FCN Logo College of Agricultural Sciences Penn State

August 6, 1999 Vol. 99.9

IN THIS ISSUE:

Mark Your Calendar

Production

Pest Management

Agents Corner

Degree Day Accumulations

Production:

EVALUATING THE NITROGEN STATUS OF YOUR CORN CROP

One of the most difficult management problems for farmers who grow corn is deciding how to manage nitrogen fertilization. Nitrogen is usually the most limiting nutrient for corn production and is needed in fairly large amounts by the crop. Also, there is considerable concern about the potential for non-point source pollution by nitrogen from agriculture. Thus, decisions about nitrogen management are critical to profitable and environmentally responsible corn production. Management of nitrogen is especially difficult because nitrogen behavior is very dynamic. Nitrogen is constantly changing forms and moving around the soil-plant-water system. Most of these changes and movement are determined by the weather. Our inability to make long range weather predictions makes it equally difficult to predict nitrogen behavior. Also complicating nitrogen management, are the many sources of nitrogen such as the soil, fertilizer, manure, crop residues, and legumes. All of these sources vary in their availability to crops. Finally, there are many possible combinations of materials, methods and timing of nitrogen applications that will influence how much nitrogen is available for the crop.

A major challenge is how to assess whether a nitrogen management program is performing well. Obviously if the management is way off the mark and nitrogen availability is not adequate, the plants will show classic nitrogen deficiency symptoms. Nitrogen deficiency in corn is characterized by a general yellowing of the plant and more specifically by yellow tissue starting at the tip of the corn leaf and going down the midrib of the leaf in a "V" shape. The symptoms will begin at the bottom of the plant and progress up the stalk as the deficiency becomes more severe. As the deficiency progresses the lower leaves may die and fall off the plant. Finding plants with many leaves showing nitrogen deficiency symptoms is a clear sign of inadequate nitrogen for the crop. This may be due to not enough available nitrogen or to larger than expected loss of the available nitrogen. Be sure to look beyond the edge of the field. Often corn plants at the edge will show nitrogen deficiency because the very edge of the field is sometimes missed by fertilizer or manure applications.

Under optimum management for corn grain production, a few leaves at the bottom of the plant will show some nitrogen deficiency as the plant approaches maturity. At the dent stage in corn development, if the lower leaves of the plant are completely green, nitrogen was probably in excess of that needed for optimum grain yield. If the plant is showing nitrogen deficiency symptoms on leaves up to the ear, then nitrogen was probably deficient for optimum yield. A corn plant at this stage of growth should have approximately 4 to 5 green leaves below the ear if the nitrogen management was adequate for grain production. There are factors other than nitrogen that can affect the number of green leaves on the plant so this is not an exact method of determining the nitrogen status of the crop, but it is a relatively quick and easy way to get some assessment of how well your nitrogen management program is working. It will certainly highlight the extremes. With corn silage, while there will not likely be a higher yield if the entire plant remains green, this higher nitrogen status may result in a slightly higher crude protein level in the silage.

The important thing is to at least observe the corn crop regularly for indication of deficient or excess nitrogen to evaluate your corn nitrogen management program.

Douglas Beegle,
Agronomy, Soils

Pest Management:

CONSIDER HERBICIDE RESIDUES IN DEALING WITH SUMMER DROUGHT

Two issues that arise with the current drought situation in much of the Northeast are the potential for herbicide residues in soil and subsequent carryover to rotational crops and grazing/forage restrictions following the use of herbicides if early harvest or emergency forage is needed. Let's first deal with the carryover issue.

Carryover. Herbicide recrop restrictions are based on susceptibility of potential rotation crops to herbicide residues or are based on limits set by EPA for potential residue in feed or food crops. In drought conditions, several herbicides have the potential to persist longer in the soil and injure susceptible follow crops. In corn, pay particular attention to atrazine and simazine (Princep) which can cause problems even in a more "normal" year. Drought conditions will certainly accentuate the problem. Most of the other corn herbicides with a few "exceptions" should not limit the ability to establish a fall forage crop if necessary.

