CMEG Crop Management Extension Group

Field Crop News

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

September 19, 2007    Vol. 07:29

IN THIS ISSUE:

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Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The second half of September will be dominated by above normal temperatures and well below average rainfall. In fact, there may only be two opportunities for showers during the next two weeks and both are expected to be next week. In addition to the warm, dry weather, there will be an abundance of sunshine (expect for lingering morning fog) and relatively light winds. Humid weather should come in three surges; the first occurring late this week, the second expected in the early part of next week and the last surge during the final few days of the month. Early indications point to continued milder than normal and dry conditions into October, though interrupted by a couple of punches of cold air.

Week One (Sept 18 – Sept 24): It will be progressively warmer and somewhat more humid through Friday. A weak front will bring less humid air and not as warm conditions by Sunday. However, very warm weather will return early next week. Apart from morning fog, most of the days will be mainly sunny. Winds will blow from the west and southwest later Thursday into Saturday. The vast majority of the state will have no rain at all through next Monday.

Week Two (Sept 25 – Oct.1): The period will begin very warm and rather humid. A cool front will push through the region either later Tuesday or Wednesday with some showers and a couple of thunderstorms. Even in the wake of the front, readings will stay near or above seasonal levels. A return to very warm conditions appear likely at the end of the month before a more potent cold front with showers arrive between Sept 30–Oct 2.

Check out the predicted Growing Degree Days (base 55) for Pennsylvania for the next two weeks at: http://climate.met.psu.edu/data/regional_gdd.php

Weedy Bromus Species Management in Small Grains — Bill Curran, PSU Weed Specialist

Several weedy annual brome species have become problematic in our fall seeded small grains. These weedy bromes include at least four closely related species; downy brome (Bromus tectorum), Japanese brome (Bromus japonicus), hairy chess (Bromus commutatus), and cheat (Bromus secalinus). Downy brome is generally considered the most common of these different winter annual grassy weeds, and although herbicide susceptibility can differ the biology, ecology and control are similar for the four species. Downy brome was first introduced to the U.S. way back in the early 1860’s. This is one of the most troublesome grassy weeds in winter wheat, alfalfa, grass hay, pastures, spring no—till, and noncrop areas. Other names for these grassy weeds include cheatgrass, cheat, downy chess, wild oats (not to be confused with the real wild oats — Avena fatua), and others.

Managing these weedy grasses in small grains includes: 1. Prevent successful seed production. Seed do not persist long in the soil (1 to 2 years), so preventing seed production can quickly reduce the soil seedbank and the problem. 2. Rotate to summer annual crops to prevent their success. These grasses are generally not a problem in spring planted crops and can easily be controlled in no—till. 3. Delay fall planting of winter grains to allow early flushes and kill with tillage or herbicides. This may require waiting until mid October before small grain seeding which may not be practical for barley or in some regions of the state. 4. Use herbicides in small grains to control or suppress. The effectiveness of herbicides varies by product and control/suppression is limited. There are currently only two to three products that claim control of some Bromus species. Most effective products have rotational crop restrictions (See table below). No herbicides are currently labeled for control in grass hay.

The EPA recently approved Axiom herbicide from Bayer CropScience for control of certain annual grass and broadleaf weeds when applied early postemergence in winter wheat. Target weeds for this application are Italian or annual ryegrass as well as downy brome. Axiom is a mixture of flufenacet (Define) and metribuzin (Sencor). Application timings are from spike to the 3–leaf growth stage of winter wheat. Axiom is not very effective on emerged weeds and will not control grasses beyond the 1–leaf stage. Do not apply to wheat that has not yet emerged and certain wheat varieties are sensitive to Axiom, so check a current herbicide label for special precautions and restrictions.
Penn State has not adequately investigated this potential new use.

