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.

Generally, the time it takes for submerged soil to dry out enough to get equipment on for replanting, is usually time enough to make a determination whether or not plants have survived. However, it can be difficult to determine survivability when plants are covered with soil and plant residue left behind by receding water. In these cases, split a plant lengthwise through the stem. The growing point should be relatively firm and white or cream colored. Darkening or softening of the growing point indicates a nonviable (dead) plant. A step by step worksheet (MSU E Bulletin # E-1961) to guide producers through a replant decision is available through local MSU Extension offices.

How late can I plant/replant and still expect a reasonable chance of maturing grain?
There is still time to replant drowned out corn or soybeans with varieties having appropriate maturities in Michigan. If the rains continue and field operations are delayed until the end of May, growers may want to consider planting an earlier maturing, short season hybrid. The lower half of the Lower Peninsula will on average, accumulate 2000 to 2200 growing degree days from June 1 to first frost. This is sufficient to mature 80-90 day corn and soybeans with a group II or less maturity classification. It is not recommended to plant corn after June 15. The rule of thumb most commonly applied to lost yield potential for delayed planting is one bushel per acre per day after May 10, and up to 2 bushels per acre per day after June 1. Soybeans can generally be planted up to the end of June, although yields will likely be reduced commensurate with the later planting date.

Considerations for replanting into existing stands
When replanting flooded out areas that still have some viable plants, it is usually best to tear up the existing stand and start over with an even-emerging stand. This may require you to manage the area differently than the non-flooded parts of the field with regard to activities based on plant growth stage such as weed control and time of harvest. Other considerations in flooded out areas include potential weed problems from weed seed brought in by encroaching waters, herbicide residue washed in from adjacent fields, loss of herbicide control from excessive leaching or erosion, loss of nitrogen through denitrification or leaching and increased incidence of phytophthora and other root disease. Nodule function in soybeans is also reduced in saturated soil. However, nodule activity resumes to normal levels once the soil dries out. Scout fields closely for these factors and use a PSNT soil test to determine nitrogen losses.

Bt corn hybrids. For most Michigan corn production systems, economic benefits from the use of transgenic Bt corn hybrids resistant to corn borers are more likely to occur with delayed plantings, especially when there is earlier planted corn in the vicinity. Consequently, growers may want to consider switching some of their late-planted intended non-Bt corn acreage to Bt hybrids as insurance against the higher risk of infestation by late brood corn borers.

Previous herbicides applied. Before replanting, review potential label restrictions associated with previously applied herbicides.

Seeding rates. There is no need to consider changing seeding rates for corn simply because planting is delayed. Optimum seeding rates for most growers’ fields range from 28,000 to 33,000 seeds per acre. Lower rates (low to mid-20’s) are suitable for fields with yield levels historically near or below 100 bushels per acre. Unlike corn, soybean has a great propensity to compensate or “flex” when plant populations vary. Therefore, the optimal planting population range is wider for soybean than it is for corn. Determining the minimal scale of that optimal soybean planting population range will optimize profitability and still maintain yield. As a starting point, begin with a planting population of 175,000 seeds per acre for drilled systems and 130,000 seeds per acre for 30 inch rows and then adjust down or up from there based upon field productivity, planting date, and planting conditions. When planting late, resulting soybean plants will be smaller than earlier planted soybeans. To compensate for the potential yield decrease of smaller plants due to late planting, increase your planting population by 20%.

Seeding depth. The key factor that should be used for determining seeding depth for corn is the importance of adequate and uniform soil moisture in the seed furrow. Some might say this is a moot point given the current soggy soil conditions. Remember, though, how quickly Mother Nature can change and how quickly shallow-placed seed can find themselves in bone-dry soil. A seeding depth of 1.5 to 2.5 inches for corn and 1.0 to 2.0 for soybean is acceptable over a range of soil conditions. Shallower depths for corn are risky if rains stop altogether and surface soils begin to dry rapidly.