Soybean herbicides may be another matter. Several of our commonly used soybean herbicides limit the planting of fall seeded crops as well as normal rotational crops. However, with the introduction of Roundup Ready soybean and the use of Roundup, herbicide residues and rotation restrictions are less of a concern. Some of the more common crop rotation restrictions are provided in the following table for some potential late summer or fall seeded forage/grain.

Early harvest for forage. As for grazing and forage restrictions, most corn herbicides allow grazing or harvesting of corn for silage following their use. However, almost all products have some time interval or waiting period ranging from 0 days (e.g. Aim) up to as much as 85 days (e.g. Hornet) following herbicide application. Other products specify a certain crop maturity necessary before harvest (e.g. Banvel specifies after milk stage in corn). According to Monsanto, a recently amended Roundup label allows two in-crop applications of Roundup in Roundup Ready corn harvested for either silage or grain. Roundup Ultra treated Roundup Ready corn may be harvested for silage 50 days after the last application. Liberty Link or GR corn, another new genetically modified crop, may be harvested for silage 60 days after Liberty application.

Table 1. Rotation restrictions in months for some potential late summer or fall seeded crops following corn or soybean.
Herbicide  
  Alfalfa Clover Sorghum Winter
Barley		 Spring
Oats		 Winter
Rye		 Winter
Wheat
Corn (Months to planting)
Accent 12 12 10 4 8 4 4
Atrazine productsa 24 24 0 18 24 18 18
Beacon 8 18 8 3 8 3 3
Exceed 18 18 10 3 3 3 3
Hornet 10.5 26b 12 4 4 4 4
Lightning 9.5 40 18 9.5 18 4 4
Permit 9 9 2 2 2 2 2
Princep 24 24 12 18 24 18 18
Pursuit 4 40 18 9.5 18 4 4
Python 4 26 12 4 4 4 4
Soybean  
Broadstrike / Dual 4 26 12 4.5 4.5 4.5 4.5
Canopy 10 12 12 4 30 4 4
Canopy/XL 12 18 10 4 30 4 4
Classic 12 12 9 3 3 3 3
Command 16 16 9 16 16 16 12
FirstRate 9 30 9 30 30 30 3
Raptor 9 18 9 4 9 4 3
Sceptor 18 18 11 11 11 18 3
Synchrony 12 12 9 3 3 3 3
a Some atrazine containing products may be slightly less restrictive.
b 9 mo. For CRP/ARP

Many soybean herbicides are more restrictive. In fact, only Basagran, FirstRate, Lexone, Sencor, Lorox, Liberty, Micro-Tech, Poast or Poast Plus, Prowl, Treflan, and Roundup allow feeding of soybean forage following herbicide application. The Roundup label specifies a 25 day preharvest interval following an in-crop application of Roundup.

Check specific product labels for the correct time interval necessary before harvesting either corn or soybean for forage/silage and for more detailed information.

PESTICIDES AND GMO'S IN THE NEWS

Strained peace: Gerber baby food, grilled by greenpeace, plans swift overhaul…..
(The Following was taken from The Wall Street Journal, July 30, 1999, p A1, 6.)

A letter arrived on the fax machine at the Gerber baby food company in Michigan on May 28 and it certainly got attention. Soon top executives were formulating plans to change its decades-old product that has sales totaling $1 billion a year.

Written by Charles Margulis and addressed "to the CEO," the letter displayed the logo of Greenpeace, the activist European environmental group.

The letter stated, "As you know, there is growing concern around the world about genetically engineered food." Greenpeace is "concerned that the release of genetically engineered organisms into the environment and food supply may have irreversible consequences." It asked if Gerber used genetically engineered ingredients in its baby foods. If so, what products? Mr. Margulis also wanted to know "what steps have you taken (if any) to ensure you are not using" genetically modified substances. He asked for a reply within five business days.

European opposition to genetically modified foods has already taken its toll on American agricultural exports. American consumers have reacted more mildly about the whole issue. The Food and Drug Administration has tried to reassure the public that genetically modified foods "are as safe as other foods in the grocery store."

