CMEG Crop Management Extension Group

Field Crop News

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

May 20, 2008    Vol. 08:11

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The unseasonably cool weather will persist until Friday when a steady warming trend will begin lasting into Monday. Mainly afternoon showers will be noted on Wednesday and Thursday with a couple of scattered thunderstorms in eastern sections, perhaps with small hail. Winds will be gusty again on Wednesday, Thursday and Friday afternoons. Calm winds on Thursday, Friday and perhaps Saturday nights will let chilly air collect in the valleys of northern and central Pennsylvania leading to scattered frost in some sections.

The Memorial Day weekend is promising to be dry and noticeably warmer. Mornings will be cool with a few patches of fog, but afternoon readings will reach the low 70’s on Saturday, upper 70’s on Sunday and perhaps into the 80’s on Monday. A cold front approaching from the northwest may bring a late thundershower to the Lake Erie area at the end of the holiday weekend. A cool front should cross the state either Tuesday or Wednesday with a scattering of thunderstorms. More seasonable conditions will follow, though there are indications that the front may stall across southern parts of the state producing a spell of wet weather at the end of the month.

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

Preharvest application of glyphosate in alfalfa and other legumes — Bill Curran, Weed Science

In the FCN article I wrote last week, I neglected to mention the option of using glyphosate as a preharvest application for stand removal in alfalfa and clover. Glyphosate may be applied to declining stands to help control the legumes and other plant species. This can be particularly helpful for control of perennial grasses including quackgrass. If the crop is harvested or grazed by livestock, use up to 1.5 lb ae/acre (2 quarts of a 3lb ae/gal) in alfalfa or 1.125 lb ae/acre (1.5 qt of a 3lb ae/gal) for clover. The minimum interval between application and harvest is 36 hours for alfalfa and 3 days for clover. This treatment will not provide sufficient control of the legume, but it will suppress it and potentially allow for more timely control and reduced competition in no—till corn. In no—till corn, a postemergence application should be made to control the legume regrowth. As discussed in last weeks article, the plant growth regulator herbicides (including 2,4–D, Banvel, and Stinger or clopyralid) are most effective for control of alfalfa. In Roundup Ready corn, glyphosate can also help suppress the legume, but will probably not be sufficient alone for complete control.

Herbicide application to stressed corn — Bill Curran, Weed Science

Some questions have arisen about herbicide stress to corn under these cold wet conditions. In some areas of the state, corn that has emerged and has 1 to 3 leaves and looks stressed (chlorotic), while in other areas, corn is still trying to emerge or hasn’t been planted. If the corn is in the ground trying to emerge and has already been treated with a PRE herbicide program, all you can do at this point and wait and see what results. If weeds are breaking through, start thinking about POST options after the corn is up. If the corn is up and weeds have also emerged, avoid making any POST herbicide applications until after the corn has had a chance to “recover” from the cold weather. Cold nights (and days) and wet soils in combination with stress from an herbicide can reach the injury “tipping point”. Give the corn crop at least 3 or 4 days of better weather (70+ and sunshine) before you consider applying additional weed control.

Rock Springs Agronomy Weed Tour — July 10, 2008 — Bill Curran, Weed Science

Attend the Annual Agronomic Weed Control Research Tour at Penn State — July 10, 2008 at the PSU Agronomy Research Farm, Rock Springs, PA (Meet at the Agronomy Farm, Rock Springs, Rt. 45 west of State College, enter Gate D). A number of experiments will be showcased and available for viewing including new corn, soybean, sweet corn, and snap bean weed control trials. New herbicides include Balance Flexx, BAS 800, Corvus Capeno, Envive, Halex GT, Ignite, Impact, KIH–485, Laudis, SureStart, Prefix, Resolve and Require Q, Sonic, and Valor to name a few. Also, compare the effectiveness of different herbicides for burning down hairy vetch and annual ryegrass in no—till corn. In addition see how the roller/crimper is working on cereal rye and hairy vetch in reduced and no herbicide systems.

Pest Management CCA CEU’s and Pesticide Recertification Credits will be available.

PreRegistration for this event is $20.00 and includes lunch and a tour book. You must register by July 8 to get the discount Rate. Late and Walk—in Registration the day of the event is $25.00.

Please register on—line for the 2008 Rock Springs Agronomy Weed Tour at: http://cmeg.psu.edu/cmegnews.cfm. You must pay on—line with a major credit card (Master Card, Visa, Discover, or American Express).