Field tillage operations. Remaining pre-plant field operations should be scrutinized carefully to determine whether they are truly necessary. With today’s modern corn planters, there is little reason to overly-prepare a field to create a picture-perfect seedbed. In delayed planting situations, every day wasted overworking a field is a day lost to planting and represents lost yield potential. Furthermore, unnecessary tillage operations on soils that may be marginally wet increase the risk of creating tire and tillage compaction layers that can haunt root development and corn health later if excessively dry conditions suddenly become the norm.

Planter sidewall compaction. Another concern to watch for is the potential for significant root restriction by severe sidewall compaction when a rapid shift from wet to dry conditions occurs. If at all possible, avoid planting fields when soil moisture conditions favor the smearing of furrow sidewalls by the coulters or double-disc openers of the planter. The potential yield loss from planting in fields that are too wet far outweighs the potential yield loss from delaying planting until field conditions are suitable. Planting in wet conditions often results in sidewall compaction of the seed furrow. This causes poor seed to soil contact which has several negative consequences including: reduced germination and poor stands; uneven emergence which reduces yield due to plant-to-plant competition; and, restricted root growth which compromises the plant’s ability to withstand moisture stress later in the growing season. In addition, the limited rooting can result in phosphorus deficiency even though soil test phosphorus levels are adequate. This occurs because the plant uses all of the phosphorus that is immediately available within the seed furrow. The roots of these plants will appear thickened and gnarled – a visual sign of compaction. After a period of time, the roots may break through the compacted sidewalls and explore more of the soil. As this occurs, the phosphorus deficiency may be overcome and the plant will begin growing normally again. However, the sidewall smearing and compaction is likely to have set the crop back by a week or more as it tries to overcome the inhospitable soil environment.

Nitrogen fertilizer applications. Because the recent flooding will likely delay planting until the end of May or early June, growers may want to consider backing off on their intended nitrogen fertilizer application rates due to the expected lower yield of the late-planted corn. The rule of thumb most commonly applied to lost yield potential for delayed planting is one bushel per acre per day after May 10, and up to 2 bushels per acre per day after June 1. Consider using a pre-sidedress soil nitrate test to further fine-tune your nitrogen application rates.

As the end of May quickly approaches dry beans will soon be planted throughout most of the state. One pest that can lead to major yield reductions, quality problems and issues with harvest are weeds. To help stay ahead of these pests, below is a summary of what weed control options are available in dry edible beans with approximate herbicide costs. Estimations of herbicide costs are calculated from an average of three 2005 in-season herbicide price lists. For additional information on weed control in dry beans please consult the 2006 MSU Weed Control Guide for Field Crops (E-434) http://www.ipm.msu.edu/cat06field/06weedguide.htm.

Trifluralin (Treflan), pendimethalin (Prowl H 2O, Prowl, Pendimax), and Sonalan: Annual grass control is excellent with all three herbicides. Trifluralin and Sonalan provide better pigweed control than pendimethalin. Pendimethalin and Sonalan provide better common lambsquarters control than trifluralin. None of these herbicides will control eastern black nightshade or common ragweed. Eptam should be tank-mixed with each of these herbicides for additional annual grass and broadleaf weed control. The application rate of Trifluralin 4L is 1 pt/A (~$2.50/A); Prowl H 2O is 1.6 pt/A (~$5.85/A); Sonalan is 2 pt/A (~$6.80/A).

Eptam: Eptam provides excellent control of several annual grasses and good control of common lambsquarters. Eptam also will suppress common ragweed, wild mustard and nightshade species. Thus tank-mixing Eptam with trifluralin, pendimethalin (Prowl), or Sonalan will improve control of these weeds. Eptam is applied at 1.25 qt/A (~$10.30/A). It is important to weigh these costs against the weed control benefits. A Section 18 has been granted for Reflex for the 2006 season, so Reflex could be applied postemergence for control of common ragweed and nightshade.

Pursuit Plus: Pursuit Plus provides fair control of common cocklebur, jimsonweed and smartweed and good to excellent control of several broadleaf and annual grass weeds. Common ragweed is not controlled. Pursuit Plus is typically applied at 20 fl oz/A (~$7.60/A). On heavy soils with more than 2% O.M. this rate can be increased to 30 fl oz/A. Crop injury can occur from applications of Pursuit Plus. Precautions that need to be taken to avoid crop injury include: do not apply on sands or loamy sand soils, do not apply if cold or cold, wet conditions are predicted one week after planting and remember that dry bean varieties can vary in their sensitivity to Pursuit, so keep this in mind when trying a new dry bean variety. Rotation restrictions are also critical with Pursuit Plus. These restrictions include 40 months and a bioassay for sugar beets, cucumbers and tomatoes; 18 months for oats; and 26 months for potatoes.

