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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2008-17

Dates Covered: 
June 9, 2008 - June 17, 2008
Jonah T. Johnson

The Weather and Wheat

Authors: Jim Beuerlein

Attempting to produce ultra-high yields by using extra inputs is not profitable for most Ohio wheat producers. That is because the climate of Ohio limits maximum wheat productivity. Most years, Ohio’s weather is often too wet in May and early June, resulting in serious disease and loss of yield. Late June and early July is often too hot and kills our crop well before it has time to reach its maximum yield potential. When we have one of those rare dry springs with low disease levels followed by a cool June, the yields of some fields have reached 120 bushels per acre or more. The yield potential of most Ohio adapted varieties is greater than 175 bu/ac but the weather usually prevents us from reaching those high potential yields. Because those really good growing seasons are rare, we should manage for the more normal weather.

The most prudent production system is one of defensive management - planting after the fly-safe date to dodge diseases; holding seeding and nitrogen rates down to reduce disease and lower the cost of production; using resistant varieties instead of applying fungicides, etc. This management system will not produce the maximum possible yield in those really good growing seasons, but it will be the most profitable system most years.

Most years it is the air temperature during the grain fill period that determines wheat grain yield. Wheat is a cool season crop adapted to survive cold winter temperatures which also makes it intolerant to high temperatures. Wheat produces best when the daytime temperatures during grain fill range from 65 degrees to 80 degrees; there is ample soil moisture, bright sunlight, and a nice breeze to stir the air. When leaf temperatures are in this range, the chemical reactions of photosynthesis are very fast, resulting in rapid grain production. As soil moisture levels decrease or as air temperatures increases, the crop cannot evaporate enough moisture to maintain leaf temperatures in the optimum range. As leaf temperatures increase above the optimum range, photosynthesis slows and less carbohydrate is produced. At the same time the large demand for carbohydrate by the grain heads stops carbohydrate flow to the root system which then loses its ability to transport water to the leaves, which ultimately overheat and die. The competition for carbohydrate starts in early grain fill and continues until the crop dies. Cool temperatures, adequate soil moisture, and low evaporative potential allow for long grain fill periods and high yields. The grain fill period is shortened and yield reduced by high temperatures, inadequate water and foliar diseases. The ability of the root system to extract and transport water starts to decrease soon after grain fill begins. When the air temperature reaches 85 degrees for several hours each day, the plants are barely able to maintain themselves and temperatures of 90 degrees late in the grain filling period usually caused plant death followed by the loss of all green color within 3 to 6 days.

Some of the keys to longer grain filling periods are: 1) Plant as soon as possible after the Fly Safe date in the fall, 2) Speed up fall growth with the application of 20-25 pounds of nitrogen at planting, 3) Select and grow varieties with resistance to the more serious diseases in your area of the state, 4) Monitor the crop for weed, insect and disease problems and take action if needed.

Determining the Cost of Hay

Authors: Rory Lewandowski

I've had several conversations regarding the cost of hay recently. One person, trying to determine what to charge for essentially renting hay ground, reasoned that if the renter was going to sell small square bales for $5 or more per bale, then they ought to have at least $2 per bale as their share. Another person told me that if there is a lot of grass growing that gets made into a lot of hay then hay will again be cheap ($50-60/ton?) as in past years. The cost of producing hay can be determined from the value of nutrients removed plus the equipment costs. Whether hay is actually worth what it costs to produce it is yet another question.

According to the Ohio Agronomy Guide, each ton of grass hay removes 40 lbs of nitrogen, 13 lbs of phosphate (P2O5) and 50 lbs of potash (K2O). I called two local fertilizer dealers to get prices on per ton bulk quantities. Urea (46-0-0) was quoted at $690 and $788/ton; DAP (18-46-0) was quoted at $1050 and $1375/ton and potash (0-0-60) at $600 and $665/ton. Using these prices to replace the nitrogen, phosphate and potash removed in a ton of hay resulted in a cost of between $61.41 to $70.66 per ton. Since I was using DAP to replace the phosphate removed, this also provided about 5 lbs of nitrogen. The remaining 35 lbs was replaced using urea. Besides the fertilizer cost, there should be something figured in for spreading the fertilizer. Using the 2008 Ohio Farm Custom Rates, the average cost for spreading dry bulk fertilizer is about $4.50/acre.

