CMEG Crop Management Extension Group

Field Crop News

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

May 12, 2009    Vol. 09:10

IN THIS ISSUE:

Weather Outlook — Paul Knight, Pennsylvania State Climatologist

Expect a warmer period from Wednesday into Saturday as winds from the south predominate (and they will be rather gusty on Wednesday afternoon). There will be a broken band of showers (and scattered thunderstorms) crossing the state starting late Wednesday night in the northwest and ending by Thursday evening in the southeast sections. Rainfall amounts will average near a half inch in the western third of the state to less than a quarter of an inch in the eastern counties. After a mainly dry and pleasantly mild Friday, more humid air will enter the region on Saturday preceding a strengthening cold front. Showers and a few thunderstorms will dampen many sections between Saturday afternoon and sunrise on Sunday. Amounts will be similar to Thursday’s rainfall. A push of much cooler and drier air will arrive during Sunday. Odds favor many sections from I-80 north having some frost on Monday morning (May 18). This cool snap will be followed by a generally drier regime for the last two weeks of May.

Odds still favor above average temperatures for the June through August period with a notable wet period in the latter half of July or August. The hurricane season should have a late start with notably fewer storms than recent years.

Assessing Corn and Soybean Stands — Del Voight, Acting Grain Crop Specialist

As Corn and Soybeans begin emerging most farms will have 1 or 2 fields in question as to emergence and stand. Many factors come into play as the crop emerges. Insects, fertility, diseases and compaction can severely impact viable plant stand. Here are the factors to consider for replanting efforts.

