CMEG Crop Management Extension Group

Field Crop News

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

May 16, 2007    Vol. 07:11

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The regular up—and—down of temperatures will continue through the second half of May. Associated with these changes will be some showers, but the progressive nature of the weather pattern will not lead to prolonged rainy spells, except perhaps along the East Coast (the eastern quarter of Pennsylvania). As a result, rainfall will average a bit below normal in the western three—quarters of the state and may average well above normal in the eastern—most sections. Temperatures on balance will average near or slightly above normal — mainly due to the warm spells being more intense than the cool snaps.

Week One (May 16–22): Showers and a few thunderstorms will mark the transition to cooler weather on Wednesday. Most sections will receive less than 0.50 inches. Cooler than average conditions will dominate the period from Thursday through Sunday. A few showers or a thunderstorm will develop each afternoon or evening. Expect a warming trend early next week.

Week Two (May 23–30): This period will be dominated by above average temperatures. A slow—moving cold front should generate showers late in the week or during the beginning of the Memorial Day weekend.

Scout Now for Cutworms — Del Voight, Regional Field Crop Pest Management Educator

Cutworm is a term to describe numerous wormlike insects that are destructive to field crops. Most producers are familiar with the black cutworm and recently with the true armyworm from lessons learned in the past couple of years. One of the best write ups I have found useful is from a 2001 publication from Iowa State that puts the pieces of management of cutworms together. This link provides the fact sheet that will allow one to understand the management of the pest. http://www.ipm.iastate.edu/ipm/icm/2001/5-7-2001/earlyscout.html

To summarize and apply this to current conditions. I observed cutworm moths in Lebanon area fields on April 20th (200 heat units)while this is not the peak flight it is in the ball park. The years that I have had traps out average moth flight occurred on April 9. This year was a little later. With the flight information and my keeping heat units in the office after 300 heat units from peak flight we should begin to see cutting. Currently we have 450 heat units as of this note and by subtracting 200 from 450 we get a development of 250 heat units that apply to cutworms. Knowing that they require about 300 heat units to begin cutting producers should be able to scout (look for holes and feeding on the leaves and any clipped plants) for this pest in the next week and see some chewed leaves and cutting. They feed a night so look for a cut plant plugging a hole that they hide in.

Here is the Agronomy Guide scouting recommendations: Cutworm Responsive Treatments Threshold: (Plants cut per 100.) Seeding: 2, V2: 3, V3: 5, V4: 7, V5: Seldom and economic problem.

Here are the insecticide recommendations. Poncho 1250 and Herculex will provide some relief from the pest. Keep to scouting if there are cut plants and healthy insects at threshold levels for treatment.

Some Insecticides labeled for black cutworms in corn
Insecticide Rate
Ambush 6.4–12.8 oz/acre
Asana XL 5.8–9.6 oz/acre
Baythroid 2 0.8–1.6 oz/acre
Capture 2EC 2.1–6.4 oz/acre
Discipline 2EC 2.1–6.4 oz/acre
Lorsban 4E 1–2 pt/acre
Mustang Max 1.28–2.8 oz/acre
Nufos 4E 1–2 pt/acre
Penncap-M 4 pt/acre
Pounce 3.2EC 4–8 oz/acre
Sevin XLR Plus 2 qt/acre
Warrior 1.92–3.2 oz/acre

I also viewed armyworm moths (they have a white fleck on an otherwise dark wing) flying in the last couple of weeks. They are typically later occurring that cutworms but may be observed feeding now. They are active during the day and will not typically cut off plants at the surface like cutworms do. They also normally are not an issue in conventional tillage. In no till however scouting is critical particularly after a small grain cover. Here are the thresholds:

Armyworm (True) Early Season - 25% of plants damaged or some plants are being killed.
Pseudaletia unipuncta Late Season - Feeding occur above the ear corn on 10 to 20% of plants.

More on worms later once European corn borers begin their flight and earworms move in.

Scout Now for Wheat Diseases — Del Voight, Regional Field Crop Pest Management Educator

Producers are calling in about whether to treat for powdery mildew or not. First one needs to get into the field and scout to determine if they disease is there and where on the plant it is infected. Conditions have been ideal within the canopy for the disease despite dry conditions. Here are the specifics for scouting:

Symptoms Environment Survival

Ohio State has some management recommendations which include pertinent links to timing and efficacy. The key is that most products need to be applied before (treatment decision at GS8) prior to heading so this decision needs to be made fast and acted on immediately. Control and click on varieties, timing, and efficacy to follow links.