But, with the involvement of Greenpeace, industry officials worry that the climate in the US could change overnight and damage companies like Gerber, Heinz and Beech Nut Nutrition Corporation.

Already, the maker of the Earth's Best line says it has just decided that all baby food it produces will be made without modified crops. In California, Healthy Times Natural Foods has switched from Canola oil (which is sometimes altered) to safflower oil after hearing from Greenpeace.

Gerber is going a step further than that. The company plans to use corn flour and soy flour that is "organic," with no genetic modifications or insecticides or herbicides. Al Piergallini, president and chief executive officer of Gerber's parent company, Novartis AG, said, "I want our mothers to be comfortable."

Headquarters Press Release, Washington DC EPA Acts to Reduce Children's Exposures to Two Older, Widely Used Pesticides

The U.S. Environmental Protection Agency announced today cancellation agreements and risk reduction strategies to increase protections for American families and their children from risks posed by two of the oldest, most widely used chemical compounds that remain in use as pesticides today. EPA is eliminating specific uses of methyl parathion, and significantly lowering allowable residues for azinphos methyl on a wide variety of produce, including several fruits and vegetables regularly eaten by children.

EPA today also laid out a rigorous 18-month schedule for completing its review of all the "organophosphates," a group of 39 older, common pesticides, which include methyl parathion and azinphos methyl. In addition to the organophosphates, the Agency has targeted several other older, widely used pesticides for priority review within the next year and a half, including the pesticides atrazine, aldicarb and carbofuran, among others.

"Our nation enjoys the safest, most abundant food supply in the world," said EPA Administrator Carol Browner. "I want to emphasize that for children and adults alike, the benefits of a diet that includes fruits and vegetables far outweigh the risks of pesticides.

"Nonetheless, as our scientific understanding of the health risks and environmental effects of pesticides improves, it is becoming increasingly clear that foods can be made even safer, especially for children. Our actions today will protect children from the adverse effects of exposure to pesticides commonly used on foods. The Agency also is on schedule to meet all deadlines for ensuring safer pesticide use under the new Food Quality Protection Act."

EPA's actions are being taken after an extensive scientific review of the risks posed by these chemicals. EPA has worked closely with the U.S. Department of Agriculture and the agricultural community to ensure that our decisions will not disrupt the growing and marketing plans of farmers. As adjustments are made to reduce pesticide risk, EPA and USDA also are working together to ensure that farmers will have alternative pest management tools and substitutes.

The Food Quality Protection Act (FQPA), which was passed unanimously by Congress under the leadership of the Clinton Administration and based on recommendations from the National Academy of Sciences, provides the public, especially children, with unprecedented protection from the risks of pesticide exposure. Under the Act, which the President signed in 1996, EPA is to apply, for the first time, a comprehensive set of new, more protective health-based standards. These standards incorporate the most current scientific knowledge available on pesticide risks, and include an additional 10-fold safety factor to address the special risks of children's exposures to pesticides.

The reductions EPA is making today will address the unique risks children face when exposed to pesticides. For example, it is known that some pesticides pose a greater risk to infants and children because their bodies and internal organs are still developing, which makes them much more susceptible to the effects of pesticides. Children also ingest greater quantities of food and drink relative to their body weight, as compared to adults, which increases their exposure to pesticides.

Based on its concerns, EPA is today eliminating the continued use of methyl parathion - one of the more potent organophosphates - on apples, peaches, pears, grapes, nectarines, cherries, plums, carrots, certain peas, certain beans, and tomatoes, among other fruits and vegetables. For azinphos methyl, also considered to be a pesticide of concern, the Agency is reducing application rates and requiring practices that will result in significant reductions in allowable residues on apples, pears and peaches.

The major manufacturers to enter into these agreements are, for methyl parathion, Cheminova Inc., Wayne, N.J., and Elf Atochem North America Inc., Philadelphia, Pa. For azinphos methyl, the two primary manufacturers are Bayer Corp., Kansas City, Mo., and Makhteshim-Agan, Beer-Sheva, Israel.