Severe Blunt Ear Symptoms Reported — Greg Roth, Grain Production Specialist)

We have seen sporadic cases of blunt ears or “beer can ears” in the past in Pennsylvania and this year there have been reports of this phenomenon occurring this year and throughout the Midwest as well. Recently I visited several fields with a crop consultant and observed perhaps the most severe symptoms that I have seen to date. The incidence of these symptoms in the field was also quite high, ranging up to 70–80% in one field.

Several fields we visited had what I would call the typical blunt ear symptoms, with plants that appeared normal, with normal husks, but then inside the husk was an ear that ranged from 30 to 60 percent of normal. http://fcn.agronomy.psu.edu/images/roth0729image3.jpg Unlike typical drought stressed corn, the cob development was arrested, apparently early in the development of the ear. Often ears have a rudimentary ear shoot on the end of the ear.

This year, we found more serious cases of this arrested ear development than we have seen before. On these ears, only a very short ear with a few ovules http://fcn.agronomy.psu.edu/images/roth0729image2.jpg or even only a tiny ear shoot developed http://fcn.agronomy.psu.edu/images/roth0729image4.jpg. In our fields some of the severe plants had an unusual white flashing above the collar on upper leaves. http://fcn.agronomy.psu.edu/images/roth0729image1.jpg. Crop records on the fields indicated adequate to high soil nutrient levels, recommended herbicide programs, no fungicide applications, and no unusual practices. According to the consultant, there seemed to be some hybrids that were more prone to the problem, but it was not consistent.

My colleague, Bob Nielsen, at Purdue University, has been finding the same problem in Indiana and has written a good summary of the symptoms and potential causes of the problems (http://extension.entm.purdue.edu/pestcrop/2007/issue23/index.html). Bob suggests the normal blunt ear symptoms may be associated with dramatic changes in temperature or a cold temperature shock during ear development. He has suggested that the more severe arrested ear development symptoms may be associated with post emergent herbicide, fungicide or other chemical applications near the V12 stage.

In our fields, the only issue that seems to be consistent with these potential causes is the dramatic change in temperature. On June 9, a high of 90 F occurred, followed by lows of 53 and 48 on June 10 and June 11. Also, on June 20 we had a high of 87 F followed by lows of 53 and 47 on June 21 and 22.

We are continuing to evaluate this problem and will be evaluating plant tissue tests as well. I would appreciate learning about more instances of this phenomenon if you come across any. Plants in problem fields should be turning red as the crop ripens.

Low Cutting Height Can Result In Loss of Orchardgrass Stands — Les Vough, University of Maryland Forage Specialist Emeritus

Cutting height may be the cause of loss of orchardgrass stands as much as insect and disease problems. Insects such as grubs and billbugs and leaf diseases are certainly contributors to loss of stands but the advent and popularity of disc mower—conditioners somewhat coincides with the shorter stand life and slower recovery of orchardgrass fields after cutting. There is a tendency to set disc mower/conditioners to cut closer to the ground than with sickle bar mower/conditioners. I see much more scalping of the ground where disc mower—conditioners are used than where sickle bar are used. With disc mower—conditioners, some farmers are cutting as close as an inch or inch—and—a—half, sometimes even lower. This is analogous to overgrazing of pastures and if done repeatedly the outcome can be the same — loss of stands.

In contrast to alfalfa which has large taproots and stores its reserves primarily in the roots, orchardgrass stores its reserves principally in the lower 3 to 4 inches of the stem bases or tillers. When growth begins in late winter or after cutting or grazing, leaf area for photosynthesis is low and stored carbohydrates are used to support new growth. In the case of alfalfa, depletion of carbohydrates in the roots continues until the topgrowth is about 6 to 8 inches tall, at which point there is usually enough leaf area to meet growth and respiration needs. If orchardgrass is cut low and most of the leaves removed, depletion of carbohydrates in the stem bases will continue until there is enough leaf area once again to meet growth and respiration needs.