Alachlor (IntRRo, Micro-Tech): Alachlor provides excellent control of several annual grasses and good control of pigweed and eastern black nightshade. Alachlor should be incorporated in the top 2 inches of soil to minimize dry bean injury. Do not use alachlor on sands or sandy loam soils or injury can occur. Alachlor can be tank-mixed with Eptam, pendimethalin (Prowl), Sonalan or trifluralin for common lambsquarters control. Postemergence applications of a broadleaf herbicide may be needed for additional broadleaf weed control. IntRRo is typically applied at 2 qt/A (~$9.90/A).

Preemergence or preplant incorporated

Dual Magnum and Outlook: A preplant incorporated application of either Dual Magnum or Outlook minimizes crop injury compared with preemergence applications. Navy and black beans are more sensitive to Outlook than Dual Magnum. Dual Magnum and Outlook both provide good control of pigweed and excellent control of annual grass weeds. However, Outlook provides better pigweed and eastern black nightshade control compared with Dual Magnum. Dual Magnum and Outlook can be tank-mixed with Eptam, pendimethalin (Prowl), Sonalan, or trifluralin for common lambsquarters control. Postemergence applications of a broadleaf herbicide may be needed for additional broadleaf weed control. The typical use rate for Dual Magnum is 1.33 pt/A (~$16.80/A) and Outlook is 14 fl oz/A (~$15.50/A).

Pursuit: Pursuit may be applied preemergence or preplant incorporated. Pursuit 70DG at 0.72 oz/A (~$8.75/A) can be tank-mixed with other soil-applied herbicides for additional broadleaf weed control and to control annual grasses. Remember Pursuit will not control common ragweed. Similar to Pursuit Plus, crop injury can occur and precautions need to be taken to avoid injury. These precautions include: do not apply on sands or loamy sand soils, do not apply if cold or cold-wet conditions are predicted one week after planting, and dry bean varieties vary in their sensitivity to Pursuit applications. Rotation restrictions are critical with Pursuit. These restrictions include 40 months and a bioassay for sugar beets, cucumbers, and tomatoes; 18 months for oats; and 26 months for potatoes.

Permit/Sandea: Permit provides excellent control of pigweeds and wild mustard and good control of common ragweed and velvetleaf. Permit is an ALS-inhibiting herbicide, so it will not control ALS-resistant weeds such as ALS-resistant common ragweed. Permit can be tank-mixed with Dual Magnum or Outlook for grass control. Application rates of Permit range from 0.5 oz/A (~$10.90/A) to 0.67 oz/A. The lower use rate should be used on sandier soils. Dry bean varieties appear to vary in their sensitivity to Permit, so precautions should be taken. The rotation restriction for Permit to sugar beets is 21 months.

When looking at these different options there are a few things to consider when using these herbicides alone or in combination. One of the first things to consider is, “What are the weeds that need to be controlled?” These weeds will typically be ones that escape control from soil-applied herbicides and may include common ragweed, common lambsquarters and eastern black nightshade. Selection of an herbicide or combination of one or more of these herbicides will be dependent on the weed complex in the field (Table 1). When making these weed control decisions it is important to consider certain guidelines such as rotation restrictions, herbicide use rates, adjuvant selection, application timings and tank-mixtures with other herbicides.

Rotational restrictions: All postemergence broadleaf herbicides, with the exception of Basagran, have rotational crop restrictions. Some of these restrictions may influence your herbicide selection, depending on your cropping system. For example, the rotation restriction for Reflex is 10 months for corn and 18 months for alfalfa, sugar beets, potatoes, cucumbers, canola and tomatoes. The rotation restriction for Raptor is 18 months for sugar beets (extended to 26 months if pH is less than 6.2) and canola. Pursuit’s rotation restriction is 40 months and a bioassay for sugar beets, canola, cucumbers and tomatoes.

