August 13, 2012
URBANA - The USDA's August Crop Production report confirmed prospects for small U.S. corn and soybean crops and the need for consumption of both crops to decline sharply in the year ahead. Price behavior since the release of the USDA reports last Friday suggests that both the corn and soybean markets believe that production forecasts will increase and/or prices are already high enough to motivate the necessary rationing. University of Illinois agricultural economist Darrel Good said such conclusions may be premature.
"Prices will now begin to reflect expectations for any changes in the production forecasts and confirmation that the necessary rationing is occurring," Good said. "Indications of the pace of consumption will be provided by weekly reports of exports, ethanol production, and broiler placements and monthly reports of the domestic soybean crush, cattle feedlot inventories, and dairy cow numbers."
Good noted that new production forecasts will be released in September, October, and November and the final estimate will be released in January.
"Expectations for changes in yield forecasts this year are partially influenced by changes in those forecasts in previous dry growing seasons and by weather conditions the rest of this month, particularly for soybeans," Good said. "The history of changes in yield forecasts in dry years provides a mixed picture, particularly for corn."
The U.S. average corn yield estimate in January following harvest was below the August forecast by 2.2 bushels in 1980, 18.3 bushels in 1983, 12.1 bushels in 1995, 12.2 bushels in 2010, and 5.8 bushels in 2011. The January yield estimate was above the August forecast by 0.8 bushel in 1991, 6.1 bushels in 1988, and 4.8 bushels in 2002.
For soybeans, the January estimate was below the August forecast by 0.6 bushel in 1980, 4 bushels in 1983, 2.3 bushels in 1984, 1.5 bushels in 1995, 6 bushels in 2003, and 0.5 bushel in 2010. Good said the large decline in 2003 reflected, at least in part, widespread damage from soybean aphids. The January estimate was above the August forecast by 0.8 bushel in 1988.
The pattern of yield forecast changes was different in each year for both corn and soybeans.
Good said current expectations for corn appear to be in a range of 5 bushels above to 5 bushels below the August forecast of 123.4 bushels, wheras expectations for soybeans are 1 or 2 bushels above to 1 or 2 bushels below the August forecast of 36.1 bushels.
"Changes in production forecasts will also be influenced by any changes in the estimates of harvested acreage," Good said.
In the years identified above, the difference between planted acreage of corn and harvested acreage for grain ranged from an unusually low 6.269 million in 1991 to 11.082 million in 1980. The USDA's August survey found an expected difference of 9.044 million this year, less than the 9.467 million of 1988 and the 9.564 million of 2002. The difference between planted and harvested acreage of soybeans ranged from only 788,000 in 2003 to 2.117 million in 1980. The August survey this year found an expected difference of 1.445 million, very similar to the difference in 1988.
"Based on the August production forecasts, the USDA's World Agricultural Supply and Demand Estimates August report projected minimum 2012-13 marketing year-ending stocks for both corn and soybeans," Good said. "Even with larger imports and a draw down in stocks, consumption of U.S corn needs to decline by 1.265 billion bushels (10.1 percent), and consumption of U.S. soybeans needs to decline by 399 million bushels (12.7 percent) during the year ahead," he said.
Good said that for corn the biggest question for demand centers on the ethanol market.The USDA projects a 500 million bushel year-over-year decline in the use of corn for producing ethanol and byproducts.
"Ethanol demand will depend on a number of factors, including export demand, expected domestic fuel consumption, and the use of credits from previous discretionary blending to meet part of the 2013 mandate," Good said. "However, the transition to a heavy dependence on ethanol as an octane enhancer and the low price of ethanol relative to gasoline suggests that the decline in corn used for ethanol will be less than 500 million bushels. That conclusion would not change even with a partial waiver of the mandate. The 250-million-bushel expected decline in exports depends to some extent on the expectation of very large crops in South America in 2013 and a slowdown in Chinese imports. If ethanol and export demand is stronger than projected, as we suspect, the reduction in feed and residual use of corn will have to be larger than the current projection of 475 million bushels (10.4 percent)," he said.
Good reported that for soybeans, the small crop is expected to result in a 175-million-bushel (10.4 percent) cut in the domestic crush and a 240-million-bushel (17.8 percent) cut in exports. The large cut in exports reflects the forecast of a record-large harvest in South America in 2013. U.S. export sales for the 2012-13 marketing that begins on Sept. 1 already account for 51 percent of the projected exports for the year.
August 2, 2012
URBANA - Many Illinois farms are starting to, or plan to, harvest drought-stressed corn, hoping to salvage it as livestock feed. University of Illinois beef extension specialist Travis Meteer answers some frequently asked questions.
Q: Do I need to test for nitrates?
A: Yes, elevated levels of nitrates have been well documented across the state. Cattle are valuable, and the test is inexpensive.
Q: When do I test for nitrates?
A: In most cases, before harvesting and after ensiling. Testing before harvest is a must if the drought-stressed corn will be grazed or green chopped. If the corn will be chopped for silage, test it after the ensiling process has finished, at least 3 to 4 weeks after ensiling. Do not feed it to livestock before knowing the test results.
Q: Where do I get a nitrate test?
A: There are labs in Illinois and surrounding states. ADM in Quincy, Ill., and Agri-King in Fulton, Ill., are certified with the National Forage Testing Association. A complete list is available at http://web.extension.illinois.edu/oardc/downloads/43921.pdf .
Q: What happens if I feed too much high-nitrate corn silage to my livestock?
A: They can get nitrate poisoning. Symptoms are blue-gray discoloration of skin, difficult rapid breathing, weakness, lack of coordination, rapid heartbeat with a subnormal temperature, and dark, chocolate-colored blood. Death occurs soon after the symptoms appear.
