Field Crop News

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

September 22, 2009    Vol. 09:28

IN THIS ISSUE:

• Weather Outlook
• Insect Pest Considerations in Winter Wheat
• Grain Bin Preparation and Maintenance
• Combining Soybeans in Mid—September
• Liming in Difficult Economic Times
• Fall Herbicide Applications
• Blue Green Algae poisoning and its Control
• Upcoming Events

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

The anticipated arrival of very chilly air has been delayed for about a week as the atmosphere continues its meandering motions into the first few days of autumn. The very cool air has instead settled into the high Plains and eastern Rockies rather than pushing toward the East Coast. As a result, a very mild, moist air flow will cover the Commonwealth into the first part of Thursday. Showers will be widely separated and rainfall will generally be less than a quarter of an inch. A surge of somewhat cooler and much drier air should arrive by Thursday afternoon and be followed by a pleasant end to the work week and a decent start to the weekend. However, the disturbance in the middle of the nation will be propelled eastward on Saturday bringing a band of showers late in the day and during Sunday morning to most of the state. It will remain mild later Sunday and Monday until a sharp cold front finally arrives with some showers late in the day. Blustery, much cooler weather is expected by next Tuesday and should persist into Thursday.

Despite the very cool weather at the start of the month, the first half of October is expected to average above normal and then it should turn much colder during the second half of October. There are increasing signs that November will be rather mild in this region and December will turn seasonably cold. The development of a moderate El Nino in the Pacific portends a wetter winter (and probably snowier) in the state with the period December—February expected to average below normal temperatures.

Insect Pest Considerations in Winter Wheat — John Tooker, PSU Entomology Specialist

As the time to plant wheat approaches, we thought it would be good to consider some best management practices for a few of the major insect pest species that attack wheat, particularly Hessian fly and aphids. While Hessian fly has largely been an historic pest, the past few years have seen an increasing number of outbreaks in eastern states, including Delaware, Virginia, and North and South Carolina. This pest has not been common recently because most farmers plant wheat after “fly—free dates”—— dates after which egg—laying Hessian fly adults are not likely to be active. (For best estimates of fly—free dates in PA, see this Department of Entomology website: http://ento.psu.edu/extension/factsheets/hessian-fly-on-wheat.) However, some growers have been planting wheat as a cover crop (or some other reason) in late summer or early fall. These early—planted fields can be colonized by Hessian fly larvae, fostering populations of Hessian flies that can then emerge in spring and further infest production fields and cause more economic damage. Insecticides are generally not effective for control of Hessian fly so the best tactic for farmers is to adhere to the fly—free dates as well as plant Hessian fly—resistant lines of wheat.

Another major pest of winter wheat is a suite of aphids. Collectively known as “cereal aphids,” they include bird—cherry oat aphid, corn leaf aphid, English grain aphid and greenbug (for aid in identifying these species and distinguishing them from one another see this site from North Dakota State University: http://www.ag.ndsu.edu/pubs/plantsci/pests/e493w.htm). Most of these aphid species usually do not inflict economic damage by themselves and are usually kept in check by natural—enemy populations. Greenbug is an exception however because they feed by injecting toxic saliva into plants causing yellowing that resembles nitrogen or moisture stress. All these aphid species are a further concern because they can transmit barley yellow dwarf virus (BYDV).

We have heard that some agricultural companies are promoting preventative insecticide applications to avoid aphids and possible virus infestation. We would like to stress, however, that aphid populations are notoriously patchy with adjacent fields often having drastically different populations; therefore, the best strategy for managing aphids is to use an IPM framework and only apply an insecticide when it makes economic sense. That is, when scouting reveals that the aphid population exceeds the economic threshold. The threshold published in the Penn State Agronomy Guide is 100 aphids per foot of row. This threshold was not developed with the current higher price of wheat, but growers should be wary of expecting a yield advantage for applications of insecticides against typical populations of cereal aphids.