Use rates: The use rate for Reflex is 1 pt/A (~$12.70/A). Reflex can only be used once in a two-year period. Common ragweed less than 4-leaf will be controlled ½ pt/A of Reflex.The use rate for Raptor is 4 fl oz/A (~$15.70/A) in edible legumes. Pursuit 70DG is generally used at 0.72 oz/A (~$8.75/A) and Basagran rates range from 8 fl oz to 2 pt/A (1.25 pt/A ~$13.60/A) depending on weed species, size and herbicide tank-mixture.

Grass control: Foxtail control is good when Raptor is tank-mixed with Basagran at 8 fl oz/A + COC + 28%N (or AMS – ammonium sulfate). Barnyardgrass and crabgrass control are only fair. Assure II, Targa, Select, Arrow and Poast can be tank-mixed with Basagran, Reflex or Basagran + Reflex for grass control. However, do not tank-mix Assure II, Targa, Select, Arrow or Poast with Raptor or Pursuit, because grass control will be compromised.

Adjuvant selection:Basagran alone should be applied with 1 qt/A of a crop oil concentrate (COC). Reflex should be applied with a non-ionic surfactant (NIS) at 0.25 to 0.5% v/v or a COC at 0.5 to 1.0% v/v. Include COC when tank-mixing Basagran + Reflex. Raptor or Pursuit alone should be applied with 0.25% v/v of NIS. These herbicides alone will only provide limited control of selected weed species. To increase control, 12-15 lb/100 gal of spray solution of AMS can be added to Raptor + Basagran + COC or Pursuit + Basagran + NIS applications. The addition of at least 8 fl oz of Basagran to Raptor or Pursuit will “safen” these applications. To control common cocklebur, jimsonweed or provide good control of common lambsquarters, increase the rate of Basagran to 16 fl oz when tank-mixed with Raptor and use COC + AMS. Do not add AMS when tank-mixing Raptor and Reflex.

Application timing:Raptor, Reflex, Basagran or Pursuit should only be applied after dry beans have one fully expanded trifoliate. Do not apply these herbicides once dry beans start to bloom.

Rain-free periods: The rain-free period is 1 hour for Assure II, Targa, Select, Poast, Pursuit, Raptor, and Reflex and 8 hours for Basagran.

View weed response table.

Soil-applied herbicides remain an important part of weed control programs in corn and to a much lesser extent in soybeans. Because of the dry soil conditions that we experienced in April and the first couple of weeks of May, soil-applied herbicides were applied under conditions where there was little or no rainfall for incorporation leaving many of these herbicides on the soil surface. With the latest rainfall events the question remains, “How effective will these herbicides be that were applied in early to mid-April?” In order to answer this question, here is a quick review on how soil-applied herbicides work.

In order for a soil-applied herbicide to be effective, the herbicide needs to be available for uptake by the weed seedling. This usually means that the herbicide needs to be in solution before the seedling emerges, however there are a few herbicides that can control small emerged weeds under certain conditions (i.e., atrazine). Processes such as herbicide adsorption to soil colloids or organic matter can reduce the amount of herbicide available for weed absorption. Soil-applied herbicides do not prevent weed seed germination!! Soil-applied herbicides work by being absorbed by the root or shoot of the weed seedling as it emerges. Generally, this happens before the seedling emerges from the soil. For a herbicide to be absorbed by weed seedlings, the herbicide must be in the soil solution. Herbicides can be made available in the soil solution by mechanical incorporation (PPI applications) or incorporation by rainfall. Generally, with most of the soil-applied herbicide applications that we make in Michigan we rely on rainfall for herbicide incorporation. If we don’t receive adequate rainfall, the herbicide remains on the soil surface and is prone to dissipation processes, such as volatility and photolysis (depending on the herbicide). More importantly if the herbicide is not incorporated by rainfall or mechanically, the herbicide is not in the area of the soil where it would come into contact with germinating weed seedlings.