  1. What is the ideal planting date for your area? In the Agronomy Guide, the state is broken into climatic zones and the research in PA when 100% of your yields are achieved at a set population is listed below.
    1. Corn
      1. Zone 1 — 5/15-5/25
      2. Zone 2 — 5/1-5/15
      3. Zone 3 — 4/25-5/7
      4. Zone 4 — 4/15 to 5/1
    2. Soybeans — The state is divided into group zones and is much more difficult to assess. In the major soybean growing areas it is recommended to get the ideal yield to plant between May 10 and May 20. Further research is needed to assess the extremely early plantings with new seed treatments and its impact on yield.
  2. What is the population?
    1. Corn — Estimate population by walking the field and counting the number of plants in a given row length. Do this in at least 5 areas of the field and average the total counts to arrive at a population. I use 17.5 feet for 30 rows which is 1/1000 of an acre so I can simply add 1000 to my counts and get a population.
    2. Soybeans — Again estimate the population by counting plants in several areas of the field. There are a number of methods to assess soybean stands from row counts to hula hoops. Pick one and go with it.
    3. How even is the population across the field?
      1. This might take standing on the top of your truck but generally if you see that large areas are devoid of plants this will impact your decision. If more than a third of the area is lost you will need to factor that into your population counts.
  3. What is the replanting date?
    1. Once the ideal date for 100% of yield is known then later plantings can be compared to the ideal and calculations may be made to determine the need to replant.
    2. Is there a replant policy from the seed company?
  4. What impact does late planting date and lower populations have on yield?
    1. Corn (see Table 1)
    2. Soybeans
      1. May 10 – 100%
      2. May 20 – 98%
      3. May 30 – 95%
      4. June 10 – 88%
      5. June 20 – 76%
    3. Example, If you planted Corn on April 30th at 100% of yield and you find that on May 29th you have 20,000 ppa or 73% of your yield. Then you can calculate that you will lose about 30% of your potential yield. So if you had 150 bu/acre potential, you may lose 45 bushels. While if you replanted on May 29th at 30,000 you would get 81% of yield and still lose 28.5bu/acre. The difference 45bu/acre less 28.5 bu/acre or 16.5 bu/acre, represents the benefit to replanting.
  5. What are the costs to replant?
    1. In most cases it will take a burn down material to kill the corn and the addition Seed costs.
  6. What herbicide was used that might impact replants?
    1. Most corn herbicides labeled allow for replants. Products like Prowl are prohibited however in past experience by no till and get the seed below the herbicide zone as worked well.
  7. Example, If you planted Corn on April 30th at 100% of yield and you find that on May 29th you have 20,000 ppa or 73% of your yield. Then you can calculate that you will lose about 30% of your potential yield. If you had 150 bu/acre potential, you would lose 45 bushels. If you replanted on May 29th at 30,000 you would get 81% of yield and still lose 28.5bu/acre. That difference (45 less 28.5 bu/acre or 16.5 bu/acre) is the benefit to replanting. At 5 dollar corn this would equate to $82.50/acre benefit. Subtracting the replant costs of 10 dollars to kill the existing corn and another 50 dollars for seed the benefit to replanting would be only 20 dollars per acre. At least you will have some information to make informed decisions on how to proceed.
  8. This interactive site from Missouri takes into account the questions you need to ask yourself. One may place in it the specific yield potential and a date and it will give you some idea of the cost of replant. This is based in Missouri however most will apply to Pa conditions and steer one to the right answers Here is the link to actually use the program. Calculating corn and soybean replant decisions.
  9. Resources useful in assessing poor stands and other emergence-related maladies are listed below: (Source R Elmore Iowa State University)
    1. Information on normal corn root development
    2. Early-season corn stress and some things that go wrong
    3. Rootless corn syndrome
    4. Uneven corn emergence and heights due to variable soil conditions and planter adjustment: with a tool to assess uneven emergence
    5. Problem stands and replant decision making:
    6. Off-color corn
Table 1
Planting date Plants/A at harvest
10,000 12,500 15,000 17,500 20,000 22,500 25,000 27,500 30,000
% of optimum yield
Figures shown are most applicable to corn fields with greater than 125 bushels per acre.
Source: University of Illinois
April 10 62 70 76 82 86 90 92 94 94
April 15 65 73 79 84 89 92 95 97 97
April 20 67 74 81 86 91 94 97 98 99
April 25 68 75 82 87 92 95 98 99 100
April 30 68 75 82 87 92 95 98 99 100
May 4 67 75 81 86 91 94 97 99 99
May 9 65 73 79 85 89 93 95 97 97
May 14 63 70 76 82 86 90 92 94 95
May 19 59 66 73 78 83 86 89 90 91
May 24 54 62 68 74 78 82 84 86 86
May 29 49 56 63 68 73 76 79 80 81

Spring Pastures Can Bring Bloat — Jonathon Rotz, CCA Cumberland County

Spring time is here and pastures are growing quickly. With this new lush growth also comes an increased concern for bloat. Bloat typically occurs on young fast growing pastures that have more than 50 percent legumes (clover, alfalfa, etc.). Bloat is simply a condition brought on due to excess protein in the rumen which creates foam that will not allow gasses to escape the rumen. This condition leads to excess pressure in the cattle’s rumen and in worst cases can lead to death. Bloat can be a major problem on lush spring pastures, however it can be managed.

The first step in managing bloat is to identify your pastures containing more than 50 percent legumes. These pastures will contain high protein levels especially in the spring when all of the growth is new and lush. Identify your pastures that are most likely to be a problem and use extra caution when animals are on those pastures. If all of your pastures contain high portions of legumes you want to take special care to give animals time to get used to the pastures early in the spring.

Management strategies such as feeding a grass hay prior to the grazing period and not allowing access to pastures when excess moisture is present due to rain or heavy dew will help minimize the occurrence of bloat. Over-eating frequently occurs when hungry cattle are turned onto fresh pastures with high percentage of legumes. Bloat is probable if these animals have not been accustomed to the legume mixture. Feeding grass hay prior to grazing allows the cattle to fill the rumen with a lower protein feed and will decrease the occurrence of over eating and thus minimizes the risk of bloat. Continue to feed hay prior to grazing for 5–6 days. During this time decrease the amount of hay fed until they are dependent totally on the pasture.