Grasses store relatively little carbohydrates in the roots. The highest concentration of carbohydrates in grasses is in the leaf sheaths and stem bases in the vegetative stages of growth and in the lower stem in the reproductive stages of growth. Therefore it is critical in cutting or grazing management to leave enough stubble to retain sufficient stored carbohydrate and basal leaf area to support regrowth. Production of the first 1 to 3 leaves requires a substantial amount of stored energy (carbohydrates). If mowing or grazing removes too much of the lower stems and sheath area of tillers, too much of the stored carbohydrates can be removed, not leaving enough to support root maintenance and shoot regrowth. In addition, with summer regrowth cuttings, higher temperatures usually increase respiration rates, so less storage often occurs in midsummer.

If mowing or grazing removes too much leaf area and too much of the stem bases, growth rate is slowed substantially. Because there is not much leaf area for photosynthesis and manufacture of carbohydrates, additional reserves may be required for regrowth until there is sufficient leaf area and photosynthesis to meet growth needs. If much of those reserves have been removed by cutting too low, ultimately the point may be reached where reserves are totally depleted and the plant dies.

Root growth is also affected by heavy defoliation (either mowing or grazing), which makes the plant less competitive and more vulnerable to heat, drought, insect and disease stresses. Orchardgrass plants that are repeatedly cut at 1 to 1½ inches will have shallower and less extensive root systems, thus less able to obtain moisture from the soil than plants cut at 3 to 4 inches.

Grasses can withstand greater defoliation during early and rapid growth stages in the spring and early summer than they can later in the growing season when less opportunity for growth exists. Forage researchers and farmers in Missouri have observed less damage to plants from summer heat and drought when the first harvest is made early and plants have time to re—grow before the stress occurs. Some farmers in southern Missouri have reported almost 100 percent loss of stands when harvest was delayed to the late bloom stage. When little opportunity for regrowth exists during midsummer or drought, sufficient leaf material should be left after cutting or grazing to maintain carbohydrate levels within the plant.

A number of farmers have commented to me over the last several years that their orchardgrass not only doesn’t last as long as it used to but it also doesn’t come back as fast as it used to. They wonder what has happened to orchardgrass varieties today. Well, we are still using some of the same varieties that we used 20 or more years ago and today’s newer varieties are better than they have ever been, so these comments are a signal that something else, like the management practices, has changed, not the varieties. One of the most likely reasons that the orchardgrass is not coming back as quickly is that the cutting height is too low.

If you are presently having problems with slow regrowth and loss of stands and want to see if increasing the cutting height will improve regrowth and stand longevity, try several different cutting heights in the same field this year. Do it within the same field, not different fields due to differences between fields and stand conditions. Use a relatively new stand, preferably one only a year or so old. Make several rounds around the field cutting at your usual height. If your usual cutting height is 1½ inches, after several rounds readjust the cutting height to 2½ or 3 inches. After several more rounds readjust the cutting height again to 3½ or 4 inches. Record the number of rounds made at each cutting height so that the same heights can be used in the same areas of the field for subsequent cuttings the rest of this year and next year. This will show you what impact cutting height has on performance and persistence.

I think you will find that cutting at a height of 3 to 4 inches will help maintain strong root reserves, leading to faster recovery of regrowth and better stand persistence. While we will still face problems from insects and diseases, more healthy and vigorous plants that are not stressed from low cutting heights will be better able to withstand the impacts of the insects and diseases and should help improve yield and stand persistence.

Grain Markets — John Berry, Lehigh County Extension

Corn may be $0.70 off season high’s, but its still in top third of expected prices and it looks like we’re in for the second biggest crop in history. Add to this the combines running in the fringe states and the heart of the Corn Belt harvest is underway. It looks like prices may have stabilized (for now) even with yields coming in on the “real good” side.

What I can hardly believe is the CBOT price for beans. Not too many months ago I was happy to sell soybeans above $6.00. Talking of prices — wheat is pulling out all the stops to see if it can pull some of those 2008 corn acres back by setting unbelievable price levels.