Q: Can I chop following a rain?
A: Wait 3 to 5 days. After rainfall, the increase in available moisture causes plant nitrate uptake to increase. The plant needs time to metabolize the nitrates. Some of the highest nitrate test results have come from samples that were taken after a rain. Be very cautious about chopping corn silage following a rain.
Q: What is the best way to harvest drought-stressed corn?
A: Chop for silage and ensile it.
Q: I have problems with uneven dry matter (DM) in my fields (hillsides are dryer than bottoms).
A: The moisture in the field may not be ideal for harvesting. Strongly consider using an inoculant to help mitigate risk.
Q: Is it beneficial to add inoculant this year?
A: Yes, the corn this year will likely be uneven, with DM hard to predict, and have low bacteria levels.
Q: Can I round-bale this drought-stressed corn?
A: Yes, but it will NOT reduce nitrate levels. Round-baling corn is challenging and puts considerable strain on equipment. Dry down of the stalk is crucial; the stalk dries better if crushed. Uneven moisture can result in bale spoilage. The stalk portion could be dangerous to the cattle. Many times the cattle will sort bales and leave the stalk last. If they are forced to eat the stalk and the stalk is high in nitrates, problems could follow. Make sure to test the bales for nitrates, preferably both before and after harvest.
Q: What about wet-baling drought-stressed corn?
A: Wet-baling corn is not a common practice. In theory, the material in the bales should ferment, decreasing nitrate levels by nearly 50 percent. A thicker plastic may be needed (6 ml) to prevent the corn from poking holes in the plastic and compromising the anaerobic environment.
Q: What is the feed value of drought-stressed corn silage?
A: Usually around 80 percent of the value of normal corn silage, ranging from 70 to 100 percent. The net energy of gain may be lower, but the net energy of maintenance is comparable. Protein will be higher, and the feed value is still good.
Q: What happens if the test results indicate high nitrate levels?
A: Hay, straw, corn silage with lower nitrate levels, and by-products can be used to dilute the feed so the nitrate levels are below the toxic level (>17,600 ppm nitrate). Consult with a nutritionist or extension specialist before feeding.
Q: I do not have a mix wagon. How do I dilute the corn silage with other feeds?
A: Limit-feed the corn silage and offer hay or another roughage free-choice. This is not a precise dilution method, but it will work. Make sure to have the silage tested to determine what portion of the total ration it can be.
More information about drought-stressed corn is available at http://web.extension.illinois.edu/oardc/.
July 30, 2012
URBANA - The National Agricultural Statistics Service (NASS) of the USDA will release the first yield and production forecasts for the 2012 U.S. corn and soybean crops on August 10. The first forecasts of the season are always highly anticipated, but none more than this year as widespread drought conditions have resulted in a wide range of yield and production expectations, according to University of Illinois agricultural economist Darrel Good.
"While the USDA's August forecast will provide a benchmark for the size of the 2012 corn and soybean crops, the market will continue to form yield expectations beyond the release of the report," Good said. "Analysts use a combination of techniques to judge yield potential, including crop condition ratings, crop weather models, satellite imagery, and analogue years. In the case of analogue years, there were six previous years since 1960 when the U.S. average corn yield was more than 10 percent below the unconditional trend yield. The shortfall in those years ranged from 10.4 percent to 25.6 percent and averaged 17.5 percent. A U.S. average yield 17.5 percent below trend would result in a 2012 average yield of 131 bushels, while a yield 25.6 percent below trend would result in an average yield of 118 bushels.
"There were also six previous years since 1960 when the U.S. average soybean yield was more than 10 percent below the unconditional trend yield. The shortfall in those years ranged from 11.8 percent to 19.3 percent and averaged 14.9 percent. A U.S. average yield 14.9 percent below trend would result in a 2012 average yield of 36.7 bushels while a yield 19.3 percent below trend would result in an average yield of 34.8 bushels," Good said.
Good reported that, in addition to yield, the size of the 2012 crops will be influenced by the magnitude of harvested acreage. "Harvested acreage, particularly for corn grain, may be unusually small in relation to planted acreage, further reducing production potential. The corn and soybean markets continue to trade smaller and smaller crops, but prices may not yet reflect the full extent of production shortfalls," he said.
Good provided a review of the NASS methodology for making corn and soybean yield and production forecasts. Data for the forecasts are collected in two separate surveys conducted roughly in the last week of July and the first week of August for the August report.
The Agricultural Yield Survey (AYS) queries farm operators in 32 states for corn and 29 states for soybeans asking operators to identify the number of acres to be harvested and to forecast the final average yield. The sample of operators is based on a sophisticated sample design to achieve the desired sample size, and each state is expected to achieve a minimum response rate of 80 percent. In 2011, approximately 27,000 operators were surveyed for all crops for the August report. Each operator is surveyed in subsequent months to obtain new forecasts of acreage and yield. Historical relationships indicate that respondents tend to be conservative in early forecasts of final yields (to underestimate yield potential), particularly in drought years. This tendency is quantified and factored into official yield forecasts.
The second survey is the Objective Yield Survey (OYS) and is based on an area frame sample of cultivated land in 10 principal states for corn and 11 states for soybeans. Based on the June acreage survey, a random sample of fields is drawn in each state and enumerators visit these fields to take measurements needed to forecast yields in predetermined segments of the fields.