It is true that hay can be produced without fertilizing. I see it happen all the time here in Athens County. So, should fertilizer cost be part of determining the cost of hay? Yes, because each ton of hay removes those nutrients whether they are replaced or not. It is a matter of pay now or pay later. The soil can get mined to the point where it is no longer practical to produce hay. To restore soil to good productivity, one must takes a massive investment to restore soil fertility. Every year I get phone calls where people say they will fertilize in the future, or they are waiting for fertilizer to get cheaper because it is too expensive. If your soil fertility levels are good, and you are pretty sure fertilizer prices are going to decrease, then go ahead and delay fertilizing. However, you should still include some fertilizer charge into your hay cost calculation based on that future fertilization.

The next part of calculating the cost of hay production is machinery/equipment expense. I used average cost figures from the 2008 Ohio Farm Custom Rates ( These rates are based on survey responses of Ohio farmers. Your own equipment costs may vary, and if you know what they are, plug those in. For those who don't know, this is a good place to start. Mowing is valued at $11.13/acre, tedding at $6.13/acre, raking at $6.59/acre and large round bale baling and hauling at $8.81 per bale. Since we talk about hay in terms of price/ton, these per acre costs will have to get converted into costs /ton. Here is where fertility will pay some dividends. As tonnage yields increase, the machinery costs of mowing, tedding and raking decrease on a per ton basis.

Let's consider an example where hay production is at 2 tons per acre and large round bales weigh 1000 lbs. The machinery costs are $5.56/ton for mowing, $3.07/ton for tedding, $3.29/ton for raking and $17.62/ton for baling and hauling the bales. If we need to do one tedding and one raking before baling, our total machinery cost is $29.54/ton. Adding the machinery cost to the lower of our fertilizer quotes ($61.41) results in a total hay production cost of $90.95/ton. At the higher fertilizer quote ($70.66), the cost is $100.20/ton. This does not include the cost of spreading fertilizer.

Now, it may be possible to reduce these hay production costs somewhat. You might find a better deal on fertilizer. Maybe you have an even distribution of 30% or more legumes in your hay mix, so the legumes provide nitrogen. Possibly you can spread some livestock manure that accumulated on a heavy use-feeding pad. You might be able to take out a pass with the rake if the weather is right and just tedd the hay. Maybe your machinery costs are a little lower. The point is, even with some of these conditions, hay is still going to be an expensive commodity. If you are making your own hay, these production costs are there whether that hay is mowed and baled at 15% crude protein and 65% TDN or at 7% crude protein and 48% TDN.

Then again, maybe the best situation is to find a neighbor or some other person who likes to make hay and hasn't pushed a pencil on the costs. You just might run into a good deal.

Staging early season corn growth

Authors: Peter Thomison

When estimating yield losses in corn due to hail, frost, and other types of plant injury, it’s essential to establish the stage of plant growth at the time damage occurred. In recent years, it’s also become increasingly important to know corn stage of development in order to apply post-emergence chemicals effectively with minimum crop damage.

Several systems are currently used to stage vegetative growth in corn. The "leaf collar" system is probably the method most widely used by university and seed company agronomists in the Corn Belt. With this method, each leaf stage is defined according to the uppermost leaf whose leaf collar is visible. The first part of the collar that is visible is the back, which appears as a discolored line between the leaf blade and the leaf sheath. The oval shaped first leaf is a reference point for counting upward to the top visible leaf collar. This oval shaped leaf is counted as the number 1 leaf when staging. If a plant has 4 visible leaf collars, then it is defined as being at V4. Normally a plant at the V4 stage will have parts of the 5th and 6th leaves visible, but only four leaves with distinct collars. A field is defined as being at a given growth stage when at least 50% of the plants show collars.

