CMEG Crop Management Extension Group

Field Crop News

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

August 27, 2008    Vol. 08:25

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The long dry spell (lasting 2–4 weeks in most locations) will be dented by the remnants of Fay in the western half of the state starting later Wednesday and continuing into Thursday. Clouds will arrive on Wednesday with showers following in southwest counties during the midday and afternoon hours. Rain will spread slowly into the central sections during Wednesday night and Thursday morning. The eastern areas will turn cloudy with scattered light showers and drizzle on Thursday with fog in many sections as humid air returns. Rainfall amounts will range from 0.50–1.50" in the southwest sections to generally less than 0.50" in the central counties. The eastern half of the state will average less than a quarter inch and a few places will see no rain at all. With the clouds, a humid flow from the southeast will keep readings mainly in the 60’s on Thursday.

Only widely separated showers are expected on Friday, though low clouds and drizzle are still likely in eastern sections. A cold front from the Great Lakes should cross the region between Friday night and Sunday morning accompanied by some thunderstorms, mainly in the western third of the Commonwealth. A spell of pleasantly warm days and comfortably cool nights are expected from Sunday into the middle of next week. It remains to be seen, what if any effect Gustav will have on our weather.

There are increasing indications of a warmer than normal October and a cooler than average November.

Considerations for Hail Damaged Corn — Jeffrey Graybill, Lancaster County Educator

It’s been almost two weeks since the worst of the hail damage occurred in south central PA. In this time we have begun to see some of the effects on the plants and to consider different management schemes to meet these challenges. I believe that by far the biggest challenge will be in dealing with the ear molds we are seeing and the potential mycotoxins which they can produce.

If you have significant hail damage (majority of the leaves stripped away) it is very important to watch your crop as it develops. Fields with different planting dates and differing stages of maturity are responding very differently. So, carefully check each planting. In many cases, severely damaged fields have begun to show significant mold development on the ear. The presence of some mold is normal, such as that caused by insect feeding and other stresses. However, the more mold the greater the chance of mycotoxins. Good ensiling stops mold growth quickly (within 3–4 days the pH should begin dropping as oxygen is consumed and the anaerobic bacteria produce lactic and other beneficial acids). While the molds will be quickly stopped, many mycotoxins potentially produced in the field will not be destroyed by the ensiling process. Also, many mold spores will remain which can renew growth and cause heating at feed-out.

Our goal as silage producers should be to chop as soon as the silage moisture is fit, fill as fast as possible, and avoid putting up any silage on the dry side. I would strongly consider putting the worst fields into a bag and even a little early to stop molds and mycotoxins as quickly as possible. Segregating the worst fields will give you the opportunity to blend or even discard silage of poor quality.

Many farms are considering chopping all of their damaged corn and purchasing grain. This will get the corn out of the field quickly preventing the ear molds from having several more weeks to grow and develop. Temperature, rainfall, and humidity all influence the growth of molds. If we experience a “wet” late summer and fall, chopping most or all damaged corn should be considered. However, as stated above, ensiling does not de-toxify a field with extensive ear molds.

What if I really need the grain? What about high moisture shelled corn (HMSC) vs. dry corn? Putting up a bag of HMSC will get that corn out of the field a few weeks ahead of the dry corn. HMSC is notoriously difficult to make and many farmers and industry folks are very afraid of this option for molded ears. Also, most mycotoxins are produced in and around the ear. So in both cases, you could actually be concentrating the toxins by harvesting the grain. A buffered acid such as proprionic would be beneficial in helping drop the pH of the HMSC quickly and stopping mold growth.

The other consideration is cribbing or shelling dry partially moldy ears. There are two options with dry corn that you do not have with HMSC. First, you can roast the grain. Proper roasting at high temperatures with destroy mold and many mycotoxins that ensiling will not. There are commercial roasters who can come to the farm or who will receive moldy corn, roast it and truck it back to you. I feel that this may be a good option to explore. Secondly, in some cases you could sell slightly moldy corn if you decide not to feed it. Check with your local elevator, many of them will accept somewhat moldy grain at a discount.

Damaged corn often advances in maturity quickly. Much of the early corn was targeted for picking or shelling with later corn reserved for silage. You need to quickly examine your fields, assess the level of molds and decide what your plan of attack will be.

Considerations:

Fall Seeding Updates and Considerations — Del Voight, Interim Grain Crop Specialist

With many harvest activities taking place this time of year managing fall seedings can be challenging but is a critical time to set the stage for next season. Further high prices for seed, fertilizer and other inputs has growers considering other crops such as small grains and cover crops to decrease dependence on inputs. Here are some considerations.