Management
Wheat Disease Thresholds for Foliar Fungicides
Wheat growth stage Disease Leaf * Disease Level
  • * Leaf number counted from top leaf (flag leaf = leaf 1) down to tiller.
  • ** Disease level based on average of 30–50 tillers randomly collected throughout field.
Flag leaf emergence GS8 to Boot (GS10) Powdery mildew 2 2–3 lesions
Flag leaf emergence GS8 to Boot (GS10) Stagonospora leaf blotch 2 1–2 lesions
Head emergence (GS10.1) to flowering (GS10.5.4) Stagonospora leaf blotch 2 1–2 lesions
Head emergence (GS10.1) to flowering (GS10.5.4) Leaf rust 1 (flag) 5–10 pustules
EFFICACY OF FUNGICIDES FOR WHEAT DISEASE CONTROL BASED ON APPLICATION AT THRESHOLD LEVEL
Product Rate/A Powdery mildew Stagonospora leaf/glume blotch Septoria leaf blotch Tan spot Leaf Rust Head Scab
  • * The greater the number of + signs the greater the relative efficacy.
  • ** (+) indicates greater efficacy at higher application rates.
Tilt 3.6 EC 4 fl. oz +++* +++ +++ +++ +++ +
PropiMax 3.6 EC 4 fl. oz +++ +++ +++ +++ +++ +
Quadris 2.08 SC 6.2 (to 10.8) fl. oz +(+)** +++ +++ ++++ ++++  
Quilt 200 SC 14 fl. oz +++ +++ +++ +++ +++  
Stratego 250 EC 10 fl. oz ++ +++ +++ +++ ++  
Headline 2.09 EC 6.0 (to 9.0) fl. oz ++ +++ +++ ++++ ++++  

Here is a link to Ohio States scouting for wheat that will provide the necessary information to make application decisions. http://ohioline.osu.edu/b827/0004.html

Corn Herbicide Application Timings and Restrictions — Dwight Lingenfelter, PSU Weed Science

In the past there were generally two or three times when herbicides were applied in corn — preplant, pre or postemergence. Now with more and newer products, post application timings in particular are being subdivided into different timings (i.e., delayed pre, early post, mid post, post, late post, etc.). Unfortunately there are no exact definitions for these various timings. In general, the standard preplant, pre, and post definitions are adequate for most products, but if you would like a more refined breakdown of herbicide application timings, please read on. Below are some general guidelines to follow, based on our opinion. Keep in mind, these definitions may vary between parties, so always refer to the product label for the proper application timing with respect to corn and weed growth stages.

Also, for a more in depth discussion and pictures of corn growth stages, refer to the Iowa State publication entitled "How a Corn Plant Develops".

Herbicide application timings with respect to corn and weed growth stages and weeks after planting.
Application timing Number of corn leavesa Number of corn collarsb Average corn heightc Weed height WAPd Comments
  • a number of leaves with greater than 50% of leaf exposed
  • b number of leaf collars fully exposed
  • c Average corn height measured to the arch of the highest leaf that is >50% emerged
  • d WAP= weeks after planting
Preplant 0 0 0 Varies 0 Typical of standard preplant or preemergence applications such as Bicep, Harness Xtra, Guradsman Max, Keystone, Balance, etc. Include burndown herbicides if necessary.
Pre 0 0 0 0 to 2 0 to 1 Typical of standard preplant or preemergence applications such as Bicep, Harness Xtra, Guradsman Max, Keystone, Balance, etc. May need to include burndown herbicide if weeds are present.
Delayed pre 0 0 <1 inch 0 to 2 inches 1 to 1.5 Ideal application timing for Prowl. Other products can vary, see label.
Spike 1 (tightly wrapped) 0 <2 inches 0 to 2 inches 1 to 3 Typical application timing for Prowl
Early post 1 to 3 ≤2 ≤6 inches ≤3 inches 2 to 4 Ideal application timing for dicamba - Clarity/Banvel and Basis. Some chloroacetamide + atrazine products can still be applied at this stage.
Mid post 3 to 6 2 to 4 Up to 12 inches 2 to 6 inches 3 to 5 Typical of many post applications (Steadfast, Spirit, NorthStar, Callisto, Impact, glyphosate, Status, etc.)
Post Varies Varies Varies Varies Varies General term that may encompass early, mid, and late post applications.
Late post (not split) 7 to 11 5 to 9 12 to 20 inches 8 to 12 inches 7 to 8 Typical of some applications (e.g., glyphosate). Later timings generally not recommended except as a rescue.
Late post (as split treatment) 7 to 11 5 to 9 12 to 20 inches 2 to 6 inches 7 to 8 Usually the second application in a planned pre/early post followed by a late post herbicide program.
Layby (use drop nozzles) 11 to 13 9 to 10 20 to 36 inches Varies 8 to 9 Layby refers to an application at the last cultivation time or the equivalent.