In addition to significantly reducing the use of methyl parathion and azinphos methyl on foods popular among children, EPA has taken a number of additional measures to reduce pesticide risks, as called for by FQPA, including:

By the end of next year, EPA is scheduled to complete its reassessment of the organophosphates and several other older, more commonly used pesticides, and to meet the FQPA's food safety goals. A schedule outlining the review of the organophosphates, and a progress report on FQPA is available at: www.epa.gov/pesticides.

World and U.S. Agrochemical Market in 1998

Data recently released by consultants, industry associations and the U.S. Department of Agriculture provide new information on agrochemical sales worldwide and use of pesticides on U.S. field crops.

Several sources estimated the world agrochemical market at approximately US$31 billion in 1998. This represents less than 0.2% growth over 1997 sales, after figuring in currency and inflation factors. Sales of genetically engineered seed, however, increased by 145% over 1997 figures to US$1.6 billion.

According to the American Crop Protection Association, U.S. agrochemical sales by member corporations grew by 1.1% to almost US$9 billion in 1998. Agricultural pesticide use accounted for approximately 82% of sales. Exports remained the same as in 1997 at about US$2.9 billion; however, volume of exports rose by 8.7% to over 700 million pounds.

Herbicides accounted for 68% of total U.S. pesticide sales at approximately US$6 billion. Sales of herbicides for agricultural use fell by 1.8% to US$5.2 billion, while non-crop herbicide sales rose by almost 19%.

Almost 53% of all U.S. agricultural agrochemical sales were for pesticides used on corn and soybeans. Sales of soil-applied corn insecticides increased by 27% in 1998 to US$255 million. Cotton is still the third largest market, but sales were down by 11% from 1997 figures to US$732 million. Rice showed the greatest increase in pesticide sales in 1998, with the market increasing by 28% to US$191 million.

In the U.S. last year, Monsanto's Roundup (glyphosate) replaced Cyanamid's imazethapyr as the most widely used herbicide on soybeans, according to the U.S. Department of Agriculture's National Agriculture Statistics Service. The volume of glyphosate used almost doubled to 28.1 million pounds as a result of increased plantings of Roundup Ready soybeans (soybeans genetically engineered to be resistant to glyphosate).

In the 16 states surveyed, herbicides were applied to 95% of the 65.7 million acres of soybeans that were planted, representing 91% of total U.S. soybean acreage. Glyphosate was applied to 46% of the surveyed acreage at an average rate of 0.7 pounds per acre. In contrast, only 28% of the surveyed acreage was sprayed with glyphosate in 1997.

Herbicides were applied to 96% of the corn planted in the 16 states surveyed. Corn grown in those states represented 89% of total U.S. corn. Atrazine was applied to 69% of the corn and remains the most widely used herbicide on the crop. Insecticides including chlorpyrifos and terbufos were applied to 30% of the corn crop surveyed in 1998.

Ten states were surveyed for upland cotton in 1998, representing 92% of the total acreage. Trifluralin was the most widely used herbicide and was applied to 57% of the area surveyed -- followed by fluometuron (32%) and glyphosate (30%). Insecticides were applied to 71% of upland cotton, with aldicarb being the most widely used.

The USDA's Agricultural Chemical Usage 1998 Field Crops Summary can be accessed from the National Agriculture Statistics Service web site at http://usda.mannlib.cornell.edu:80/usda/

Bill Curran
Agronomy Weed Science

Agents Corner:

CENTRE/CLINTON COUNTIES

The main story here, as elsewhere across the state, is the drought. Although it has not been as severe in these two counties as it has been in others, the drought has reduced yields and continues to be a concern. It seems that each time we reach the point of dire need for some moisture, we receive some (though not nearly as much as we've needed).

The corn crop has been pollinating, and it appears that pollination, though hindered by the drought and heat, has been relatively successful. Depending on soil type and location, condition of the corn crop varies from good to poor.