In 2011, these measurements were taken in 1,920 corn fields and 1,835 soybean fields. For corn, the number of plants and number of ears per segment are counted, and the size of the ears is measured. For soybeans, enumerators measure row width and count the number of plants, number of main nodes, lateral branches, dried flowers and pods, and pods with beans in each segment. The data are used to forecast grain weight (yield) per acre. Each segment is visited in September, October, and November (if not yet harvested) to take new measurements and counts to form new yield forecasts. Just before the operator harvests the field, each segment is hand harvested and weighed. The data from the two surveys are combined to forecast average yield and production.
Good said that the USDA makes new yield and production forecasts in September, October, and November with final estimates released in January. "Because yield forecasts are limited by crop maturity and are influenced by subsequent weather, the August yield forecasts tend to have the largest deviation from the final estimates released in January," he said.
For the period 1970 through 2010, the August yield forecast for corn ranged from an overestimate of 18.3 percent to an underestimate of 10.1 percent. The middle 50 percent of the forecast errors ranged from an overestimate of 1.3 percent to an underestimate of 5.1 percent.
For soybeans, the August yield forecast ranged from an overestimate of 16.2 percent to an underestimate of 10.2 percent. The middle 50 percent of the forecast errors ranged from an overestimate of 3.0 percent to an underestimate of 4.5 percent.
July 20, 2012 - PENN STATE AG SCIENCES NEWS
UNIVERSITY PARK, Pa. -- A unique set of circumstances could lead to a heightened threat of deadly gas being created in silos across the Northeast, according to a farm-safety expert in Penn State's College of Agricultural Sciences.
The phenomenon may have started with the scorching heat wave the region experienced in July -- which has some areas on the edge of drought conditions, according to Davis Hill, senior extension associate in agricultural and biological engineering. It could develop if the region receives normal amounts of rainfall through the rest of the summer.
"There is a now lot of drought-stressed corn, particularly on manured fields," he said. "If this crop receives sufficient rainfall later in the season, there will be a potential for higher-than-average nitrates to build up in the corn plants just prior to harvest. This condition can lead to high gas levels in silos."
During the fermentation process of silage, a number of gases are given off, Hill explained. Of particular concern is a family of gases called oxides of nitrogen -- often referred to as "silo gas."
"The formation of these gases peaks in one to two days after filling and can last for 10 days to two weeks after the fresh, green forage is chopped and blown into the silo," he said. "This is a naturally occurring process and is necessary to ferment the forage so it is usable feed for livestock and for long term storage.
"Sometimes, gas production is so great that it is mistaken for a silo fire. Farmers and passerby’s may witness "smoke" coming from the silo chute and believe the silo is on fire. There has been at least one instance where a fire company was called to a farm for a 'silo fire' just two days after the farmer finished filling the silo.
"Firemen proceeded to pump water into the top of the silo, only to later learn that the silo was just gassing off."
Farmers and fire personnel need to realize that it would be nearly impossible for a silo fire to start so soon after filling, Hill noted. "This is why we always talk of attempting to locate the actual fire location within the silo before any attempts of extinguishment proceed," he said.
Silo gas sometimes has a bleach-like odor and under certain conditions can be visible as a fog from a distance (thus the mistake for smoke). If the gas is high enough in concentration, this fog will appear to be yellow to reddish brown in color and the silage surface, silo wall, base of the chute and other structures of the silo may be stained (yellow, orange, reddish) from the gas.
This gas is heavier than air, which means it will settle at the surface of the silage instead of rising to the top of the silo, exiting through the fill door. This is an important factor, Hill pointed out.
"The highest concentration of gas will be at the surface of the silage, which is where a person will be going if he/she needs to enter the silo for any reason," he said. "Also, if a silo door is open near the surface of the silage, the high concentration of gas (being heavier than air) could exit the silo through this door, and flow down the chute and settle at the base of the silo in the feed room or into the barn area.
"If there is little ventilation in the barn area, a dangerous buildup of silo gas can occur, which can affect livestock or people who enter the area."
The presence and concentration of silo gas is dependent on the storage structure and the quality of the forage material that is chopped. Those crops that have received nitrogen fertilizer (corn) and those crops that have suffered prolonged drought or especially prolonged drought conditions followed by rain just prior to harvest often lead to high gas production.
That could happen this summer, Hill worries. "It appears that this year, with the long droughty period that much of the state endured -- which stunted the corn crop -- there will be more corn harvested for silage and that will be done fairly early," he said.
" The high levels of nitrates in this crop will lead to higher than normal concentrations of silo gas produced during the ensiling process. Operators need to be aware of this and take precautions."
These precautions include assuring all spaces at the base of the silos are well ventilated, silo doors are closed well above the level of the silage surface, stay out of the silo for three weeks after filling the silo and always ventilate the silo with the silo blower for at least 20 minutes prior to entry (however, this is only effective if the silo is over half full). Also, consider leaving the lower 10-12 inches of stalk in the field (chop higher than normal) as this part of the plant may have the highest level of nitrates accumulated.
Individual reactions to silo gas depend on the concentration of gas that is inhaled and the length of exposure, Hill cautioned. Very high concentrations of gas will cause immediate distress, which will result in a person collapsing and dying within minutes. "When gas levels are this high, normally the individual will not be able to withstand the symptoms felt and will vacate the area quickly," he said.
"More mild concentrations could cause upper respiratory congestion, eyes watering, cough, difficulty breathing, fatigue, nausea, etc. If symptoms are mild, an individual may stay in the area to finish the job at hand. This can make the effects of silo gas worse, as these effects can last for many hours in the body, causing symptoms to become progressively worse over the course of the next day or two."
Anyone experiencing any of these symptoms when inside or near a freshly filled silo should immediately exit to fresh air and leave the task for another day. They should also immediately go to their doctor or the hospital emergency room and report he or she has had a serious “silo gas poising” exposure. One after effect of silo gas poisoning is fluid in the lungs leading to chemical pneumonia and perhaps death if not treated promptly. The effects of fluid filling the lungs may not present itself until several hours after the exposureâ€”and then it may be too late.