Grain Storage Preparation and Maintenance Saves Quality — John Rowehl, York County Educator and John Tooker, PSU Entomology Specialist

Corn harvest is not too far away and with current prices, steps to protect grain from insect infestation and preserve grain quality pays off faster than ever. Starting out with a grain bin free of old, insect infested grain is essential to getting a good start, particularly if no other protection will be applied to the grain. Sweeping down the walls of the bin and getting old grain out of the cracks and crevices is essential to prevent problems later.

Malathion, Storcide II ^™, Tempo Ultra SC ^™, Suspend SC ^™, and several pyrethrin products can be used to apply a surface treatment to the inside of the bin and provide a residual. Note that on the label for Storcide II there are restrictions on the application method. Chloropicrin is no longer labeled to fumigate underneath false floors and in air ducts. Phostoxin is the only product that can be used for this purpose.

Once the bin has been properly cleaned, it is important to put clean, insect—free new grain in the bin. The first step to accomplish this is to make sure your equipment has been cleaned out before you begin harvesting. Otherwise, you could bring in insects that have been living inside of your combine.

Make sure the combine is adjusted to minimize breakage of grain. Whole grain is more difficult for molds and insects to get started on and also makes aeration of the bin more efficient. If possible, grain should be run through a cleaner before placement in the bin. Sanitation and surface treatment should be sufficient to control insects for a six to nine month period.

If you are not able to clean out the bin or don’t fumigate under floor areas, or if you think the storage period may be longer, application of a residual insecticide to the grain as it goes into storage will help keep insects controlled. Actellic 5E is labeled for this use on corn and sorghum whereas Storcide II is labeled for barley, oats, sorghum, and wheat. Application of methoprene (Diacon II) is also an option and this hormone mimic will prevent larvae from becoming adults, stopping the cylcing of generations. A dust formulation of malathion (check the label) may possibly still be available for treating grain. If you do not treat the whole bin this way you can treat the last load going in with a protectant or mix in a Bt product into the top four to six inches of grain in the bin to control Indian meal moth.

During winter months, the cool temperatures keep insect activity in check but as spring approaches and grain temperatures rise above 40–50°, insects can become active and reproduce. If insect populations do develop in your bin, in most cases, your only option is to fumigate. Aluminum or magnesium phosphide is labeled for grain fumigation. You must be a certified applicator to use these products. Remember, fumigation only kills insects that are present and does not provide long—term residual protection.

A handy reference you can download is the University of Tennessee 2006 Insects in Farm Stored Grain. http://www.utextension.utk.edu/publications/pbfiles/PB1395.pdf

Grain storage insecticide labels have been changing frequently over the last several years. As always, check to make sure you are following the instructions on the product label.

Combining Soybeans in Mid—September — Kevin Fry, Armstrong County Educator

How would you like to be combining soybeans by September 16^th? That is exactly what a Fayette County farmer was able to achieve this year. How is that possible you may ask? He planted a 2.3 maturity soybean on May 10^th. Beans were no—till drilled at 196,000 seeds per acre and harvest population was estimated at nearly 180,000. A total of 25 acres were harvested with an average yield of 42 bushels per acre at 13.4% moisture.

Is there a yield penalty for planting that early maturity soybean? Unfortunately we won’t be able to answer that question, as there was not a later maturity planted at the same time on this particular farm. But looking at the field and knowing its history, I would guess there was little to no yield penalty. This brought about an interesting conversation of how much of a yield penalty could you afford in order to harvest soybeans this early in the season?

The ultimate goal of the farmer was to spread out his harvest workload and follow up with a small grain seeding. In this case it was a complete success, as he achieved his goals and exceeded his early season yield goal by 2 bushel. Additionally, he was able to market a trailer load of beans to a local mill in need of soybeans for a premium. Instead of pushing soybean maturities into the late group threes, maybe you want to look in the opposite direction. There is a good probability of nice weather in September, there could be an early market premium, there is ample time to seed cover crops or small grains, and the yield penalty may not be as large as you thought. It might be something to think about for next year.