The recent and continuing stretch of cold, wet weather has resulted in soils that are water saturated and may remain cool and wet for several weeks. These conditions are particularly suitable for the development of lower stem and root-rotting pathogens for example, Phytophthora spp., Rhizoctonia, Pythium, Fusarium and other soil-inhabiting fungi and bacteria such as soft-rots (Erwinia caratovora). Spores of these fungi and water-molds can remain dormant in the soil for many years, and it is likely that with current soil conditions and retarded development and growth of roots, that many plants are vulnerable. (see photos) Infected plants may exhibit symptoms that start with wilt and apparent nutrient deficiencies and ultimately become necrotic and die. The roots lose integrity and adhesion to the soil.

To check for lower stem rot or root rot, gently but firmly pull the plant upwards, if the plant comes away from the soil with minimal resistance and the roots are darkened, root rot may be the problem. Samples should be sent immediately to the diagnostic clinic for confirmation and diagnosis of the problem in order to implement appropriate control recommendations. Some accompanying images of root and lower stem rot symptoms in potatoes are included.

It is also possible that fungicidal seed treatments and in-furrow applied fungicides are no longer present in sufficient quantity in the soil to be effective. Once the soil has dried out sufficiently (about 15 to 20% volumetric soil moisture) appropriate fungicides for soil-borne and root diseases may be applied. Use only fungicides recommended for the diagnosed pathogen and use label recommended rates and application methods (Table 1). Application of azoxystrobin (Quadris 2.08SC) shortly after emergence inhibited Rhizoctonia black scurf in trials at MSU in 1998 and has continued to be effective in more recent trials (see Figure 1).

Rhizoctonia root and crown rot caused by Rhizoctonia solani Kuhn AG2-2 is the most common and serious soil-borne disease of sugar beet. R. solani survives as mycelium or sclerotia in the soil in organic debris and is thought to be most active at soil temperatures between 77 to 92 oF. However, we have found that the pathogen is active at lower soil temperatures and serious losses have occurred in areas with a history of Rhizoctonia especially after wet and cool springs. Over the past few years effective fungicides for control of Rhizoctonia have been successfully used in Michigan. For this season, after the wet, cool spring, we are recommending that growers apply Quadris 2.08SC as soon as they are able to re-enter fields. Application rates of 7 to 10.5 fl. Oz/A have proved effective in years when conditions have been particularly conducive for disease development. Results form trials exposed to natural incoulum are shown below and of course the more resistant varieties have relatively less yield loss due to Rhizoctonia, but even resistant varieties responded positively to the application of Quadris (In these trials the application to the resistant cultivar was in-furrow.).

a Rate of application of Quadris 2.08SC (fl oz/A).
b Relative area under the plant stand curve from planting to 122 days after planting. Indicates combined effect of damping-off and crown and root rot (R. solani) on plant stand.
c Means followed by same letter are not significantly different at P = 0.05 (Tukey test).

a Application dates and days after planting.
b Means followed by same letter are not significantly different at P = 0.05 (Tukey test).

Wheat disease update
Diane Brown-Rytlewski and Willie Kirk
Plant Pathology

Powdery mildew
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. In the last issue of the Field Crop CAT Alert, we gave you a reference for good pictorial guide to scouting for leaf diseases of wheat developed by Ohio State University: http://ohioline.osu.edu/b785/b785_11.html

The guide explains how to rate wheat for several foliar diseases and gives treatment thresholds for powdery mildew, Septoria leaf spot and leaf rust, including considerations about whether or not it’s economical to spray. To evaluate the infection level of mildew in your field, make 10 random stops in your field and examine the leaf just below the flag leaf for mildew. The threshold for fungicide application is 2 to 3 lesions (about 1% of the leaf area) on the leaf below the flag leaf. In addition to the infection level, some points to consider in whether it is economical to apply a fungicide are the yield potential of your field for both the wheat grain and the straw and the market price for each. Applying a foliar fungicide doesn’t necessarily increase yield, but it can help protect yield when disease pressure is severe.