  1. With Small grains one needs to select a performing variety. Prices from $21-$30 dollars per bag require that one checks numerous performance tests to arrive at a variety that will perform. Penn State Small Grain Variety test reports are completed.
  2. If a producer desires to save seed be sure a germination test is performed to allow for a proper seeding rate to be determined. A seed treatment should be considered as well to ensure adequate protection from disease and insect pests.
  3. Never raised a small grain? Then consult the Agronomy Guide for date of planting, seeding rates, row spacing and pest control.
  4. Cover Crops can provide tools to either hold nitrogen applied from manure or actually produce nitrogen. For legumes strive to get them planted as early as possible after silage preferably after a small grain in the next week. Legumes that have proved to be effective in producing 100lbs of nitrogen per acre are hairy vetch and crimson clover planted early. Grass cover crops such as oats and cover crop rye are great scavengers of nitrogen and will hold it for use next season. Many producers have found that by planting rye directly after silage and waiting until the rye has some growth on before spreading manure that they lose little of the available N from manure to volatilization and thereby do not need to incorporate manure. View this video on how other producers are using cover crops to assist in cropping programs.
  5. High nitrogen prices affect pasture producers and the use of legumes can also help in pasture management. If weeds are not an issue in the stand improved white clovers may be an option to seed either now or as a frost seeding in the spring to produce nitrogen for the pasture grasses. Last week at APD I had numerous questions on this for pastures as well as for home lawns. Weed control products are limited in a legume mix with grass. My general guidance is to first establish the grass stand and eliminate perennial weeds with numerous effective herbicides. Then frost seed or interseed the clover into the stand.
  6. Too late for Alfalfa? Yes, as reported in an early publication of FCN, early to mid-August is the preferred time to sow alfalfa in south-central PA to ensure optimum establishment and production next spring. However later seedings do occur with some stands sown as late as mid September. Work at Penn State by Dr. Marvin Hall, forage specialist has taken a look at optimum summer seeding dates. Dr. Hall’s work has shown that delays in forage seeding results in a reduction in plant height in late November, a reduction is the amount of the field that is occupied by the alfalfa (plant vigor) and a lower DM yield the next growing season for delays after August 1 in central PA. He concluded that delaying planting by 2 weeks after August 1 can result in a loss in production the following year by approximately 0.5 ton/acre. By delaying 4 weeks (late August) to plant alfalfa the yield reduction was 1 ton/acre the following production year. Dr. Hall also compared summer planting dates for three grass species, Orchardgrass, Ryegrass and Reed Canarygrass. His results with grasses indicate that late August seedings are preferred for orchardgrass and ryegrasses; however, Reed Canarygrass yields were higher with the earliest seeding dates and planting canarygrass after September 5 resulted in poor plant vigor and lower DM yields the following spring.
  7. Finally, drills are great tools to seed fall crops. However they need to be set to deliver the proper seeding rate and at the proper depth. Small seeds require shallow planting large seeds can be deeper. It is important to get off the tractor and check for depth. For small seeded crops like alfalfa and clovers be sure you see some seed on top.

Brown leaf Blues — Jonathan Rotz, Cumberland County Educator

Corn silage harvest is here for some of us and soon to come for the rest. As harvesters pull into fields across the state some may question the health of their corn fields. One note that will be made is the number of brown leaves on the corn, is this a problem?

With this wet spring many producers had a very real possibility that some nitrogen (N) was lost to nitrification, a process where microbes remove oxygen from nitrate molecules in saturated soil. Once this oxygen is removed the N is lost from our fields as gaseous N. This can be an exceptional issue in fields that have their entire N applied early in the spring prior to planting in the form of either manure or commercial fertilizers. Once this N is gone, unless additional N is added, a real possibility is that the corn crop may run out of N and thus will not reach its maximum yield potential. So do those brown leaves mean the crop lost some yield? Not necessarily.

Research done in central and southeastern Pa. has shown that when 4 green leaves are present at and below the corn ear leaf there is no N deficiency over 95% of the time (Fox et al. 2001). This research went on to state that of those plants with less than 4 green leaves only 50% were N deficient. Therefore, at harvest time brown leaves can be present on a perfectly healthy plant. Additionally, a plant that is green the whole way to the ground may have had N over applied, an expensive mistake that should be accounted for next year.