Another widely used staging method is the "hail adjustor's horizontal leaf method" developed by the crop insurance industry. Rather than using the uppermost leaf collar, hail adjustors identify the uppermost leaf that is 40 to 50% exposed and whose tip points below the horizontal. Typically, a given "horizontal leaf" growth stage based on the hail adjustor's method will be 1 to 2 leaf stages greater than the collar method. From growth stage V1 through about V5 there is typically one additional leaf (above that leaf with the last visible collar) whose leaf tip is pointing below the horizontal. Beyond growth stage V5, two or more additional leaves with 'droopy' leaf tips will usually be evident above the leaf with the last visible collar (so a V6 plant according to the leaf collar method will typically be a 8-leaf plant according to the hail adjustor's horizontal leaf method). One problem with the horizontal leaf method is that it is often difficult to identify the uppermost horizontal leaves in fields that have recently experienced severe leaf damage. Hail adjustors get around this problem because they generally assess hail damage 5 to 10 days after the storm, by which time one or more leaves have emerged from the whorl.

Corn leaf stage is a more reliable indicator of corn development than plant height. This is especially true in a cool, wet spring when corn is growing more slowly from a height standpoint. Differences in tillage and soil type often have a pronounced effect on plant height but relatively little effect on the stage of vegetative development. For example, within a field, corn may be taller in those areas characterized by darker soil (with higher organic matter) than in areas with lighter soil, especially the clay knolls, yet plants in both areas of the field may be at nearly the same stage when counting leaf collars.

At about V6 stage, or 8-leaf stage of the hail adjustor's method, increasing stalk and nodal growth combine to tear the smallest lower leaves from the plant. This results in degeneration and eventual loss of lower leaves. Hail damage, insect feeding, and fertilizer/herbicide burning promote this process. There may also be occasions when the lower leaves are hard to identify prior to V6 stage. When extensive early season leaf damage has occurred, identification of the first rounded leaf and subsequent leaf collars may be difficult. What do you then? See the following article.

Predicting leaf stages in early season corn

Authors: Peter Thomison

Dr. Bob Nielsen at Purdue has described a method for predicting leaf stage development using accumulated heat unit or growing-degree-day (GDD) information. Given an understanding of corn leaf stage development and heat unit calculation, a grower can predict what leaf stage of development a particular field is at given its planting date and temperatures since planting. It is useful to know when the crop emerged, but if you do not you can estimate that event also. Corn emergence typically requires 100 to 150 GDDs.

Dr. Nielsen proposes that corn leaf developmental rates may be characterized by two phases. From emergence to V10 (ten visible leaf collars), leaf emergence occurs approximately every 82 GDDs. From V10 to tasseling, leaf collar emergence occurs more rapidly at approximately one leaf every 50 GDDs. Previously, about 60 to 65 GDDs were associated with the appearance of new leaf collars during vegetative growth.
Example (from reference noted below): A field was planted on April 28, but you do not know exactly when it emerged. Since planting, approximately 785 GDDs have accumulated. If you assume that the crop emerged in about 120 GDDs, then the estimated leaf stage for the crop would be about V8. This estimate is calculated by first subtracting 120 from 785 to account for the estimated thermal time to emergence, then dividing the result (665) by 82 (equal to 8.1).
If we continue to get hot days and nights (w/highs in low 90s and lows in mid 60s) for next week, we will be accumulating about 25 to 26 GDDs per day and at these temperatures it will take about 3 to 4 days to put on a new leaf. Dr. Nielsen warns that these predictions of leaf stage development are only estimates. One of the factors that most influences the accuracy of these estimates is the existence of other growth-limiting stresses and conditions (nutrient deficiencies, compaction, etc.). Despite these potential drawbacks, this method may be useful in timing when plants will reach an approximate stage of growth.