It may be time to consider some forward pricing for ’08 and possibly even ’09 crops. I am thinking of usual crop price expectations, the volatility in the market, and the projected price we will be paying for our inputs.

Dr. Jim Hilker at the University of Michigan uses a computer program to “guess” what commodity prices will be in the future based on today’s CBOT option costs. Below is the current calculations of what corn could be expected to do (given today’s options)

What I get from the above is that CBOT corn in December will be $3.38 (there is a 50% of the price being higher than 3.38 and a 50% chance it will be lower). Unless something wild occurs between now and December we are not likely to see the board price for corn above 3.62. It is not a hard science, but it does give some insight into how we might want to plan for harvest.

For the PDA weekly market reports by region check: http://www.agriculture.state.pa.us/agriculture/cwp/view.asp?a=391&q=131575&pp=12&n=1

For the Hay market report: http://www.agriculture.state.pa.us/agriculture/cwp/view.asp?a=391&q=131575

Considerations for Fall and Winter Manure Application — Sjoerd W. Duiker, Soil Management Specialist

As we enter the fall and winter manure will be spread in Pennsylvania. Manure helps improve soil quality and supplies nutrients for crop growth. Manure is a source of carbon, helping to increase soil organic matter contents. Manure supplies feed stock to soil organisms, and supplies nitrogen, phosphorus, potassium and other nutrients. In short, manure is a great resource. To make the best use of manure, it is important to have a growing crop present at time of application to take up nutrients and improve soil structure and soil cover so infiltration is maximized and runoff minimized. Farmers should therefore plant a cover crop after annual crops, especially if they plan to apply manure to these fields. The choice of cover crops and time of establishment have already been addressed in past Field Crop News issues. In short, the drill should be in the field at harvest time to establish cover crops. A cover crop is in the interest of the producer as nutrients taken up by the cover crop will be returned to next year’s crop, and the soil will be protected and even improved.

Act 38 (the nutrient management law of Pennsylvania) also calls for the presence of a cover crop if manure is applied in the fall and winter. All farmers who have more than 2,000 lbs of live weight animal per acre of land where manure is applied, AND have more than 8,000 lbs of animals on the farm are required to have a nutrient management plan. The Law states that, for fall applications, the field needs to have at least 25% cover or a growing cover crop, or manure needs to be injected or incorporated within 5 days using low—disturbance methods consistent with no—till practices. In the winter, the soil must have at least 25% cover or manure cannot be applied. Winter is defined as the period from December 15 to February 28, or if ground is frozen to 4“ depth, or if ground is covered by snow. A farmer’s nutrient management plan must specify the fields and conditions of the field where winter application is planned. In addition, manure cannot be applied in the winter within 100 feet from wetlands adjacent to streams, or from drainage system intakes. Year—round setbacks for manure application are 100 feet from streams, lakes, ponds and open sinkholes (unless there is at least a 35 foot permanent vegetated buffer next to the stream, etc., in which case manure may not be applied within 35 feet of the stream, lake, pond or sinkhole) and 100 feet from active drinking water sources (wells, springs).

Consider Horseweed/Marestail Management Now — Bill Curran, PSU Weed Specialist

We are continuing to see an explosion of horseweed or marestail in many areas of the state this summer. Horseweed in present in agricultural fields in some areas of the state, and is a frequent species along roadsides and in noncropland. This time of year, the seeds are moving with the wind in hopes of landing in an opportune location where they can germinate and begin the next generation. We don’t know how much of this horseweed is herbicide resistant, but rest assured that the resistance problem continues to grow and spread in the Southeast and South Central parts of the state.