With all these possibilities a few questions are bound to surface. Did your N management allow for adequate N, N deficiencies, or over application of N? How should you management change next year according to these, for example if you over applied N retain some of it for next year’s crop with a grass cover crop. If you have been reading Field Crop News regularly you have heard of various tests for N levels such as the chlorophyll meter and the Pre-sidedress Nitrate Test. These tests help us forecast our crop needs under normal conditions. However at the end of the year another test can be utilized as a review of how well management reflected crop needs, this test is called the stalk nitrate test. This test is very good at identifying sufficient, deficient, or excess levels of nitrate in the stalk prior to harvest. Once this is known this season’s management can be scrutinized for its strengths and weaknesses so next year we can come closer to maximizing yield while minimizing N cost and environmental impact. For more on how to utilize the stalk nitrate test watch an instructional video or call or go to your local extension office and get more information on this test.

One last point, if corn has been N deficient it will not only lead to lesser yields it will also affect the quality of the silage. Low N levels will lead to lower protein levels and higher fiber levels in the silage. If this is a problem you are facing one possible solution may be to harvest alfalfa a little younger for haylage than normal to try to boost its protein level. This may help make up for the shortfall in the corn silage. With this being said also remember that harvesting alfalfa in short intervals can have an effect on the longevity of your stand. Additionally you will sacrifice yield to increase the quality of your alfalfa haylage, however with soybeans over 13 dollars, protein will not be cheap to supplement into your ration. As always feel free to contact your local extension agent for further information.

Corn Silage Harvest in Full Swing — Paul Craig, Dauphin County Educator

The exceptional dry period the majority of the state and region is currently experiencing is rapidly bringing about the early maturing of the corn crop. Silage harvesters across the region have jumped on the drought affected fields and reporting moistures already below 61% in some short season droughty fields. In some of the better looking fields’ moistures in the 67–69% are found.

Corn silage harvest moisture timing is critical and harvest in 2008 will be highly variable across the region and even across the valley. A few years ago a farmer told me that he determined when to harvest silage by squeezing the stall at the ear leaf junction with his thumb and forefinger. I doubt the results would ever be as accurate as is required for the production of highest quality corn silage. Taking representative plant samples and chopping and then running accurate dry matter testing is critical. Run 6 to 10 of these plants through some type of chopper or lawn mower and thoroughly mix together. Use a Koster tester or a microwave to determine whole plant dry matter. Don’t rely on your neighbor to start chopping before you make plans for silage harvest.

The expected dry down rate for corn silage is 0.5 to 0.6% per day however rates will rapidly fall under droughty field conditions and once the moisture level nears 64%. Expected harvest dates can be anticipated by monitoring plant moistures. Be sure to frequently test actual moistures during harvest.

Depending on storage structure type corn silage is harvested when whole plant moisture reaches 32 to 45% dry matter. Optimum dry matter content for bunker silos is 32 to 35%; ag bags — 32 to 37%, conventional upright silos — 32 to 37% and oxygen-limiting silos — 40 to 45% dry matter.

Additional Reminders — Length of Cut

Recommendations for length of cut for silage vary depending on crop condition. Drier crops (<63%) should be cut finer to produce smaller particles that minimize air pockets. Use of highly digestible hybrids requires a slightly longer cut to maintain effective fiber. General recommendation is a 3/8 inch theoretical length of cut (TLC) but more mature crops may require a shorter length. For non-processed silage the recommended chop length is 3/8 to ¾ inch TLC. Some farms rely on their nutritionists to fine tune the chop length based on farm specific conditions.

Height of Cut

In recent seasons some producers are cutting silage at a 10 to 20 inch height. This practice reduces silage fiber and lignin percentage and increases starch and energy content. However silage yields are reduced five to ten percent. Higher chopping can also be used to change whole plant moisture contents. By cutting higher, harvest may advance by 3 to 4 days. Higher chopping may be an option if excess forage dry matter is available. However, this will increase the final cost per ton. To balance this trade-off between quality and yield, the decision should be based on an economic assessment.

Processing Silage

At lower whole plant moistures, crop maturity may affect silage quality. Fiber and starch digestion decreases as corn dries down. Processing at harvest may be needed to maximize digestion on more mature crops. The goal of processing is to ensure breakage of the kernel and cob to assist digestion. Processing also can affect fiber length so choppers equipped with a processor typically lengthen their cut to ¾ inch.

Pricing Corn Silage Part 2 — Paul Craig, Dauphin County Educator

Last week’s article by Griswold, Beck and Craig about pricing standing corn for silage harvest generated a few emails and phone calls. The issue of basing the value of corn grain and fodder seemed to be the most frequent. A few thoughts summarize comments from the authors. First there are a number of factors to consider when establishing the value of corn silage. The purpose of the article was to suggest where a grower and feeder of corn silage could starta negotiation by providing options to buying silage or selling standing corn.