Fore more on Dr. Nielsen’s prediction system, check out the following –

Nielsen, R.L.. 2008. Use Thermal Time to Predict Leaf Stage Development in Corn
Corny News Articles, Purdue Univ. [On-Line]. Available at (URL verified 6/6/08)

Ponding and flooding effects on corn

Authors: Peter Thomison

Heavy rains last week resulted in localized ponding and flooding of corn fields; mainly in parts of south central and southwest Ohio. If the ponding and flooding was of a limited duration, i.e. the water drained off quickly within a few hours, the injury resulting from the saturated soil conditions should be minimal. The following are some tips to consider when evaluating possible damage from water saturated soil conditions.

The extent to which ponding injures corn is determined by several factors including: (1) plant stage of development when ponding occurs, (2) duration of ponding and (3) air/soil temperatures. Prior to the 6-leaf collar stage (as measured by visible leaf collars) or when the growing point is at or below the soil surface, corn can usually survive only 2 to 4 days of flooded conditions. The oxygen supply in the soil is depleted after about 48 hours in a flooded soil. Without oxygen, the plant cannot perform critical life sustaining functions; e.g. nutrient and water uptake is impaired, root growth is inhibited, etc. If temperatures are warm during ponding (greater than 77 degrees F) plants may not survive 24-hours. Cooler temperatures prolong survival. Once the growing point is above the water level the likelihood for survival improves greatly.

Even if ponding doesn't kill plants outright, it may have a long term negative impact on crop performance. Excess moisture during the early vegetative stages retards corn root development. As a result, plants may be subject to greater injury during a dry summer because root systems are not sufficiently developed to access available subsoil water. Ponding can also result in losses of nitrogen through denitrification and leaching.

To confirm plant survival after ponding or flooding occurs, check the color of the growing point. It should be white to cream colored, while a darkening and/or softening usually precedes plant death. Also look for new leaf growth 3 to 5 days after water drains from the field. Sometimes the growing point is killed by bacterial infections during and after ponding, but plant growth continues in the form of non-productive tillers (suckers).

Disease problems that become greater risks due to ponding and cool temperatures include pythium, corn smut, and crazy top. Fungicide seed treatments will help reduce stand loss, but the duration of protection is limited to about 10-14 days. The fungus that causes crazy top depends on saturated soil conditions to infect corn seedlings. There is limited hybrid resistance to these diseases and predicting damage from corn smut and crazy top is difficult until later in the growing season.

For more information on ponding and flooding damage, check out a recent article written by Dr. Bob Nielsen at Purdue University -
Nielsen, R.L. 2008. Effects of Flooding or Ponding on Young Corn. Corny News Network, Purdue Univ. [On-Line]. Available at: [verified 6/6/08].

Fertilizer Prices Continue Higher

Authors: Barry Ward

Retail fertilizer prices in Ohio continue to surge as a combination of strong world demand, supply shortages, supply disruptions, high energy/transportation costs and a weak U.S. dollar make for a bad combination for farmers looking to make purchases.

Retail fertilizer price surveys show anhydrous ammonia prices to be 14% higher than they were in mid-March. Anhydrous Ammonia prices averaged $895 per ton on June 5th compared to $782 per ton on March 26th. Retail UAN (28%) averaged $422/ton on June 5th while UAN (28%) shipped direct to farm storage averaged $403/ton. Urea prices are significantly higher (34%), averaging $697/ton on June 5th compared to $520/ton on March 26th.
Phosphorous fertilizer prices continue to hit new records as MAP and DAP both are averaging over $1000 per ton. As of June 5th, our survey showed MAP averaging $1047/ton and DAP averaging $1106/ton. This compares to the March 26th spot prices of $914/ton for MAP and $917/ton for DAP.
Potash is also experiencing big run-ups in price as the average price on June 5th was $633/ton. This is a 14% increase over the March 26th price of $557/ton.