As everyone knows, the biggest problem has occurred in no—till Roundup Ready soybeans where glyphosate is used exclusively as the weed control tool. Even with two well—timed glyphosate applications, resistant horseweed may/will not be effectively controlled. Horseweed can emerge in the fall as well as in spring and early summer. Emerged horseweed is more easily controlled when small in late fall or early spring. As it matures and bolts in the spring and early summer, herbicides become less effective at killing this weed (this is true even for glyphosate susceptible biotypes and also for 2,4–D). In addition to glyphosate resistance, populations in Ohio and Indiana are also resistant to the ALS inhibitors (Classic FirstRate, etc.). We are also hearing reports of FirstRate failure in Pennsylvania. At this point, the most economical treatments for control includes 2,4–D ester at 1 to 2 pints/acre probably in combination with glyphosate or possibly Gramoxone. A primary goal for horseweed management in soybean should be effective control of emerged plants prior to planting. Here are some important principles for horseweed control:

  1. 2,4–D ester should be included in herbicide treatments if at all possible. In the spring time, apply at least 30 days before planting at 1 qt/A.
  2. Herbicides applied in the fall will control emerged horseweed, but may not adequately control spring emerging plants. Residual herbicides such as Canopy, Valor, or Sencor applied in the fall can control horseweed through soybean planting. In Penn State trials, Canopy products (Canopy, Canopy EX, Canopy XL, etc.) have been the most consistent fall applied products for general winter annual weed control before soybeans. Include 2,4–D with the fall application and glyphosate if grassy weeds are present.
  3. Spring herbicides should be applied when horseweed plants are no more than 4 to 6 inches tall. Horseweed seedlings or rosettes (April) are easiest to kill.
  4. Spring applications prior to May should include a residual herbicide to control later–emerging plants.

Lastly, as I mentioned last year, Mark VanGessel at Delaware has demonstrated some promising results with fall seeded cover crops such as cereal rye. The Delaware research suggests that horseweed is not very competitive when other plants such as cereal rye are growing in the field. A fall seeded cover crop may not only provide winter cover, hold nutrients, and other important benefits, but could also help reduce horseweed establishment and success.

Long-term Benefits of No-tillage and Organic Cropping Systems — Sjoerd Duiker, Soil Management Specialist

Several certified crop advisors contacted me about recent press releases of a study comparing no-till and organic systems performed at the USDA-ARS Sustainable Agricultural Systems Lab in Beltsville, MD. Many of the press releases misrepresented the actual results of the study, claiming, for example, that yields in the organic system were better than no till. I’d therefore like to lift some highlights from the full report of this study which was published last week in the Agronomy Journal (the official publication of the American Society of Agronomy).

In the study, four cropping systems were compared: no-till (NT), no-till with cover crop (CC), no-till with crownvetch living mulch system (CV) and a reduced tillage organic cropping system (OR). The study began in 1993. In the NT system corn was followed by wheat and double—cropped soybeans. In CC hairy vetch preceded corn and rye preceded soybeans. The CV crop rotation was similar to NT until 1998, after which soybeans were dropped from the rotation to allow the crownvetch time to develop. In the CV system a living mulch of crownvetch grew below the economic crops. The OR system followed the corn—wheat—double cropped soybean rotation with an overseeded crimson clover cover crop in soybeans until 1998 when the rotation was expanded to a 3–yr corn—soybean—wheat rotation to allow earlier establishment of crimson clover after wheat and the opportunity to control problem weeds. Chemical fertilizer was applied in all rotations except OR, which received dairy manure to supply crop nutrients. Weeds were controlled with herbicides in all rotations except in the OR rotation, which included chisel/disking, rotary hoeing, and sweep cultivation until 1999 and no—till with high-residue cultivator from 1999–2002. The whole trial was converted to the NT system (with inputs such as herbicides and fertilizers) from 2003–2005.