Remember, Hill pointed out, it is rare for a silo to begin burning in the first week of filling. If a cloud is seen escaping the silo, it is most likely due to silo gas. If the fire company is called, make sure firemen don’t just start pumping water into the silo.
"Ask them to use a thermal-imaging camera to try to identify any excessive heating of the silo," he urged. "A burning silo will give off temperatures of more than 190 degrees at the general location of the fire as viewed with a thermal-imaging camera."Several technical experts are available throughout Pennsylvania to help farmers and firefighters think through the many management strategies when dealing with silo fires. This emergency information can be found by calling (814) 865-2808 during working hours or (814) 404-5441 after hours. The website www.farmemergencies.psu.edu has an excellent resource for fire companies to use in managing silo fires.
EDITORS: Contact Davis Hill Sr. at (814) 865-2808 (office), (814) 404-5441 (cell) or by e-mail at www.farmemergencies.psu.edu.
July 5, 2012
URBANA -- High temperatures and sustained drought, especially in the extreme southern part of the state, have resulted in severe damage to many cornfields, which now are unlikely to produce economic grain yields.
University of Illinois extension educator Robert Bellm reminded producers wanting to salvage this drought-damaged corn for livestock feed to do so very carefully because there may be high nitrate levels in the forage.
“These levels will be highest in fields that received high nitrogen fertilizer or manure applications and in plants that are severely stunted and did not form an ear,” he said.
Nitrate concentrations are highest in the lower third of the stalk. Harvesting or grazing only the upper two-thirds of the plant will greatly reduce the potential for nitrate toxicity.
Forages containing high levels of nitrate may still be safely fed if they are diluted with grain or other feedstuffs that are low in nitrate. “Within limits, animals can be conditioned to consume high-nitrate forages as long as they are introduced to them slowly,” Bellm said.
Drought-damaged corn that is going to be green-chopped and fed should be tested prior to harvest. “Animals should be limit-fed and introduced to the forage slowly,” advised Bellm.
“Making hay from drought-damaged corn will NOT reduce nitrate levels,” he added. “Hay made from drought-damaged corn should be tested prior to feeding.”
Ensiling the forage can reduce nitrate levels by 30 to 60 percent. Because fermentation may take up to 21 days, silage should not be fed for at least 3 weeks after being put into the silo or bag.
“Care should be taken when ensiling high-nitrate forages because of the potential for production of nitrogen oxide silo gases, which are toxic,” Bellm warned.
Because of the variability of nitrate reduction during the ensiling process, silage made from high-nitrate forages should still be tested prior to feeding. Recommended safe feeding levels vary from state to state and are usually given as a range.
Laboratories may report results on a dry matter basis, or “as is” moisture. Test levels based upon “as is” moisture will always be higher when converted to a 100-percent dry-matter basis. Make the conversion for the sake of consistency.
Finally, some areas of the state received scattered rainfall this week. Harvesting drought-damaged forage should be delayed at least five days following a rain event. Immediately after rainfall, there is a rapid uptake of nitrate by the plants. Waiting a few days will allow them to metabolize the nitrate and reduce the nitrate concentrations within the plant.
June 21, 2012
URBANA -- Potassium deficiency symptoms are developing in corn and soybean crops in many parts of the state according to University of Illinois assistant professor of crop sciences Fabián Fernández.
Many farmers are observing this phenomenon for the first time. Conducting nutrient-deficiency diagnostics for crops based solely on visual symptoms is not always easy, but potassium deficiency symptoms are very distinct for corn and soybean.
“For both crops, symptoms start to develop in the older leaves with yellowing of the leaf margins,” Fernández explained. “The yellowing normally starts in the leaf tip and extends to the base of the leaf along the edges of the leaf.”
In more severe cases the leaf edges look dead (brown) while the new leaves remain green because the potassium in the older tissues is remobilized to supply potassium to the newer tissues.
“Sometimes people confuse potassium deficiency symptoms in corn with nitrogen deficiency,” Fernández said. “While nitrogen deficiency also occurs in the older leaves starting at the tip of the leaf, yellowing develops along the midrib toward the leaf base forming a ‘V’ shape.”
What is causing the deficiency?
The symptoms that are showing up in so many fields reflect either 1) insufficient supply due to low soil-test potassium levels or 2) reduced potassium availability due to less-than-ideal soil conditions and slow root activity.
A survey conducted in 2007-2008 found that potassium levels in approximately 45 percent of nearly 550 randomly selected Illinois fields were below the critical level needed to maximize yield. “When soils are below the critical level there is a strong probability of yield reduction even if the crop does not develop deficiency symptoms in the leaves,” said Fernández.
He said that this year, the appearance of deficiency symptoms is a signal that potassium should be applied this fall. “The crops in most of these fields will likely not recover even after growing-season conditions improve,” he cautioned.
Some fields are showing potassium deficiency despite having adequate soil-test potassium levels. This problem is due to the dry soil. Potassium ions need water to diffuse in the soil solution from areas of high concentrations near the soil particles to areas of low concentrations near the crop roots. When soil pores have more air than water, the potassium ions cannot reach the root because they cannot diffuse through air.
“Under droughty conditions, as far as the crop is concerned, it is as if the ions were not present,” Fernández explained. “The problem should disappear soon after growing-season conditions improve.”
Dry conditions also limit root growth and activity, further reducing the crop’s capacity to take up potassium. Other factors that could limit root growth include: soils that are too loose or compacted, root damage by disease or insect pruning, shallow seed-planting depth, and seed-furrow sidewall compaction that occurs when planting in wet soils.