Fertilizer Prices as of 6/5/08
N Source Price per Ton ($) Price per Pound ($)
Anhydrous Ammonia 895 0.546
UAN (28%) 422 0.754
UAN (28%) Direct 403 0.720
Urea 697 0.758
P2O5 Source* Price per Ton ($) Price per Pound ($)
MAP (11-52-0) 1047 1.01
DAP (18-46-0) 1106 1.20
K2O Source Price per Ton ($) Price per Pound ($)
Potash (0-0-60) 633 0.528

*Value of Nitrogen not considered for this illustration.


2008 OSU Enterprise Budgets

Authors: Barry Ward

Budgeting is essential to helping you make important decisions regarding the commitment of resources to the most profitable enterprises on the farm. Budgeting will help you answer many questions. Crops or Livestock? Corn, Soybeans, or Wheat? Should I invest more of my resources in high-value crops?

Budgets that are well thought out and prepared, showing all revenue and costs can help you answer these questions. Without some form of budgeting and some method to track your enterprises’ progress, it will be a very difficult process to determine your most profitable enterprise(s) and if you’ve met your goals for the farm.
Ohio State University Extension has had a long history of developing “Enterprise Budgets” that can be used as a starting point for producers in their budgeting process. Newly updated Enterprise Budgets for 2008 have been completed and posted to the Farm Management Website of the Department of Agricultural, Environmental, and Development Economics. These budgets can be found at the following website:

Enterprise Budgets updated for 2008 include:
• Corn – Conservation Tillage (NH3, UAN and Urea as Nitrogen sources)
• Soybeans – Round-up Ready, No-till
• Wheat – Conservation Tillage, (Grain and Straw)
• Alfalfa Hay – Spring Seeding
• Grass hay – Large Bale System
• Dairy Cow and Replacement – Large Breed
• Ewe and Lamb - Winter Lambing
• Retail Sweet Corn – Conservation Tillage, Hand Harvested
• Large-Scale Popcorn – Conservation Tillage
Our enterprise budgets are compiled on downloadable Excel Spreadsheets that contain formulas for ease of use. For those of you without Microsoft Office, you can use the freeware office suite “OpenOffice” to view these files. You can access this at Users can input their own production and price levels to calculate their own numbers. These Enterprise Budgets have a new look with color coded cells that will enable users to plug in numbers to easily calculate bottom lines for different scenarios. We have included detailed footnotes to help explain the methods and sources used to obtain the budget numbers. Starting this year, we will be updating these Enterprise Budgets periodically during the year to reflect any large changes in prices or costs. Budgets will include a date in the upper right-hand corner of the front page indicating when the last update occurred.

Another major update to these budgets is the addition of a “Machinery Costs” page. We make it available to show all the steps involved in the calculations of the machinery. Click the “Machinery Costs” tab at the bottom of the spreadsheet to view these expanded calculations.

Included in the Sweet Corn budget is a new system for calculating chemical costs. As an alternative to inputting the chemical costs directly, the budget separates the chemical applications by different growth periods (i.e. at planting and during silking for insecticides). Users can input the application rate (by typing the number in the yellow box, then selecting the unit in the dropdown cell in green) and their cost per unit (the unit will automatically change, so users can leave this as is) and the budget formulas will do the calculations for you and give you the chemical costs at various stages. This system is a trial and we are asking for feedback. Please e-mail your constructive feedback to Brian Freytag: Highlights (or lowlights) of this years Crop Enterprise Budgets include increased prices for diesel and nitrogen. Three different Corn Production Budgets were developed to view the cost implications of using different nitrogen sources. We have included Anhydrous Ammonia (NH3), UAN (or 28% Nitrogen), and Urea. To help streamline your ability to view the costs of the fertilizers per acre, simply go to the Fertilizer footnote in any crop budget (usually footnote 3 or 4) and input the costs per ton of Nitrogen, MAP and Potash, and the budget formula will automatically calculate the cost per lb. of actual N, P2O5, or K2O for you.