Soybean, which tends to be a more drought tolerant crop, is flowering now. Spider mites have been thriving in the hot, dry weather and have damaged many fields, especially along the outer edges. A few growers have sprayed for spider mites, but most question the economics of spraying with a questionable crop in the field. Early planted beans look good, while later planted and especially double crop soybeans are quite small and have a long ways to go before they produce much of a crop.

Alfalfa has been taking a beating all season, and yields have been greatly reduced. In many fields, potato leafhoppers have reached damaging populations, but many growers have chosen not to spray because of the low yields associated with the weather.

Like everyone else, we keep looking and hoping for rain to break this drought and make some crops before the season ends.

Gary Dauberman
Centre/Clinton Counties

MIFFLIN/JUNIATA/PERRY COUNTIES

The constant concern in our area, as with the rest of the Northeast is still the dry weather conditions. Area farms have soil moisture conditions varying from slightly below normal to extremely dry. Scattered thunderstorms have provided some areas with timely rains while areas within 5 miles received little or no rain.

The soybean fields are doing fairly well with plant heights ranging from knee high to chest high. Soybeans plants are still flowering and are putting on more pods. Some dairymen are contemplating harvesting their soybean acreage as forage then planting a small grain crop for late fall harvest as forage. One unusual situation reported in our area was soybean leaf damage after a post application of Roundup. Sprayer tank contamination has been ruled out and weather conditions appear to be the reason for the situation.

Corn is extremely variable across the area. In general, earlier planted corn has moderate height and has pollinated. Ear fill is not going to be very good in most fields. Later plantings and fields planted after first cutting hay just did not have enough moisture to grow. Corn plants are still alive, but 2 - 4 foot heights are very common, with not enough growing days left to make any ears.

Alfalfa continues to regrow after cutting, but yields are very low. Second and third cuttings have been 1/3 of normal yields. Leafhoppers are still active and a problem in some fields. Grass hay and pasture fields are mostly brown. A few farmers have gotten a second cutting but most have had little regrowth in these fields. Fields of reed canarygrass have produced a light second cutting.

Greg Hostetter
Mifflin/Juniata/Perry Counties

MONTGOMERY COUNTY

The corn down here is drying quickly. Most of the corn is less than 3 feet tall and earless. Much of it never tasseled. No one will harvest grain this year. Many producers are chopping corn this week. As one producer put it "I'm chopping because I'm tired of looking at it. Its very depressing." I have received many questions about moisture and nitrate testing, and on the value of this material. I didn't realize that there were that many producers here.

Soybeans are short, very short and are beginning to yellow in many fields. There was no second cutting of hay down here, and there will likely not be a third. Grazers have had it very tough for 2 months.

It is difficult to write this report without feeling a little down. Producers will lose a lot of money this year. Literally tens of thousands of dollars. I can't imagine what they are going through. I get down thinking about it, but they are living through it. We can answer the agronomic questions easily, but it's the economic ones that become difficult. Many producers are considering selling their cows and their land.

The Philly High has settled in a bit too long. In the western part of this county it hasn't rained a drop since Memorial Day. The ground is brick hard. Mother Nature is indifferent to all of her species. For a change this Mediterranean rooted homosapien is looking forward to winter.

Lou Saporito
Montgomery County

YORK COUNTY

Several scattered thunderstorms have come through York County, so crop conditions are quite variable, depending on location. In some areas you'd be considered an alarmist if you said there was a bad drought. In other areas it is clear that significant damage has occurred. Soybeans are showing spider mite problems in dry areas, as you might expect. Some spots in certain fields will be a complete loss. Lots of short and yellow alfalfa fields around too. Some double crop soybeans have been planted, variable in stand success, again, depending on the amount of moisture. On the bright side, wheat and barley yields were very good this year, several wheat growers saying they averaged 70 bu/ac.

Unfortunately with reports of the main corn/soybean states looking excellent in crop condition, we shouldn't expect any price gains.

John Rowehl
York County

Degree Day Accumulations:

1999 DEGREE DAY ACCUMULATIONS

To track corn and insect development, compare the 1999 cumulative degree-days shown in Table 2 to the required values in Tables 3 and 4. Choose a location that is closest to your site when making a comparison.