A concern was often noted that this pricing system based on grain prices does not account for the crop removal of P and K as well as potential soil organic matter which is of value to the corn producer. The goal is to develop a spreadsheet with accompanying information on establishing the value of standing corn and corn silage to consider these and additional production factors from both the producer and the dairy farmer to assist management decisions and negotiations.

All discussions and comments included the need for dairy farmers and corn silage producers to receive more income. Thanks for the comments and suggestions.

Invasive Weed “Apple of Peru” Found Again In PA — Melissa Bravo, PDA Botanist and Bill Curran, PSU Weed Specialist

Apple of Peru (Nicandra physalodes) was again recently identified in a soybean field in Southeastern PA. We first became aware of this weed back in 2006 when it was discovered also in soybeans. Here’s a recap of an article we published back in 2006.

Also known as shoofly, this weed is an invasive member of the nightshade family and although the plant was first identified over 100 years ago in Pennsylvania, it has not had a common presence. Most if not all of the previous sightings occurred along railroad tracks, roadsides, or in coal yards, not in agricultural fields. This weed has caused problems in other states and countries, so pay note to any unusual weed species that you encounter this harvest season. Here’s a little more information about Apple of Peru.

“Apple of Peru” is an annual weed in the nightshade family, reproducing only by seed. Seeds have a relatively thick seed coat consisting of an outer and inner layer, and are dormant at maturity. Germination occurs in mid- to late spring and continues through the summer if moisture is available. Leaves are arrowhead shaped and pointed at the tip (much like eastern black nightshade), with irregularly toothed margins. It has trumpet-shaped lavender flowers that may occasionally be white. Fruits (berries) are borne singly in a bladder casing structure resembling that of smooth and clammy ground cherry. Plants have been known to emerge in late summer and still flower and produce viable seed.

This weed has been more common in Ohio, where it is estimated to infest about 2500 acres and upwards of 100 acres where it is heavy. It is most severe in vegetables and cannot be controlled with many commonly used herbicides. Ohio State research showed unsatisfactory control with preemergence applications of Dual (metolachlor) and Command (clomazone) as well as several other products. Glyphosate was moderately effective, but later emerging seedlings may escape an application in soybean or other Roundup Ready crops. Ohio State has produced a nice fact sheet with more details of the problem in Ohio, their research results, and some photographs to help with identification. Some addition information can be found at www.oardc.ohio-state.edu/weedworkshop/appleofperu.asp.

Measuring and Reducing Soybean Harvesting Losses — Del Voight, Interim Grain Crop Specialist

Adapted from the fact sheet that Charles W. Shay, Lyle Ellis and William Hires produced from the Missouri Department of Agricultural Engineering

Over the last several years of working with what I consider the top soybean producers in Region I have learned the importance of timely harvest of soybeans. In one case during a soybean contest harvest we took the harvest early and then finished the field three weeks later. As a result there was about a 20 bushel per acre difference in a three week period! Further just last year I was asked to check a field and even before the combine entered the field I measured 12 bushels per acre on the ground from premature shattering. Again delay harvest of three weeks. It has been my experience that once 95% of the leaves turn brown about a week later its time to combine. That may mean some green leaves are still on the stalk.

I still remember John Yocum referring to the fact that after it the plants first reach harvestable moistures dry matter losses occur simply by the alternating day night. I found the following excerpts from a Missouri article useful during harvest to capture the losses that may occur during harvest.

Numerous tests of soybean combine losses show that up to 12 percent of the soybean crop is lost during harvest. Harvesting losses cannot be reduced to zero, but they can be reduced to about 5 percent. Combines can be operated to reduce losses without affecting the harvesting rate. This guide describes the major sources of loss. Consider shatter losses of 2 percent acceptable. Average losses are 5 percent or more.

Tips for keeping combine losses low

Your best guide for correct combine adjustment is your operator’s manual.

Remember that more than 80 percent of the machine loss usually occurs at the gathering unit. The following suggestions will help keep these losses to a minimum.

For a specific methods and sheet to take to the field refer to this publication and enter your own information. You may also call me directly for copy to have on hand.

Contributors: Del Voight (Lebanon), Paul Craig (Dauphin), Kevin Fry (Armstrong), Mark Madden (Sullivan), and Jonathan Rotz (Cumberland)

Editor: Kevin Fry

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