The registered fungicides differ in how late they can legally be applied. Stratego (a combination of trifloxystrobin and propiconazole) can be applied up to Feekes growth stage 8 (flag leaf emergence). Propimax (propiconazole) can be applied up to Feekes growth stage 9 (flag leaf collar visible). Depending on the growth stage your wheat has attained, it may already be too late to legally use these products. Quilt (a combination of azoxystrobin and propiconazole) and Tilt (propiconazole) can be applied up through heading (Feekes 10.5). Quilt (a combination of azoxystrobin and propiconazole) and Propimax (propiconazole) can be applied up to Feekes growth stage 9 (flag leaf collar visible). Depending on the growth stage your wheat has attained, it may already be too late to legally use these products. Tilt (propiconazole) can be applied up through heading (Feekes 10.5). If Fusarium head blight (head scab) is a concern, it is probably best to apply a triazole product rather than a strobilurin fungicide. It has been shown in some trials that wheat treated with strobilurins can increase mycotoxin (vomitoxin or DON) levels under certain conditions. The strobilurin products Quadris (azoxystrobin) and Headline (pyraclostrobin) can be applied through heading (Feekes 10.5). If Fusarium head blight (head scab) is a concern, it is probably best to apply a triazole product. Be sure to read the label for rates, REIs and other information.

Septoria leaf spot
Although we found relatively little Septoria on wheat during our visits to fields in other locations, Jim Howe, of Star of the West Milling, has reported Septoria – mainly in no-till wheat in the Saginaw County area. The same fungicides registered for powdery mildew will provide control of Septoria. Septoria leaf spot and Stagnospora glume blotch are caused by closely related fungi. We may have not seen much Septoria yet because the temperatures have been cooler than optimum for the disease. Both diseases are favored by wet, windy conditions and moderate temperatures. Both fungi move from infected lower leaves upward. Septoria leaf spot does not attack glumes, only leaves. Symptoms begin as small light green to yellow spots between the veins of lower leaves. The spots enlarge to become irregular reddish-brown lesions. Small pimple-like fruiting bodies can be seen within the lesions by using a hand lens. Stagnospora glume blotch develops after the wheat heads emerge and spreads across the field, infecting the heads. Symptoms include small grayish-brown, oval spots on the leaves and purplish-brown blotches on the glumes (glume = bract at the base of a wheat spikelet).

Anthracnose
In several wheat fields we found lower leaves turning brown at the leaf tip and also at the point where the leaf blade attaches to the stem. In some ceases, the fungus had girdled the leaf base, and it was breaking off from the stem. It initially looked as if it could have been caused by fertilizer burn, but turned out to be caused by a fungus known as anthracnose (Colletotrichum graminicola). (see photo) If you look with a hand lens, you can just make out black fruiting bodies with dark spines (setae). They are considerably easier to see with a dissecting scope. Anthracnose is generally a minor disease, controlled by crop rotation and managing crop residue. If seed is kept from infected fields, it should be thoroughly cleaned and chemically treated before using it for planting.

After the rains of this past week many are concerned about the availability of applied nitrogen. Answering this concern is a bit challenging. The good news was that the soils were actually quite dry prior to the rains, so they were able to absorb much of the initial water. However, many areas of Michigan have received more than 3 inches of rain in a few days. Sandy soils are only able to hold 1.0 to 1.75 inches of water per foot of soil whereas loam soils hold 2.5 to 3.0 inches per foot and clay loam soils hold nearly 3.75 inches per foot of soil. Therefore, the potential for downward movement of nitrate in soils will be greater in sandy soils than in loam and clay loam soils. Once the soil is saturated, water will move downward and carry nitrate with it. Where rainfall was less than 2 inches, movement of nitrates may have only been into the second foot where it may eventually be available to the crop. But, where rainfall was over 3 inches, some nitrate may have been leached beyond the potential root zone and into the subsurface drainage water, especially in sandy soils. Soil temperatures have decreased to near 50°F so that the rate of denitrification in saturated soil will be reduced.

The time of application and the form of nitrogen applied will also have an impact on potential loss. Recently applied nitrogen in the ammonium or urea form is less subject to loss than when applied in the nitrate form.

Weather
It has been rainy for the past nine days with totals of about 5 inches received. No general flooding in this area, but if more rains come soon, the water will simply have to runoff as soils are saturated.

Commodity reports
Alfalfa will be ready to cut whenever the weather cooperates.