Liming in Difficult Economic Times — Douglas Beegle, PSU Soil Fertility Specialist

When times get tough in crop production, one of the first things that often gets cut or postponed is liming. However, this could be a serious false economy because liming impacts so many other management inputs and practices. This could significantly reduce the returns on these valuable inputs. A few of the more important impacts are listed below:

1. Low pH reduces root growth. If root growth is reduced, plants can’t take up water and nutrients as efficiently.
2. Low pH reduces nutrient availability. Availability of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), and molybdenum (Mo) are all negatively impacted by low soil pH.
3. Liming supplies essential calcium and magnesium. Fertilizing with Ca and Mg is just as important as N—P—K but It is often overlooked because it is normally taken care of a side benefit of liming.
4. Many herbicides are sensitive to low pH. Effectiveness of important herbicides like atrazine can be dramatically reduced at low pH.

There are some important considerations that can help in making lime management decisions in these difficult times. Most important is to soil test to determine pH and lime requirement. Don’t waste money on lime for fields that don’t have a low pH, but at the same time make sure that you prioritize your lime dollars to lime fields that really need it. Some criteria for prioritizing your liming dollars are provided below:

1. Always maintain soil pH above 5.5. This is a critical pH for root growth for most of our crops. With limited money to spend on lime, at least try to apply some limestone to any field with a pH near or below pH 5.5.
2. Prioritize fields that will be planted to alfalfa for limestone application. The rhizobia that fix nitrogen in the nodules on alfalfa roots are less productive at low pH. This can result in N deficiency in alfalfa. Since an alfalfa seeding is a long term investment this is an especially critical time in the crop rotation to correct the pH.
3. Maintain pH in long term no—till fields. Because there is no mixing by tillage, regular liming is essential to maintain soil pH in long term no—till fields. If the pH in a no—till field is allowed to get too low, it can take a long time to correct this condition without going back to tillage. In an experiment we did, it took 9 years to raise a soil pH from 5.1 to 6.5 at a depth of 6 inches in continuous no—till.
4. Finally, for better nutrient use efficiency and herbicide activity, try to maintain the pH at least above 6.0 if possible. Even if you cannot afford the full recommended rate of lime the next priority would be to get as many fields as possible above 6.0. To determine a limestone recommendation for a target pH of 6.0 multiply the “Exchangeable Acidity” on your soil test times 750. This will give you the pounds of calcium carbonate equivalent to apply.

Be aware that low rates of high quality liming materials cannot substitute for applying the recommended amount of limestone. Products like pelletized limestone and fluid lime are excellent liming materials but simple acid neutralization chemistry dictates that you must apply the recommended amount of calcium carbonate equivalent regardless of the form to correct the pH. The benefit of these materials is in the application and they will react faster but they will not neutralize any more acidity than regular limestone on an equal weight basis. Also, don't get taken in by alternative products that claim to have liming value. There are no products that I know of that you can add a few gallons of a product and get the same benefit as a ton of limestone. If you have questions about the claims for one of these products check with the Pennsylvania Department of Agriculture Bureau of Plant Industry who register these products or contact your local Penn State Cooperative Extension Office.

Even though times are tough and you may be tempted to skip liming to save some money, it is important to think about the broad impacts that liming can have across your crop production system. If you have to cut back, think through the priorities outline above to make better decisions about your liming program.