The best way to supply potassium is to apply it in the soil before planting. Similarly, the management practices to prevent soil conditions that intensify the negative effect of dry weather on potassium availability are also done before planting. Thus, there is very little that can be done to correct the problem for this year’s crops.
If factors other than low soil-test potassium are causing the deficiency, applying potassium fertilizer to the soil is not likely to be profitable for the current crop. Even in low-potassium soils a liquid or dry application between crop rows will not be effective unless there is enough rain to move potassium into the root zone.
However, even if there is not sufficient rain to move the potassium, Fernndez points out that the application can begin to correct soil potassium levels for the next crop. An advantage of soil applications is that higher rates can be applied relative to foliar applications.
Research in the Midwest has shown that foliar potassium applications have limited and inconsistent results and are usually not profitable. “To my knowledge, none of the trials showing response to foliar applications occurred under droughty conditions,” said Fernández. “If a foliar potassium application is deemed necessary, I recommend using fluid products that do not contain potassium chloride, potassium sulfate, or other products with a high salt index so higher potassium rates can be applied without danger of canopy injury.”
Fernández suggests looking for clues that may be useful when developing strategies to address the problem. “Take note of the general condition of the roots and the physical condition of the soil, and collect soil samples for potassium analysis from adjacent areas with seemingly normal growth and potassium-deficient symptoms,” he advised.
In most fields, some areas are more severely affected than others. “It would be advisable to mark those areas with a hand-held global positioning system and go back after harvest to take samples and possibly target the area with variable rate applications,” he concluded.
June 20, 2012
URBANA -- With much of Illinois suffering from abnormally dry to severe drought conditions, the current risk of corn foliar diseases is low in most of the state.
University of Illinois plant pathologist Carl Bradley said that, although foliar fungicides are touted as increasing corn yields, these effects have not been observed consistently in U of I trials when foliar disease pressure is low.
Since 2008, the plant pathology program in the U of I Department of Crop Sciences has conducted annual foliar fungicide trials on corn across the state. In these trials, a number of products, including Headline, Headline AMP, Stratego, Stratego YLD, Quilt, Quilt Xcel, and Bumper, were applied between the VT and R1 growth stages (tassel emergence to beginning of silking). At each location, disease severity was measured four weeks after applying the fungicides by evaluating the ear leaves of each plot and estimating the percentage of leaf area affected by diseases.
The results indicated that disease pressure plays a critical role in the magnitude and consistency of yield response to a foliar fungicide application in corn. The difficult part is predicting before the VT stage the level of disease pressure likely to develop later in the season.
Predictions have to take into account disease risk factors, which include:
Susceptibility level of the corn hybrid. Seed companies can provide information on their hybrids’ susceptibility to gray leaf spot and northern leaf blight. Hybrids that are more susceptible to fungal foliar diseases tend to respond best to a foliar fungicide (if disease pressure is high enough).
Previous crop. Many foliar pathogens survive in corn residue, so the risk of foliar diseases (such as gray leaf spot and northern leaf blight) increases when corn is planted back into a field that was corn the previous year.
Weather. The risk for disease development increases in rainy and/or humid weather.
Field history. Fields in river bottoms, low areas, or surrounded by trees may be more prone to foliar corn diseases.
Scouting observations should also be taken into account. Scout for foliar diseases in corn just before tassel emergence. Current disease management guidelines suggest applying foliar fungicide under the following conditions:
For susceptible hybrids, if disease symptoms are present on the third leaf below the ear or higher on 50 percent of the plants examined.
For intermediate hybrids, if disease symptoms are present on the third leaf below the ear or higher on 50 percent of the plants examined, if the field is in an area with a history of foliar disease problems, if the previous crop was corn, if there is 35 percent or more surface residue, and if the weather is warm and humid.
For resistant hybrids fungicide applications generally are not recommended.
“According to the data from the corn fungicide trials, if at least 15 percent of the ear leaf area is affected by disease at the end of the season, a foliar fungicide applied between VT and R1 probably would have been beneficial,” Bradley said.
June 12, 2012
URBANA -- The dry conditions that continue to persist over much of Illinois and the Midwest are causing nutrient deficiency problems. Unfortunately, only rainfall will fix some of these problems.
University of Illinois assistant professor of crop sciences Fabián Fernández said he does not recommend foliar or soil application of nutrients. Many corn fields show potassium deficiency even though adequate fertility is present in the soil. One question being asked is: Why is potassium deficiency showing up in corn more often than any other nutrient deficiency?
“I believe the most likely reason is that, early in development, corn takes up larger amounts of potassium than of nitrogen and phosphorous,” explained Fernández. “Soon after the V12 development stage, corn has already taken up half of all the potassium it will need.” By the R1-R2 development stages, the plant has taken up all of the potassium it will need (around 170 pounds of K2O per acre).
In contrast, nitrogen and phosphorus are taken up until sometime after the dent stage (R5). Unlike nitrogen, which moves freely over large distances in the soil solution, phosphorous and potassium can move only a few millimeters at most; thus, when the soil dries out, their position makes them unavailable to the crop.
The reason this happens is that pore space in the soil contains water and air. Plant-available potassium ions are dissolved in the soil water or attached to soil particles ready to come into solution as the plant needs them. When there is sufficient water in the soil, the potassium ions dissolved in water have to travel (by diffusion) only a short distance to be taken up by the crop.
As the soil dries out, the pore space fills with air. The potassium ion has to travel across a larger distance to reach the root because it cannot diffuse through air. Increased diffusion time can cause important reductions in potassium availability to corn during vegetative stages when potassium demands are large.