Corn plants have been “sitting still” with cool, cloudy weather. No significant growth this past week, though we needed the rains as April was so dry. The good news is that most corn is already planted with many fields emerged. Most fields are not flooded. Weed control and herbicide persistence will be a big question mark.

Soybeans are either in the ground or in the bag as nothing happened this past week. If fields that were planted did not get sprayed, then weeds will get a head start. Fortunately, with Roundup Ready soybeans weed control is a much simpler decision.

Wheat fields are in the boot stage and will be heading. No one has been tromping in the fields, though powdery mildew and Septoria are likely present. Spraying may be difficult if fields are too wet for too long and the wheat develops past heading.

Miscellaneous

Weather
Rainfall from May 8-9 through May 15 have brought most field operations to a halt. Rainfall totals range from 2.5 to 7 inches across the region. Most areas in the southwest received rainfall at rates that allowed for infiltration with limited ponding. Soils remain very wet. A brief break in the precipitation on Wednesday allowed for some planting to resume on sand soils.

Commodity reports
Commercial corn planting is close to complete. The earliest planted corn is 4-6 inches in height. Later planted fields have yet to emerge. Ironically, one of the largest weather related crop production concerns at this point may be the delayed activation of soil applied herbicides during the extended dry period before May 8. Some herbicide applications may have been applied 12 - 15 days before rainfall moved the herbicides from the soil surface to the root zone. Grass weed seedlings that germinated before the rain may have grown through the zone where soil applied grass herbicides are considered to be effective. This is particularly a concern if the grass species that escaped is crabgrass, which has limited post emergence options for control. One material that does have post emergence grass activity against crabgrass is Callisto. Commercial corn growers who applied either Lumax or Camix pre-emergence should be aware that there is a limitation on the total amount of Callisto that can be applied to the crop in any given season.

Cass County ANR Educator and CED Dan Rajzer is concerned about nitrogen leaching out of the root zone on fields that have received heavy rainfall and nitrogen was applied before planting. Many fields in northern Cass and southern Van Buren counties received their N up front this season. Fields that had standing water or received heavy rainfall may face some nitrogen losses, especially this year, because of the warm soil conditions early in the growing season.

Seed corn producers are facing some real challenges getting back into the field. Delayed plantings of male or female inbred rows have been postponed due to wet soil conditions. Some producers were able to traffic soils on May 17, and relatively low rainfall levels from showers last night may allow for planting to continue on these light soils.

Soybeans range from early tri-foliate leaf development to remaining in the bag waiting to be planted. There are some signs of bean leaf beetle feeding, but nothing approaching threshold at this point. There have also been limited signs of black cutworm feeding at this time. Producers should continue to monitor fields for signs of this pest.

Alfalfa growth is at 18”, and we are approaching the 750 GDD Base 41 recommendations for harvesting the first cutting. Alfalfa weevil feeding has been widespread in the region, and many fields were treated for this pest. Depending upon the weather, it may be worthwhile to keep an eye on fields to make sure that the pest is not destroying the value of the first cutting before you will be able to harvest the crop.

3 -- West Central
Fred Springborn

Weather
Rain showers in many locations around the area seven out of the last eight days. Rain fall totals for the week have been in the range of 2.5 to 4 inches. The weather station at Entrican measured 2.4. High air temperatures have been in the 50s and 60s with lows in the 30s and 40s. Low soil temperatures have been in the upper 40s to lower 50s. Moisture is adequate with little damage from excessive water in this area.

Commodity reports
Corn planting stands at 65 to 80 percent planted. Many fields have emerged. Growth stages range from seed still in the bag to V1. Emerged corn appears yellow in many fields due to the recent cool, cloudy weather.

As with corn, there was no appreciable soybean planting progress this week. A few fields have emerged with some showing the first unifoliates.

Flag leaves are emerging or have emerged in most wheat fields. Powdery mildew is present at low levels in the canopy. Oat planting is complete. Stands and growth are generally good. Weeds are emerging and herbicide applications will need to be made as soon as field condition permit.

