CMEG Crop Management Extension Group

Field Crop News

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

August 1, 2007    Vol. 07:22

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

Expect a return to relatively hot, rain—free conditions for the majority of the next week with an above average amount of sunshine, but also notably humid conditions. A dwindling number of weather stations report sunshine data (and automation of observations have made these values unreliable), but the visible satellite imagery for July shows that 14 days have been mostly sunny, which is unusually high. Only 8 days have been mostly cloudy and only once back—to—back (July 18–19). The sunny weather matches the upper air flow from the northwest that has dominated this part of the nation during the first half of the summer. There are indications that an air flow from the southwest will become more established during August leading to longer periods of sultry weather, but also more regular thundershowers.

Week One (August 1–7): Initially the air mass will be comfortably very warm, but it will soon turn sultry with hazier sunshine and isolated afternoon thunderstorms on Thursday. An approaching cool front will bring a thunderstorm to about a third of the region on Friday, then most of the weekend will be partly to mostly sunny and after a short respite of drier air, it will become quite sticky again later Sunday and Monday.

Readings will peak near 100F in southeastern sections either Monday or Tuesday with thunderstorms popping up in the sultry air mass, particularly over the mountains.

Week Two (August 8–15): A significant cold front will move into the region between late Tuesday and midday Thursday with numerous thunderstorms. A break in the heat is expected for a couple of days, most likely Friday—Saturday, before very warm and humid air returns early the following week.

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

Weed Control in Small Grain Stubble — Kevin Fry, Armstrong County & Bill Curran, Weed Specialist

Now is a good time for controlling problematic weeds in your small grain stubble, especially prior to forage seeding. Once the grain is harvested and the straw is baled, a systemic herbicide can be applied at this time to control actively growing weeds. Application should be made within 1 to 3 weeks after harvest. Glyphosate control is reduced as weed size increases above 6 inches.

Your goals will be to control summer annual seed production (lambsquarter, ragweed, foxtail, etc.). Mowing alone will not control seed production, they can regrow — this is especially true for annual grasses like foxtail which will require two to three mowings to prevent seed production. An application of Glyphosate and 2,4-D will be very effective on most weeds. If weeds are tall and beginning to flower, spraying the regrowth following mowing may provide better control, but wait two to three weeks before you make the herbicide application. This can be particularly effective on perennial weeds.

Speaking of perennials, this can be also an excellent time to control troublesome perennials. At this time of year, perennial’s root reserves are at their lowest which coincides with the bud to bloom stage of growth. Frequent rainfall and good soil moisture ensure healthy perennial weeds that are susceptible to systemic herbicides. Weeds in drought stress or flooded fields may not respond as favorably and you should probably mow to prevent seed production and make a later summer application. An application of Glyphosate and 2,4-D or dicamba (Banvel/Clarity) will be effective in controlling most of those troublesome perennial weeds.

Cover Crop Season Begins Now — Sjoerd Duiker, Soil Management

Barley and wheat harvest are now behind us, and oat harvest is close. With drought stress in some counties, corn silage harvest has already started or is approaching rapidly. This opens up some great opportunities to establish cover crops early. Cover crops help protect soil from erosion, increase resilience against soil compaction, boost the organic matter content, feed soil organisms, provide some weed control, produce the mulch for next year’s crop, hold and recycle nutrients, and can produce some extra forage this fall or next spring. Here are some options:

Research has shown that incorporation (‘plow down’) of cover crops is unnecessary for full nitrogen return to the following crop. By no—tilling into the dead cover in the spring you will reap extra benefits—— such as erosion control, water conservation, etc.

2006–07 Small Grain Variety Trial Data Posted — Greg Roth, Grain Production Specialist

The preliminary results of the 2006–07 Pennsylvania winter barley and winter wheat variety trials are now available and posted on the CMEG website. The data is posted as sortable tables at the following address: http://smallgrains.psu.edu

We had very dry weather at both locations in May, especially at the Landisville site, and this reduced yield and plant height. Disease pressure was light at both locations, but we did collect powdery mildew data at the Rock Springs location and found significant differences among varieties.

There was significant winterkill injury with some wheat varieties at Rock Springs, which was unusual. This negatively impacted the yield of some varieties.

Winter barley yields were also impacted by the winter conditions at Rock Springs. The Pennco varieties and the sister lines of PA–9550–151 and PA–9550–157 appeared to have good winterkill and also good stress tolerance to the dry weather.