“Under dry conditions, the soil is unable to keep up with the crop demand even though there might be sufficient potassium in the soil,” Fernández explained.
Phosphorus availability can be limited in a similar way. However, the plant does not have high demands for it over a relatively short period of time as it does for potassium, and the crop needs less phosphorus than potassium (about 80 pounds of P2O5 per acre). Thus, the plant is probably still able to obtain enough phosphorus and the crop is less likely to show phosphorus deficiency symptoms.
In the worst case, as the soil dries out, the distance that the potassium ion has to travel becomes so large that it is not available to the plant. “This is what we are seeing in many fields,” Fernández said. “Even though these fields have adequate K levels, as far as the plant is concerned the nutrient is out of reach.”
While there is nothing that can be done to solve the current drought problems, this year has taught producers a number of important lessons.
“For the future, I recommend that we minimize the effect of drought by ensuring that any water in the soil is protected to be used by the crop,” Fernández said. “This year some farmers have seen firsthand how much water weeds can take up when not treated early in the season.”
Similarly, too much tillage in some situations has caused unnecessary water evaporation from the soil and those fields are running out of water sooner than those that were managed more carefully.
June 21, 2012
URBANA -- During the later stages of June and early July, it will become increasingly important to monitor corn and soybean fields for some important pests warned professor of entomology and crop sciences Extension coordinator Mike Gray.
“For many areas of Illinois, the dry and hot weather makes this recommendation even more important because crops are increasingly vulnerable to yield loss under these stressful conditions,” he said.
Japanese beetles can now be found throughout the state of Illinois. They can cause injury and subsequent yield loss in both corn and soybeans.
In soybeans, Japanese beetles are one of many defoliators to monitor. Rescue treatments may be warranted if defoliation levels reach 30 percent prior to bloom and 20 percent between bloom and pod fill.
In corn, the key concern is the potential for excessive silk clipping. Plants that are under severe moisture stress are vulnerable to this type of injury because they cannot grow sufficient silk tissue to keep up with the beetles’ clipping activity. During the reproductive phase of plant development, a rescue treatment may be needed if there are three or more beetles per ear and pollination is not finished.
Densities for this pest tend to be greatest along field margins in both corn and soybean fields. “Treatment decisions should be made only after scouting field interiors and border rows,” Gray warns.
The adult western corn rootworm has emerged nearly one month early. In the fields where plants have not begun to tassel and shed pollen, beetles are feeding on corn-leaf epidermal tissue and will continue to do so until pollen and silks become available. “Leaf injury reduces the plants’ photosynthetic efficiency, so some yield loss should be anticipated for those fields, particularly those that are under moisture stress,” Gray said.
As silks become available, a rescue treatment should be considered if there are five or more beetles per plant, silks have been clipped to less than one-half inch of the ear tip, and the pollination process is not complete. While scouting for silk clipping, look for lodged or goose-necked plants. This is evidence of larval injury to root systems.
“If lodged plants are observed, dig up some of the plants, wash the soil from the root systems, and look for signs of feeding or pruning,” Gray advised. “If excessive injury is found, contact your seed company representative.”
Hot, dry weather and two spotted spider mites are typically found in tandem. Many producers are still trying to forget the drought of 1988 and the severe outbreak of mites that occurred across much of the Corn Belt. Mite infestations have been reported in soybean fields that have missed the widely scattered rain showers.
Generally, soybean plants along field margins are the first to show the characteristic bronzing and mottling of leaves. “By tapping the leaves over a sheet of white paper, you can observe mites moving about the surface of the paper,” Gray said. “Often, webbing is present on the lower surface of leaves.”
A 1988 study found that as spider mite injury to soybean leaves intensified, photosynthetic efficiency decreased, stomatal resistance increased, transpiration rate decreased, and the total chlorophyll content of leaves decreased. Symptoms included pale green leaves and some yellow mottling.
If mite injury to plants is evident along field margins, and mites are found on plants with relative ease throughout a field, consider a rescue treatment, especially if hot and dry weather is expected to continue. The most common insecticides used as rescue treatments include chlorpyrifos (Lorsban 4E and generics) and dimethoate. In 1988 many fields were treated multiple times due to the continuing drought and the residual activity of the products lasting approximately one week. Many of the fields in which only border rows were treated ultimately required full-field sprays.“At this point, it’s difficult to predict where this summer is headed with respect to this pest,” Gray said. “Let’s hope we begin to see more widespread and abundant precipitation across the state. If this occurs, twospotted spider mite infestations will abate.”
July 12, 2012
URBANA -- Amid the trauma of ongoing drought and declining corn and soybean conditions in Illinois there is some good news.
According to University of Illinois crop sciences professor Emerson Nafziger, the 2012 wheat yield came in higher than expected with the July 1 yield estimate raised to 64 bushels per acre. That ties for third-highest yield on record for Illinois and is 5 bushels higher than the average over the last decade.
The good yields were of excellent quality. Test weight values - an indirect measure of quality - were among the highest ever seen. Good wheat yields and high test weights both resulted from dry weather this spring.
“Dry weather limits disease, makes harvest possible without the grain getting wet, and in general provides good conditions for wheat to fill grain,” Nafziger explained.
The very early start to spring growth under high March temperatures followed by frost the second week of April might have kept yields from being even higher. The frost did not cause much visible injury, but the crop was in the boot (pre-heading) stage in many fields and there was probably some injury to heads.
“The early warm temperatures might also have decreased tillering and head numbers some, and this might have also decreased the yield potential,” Nafziger said. “Great filling conditions after the frost, however, helped kernels get larger and minimized the effect of reduced kernel numbers.”