4 -- Central
Paul Gross

Weather
The region received any where from 3 to 5 inches of rain over the past 10 days. This has kept everyone out of the fields all week. It will take several days of warm dry weather before we will get back into the fields. The cool, wet conditions has slowed crop emergence. Field conditions are saturated and there will be some areas of fields that have drowned out. We expect weed control challenges due to excess moisture.

Soybeans are emerging slowly. There are concerns about seedling diseases with all the moisture. This year planting treated seed may pay big dividends. Many fields are in need of herbicide applications.

The wheat crop varies from Feekes 5-9. The crop generally looks good, but we are still seeing fields that are very yellow and growing slow. Samples from these fields have been analyzed and no diseases have been identified. Fields should be scouted for foliar diseases.

Alfalfa is doing very well and is approaching optimum quality. The weather station in Alma recorded 600 GDD early in the week. A fresh cut forage sample taken on Tuesday of this week in southern Isabella County has results of: NDF-40.56, ADF-28.08, P-25.22.

Harvest will start when field conditions allow.

Weather
Most of the past week has offered spotty rainfall across the Saginaw Valley and Thumb. Some areas cannot get a break to dry off, while other areas have about optimum soil moisture.

Established sugar beet stands are gaining growth quickly this past week. A few seedlings emerged with moist surface soil in later planted fields but early planted fields did not show much new emergence. Weed control with micro rate herbicides is being challenged by more than seven days out of the field with rainfall. Fungicide applications for Rhizoctonia control are also being delayed beyond the intended timing.

The wheat crop continues to grow and develop quickly. Many fields are at or near the boot stage. Septoria and powdery mildew are easy to find on the lower portion of most plants. Consistent moisture in the wheat canopy may lead to disease spread up the plant. Warmer and drier conditions may slow this spread.

Most corn fields have emerged consistently with largest plants about 4 inches tall. Visual plant health has slipped a little in the past week with cool temperatures and heavy rainfall. General yellowing has occurred but should not relate to over all plant health or grain yield.

The low pressure system that brought 2 to 5 inches of rain to much of Michigan and more than 10 inches of rain and severe flooding to portions of New England since last Tuesday (May 9) finally moved out of North America this past Tuesday (May 16). Rain associated with the system fell on an almost daily basis in many parts of Michigan during the past week. While the wet weather, at least temporarily, brought fieldwork activities to a halt, it also ended the drier than normal conditions that had persisted since late mid-March, and seasonal precipitation totals (since April 1) are back to near normal levels over most of the state.

During the past 24 hours, another upper air disturbance moving southeastward out of Canada has carved out yet another upper air troughing feature over the Great Lakes region This will lead to more showery and cooler than normal weather into the first half of the weekend.

In the short term, showers and a few thunderstorms will develop across northern sections of the state Thursday and move southward during the day and evening. Showers are also a possibility Friday and Saturday, especially across eastern sections of the state (many western areas should remain dry). Dry conditions are expected to finally materialize statewide by Sunday. Temperatures will fall Thursday to highs from the low 50s north to near 60 south with lows from the low 30s far northwest to near 40 in the south. Slightly warmer temperatures are expected Friday and Saturday. Some scattered frost and/or freezing temperatures are possible in interior western sections of Upper Michigan Friday morning. Cooler than normal temperatures are a good bet through the upcoming weekend with mean temperatures remaining 3 to 6 degrees below the climatological norms. Forecast guidance suggests moderation in temperatures by early next week with high temperatures possibly returning to the 70s by midweek. A weather system moving along the United States/Canadian border is expected to bring the next chance for significant rainfall by Tuesday or early Wednesday of next week.

Medium‑range forecast guidance is suggesting that the upper air troughing pattern across the eastern United States and ridging across the west will gradually shift eastward and become less amplified (The flow will become more west/east instead of north/south.), leading to an eventual moderation in temperatures.

The NOAA 6-10 and 8-14 day outlooks (covering May 23-27 and 25-31) both call for temperatures to moderate with mean values ranging from above normal in southwestern sections of the Lower Peninsula to near normal levels elsewhere. During the 6-10 day time frame, precipitation totals are expected to range from below normal levels in southern sections of the state to above normal in the north. During the 8-14 day time period, precipitation totals are forecast to range from near normal across southern sections of the state to above normal levels elsewhere.