Sprayer Clean—out is Important — Dwight Lingenfelter, PSU Weed Science

Proper sprayer clean—out is important especially when using the same sprayer for both corn and soybeans. Now that some are switching from applying corn herbicides to soybean products it is necessary to clean sprayers to avoid crop injury. Herbicides such as 2,4–D, dicamba, glyphosate, and some of these “newer” herbicides that are very active at low use rates can cause problems to sensitive crops if residues or small amounts of herbicides remain the sprayer system. In general, it is best to triple rinse the entire system including the tank, hoses, strainers, nozzles, etc. with water and ammonia. There are commercial tank cleaners that can also be used. It is recommended that some herbicides such as 2,4–D and dicamba use more steps to the cleaning procedure (including an overnight soaking period) than simply rinsing out the sprayer. For a more detailed discussion on sprayer clean—out including specific cleaning procedures for certain herbicides please refer to the following websites:

Crop, Insect, and Weed Phenology Maps Up and Running — Bill Curran, PSU Weed Specialist, Dennis Calvin, Entomologist, and Greg Roth, Grain Production Specialist

An integral part of IPM is monitoring pest development and predicting the potential for severity. Of course monitoring insect pest presence and development are key for managing many of our most important problem insects. With weeds, knowing when particular weed species are likely to emerge can be important for planning tillage and postemergence weed management programs. Degree models using daily soil or air temperatures have been developed to help monitor and predict the presence of a number of field crop pests.

The following website (http://psu.zedxinc.com) has real—time and forecasts for pest, soil temperature and crop growth predictions. All maps have a spatial resolution of 10 km2, meaning that you have one predicted value for every 10 km2 grid or 6.2 square miles. The website provides prediction maps for alfalfa weevil, corn root worm, European corn borer, and common stalk borer, as well as the emergence potential for 8 summer annual weed species. In addition, corn and soybean growth and development are included. The intent of this information is to help pest management specialists and consultants anticipate key life stages and to help plan management accordingly. The model uses real time temperature information to calculate degree days and determine which life stage the population should be entering at a location or the percent emergence for a particular weed species. It also uses projected temperature to give a 1, 3, 5, and 7 day forecast. Each life stage and generation or 10% increase in weed emergence is represented by a specific color on the map with an accompanying key. We hope you find this website useful and please let us know what you think about this predictive tool.

Soybean Rust Update — Greg Roth, Grain Production Specialist

The soybean rust monitoring program is up and running. Plant pathologists in Louisiana have detected soybean rust on Kudzu last week. This has caused some concern since this detection is 53 days ahead of last year’s detection in Louisiana. Detections this far west could provide a source of inoculum for the Midwest. Scott Isard, our soybean rust project leader, was in Louisiana last week and reported that conditions there were warm and humid and conducive to development of the disease. Scott is working on a project there to model spore development and movement. It is still uncertain what impact this could have on the Pennsylvania situation. We are in the process of establishing our soybean rust sentinel plot network with about half of the sites planted. Scouting will begin following emergence.

National and state updates on the situation can be found at the soybean rust website at: http://www.sbrusa.net

Corn Stand Assessment and Replanting — Greg Roth, Grain Production Specialist

Now is the time to do some assessment of emerging corn stands. Assessing corn stands early in the season allows replant decisions to be made on a timely basis. We have many good stands, but some have had issues emerging this spring.

Making a replant assessment for a thin stand should be fairly straightforward: estimate the economic potential of a replanted stand from our replant charts, subtract the cost to replant and compare that to economic potential of the existing stand. Use this table (http://agguide.agronomy.psu.edu/cm/sec4/table1-4-8a.cfm) for high yielding fields or (http://agguide.agronomy.psu.edu/cm/sec4/table1-4-8.cfm) for lower yielding fields.

Unfortunately, it’s not always that simple. In crusted fields, frost damaged fields, or those injured by a pest or herbicide, one judgment call is whether to count the sickly or injured plants in your population count. If plants haven’t emerged after a week or 10 days of the original stand, I would tend not to count them in the stand assessment for replanting. If there is more than a 2 leaf stage difference between the corn seedlings, the late emergers will have a negative impact on yield.

Another issue is silage fields. These tend to be: a) more valuable, b) often more responsive to plant populations and c) perhaps less impacted by later planting. In a recent study at two locations, on high yielding fields, a 24,000 stand produced 23.7 tons/a, a 30,000 stand produced 25.4 tons/a and a 36,000 stand produced 26.4 tons. This suggests that replanting a potentially high yielding silage field with an existing 20,000 to 24,000 stand might be justified if there is not a great planting date delay. We don’t have a great table to assess this yet, but it is something to consider.