Corn yields were highest in the NT and CC system (which had similar yields), with the exception of one year with exceptionally good rainfall distribution, in which the CV system had highest corn yields. On average OR had 28% lower corn yields than NT (due primarily to poor weed control), and CV had 12% lower corn yields than NT (due primarily to crownvetch competition for soil moisture). Soybean yields are difficult to compare because of differences in planting date between systems. Wheat yields were higher in the CV system than in NT and OR, which had similar wheat yields. Organic carbon concentrations were higher to a depth of 12 inches in the OR system than in the other three systems. The CC system had higher organic carbon concentrations than NT and CV to a depth of 6 inches. The organic carbon concentration was similar in the CV and NT systems. No—till corn yields grown from 2003–2005 were higher when following the CV and OR systems (which were similar) than when following the NT and CC systems (similar).

Despite suggestions from press releases, this study does not show that tillage leads to carbon sequestration or that crop yields were higher in the organic system. The study does show that soil carbon losses caused by tillage can be compensated for by increasing organic matter inputs. Over the entire length of the crop rotation, the OR system received approximately twice as much organic dry matter (16.5 tons/A in manure and crop residues) than the other rotations (6, 9 and 7 tons/A in NT, CC and CV systems). It is likely, however, that greater carbon sequestration could be achieved if these inputs were included in a no—till system. Secondly, the study shows that especially on drought—prone soils, higher yields can be achieved if soil organic matter contents can be increased. The mechanisms to increase organic matter contents are to reduce losses by tillage and soil erosion, as well as burning and harvesting of crop residues, and to increase inputs of organic materials in manure, composts, crop residues, and cover crops. These principles are well—known and we should continue to adhere to them.

J.R. Teasdale, C.B. Coffman, and R.W. Mangum, 2007. Potential long—term benefits of no—tillage and organic cropping systems for grain production and soil improvement. Agronomy Journal 99:1297–1305.

Upcoming Events:

No—Till Short Course — Part 1 (fundamentals and theory)
October 3–4
PSU Agronomy Research Farm / Rock Springs, PA
• This course will provide an introduction to the no—till SYSTEM approach contrasting the differences between a tilled and no—till system. Attendees will gain a understanding of the challenges and opportunities that no—till offers so they can confidently answer the questions “Why No—Till?”

No—Till Short Course — Part 2 (management and field applications)
October 10–11
PSU Agronomy Research Farm / Landisville, PA
• This course will provide applied instruction in problem solving and field decision making in a no—till farming SYSTEM. Learn practical solutions and field tested ideas that make no—till both practical and profitable.

Register online at http://www.panotill.com/shortcourse.html or call Lisa Crytser 814–865–2543 for more information.

8th Annual Pennsylvania Crop Insurance Conference
Wednesday, October 10, 2007, 8:00 a.m. to 4:00 p.m. at PA Farm Show Complex This conference is for ag industry professionals with an interest in crop insurance and risk management. Registration information for this conference is under What’s New at http://www.agriculture.state.pa.us

Field Extension Educational Lab — October 11, Southeast Research and Extension Center Contact: Del Voight 717–270–4391

Keystone Crops and Soils Conference — October 23–24, Holiday Inn, Grantville
Registration information will be coming out soon. If you don’t receive the program brochure or need more information, contact Amy Bradford 717–651–5920

Contributors: Dept. Crop & Soil Science: Sjoerd Duiker, Greg Roth, Bill Curran and Marvin Hall. Extension Educators: Andrew Frankenfield (Montgomery), Jeff Graybill (Lancaster), Mena Hautau (Berks), Joel Hunter(Crawford), Dave Messersmith(Wayne), Lee Miller(Beaver), Tom Murphy(Lycoming) and Del Voight (Lebanon).

Editor: John Rowehl, Cumberland County Extension

Upcoming Events

Real time pest and heat unit activity: http://psu.zedxinc.com/cgi-bin/site.cgi?location=2&user=psu#

Calendar of Events: http://www.events.psu.edu/cgi-bin/cal/webevent.cgi?cmd=opencal&cal=cal209&

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