The entire set of Enterprise Budgets can be accessed at:

Armyworm Update

Authors: Ron Hammond, Andy Michel, Bruce Eisley

We continue to receive numerous reports of armyworm larvae in many cereal grains, including wheat, rye, spelt, timothy, and barley. Growers are urged to scout their crops, and also be on the look out for armyworm in corn either planted into a grass cover crop or adjacent to a cereal grains. A rescue treatment on cereal grains might be needed if larvae cause significant defoliation, and you have 5-6 larvae per foot of row. Larvae should be small with significant growth left; large larvae probably have done their predominant feeding. Although head cutting is thought to occur, this is relatively rare. Do not assume head cutting will occur; larvae are more likely to move out of the crop to adjacent fields. If you are dealing with corn, you do not want significant defoliation to occur. If stand infestation is greater than 20%, consider a rescue treatment when corn is at early-whorl stage and larvae are less than 1 inch long, and you have more than 1 larva per plant or defoliation of infested plants exceeds 50%.

Soybean Aphid Update

Authors: Ron Hammond, Andy Michel, Bruce Eisley

Early June is when we would expect soybean aphids to leave buckthorn (their overwintering sites) to colonize soybean plants. However, as mentioned in earlier articles in C.O.R.N. and throughout the winter at various meetings, there were not very many aphids observed this winter. Few, if any eggs were observed, nor were any spring aphid colonies on buckthorn in much of the Midwest and Ohio. Thus, based on those very low numbers and certain other criteria, we have predicted low, non-economic populations this coming summer. However, as with all assumptions and predictions, there are often exceptions to the rule. Meaning, we could be proven wrong. Our colleague to the north, Chris Difonzo, has reported finding small aphid colonies in her plots in Michigan. Thus, we will need to keep a close eye on the situation. If aphids build up to economic populations to our north, Ohio will run the risk of problems later this year.

We plan on monitoring the soybean aphid situation throughout the summer, as should you. If scouting for aphids on your own, you should expect them to be in low numbers, perhaps only finding one or two aphid per plant. At these low densities, you need to keep from misidentifying them as small potato leafhopper nymphs (, thrips (, mealy bugs (, or other small insects. You can only do this using a small hand lens. Soybean aphids will be located on the upper most leaves of the plant at this time, those leaves that are just opening up and expanding. They are round or oval shaped with 2 cornicles (or tail pipes) and will usually remain in one spot if touched. Most of these other insects, especially the thrips and leafhoppers, will be very active on the leaf or when disturbed.

Remember, there are a lot of beneficial predators in the soybean fields that will hopefully help to keep the aphid numbers reduced. In a low aphid year, these beneficials are perhaps our most important allies in keeping aphid numbers down. We urge vigilance and continued scouting. But if aphids start to multiply, use the 250 aphids per plant threshold with a rising population before any action is taken. Even with higher soybean prices, the 250 threshold is still considered an appropriate level to use.

Finally, keep reading the CORN newsletter for up to date information. If the situation with soybean aphid changes in Ohio, the newsletter will be one of the first places to hear it. If you have soybean fields that do begin to have large populations, please let your county extension educator or us know. We want to keep on top of this.

European Corn Moths are Being Seen

Authors: Andy Michel, Ron Hammond, Bruce Eisley

European corn borer moths have been observed flying in Ohio. Those fields with the Bt corn borer gene are safe from the ravages of this insect. However, refuge areas, and fields without the gene should be checked for first brood borers. If fields are nearing the whorl stage, then signs of early larval activity may be found if one inspects a significant number of plants. Egg masses may be found on the underside of corn foliage if one searches long and hard. If whorl injury (shot holes and window-pane feeding) is apparent, then about 20 plants should be inspected at 5 locations to determine the percentage of stand exhibiting whorl injury. During scouting, a number of whorls should be pulled and opened to determine presence or absence of ECB larvae. When larvae are found, the average number of larvae per plant may be estimated based on the proportion of stand exhibiting whorl injury and the proportion of injured plants actually having larvae present. Rescue treatment for first-generation control is warranted when 50 percent or more of the plants exhibit feeding damage in the whorl and early instar larvae can be readily found either on the foliage or in the whorl. Treatment information can be found at:

10 Tips to Get the Most out of Your Sprayer

Authors: Erdal Ozkan

Paying attention to certain things will help you improve the accuracy and performance of your sprayer and save you money. Applying chemicals with a sprayer that is not calibrated and operated accurately could cause insufficient weed, insect or disease control which can lead to reduced yields. The following “Top Ten” list will help you improve the performance of your sprayer and keep it from failing you:

1) Check the gallon per acre application rate of the sprayer. This can only be determined by a thorough calibration of the sprayer. Use clean water while calibrating to reduce the risk of contact with chemicals. Read OSU Extension Publication AEX-520 for an easy calibration method (

2) How the chemical is deposited on the target is as important as the amount applied. Know what kind of nozzles are on your sprayer and whether or not their patterns need to be overlapped for complete coverage. Make sure the nozzles are not partially clogged. Clogging will not only change the flow rate, it also changes the spray pattern. Never use a pin, knife or any other metal object to unclog nozzles.

3) In addition to clogging, other things such as nozzle tips with different fan angles on the boom, and uneven boom height are the most common causes of non-uniform spray patterns. They can all cause streaks of untreated areas that result in insufficient pest control and economic loss.

4) Setting the proper boom height for a given nozzle spacing is extremely important in achieving proper overlapping. Conventional flat-fan nozzles require 30 to 50% overlapping of adjacent spray patterns. Flood-type nozzles require 50% overlapping. Check nozzle catalogs for specific recommendations for different nozzles.

5) Know your actual travel speed, and keep it steady as possible. Increasing the speed by 20% may let you cover the field quicker, but it also cuts the application rate by 20%. Similarly, a reduction of speed by 20% causes an over application of pesticide by 20%; an unnecessary waste of pesticides and money.

6) Pay attention to spray pressure. Variations in pressure will cause changes in application rate, droplet size and spray pattern. At very low pressures, the spray angle will be noticeably narrowed, causing insufficient overlap between nozzle patterns and streaks of untreated areas.

7) Don’t waste your chemical. After all, you have paid for it. Spray drift wastes more chemicals than anything else. Don’t spray when the wind speed is likely to cause drift. Don’t take the risk of getting sued by your neighbors because of the drift damage to their fields. Keep the spray pressure low if it is practical to do so, or replace conventional nozzles with low-drift nozzles. Use other drift reduction strategies: (a) keep the boom close to the target, (b) use drift retardant adjuvants, and (c) spray in early morning and late afternoon when drift potential is less.

8) Carry extra nozzles, washers, other spare parts, and tools to repair simple problems quickly in the field.

9) Calibrate your sprayer periodically during spraying season to keep it at peak performance. One calibration per season is never enough. For example, when switching fields, ground conditions (tilled, firm, grassy) will affect travel speed, which directly affects gallon-per-acre application rate.

10) Be safe. Wear the protective equipment listed on the label. Be sure you have the proper type of gloves and respirator if required.

Stagonospora leaf and glume blotch on wheat

Authors: Pierce Paul, Dennis Mills

Stagonospora blotch on the leaves and glumes of wheat is being reported in some fields in northern Ohio. This disease is favored by warm temperatures (68oF to 81oF) and frequent rainfall, both of which we have had over the past week of so. It usually first appears as dark brown flecks on the lower leaves within a few weeks of head emergence, and once conditions are favorable (warm and rainy), continues to spread to the upper leaves and spike during grain development. Well-developed lesions are oval and dark brown, with grayish-white center with tiny brown spore-bearing structures called pycnidia (dark dots in the center of the lesions).