Upcoming Events:

Cover Crop Research and Management Summit
June 5, 2007
Tuesday, 9:30am–3:30pm
Penn State Rock Springs Agronomy Farm, Centre Co.
Cost: $10
Lunch and handouts will be provided.

During this cover crop management field day, you will have an opportunity to see and hear about the latest cover crop research at Penn State as well as observe first hand some of the tools and practices being tested. Topics will include choosing cover crops based on farming goals, how to grow or capture nutrients and the importance of carbon and nitrogen, improving soil quality, controlling cover crops including using rollers/crimpers and how cover crops can help control weeds.

This tour will be given by a distinguished group of Penn State researchers from across the college who have cutting edge projects underway focused on cover crops. In addition, Rodale Institute staff will be on hand to share their management experience in organic farming systems. Certified Crop Advisor CEU’s will be available at this event.

You must pre register with Lisa Crytser at Penn State to ensure you have a spot at lunch and on the wagons. Please pre—register by May 30, 2007 by phone (814-865-2543) or email (lac8@psu.edu).

American Forage and Grassland Conference
June 24–26 — in State College
For more information check out http://www.afgc.org/mc/page.do?sitePageId=42837&orgId=afgc

Combined Agronomy Industry / Manure, Crops, Pests & No—till Field Day
Penn State Landisville Research Farm
Friday July 6th, 9:00 AM–3:30 PM
Topics will include: Weed Management in No—till; Composting: Mortality and Nutrient Recycling; Nutrient Balance Sheet and Act 38; Farm Bill and Bio—Fuels Updates;
Herbicide Trials and Chemical Industry Updates; and Cover Crop Management. Featured equipment: No—till equipment of all types: Planters, Drills, Residue Managers.
Manure handling and spreading equipment with demonstrations (water only.)
Registrations: Lancaster Extension, 717–394–6851 $3.00 in advance, $5.00 at the door
Questions? Jeff Graybill 717–394–6851. Landisville Research Farm, Dr. Dave Johnson 653-4728

Agronomic Weed Management Research Tour at Penn State
July 10, 2007
Tuesday, 9:00–12:00 noon
Penn State Rock Springs Agronomy Farm, Centre Co.
Cost: $15
Lunch and handouts will be provided.

A number of experiments will be showcased and available for viewing including many of the new corn and soybean herbicide programs plus the latest information on herbicide resistance, cover cropping and weed management research. Certified Crop Advisor CEU’s will be available at this event.

You must pre register with Lisa Crytser at Penn State to ensure you have a spot at lunch and on the wagons. Please pre—register by July 3, 2007 by phone (814-865-2543) or email (lac8@psu.edu).

2007 Penn State Agronomic Field Diagnostic Clinic — July 24 and 25
July 24 and 25
Penn State Rock Springs Agronomy Farm, Centre Co.

The dates and topics for our annual Diagnostic Clinic have been set. As in the past, the Clinic is a one—day event conducted at the Penn State Agronomy Research Farm near Rock Springs, PA. This year’s Clinic will be held on Tuesday, July 24 and then repeated on Wednesday, July 25, 2007. The topics include cover crop selection and management, no—till planter adjustments and attachments for use in cover crops, an overview of biomass crops for alternative energy use, nitrogen management issues, and pest management topics. As always, various credits will be offered.

Registration forms will be mailed and posted on our CMEG website (http://cmeg.psu.edu/) as time gets closer, so you can register and get additional information on each of the topics.

For additional information or comments about the Diagnostic Clinic contact Dwight Lingenfelter at (814) 865-2242 or by email, DwightL@psu.edu.

Ag Progress Days — August 14–16

Contributors: Dept. Crop & Soil Sciences: Sjoerd Duiker, Bill Curran, Marvin Hall, Ron Hoover, Dwight Lingenfelter, Greg Roth, Paul Knight. Extension Educators: Susan Alexander (Jefferson), Andrew Frankenfield (Montgomery), Don Fretts (Fayette), Kevin Fry (Armstrong), Mena Hautau (Berks), Joel Hunter (Crawford), Dave Messersmith (Wayne), Grant Troup (Lebanon), Del Voight (Lebanon)

Editor:Joel Hunter

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&

Readers can subscribe electronically to this newsletter at the Field Crop News Web site.

If you have problems subscribing or wish to cancel your subscription, please contact Lisa Crytser by e-mail at lac8@psu.edu or by phone at 814-865-2543.

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