The hulless lines of Doyce and Eve suffered considerable winter injury this year at the Rock Springs location and this reduced yields considerably. This demonstrates that there is a need for more winter hardy hulless lines.

Potato Leafhoppers in August — Paul H. Craig, Dauphin County

Each year at this time questions are always raised regarding Potato Leafhopper (PLH) injury to alfalfa stands. It is well established that in the later part of the summer PLH numbers drop off significantly. Typically, this is close to Ag Progress Days. However, the actual time of population crashes varies from year to year and location to location. With the known shortage of forage crops this year optimum management of existing stands for fall production may require more closely monitoring PLH levels.

The PLH is the number one pest of alfalfa. It is a small (1/8 inch long, greenish to yellowish green wedge shaped flying insect. The life cycle includes 5 nymphal stages that closely resemble adults but cannot fly and are slightly more yellowish in color. Population explosions of PLH are evident every year in many mid-season cuttings across most Eastern US alfalfa production areas. In addition to alfalfa, PLH can be found on soybeans, potatoes, many ornamental and vegetable crops and maple trees. To date, feeding on grasses by PLH has not been found.

High populations of PLH can be attributed to rapid population growth potentials of the insect. Females lay 3 to 7 eggs per day but can reproduce for 30 days or more with the potential to lay over 200 eggs. Eggs are laid into alfalfa stems and hatch into nymphs in about 9 days. Fourteen days later these nymphs can be mature and laying eggs. Investigations at the University of Wisconsin have measured a doubling in population levels in 14 days because of the long egg laying period and the overlap of egg hatching and nymph development. Hot, humid weather favors PLH survival and development under droughty conditions also stresses the alfalfa stand.

When PLH feed they insert a needle-like mouthpart into the alfalfa stem and suck out plant juices. At the same time, PLH saliva reacts with nearby plant cells and ends up collapsing nearby cells causing blockage of the transport system in the plant. This blockage prevents water and nutrients in the plant from moving to developing plant parts or the root system. By reducing carbohydrates from moving to the root crown area the long term persistence of the stand can be affected.

The fact that PLH numbers decline in late summer has been investigated by many agronomists and entomologists without any definite conclusions. What is known is that by late summer population growth will stop and numbers level off or decline. When this begins varies from year to year and even field to field. Some believe predators or disease affects the eggs or young nymphs. Others think that the females simply keep feeding but cease laying eggs and eventually begin to migrate back to southern US regions where populations survive to migrate back north next spring.

Producers of alfalfa are reminded to continue to monitor all alfalfa stands for continuing pressure from PLH this summer. All alfalfa stands at this time of year needs to be closely scouted to determine if threshold levels are nearing. As long as nymphal stages are observed then populations will be increasing. As you sweep fields note numbers of adults and nymphs. Treatment is recommended when the total number of nymphs and adults exceed threshold levels but declining numbers of nymphs may indicate the population has peaked for the season. Note that when applying insecticides for control of PLH be sure to consider sprayer boom height, application rates (20 to 25 gal/acre) and adequate pressure to ensure optimum coverage of vegetation.

Soybean Pant Health Pesticide Applications — Kevin Fry, Armstrong County

PA’s soybean crop has reached growth stage R3, generally considered the time for fungicide applications. The disease status for PA soybeans is currently low, some reports of septoria brown spot and downy mildew. The risk for soybean rust is very low. The results from 2005 and 2006 Penn State on farm studies showed an average yield increase of 3.5 – 4.1 bu/A with a fungicide and application cost of $20 per acre. For complete article about study see Capitol Region Agronomy Notes, July 2007. http://dauphin.extension.psu.edu/Agriculture/Archive.htm

What about insects? As you have been reading in the Field Crop News, soybean defoliators have been quite active and now that the soybeans have reached pod stage the level of acceptable defoliation has now decreased from 30% to 15%. Since the writing of the previous soybean defoliation article, we have a couple of new pests entering the game and another exiting. The Japanese beetle is on the decline; however adults are still present and feeding in fields. The first generation of bean leaf beetle adults is beginning to show up along with grasshoppers. Soybean aphids are present, populations are remaining low, and there is still a threat from spider mites especially in our driest areas.