Table 2. Cumulative Degree Days for Corn and Insects for the Period Ending August 1, 1999
Corn Insects
County Location 1999 30-year ave. SCM/SB AW BCW CRW ECB
50F 50F Diff 40F 48F 50F 53F 55F
Erie Waterford 1636 1333 303 2915 1934 1713 1406 1219
Crawford Meadville 1710 1425 285 3043 2031 1805 1491 1297
Mercer Mercer 1703 1421 283 3053 2033 1807 1491 1296
Bradford Towanda 1725 1444 281 3058 2036 1810 1495 1301
Lycoming Montoursville 1798 1535 263 3204 2141 1909 1584 1383
Tioga Mansfield 1639 1341 298 2921 1933 1711 1404 1217
Susquehanna Montrose 1537 1220 317 2766 1809 1593 1296 1115
Butler Butler 1771 1506 265 3180 2125 1894 1570 1369
Indiana Indiana 1755 1490 264 3168 2110 1879 1555 1355
Lawrence Lawrence Jct 1729 1443 286 3058 2047 1822 1507 1313
Blair Martinsburg 1699 1426 273 3092 2047 1817 1497 1299
Centre State College 1711 1436 274 3084 2047 1818 1499 1303
Columbia Bloomsburg 1810 1553 257 3240 2163 1929 1602 1399
Clearfield Curwensville 1702 1423 278 3061 2033 1805 1488 1293
Dauphin Elizabethville 1842 1596 247 3320 2217 1980 1647 1441
Bedford Bedford 1785 1534 251 3252 2165 1928 1599 1395
Mifflin Belleville 1793 1538 256 3232 2155 1921 1594 1391
Northumberland Sunbury 1857 1609 248 3327 2227 1990 1658 1451
Lehigh Trexlertown 1875 1635 241 3383 2259 2018 1683 1474
Schuylkill Hegins 1797 1541 256 3237 2155 1921 1594 1391
Westmoreland Greensburg 1746 1482 264 3169 2109 1876 1552 1351
Somerset Somerset 1559 1255 304 2888 1887 1663 1353 1164
Washington Washington 1820 1572 247 3301 2210 1972 1641 1434
Franklin Chambersburg 1886 1655 231 3435 2298 2053 1713 1502
York York 1934 1713 221 3526 2363 2113 1768 1553
Lancaster Ephrata 1859 1620 239 3376 2250 2009 1673 1465
Berks Hamburg 1891 1653 238 3409 2280 2038 1702 1492
Corn degree-days based on a May 1 starting date. Insect degree-days based on a January 1 starting date.


Table 3. Cumulative Degree-Days Required for Insects to Reach key Periods for Scouting or Management
  Maturity rating (days)
80 90 100 110 120
50% Silking 1100 1150 1250 1300 1400
Black Layer Formation 1900 2100 2300 2500 2800


Table 4. Cumulative Degree-Days Required for Insects to Reach key Periods for Scouting or Management
  Stalk Borer Alfalfa Weevil Black Cutworm* Corn Rootworm European Corn Borer Seed Corn Maggot
Adlt Emrg 5% Hatch 1st Gen 2nd Gen
SB AW BCW CRW ECB1 ECB2  
Initiation 1400 300 91 1283 380 WCRW** 558 1550 450***
Termination 1700 500 430 2253 478 NCRW** 1228 2045  

*Degree-day accumulation should begin at first moth capture in a black light or pheromone trap.
**These values represent degree day accumulations for optimal timing of Furadan 4F post emergence applications. WCRW-Western Corn Rootworm, NCRW-Northern Corn Rootworm
***This number of degree days represents the number of degree days required from plowdown of green vegetation until it is safe to plant corn or soybeans and avoid seed corn maggot injury.

Dennis Calvin, Entomology

William S. Curran
Associate Professor Weed Science
email: wsc2@psu.edu

Back to:

Website Address: http://fcn.agronomy.psu.edu/