Or you may mail your check made payable to ‘Penn State’ to:

Rock Springs Agronomy Weed Tour
Attn: Lisa Crytser
Department of Crop and Soil Sciences
The Pennsylvania State University
115 Ag Science and Industries Building
University Park, PA 16802

Coulter Selection — Sjoerd Duiker, PSU Soil Management Specialist

As the planting season lingers, the summer approaches, and soil conditions continue to change there are questions about which coulter is best on the planter (or, less commonly asked, drill). Yetter company publishes the best coulter selection guide that I’ve seen (http://www.yetterco.com/product_images/coulter_blade_selection.gif) . This guide can be used to select coulters from any manufacturer. The tool can be used to determine what the best coulter is depending on user goals, type of tillage, whether the coulter is used for fertilizer placement, how well it manages residue, what soil conditions you are planting into and speed of operation. To pull out a couple of common coulters, one discovers that the bubble coulter is medium in aggressiveness, not recommended for no—tillage or fertilizer placement, suited to plant in dry and sandy soils, and needs to be run at medium speed. The 13—wave coulter is very aggressive, suited for no—tillage, but not for fertilizer placement, best for residue management, can be used in all but damp and sticky soil, and can be used at slow to high speeds. The smooth coulter is least aggressive, suited for no—tillage and fertilizer placement, good for residue management, can be used in all soil conditions (dry, damp, sandy, heavy), and can be run at high speeds. As we think about the evolution of this growing season, it would make sense to replace your 13—wave or turbo—coulter with a smooth or rippled coulter to allow you to plant in more damp and sticky soil conditions. Once conditions turn dry you can put the 13—waves or Turbo—Coulters back on, although this late in the season one would also be fine with a smooth coulter because soil warming will be of little concern at this point in time.

Monitoring Slow Emerging Corn — Greg Roth and Del Voight, PSU Grain Crop Management

Extended rains, cool conditions and slow emergence have brought on questions related to stand assessments and current planting recommendations. Consider conducting some stand assessments to compare emerged stands to those dropped from the planter. This site is useful for replanting decisions and stand assessment http://lebanon.extension.psu.edu/Agriculture/FarmMgt/soybeans.htm.

In several fields I checked recently I found about 90% of the drop indicating excellent emergence. In some cases, extended exposure to herbicides during germination can increase the potential for herbicide injury. Detecting any stand problems early can lead to a timely replant decision with minimal yield loss. Assessing replanting of stands with seedlings that are questionable is tricky. I would consider using the Purdue replanting fact sheet in this situation (http://www.agry.purdue.edu/ext/pubs/AY-264-W.pdf).

Once plants emerge, they may take on a yellowish appearance for a few weeks until warm weather resumes. The yellow color may disappear with warmer conditions forecast over the upcoming weekend. Generally it is not necessary to change maturities until the last week of May and into the first week of June based on research at Penn State and Purdue. Hybrids generally have the ability to reduce their GDD requirements with delayed planting. Research conducted at Penn State and Purdue a few years ago confirmed this. To estimate the potential for replanting with hybrids of varying maturities, check out our GDD maps at this website http://cornandsoybeans.psu.edu/gddhybrids.cfm

Upcoming Events

May 27–29 Agronomy Schools for NRCS and Conservation Districts
June 1–3 Agriculture and the Environment Workshop in Harrisburg: Achieving a Balance
June 4 Small Grains Field Day at Landisville
June 24 Grain Marketing Meeting & Pig Roast, Lehigh—Berks County
July 1 Cover crop field day at Tim Rodgers’ farm, Centre County
July 2 No—Tilling For Success, Landisville Research Farm, Lancaster County
July 10 Rock Springs Agronomy Weed Tour
July 22 and 23 Agronomic Field Diagnostic Clinics, Rock Springs Agronomy Farm

Contributors: County Educators: John Rowehl (York), Joel Hunter (Crawford), Mark Madden (Sullivan), Mena Hautau (Berks), Kevin Fry (Armstrong), Delbert Voight (Lebanon), Andrew Frankenfield (Montgomery), Jeff Graybill (Lancaster), Susan Alexander (Jefferson). Department of Crop and Soil Sciences, Marvin Hall, Bill Curran, Sjoerd Duiker, Dwight Lingenfelter and Ron Hoover. Paul Knight, PA State Climatologist.

Editor:Dave Messersmith, Wayne County Educator

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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