The 2012 results of the wheat variety trials conducted at six locations each year are available at http://vt.cropsci.illinois.edu/wheat.html. Average yields by location ranged from 61 at Dixon Springs to 100 bushels per acre at Perry in Pike County in west-southwestern Illinois. Averaged over the three locations in the region, several varieties yielded more than 100 bushels per acre in northern Illinois and several yielded more than 85 bushels per acre in the southern set of trials.
One of the few downsides for wheat in 2012 is that soybean doublecropping following wheat harvest is unlikely to be successful.
With very dry soils after wheat harvest, many producers did not plant soybeans. The soybeans that have been planted are doing poorly and in some cases have failed to germinate or have died after emergence.
“Income from doublecropping helps make wheat work for many producers in the southern half of Illinois, and a poor doublecrop tends to discourage wheat production,” Nafziger said.
As has happened in some previous dry years, wheat might be the highest-yielding crop for some producers in 2012. With the ongoing struggles of the corn and soybean crop and good wheat yields, there might be more interest in planting wheat this fall.
“Even if corn or soybean crops fail or are harvested very early, we need to resist the temptation to get out and plant wheat earlier than the ideal time,” warned Nafziger. “The best time to plant ranges from mid-September at the northern edge of Illinois to mid-October at the southern tip. In the meantime, we can use results from trials to choose good varieties to plant.”
July 14, 2012
URBANA - Crop ratings continue to slide as the crop shows visible symptoms of drought stress in those areas that have received little rain over the past six weeks.
According to University of Illinois crop sciences professor Emerson Nafziger, as of June 10 the National Agricultural Statistics Service (NASS) reports that the average crop height is a record-high 29 inches, but the corn crop is rated at only 56 percent good to excellent (G-E), and the soybean crop is at only 50 percent G-E.
Midwest Regional Climate Center data show that rainfall from May 1 through June 12 ranged from 2 to 5 inches in Illinois, with deficits ranging from 1 to 2 inches along and south of I-80. The large deficit in far southern Illinois was somewhat alleviated by rainfall on June 12, but dryness persists throughout much of the state.
According to the weekly NASS measures of the dryness of the surface and subsurface soil, 26 percent of the topsoil was “very short” of moisture, 52 percent was “short”, and 22 percent had adequate moisture on June 10. Subsurface numbers were similar with 28 percent having adequate moisture.
The Palmer Drought Index of June 5 showed most of Illinois except for the northeastern part as “abnormally dry,” which is the mildest form of drought. A small part of extreme southern Illinois had “severe drought” conditions. Areas north of the severe-drought area and in central-west central Illinois were in “moderate drought.”
“Despite these conditions, soils that can hold 2 to 3 inches of plant-available water per foot of depth should have had enough water to keep the crop growing through mid-vegetative stages,” Nafziger said. However, here are several indications that this year’s crop is feeling the drought.
Water use and photosynthetic rates are closely linked, so a decrease in water availability means a decrease in daily dry-matter production. Thus, even though the recent cooler weather has slowed water use and allowed the corn crop leaves to be out and active longer in the day before rolling up, lower temperatures also mean slower photosynthesis rates.
For corn planted in drier areas or in fields planted later in the season, the current dry period will result in smaller plants. If the weather remains dry, cells that make up kernels, silks, leaves, and seeds may also be restricted in size, with direct effects on yield.
Another problem with the corn crop is that in some areas, the root system was not able to tap the water in the soil. One cause was poorly-developed nodal roots, resulting in “rootless” or “floppy” corn. In some fields that were planted later or into drier soils, soils dried between the moist soil zones and the root ends, preventing the roots from reaching the moisture. Insect or disease problems also can keep roots from reaching moisture.
The soybean crop is also showing symptoms of lack of water. Some soybean fields planted into dry soils have poor stands in places, and others have roots that have not reached soil moisture.
“Leaves don’t roll in soybean as they do in corn, but instead tend to lose turgor and droop, in some cases dropping to vertical orientation,” Nafziger explained. “This helps them avoid sunlight and the heating that comes with it when there is not enough water to keep photosynthesis going, but it also means that they are doing no photosynthesis, which means they are not growing.”
Growth is an increase in plant dry weight, which happens only during photosynthesis in daylight hours and is often not visible to the eye. By forming sugars using the energy of sunlight, photosynthesis powers the processes that result in cell expansion, which occurs when water moves into cells to push out cell walls.
Taking water into cells is not really growth,” Nafziger said. “Still, the ability to photosynthesize and to form grain is affected by cell expansion, so having enough water so cells can expand fully is critically important to the plant.” Cells have to attract water from the rest of the plant to expand, so this process is quite sensitive to water availability.”To see how well plants have been able to tap soil moisture, Nafziger advised looking at how plants are growing. Plants with enough water available will grow to normal height, while those that are unable to get enough water end up shorter than normal. “Plants do tell us, through their growth, how they are doing,” he added.
June 28, 2012
URBANA -- The Illinois corn crop condition continues to deteriorate, with less than 40 percent now rated as good to excellent on June 24, according to University of Illinois crop sciences professor Emerson Nafziger
On the positive side, the current corn crop has good color, is mostly disease-free, and has uniform stands with few drowned-out areas. These factors will contribute to increasing kernel set in fields pollinating now, at least where there is enough soil water. Cooler weather this past week has prolonged the period of adequate water, and cooler nights reduce respiration, thus helping the sugar supply.
On the negative side is the lack of rainfall, with deficits for May and June ranging from 1 to 6 inches in different parts of Illinois. On June 26 the U.S. Drought Monitor showed the entire state as dry, with most of the state in moderate to severe drought and the southern counties in “extreme drought.”