Stagonospora leaf blotch can be easily confused with other foliar lesions, some of which are not caused by pathogens. Adverse weather conditions (temperature extremes), chemical injuries, genetic features, and other pathogens may result in lesions similar to those of Stagonopora leaf blotch. Adding to this possible confusion is the fact that varieties differ in their sensitivity to weather extremes and chemical injuries, just as they differ in susceptibility to Stagonospora. However, the shape, color and presence of pycnidia are important features to help separate Stagonospora leaf blotch from other types of foliar lesions.

The greatest yield losses due to Stagonospora occur when the flag leaf and the leaf below the flag leaf become infected by the time the wheat flowers in late-May/early-June. If these leaves are killed before the soft dough stage, the grain will be lightweight and shriveled. Losses can be as high as 20 to 30 percent. Most of the fields from which the disease is being reported has completed flowering before the level of disease increased. Even if the disease continues to develop, grain fill will likely be completed before the flag leaf is damaged. However, if the variety is highly susceptible, severe blighting of the spikes and upper leaves during grain fill may still result in yield and quality losses; however, these losses will be much lower than if infection occurred at an earlier growth stage.

Several fungicides with good to very good efficacy against Stagonospora are available. However, most of the efficacy data are based on flag leaf (Feekes 8) or boot (Feekes 10) applications and not post-flowering applications. In addition, most of the products are off label and should not be applied after flag leaf emergence (Feekes 8), for Stratego, and full head emergence (Feekes 10.5) for Quadris, Quilt, Tilt, Proprimax and Headline. The pre-harvest interval for these products is between 30 and 45 days. See labels for more details.

Weather Update

Authors: Jim Noel

In this report, we will review the past week and what is on tap. We will also look at what is going wild with the pattern and what we can take from it.

1. We expect heavy rain this past week in the northern half of Ohio. We got it, but it was the southern half. That is that happens with these storm complexes, they often drift further south. 0.25 to 1.5 inches of rain fell in the north (within the normal range). However, the southern half had anywhere from 2-5 inches. Some isolated, 6 inch amounts occurred in the far southwest. Temperatures were well above “normal,” statewide.

2. We can expect another round of rain and storms across our area Monday night into Tuesday. The next round will be about Friday. Temperatures will start out this week hot, but will retreat only slightly above normal thereafter. Looking down the road, expect temperatures to be slightly above normal for the rest of June with near normal rainfall. However, note, there will be these streaks of heavy rainfall from time to time over smaller areas of Ohio in a west to northwest flow pattern. It also looks like the heaviest rains will continue to pound the central and western cornbelt, so things will be far worse west of Ohio with crop losses likely.

3. I have been looking into why the wet winter pattern, which did change by April 10th for the rest of April to a cool and dry pattern, reverted to a wetter pattern for May and especially June. The answer is complex, but it appears to revolve at least partly around 2 La Nina years biasing the strong La Nina event data and the North Atlantic Oscillation (relationship between pressure fields in the North Atlantic).

For more information see Jim Noel’s website:


Archive Issue Contributors: 

Pierce Paul, Anne Dorrance and Dennis Mills (Plant Pathology), Ron Hammond, Andy Michel and Bruce Eisley (Entomology), Jim Beuerlein (Soybean & Small Grain Production), Peter Thomison (Corn Production), Barry Ward (Agriculture Economics) and Jim Noel (NOAA). Extension Agents and Associates: Rory Lewandowski (Athens), Jonah T. Johnson (Clark), Roger Bender (Shelby), Howard Siegrist (Licking), Glen Arnold (Putnam), Greg LaBarge (Fulton), Steve Foster (Darke), Harold Watters (Champaign), Mike Gastier (Huron), Wes Haun (Logan), Marissa Mullett (Coshocton), Ed Lentz (Seneca), Les Ober (Geauga), Steve Bartels (Butler), Steve Prochaska (Crawford), Gary Wilson (Hancock), Tim Fine (Miami), Suzanne Mills-Wasniak (Montgomery).

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.