Bean leaf beetles have been recognized as a potential pest of soybeans for some time and we have seen increasing populations in PA. Another factor to consider in addition to defoliation, is beetle feeding on new growth of soybeans. With the welcomed recent rains, soybeans are putting on new growth, if a large beetle population is preventing this new growth, an insecticide application may be necessary. Watch for symptoms of bean pod mottle mosaic virus, which mimics the leaf cupping caused by dicamba drift injury. For more information on bean leaf beetle see the following fact sheet. http://ohioline.osu.edu/icm-fact/fc-23.html

What’s a producer to do? You’ve scouted your fields and discovered that you have just about every pest listed above, but none above threshold. This is where it becomes tough and conflicting recommendations exist. To spray or not to spray, you may have reputable sources telling you to do both. If you would like to experiment with a soybean plant health pesticide application, here are a few guidelines that can help you evaluate if it is truly providing any benefit.

  1. Know what the variety is and note its disease resistance. Only the moderately susceptible and highly susceptible varieties have demonstrated yield impacts in fungicide applications.
  2. Have more than one check strip, wider than your combine, and space them across the field. Three should be plenty, but two is not enough.
  3. In your comparisons, do not include the parts of the field where you have weed escapes or along tree lines, these areas are going to yield less anyway, this will be false data whether it was treated or not. Make sure other variables such as soil types, soil fertility variations and pest issues are not biasing your field experiment.
  4. Approximately 3 weeks after applications, walk some of the strips. Look at the upper canopy for downy mildew or frogeye leaf spot and on the lower canopy look at how much brown spot is present.
  5. Take averages. When you do harvest your fields, take several strips, both untreated and treated. Then take the average of the untreated strips and compare that average to the treated. Fields are not uniform and with stand issues and unevenness across fields this year, there is going to be even more variability.

(Information taken from: C.O.R.N. Newsletter 2007–21, http://corn.osu.edu/index.php?setissueID=192 )

Market Report — John Berry, Lehigh County

I am risk averse. For me, commodity marketing makes sense if fundamentals (supply/demand, acres planted, and such) are followed as the primary source of guidance. Technicals (rolling averages, stochastics) are used to support what appear to be trends. I then look to historical market data attempting to get some kind of a handle on the most important part of farming - making a sale. Current market conditions challenge my sanity as none of my guide posts seems to offer much.

Fortunately for me, I have been creating a pre-harvest marketing plan for the last two years. This effort has taken some of the emotional turmoil out of crop sales decision making. Each fall, before harvest, I create a plan of how I will market NEXT YEARS CROPS. At this time my plan for 2007 (which was created fall of 2006) has 70% of my expected corn harvest sold at an average cash price of a little over $3.67. Beans are 70% sold at $6.22 cash (very weak local basis hurt here). Wheat (2008) is 40% sold at $4.97.

What made this plan work for me were not my target price expectations, it was the use of decision dates. Historical data suggests to some that there is a relatively strong seasonality to commodity prices. By using the seasonal price fluctuations in decision making I am able to capture price trends that are outside of my definition of normal.

For those interested in workshops on how to create a pre-harvest marketing plan — it may be worth your trouble to contact your local Extension Educator and ask about bringing an educational program to your area.

Pennsylvania Weekly Cash Market Summaries: http://www.agriculture.state.pa.us/agriculture/site/default.asp

Chicago Board of Trade: http://www.cbot.com

Free Commodity Charts: http://www.tfc-charts.com/menu.html

Ag Progress Days to Recognize 100th Anniversary of Crop & Soil Sciences Department

A Century of Solutions

Department of Crop and Soil Sciences

(Formerly Agronomy)

100 years of service to Pennsylvania and beyond

We are planning several activities to commemorate our centennial year—details will be posted here as they become available. We invite all alumni and friends of the department to join us in the celebration.

Ag Progress Days Showcase — August 14–16, 2007

The Department will be featured in the College Exhibits Building. Special displays will highlight:

Visit the Crop and Soil Sciences Tent at Ag Progress Days August 14th–16th

An invitation is extended to everyone to visit the Crop and Soil Sciences Tent. Bring your questions, problematic weeds and walk the corn maze. For more information about Ag Progress Days: http://apd.cas.psu.edu/.

Contributors: Dept. Crop & Soil Science: Greg Roth, Marvin Hall, Sjoerd Duiker, and Doug Beegle. Extension Educators: Andrew Frankenfield (Montgomery), Kevin Fry (Armstrong), Jeff Graybill (Lancaster), Susan Alexander (Jefferson), Mark Madden (Bradford), Dave Messersmith (Wayne), Lee Miller (Beaver), John Rowehl (Cumberland), and Paul Craig (Dauphin).

Editor: Jeffrey Graybill, CCA Lancaster County Agronomy Educator

Upcoming Events

Real time pest and heat unit activity: http://agsci.psu.edu/news/spotlight/pa-pipe

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

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