Fall Herbicide Applications: Understanding the Utility — Dwight Lingenfelter, PSU Weed Science

Fall herbicide applications can provide effective control of various weed species. However, herbicide choice and application timing will influence the effectiveness of the procedure. Foremost, one must determine what is to be accomplished with the application. Is it to control perennials or are you looking to manage winter annuals and provide some residual control into next year’s crop? Mark Loux, Ohio State University Weed Scientist, has provided a good review of things to consider when using fall herbicide programs. His article entitled “Timing fall herbicide treatments based on weed life cycle” can be found at: http://corn.osu.edu/index.php?setissueID=316

Fall burndown herbicide programs have utility in Pennsylvania and the Northeast, however they will not fit into all systems, especially those that are more diverse. Also certain residual herbicides limit crop choice next season. For example, if one applies Basis or simazine, then only corn can be planted next season. If Extreme or Canopy EX is used then only soybeans can be planted. Other products such as Sencor, Python and Valor are not as restrictive. Below are some aspects growers must consider when using fall burndown programs:

—Severity and types of weeds (may still need to apply spring burndown)
—Cover crop issues (it can be difficult to utilize cover crops and fall bunrdown programs together)
—Economic value of this approach (better fit in southern parts of state or region)
—Timeliness of application (for herbicide uptake by weeds and residual control)
—Limited crop rotation options the following spring (including vegetable crops)
—Potential for herbicide resistance
—Time management concerns involving fall and spring farm workload

Blue Green Algae Poisoning and Its Control — Mena Hautau, Berks County Educatord

Blue green algae, which look like a pea green cover on farm ponds, can kill livestock. The blue green algae is not the type that can be picked up as clumps, but disperses easily in the water if disturbed. As the algae dies, it releases toxins in the water. These toxins affect the liver and skin. Livestock and dairy animals should not use pond water for their water source.

Algae blooms are often an indicator that a pond has too many nutrients. When pond water becomes stagnant in the late summer, has a warm temperature and has many available nutrients, algae growth can be excessive.

The best way to control algae blooms is to prevent nutrients from entering the pond. Keep a 30 foot grass buffer around the pond. If that is not practical, provide as large a buffer as possible. Do not allow livestock to create mud lanes or regularly graze the buffer area. Discourage ducks and geese from entering the water by keeping the grass high around the buffer area. Eliminate activities around the pond that can create more nutrient loading from surface water runoff, such as bare ground areas, livestock housing, etc. Algae can be controlled by using copper formulated algaecides, but it can only serve as a temporary measure. The long term solution is to reduce nutrient loading. Best practices when handling an algaecide include the following. Go to this web page on the Penn State Pond Site to read more in the individual fact sheets http://water.cas.psu.edu/PondPubs.htm

-Obtain a state permit from the PA Fish and Boat Commission. The permit does not cost but is a communication to the agency of your plans to use the algaecide as the product label describes. Improper use of algaecides could possibly cause fish kills due to oxygen depletion of the water. Make sure you fill out the state permit before use.

-Calculate the number of acre feet of water, so that you can add the correct dose for the size of the pond. It would be a waste of time and money to overdose or underdose a pond.

-Read the label and follow directions, paying attention to the rates and any environmental hazards specified.

In recent years, more people have asked about the use of barley straw to control algae in ponds. Barley straw is used for control of filamentous (clump type) algae, not blue green algae. Fact Sheet # 8, "Using Barley Straw to Control Algae" has more on how to use barley straw.

Penn State Extension has an excellent website on ponds. Worth watching is the on—line video, “Management of Aquatic Plants”. It’s a primer on pond care and how to maintain good water quality. Go to this page to find out more: http://water.cas.psu.edu/ponds.htm

Upcoming Events

Cover Crop Field Day — October 9^th in Jefferson County.

Agenda includes:

• Viewing the results from the aerial rye seeding
• No—till planting demonstrations
• Tours of cover crop plots containing 16 different mixtures
• Manure spreader calibration demonstration
• Animal composting

For more information and registration, http://jeffersonconservation.com/ or call 814–839–7463.

Keystone Crops and Soils Conference — October 27 & 28

Contributors: Extension Educators: Kevin Fry (Armstrong), Mark Madden (Sullivan), and Mena Hautau (Berks). State Specialists: John Tooker, Dwight Lingenfelter, and Doug Beegle

Editor: Kevin Fry, Armstrong County

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&

If you have any questions or would like to suggest a topic, please contact your local Extension Educator.

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