As the crop enters the critical yield-producing stage, many are wondering about the effects the lack of soil water has had, and will have, over the next weeks. “The 2012 corn crop is well-rooted, healthy, and tough, but it’s unrealistic to expect it to continue to thrive as the soil water supply continues to decline in dry areas,” Nafziger said. Plants that are unable to take up enough water to keep leaves from rolling in the afternoon are not fully productive, and this takes a toll on the crop.
“As of June 24, 17 percent of the state’s corn crop was pollinating, the highest percentage for this date on record,” he continued. “This week we would expect most of the crop that was planted by mid-April in central and southern Illinois to begin to pollinate, bringing the number by July 1 to perhaps 40 percent.”
While pollination is the most critical period in terms of yield potential, breeding for aggressive emergence of ear shoots and silks has considerably lessened the likelihood that pollination will fail completely. However, the number of kernels set may be lowered on plants that have been undergoing stress from dry soils, and the number of fertilized kernels that survive the weeks after pollination may continue to decline if the weather stays dry.
Observers in the fields note that corn is entering or approaching pollination while plants are shorter than normal. This raises questions about the connection between plant height and yield.
“Plant height is the best visible indicator of how well the plant has been able to take up the water it needs to expand cells,” Nafiziger explained. “Cell expansion is sensitive to water supply, so shortened internodes are one of the first things we notice on plants that have struggled to take up enough water to keep growing.”
This year, many fields have plants only 5 to 6 feet tall at tasseling, several feet shorter than normal. These plants may grow some after tasseling but will reach full height by the end of pollination. Some of the fields in the driest areas have tried to pollinate while the plants were still very short.
Most of these fields will produce low yields; some may produce no yield at all. Short plants may not be able to form the complete canopies needed for maximum yield because, if they have had trouble getting enough water to elongate their stalks, they may have shorter-than-normal leaves.
Even if the leaf area is normal, leaves may be stacked more closely together on short stalks, allowing for less interaction among neighboring plants and less flexibility of leaf movement. Hence, the plants’ ability to form the complete canopy that is needed to intercept nearly all of the sunlight is reduced. This problem is coupled with ongoing water stress that limits photosynthetic rates.
Is there anything we can do to help the crop get through this dry period?
Not much, according to Nafziger. “When water is clearly the major limitation to plant function, we would expect little or no response to anything we can apply that’s not water.”
As an example, he does not think that applying fungicides to reduce respiration and increase the plant’s sugar supply is likely to help much.
“Strobiluron fungicides do act by reducing respiration, some of which is considered wasteful,” he explained. “But plants that are not photosynthesizing well do not have much sugar to respire away, so reducing respiration probably won’t do much good.” Moreover, fungal diseases that would respond to fungicides are not a threat in most fields today.
By the same token, applying products said to reduce the “ethylene effects” in stressed plants is unlikely to have a positive effect when there is not enough water to keep open the stomata, which they need to do to allow photosynthesis to take place.
Protecting the crop from anything that reduces effective leaf area, such as applying insecticides if enough insects are present to do damage, can help the corn to retain its potential to fill grain if there is rainfall. Foliar nutrients are unlikely to be of much benefit, and the good canopy color in most fields indicates adequate nutrient levels.
While the focus has been on corn, soybean plants are also showing stress effects. Soybeans planted around April 20 at Urbana are now about 24 inches tall and at stage R2 or full flower. With fair-to-good growth and warm temperatures, soybeans are moving quickly into flowering, with 11 percent blooming by June 24.
“An early start to soybean flowering is generally positive, but we remain concerned about how water shortages might affect soybean pod formation,” Nafziger said.
The period over which new flowers appear will last for up to a month as the soybean plants continue to increase node numbers and stem height, and can even recur if stress is relieved after that. This longer flowering period makes the soybean crop better able to set pods and to start filling seeds even if there is some stress during July.
“But if we continue with little or no rainfall, abortion of flowers or of pods will likely continue,” said Nafziger. As with corn, applying materials promoted to reduce stress in soybean is not likely to do much good as long as water supply remains inadequate.
July 12, 2012
URBANA - There is little good news on the drought front, according to University of Illinois professor of crop sciences Emerson Nafziger.
Corn and soybean good to excellent ratings in Illinois are now at 19 and 20 percent, respectively, in Illinois. More than 90 percent of the soils are rated as short or very short on moisture. A few showers over this past weekend offered a little relief but only to small portions of the state.
Every day without rain brings further deterioration in the corn crop. The two main indicators are: 1) A decline in canopy color, from green to yellow to “bleached” white, and 2) Failure of pollination, either with tassels and ears failing to emerge or with tassels emerging but no silks.
“It’s academic which of these takes place in a field; the result will be low kernel number,” Nafziger said.
Less devastating, at least in most cases, will be the loss of fertilized kernels to abortion. Though it is unusual to lose all fertilized kernels to abortion before the start of serious grainfill, Nafziger thinks that this is not out of the question this year.
He also noted that as of July 8, 8 percent of the Illinois crop was listed as being in the “dough” stage. The extent to which these will fill out to become large kernels remains in doubt, but at least they should be recognizable kernels.
Soybean plants on most fields remain in a “holding pattern” with leaves retaining their color but with few flowers forming pods in the drier fields. “It will be a few weeks before we can get a handle on what pod numbers might turn out to be,” Nafziger said.
“We can remain optimistic for now that rainfall could restore good yield potential to the soybean crop in fields where plants have grown to a reasonable height and plants are still showing some growth,” he continued. “In the driest fields that still have green plants, however, plant and leaf size is starting to be limited by lack of water, and at some point this will decrease the ability of the plant to fill the pods that it is able to set.”