese (Mn) deficient wheat growing on soils with pH above 7.0. Manganese deficient wheat has a general yellow-green appearance from a distance with interval yellow-green pin-stripping on the leaves. See figure 10 in MSU Extension Bulletin E-486. The plants may also appear moisture stressed even though there is adequate soil moisture.

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Martin Nagelkirk and Diane Brown-Rytlewski...A Section 18 special exemption allows the use of Folicur® fungicide again this year to combat fusarium head blight (FHB) of wheat. One application of Folicur at the rate of 4 ounces per acre may be applied up through early flowering (Feekes 10.51). Folicur may be applied with ground equipment or aircraft. Applications are not allowed within 30 days of harvest.

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Diane Brown-Rytlewski and Willie Kirk...Over the years several models have been developed to help growers predict in advance whether or not an application of tebuconazole will be needed to control Fusarium head blight (FHB) and the associated mycotoxin, deoxynivalenol (DON, vomitoxin) that develops in the wheat kernels. Two such models are the Penn State Model, which predicts the risk of FHB and the DONcast model, which predicts the levels of DON.

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Diane Brown-Rytlewski and Willie Kirk...Michigan’s Section 18 exemption for Folicur 3.6F (tebuconazole) to control Fusarium head blight (scab) on wheat has been granted. The Section 18 begins on May 15 and expires on June 25. Last year there were some issues with not getting the exemption early enough for growers in the southern tier of counties to make a timely application of Folicur to their wheat fields, but this year there should be enough time, even with what seems to be shaping up as an early spring.

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Jim Kells, David Hillger and Kathrin Schirmacher...Once wheat has passed Feeke’s Stage 6, the risk of herbicide injury from 2,4-D, MCPA, Banvel/Clarity, or Curtail increases and application of these herbicides is not recommended. In this situation, the remaining herbicide options for broadleaf weed control are Harmony Extra, Harmony GT, Express, Buctril, Stinger and Starane. Harmony Extra, Harmony GT, Affinity BroadSpec and Express can be applied to wheat until the flag leaf is visible (before Feeke's Stage 8).

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Diane Brown-Rytlewski...For wheat growers, deciding whether or not a fungicide application will be needed to control Fusarium head blight (FHB) and associated levels of DON (vomitoxin) can be difficult. Major outbreaks of Fusarium head blight are associated with specific weather patterns prior to flowering of the wheat crop. Some of you may have used weather-based models in the past as a decision making tool. Models can be useful if you work within their limitations.

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