Poloxalene is another management option for those dealing with high percentage legume pastures. This chemical reacts in the rumen and decreases the instance of foam and allows excess gasses to escape naturally. This chemical is most easily fed in a molasses, salt, and poloxalene block mix. Allow one block for every 5–6 cattle and keep them in places where cattle typically gather. You may also be able to add poloxalene into any grain mixes you may be feeding. You should feed half a pound of poloxalene per animal.

Finally, the best management strategy will be to check your cattle frequently, about twice a day. This will allow you to observe any problems that may exist. The first visual sign of bloat is a notable increase in the fullness of the left side of the animal. If a cow is struggling with bloat you may be able to alleviate the symptoms by inserting a hose into the rumen to allow gasses to escape. Additionally there are oral products on the market that can be fed to aid in recovery. Consult your veterinarian about these products. If neither of these options work, you may want to attempt to use a trocar or cantula to relieve the pressure in the rumen; however, these should be the last resorts and should be observed by a veterinarian.

Using these steps you should be able to effectively manage bloat in your cattle without instances of emergency management. If questions or concerns still exist call myself or your local extension agent to assist you in your specific situation.

Cereal Leaf Beetle — John Tooker, Penn State Entomology Specialist

We have heard several reports from the southeastern part of PA that cereal leaf beetle larvae are causing damage to wheat. This exotic species, which was introduced into the United States from Europe and parts of Asia, can also be an issue in oats. Adults tend to spend the winter in leaf litter in wooded areas and begin the growing season by feeding on weedy grasses. They then move into small grain field, where adult females lay their orangish-yellow eggs along the mid-vein of the upper leaf surfaces. Larvae are similarly colored but the color is often obscured by a black slimy material, which is a combination of their feces and a mucus-like substance. This material is piled on their backs to provide some protection and gives larvae a shiny black slug-like appearance. Larval populations peak between mid-April and mid-May with older larvae inflicting most of the damage. Larvae feed between leaf veins, skeletonizing leaves, giving them a distinct silvery or frosted appearance.

This pest species can be a problem in conventionally managed fields that were planted late, have thin stands, or have poor populations of natural enemies (it appears that parasitoid wasps can effectively control this pest in some parts of its range). If you see adults, it is likely too late to manage this pest, but if scouting reveals 25 eggs and larvae per 100 tillers or one one-eighth-inch-long larva per stem or flag leaf, treatment may be warranted. Be aware that this pest can be patchily distributed so thorough scouting is necessary and localized treatment is an option. There are reasonable options should an insecticide be needed against this pest; see the Penn State Agronomy Guide for details.

No-tilling Corn after First Cutting Alfalfa: Remember Glyphosate can be used Pre-harvest — William Curran, Penn State Weed Scientist

Harvesting first cutting alfalfa and then no-tilling corn into the alfalfa stubble can be challenging and certainly risky. Two of the biggest challenges are 1.) Getting acceptable control of alfalfa after first cutting, and 2.) Even with acceptable control, what impact can the dying alfalfa crop have on corn yield? To start, choose the correct herbicide program and make sure there is adequate regrowth before making the herbicide application. Cutting the alfalfa a bit high and leaving some leaf tissue will probably increase successful control. In some research we conducted at Rock Spring and Landisville, we harvested the alfalfa in early to mid May and no-tilled corn into the stubble shortly thereafter. We compared PRE applications about 5 days after harvest to an EPOST application about 10 days after harvest (6 inches of regrowth) to a MPOST application about 17 days after harvest (10 inches of regrowth). Our herbicide programs focused on 2,4-D and dicamba (Banvel or Clarity) alone or in combination. The combination of these two herbicides is probably the most consistent for control of alfalfa. Glyphosate will add some alfalfa control and is a definite must if annual or perennial grasses are present, but it really doesn’t alter the success of application timing. In short, none of the PRE treatments were effective (40% or less). Waiting about 10 days after harvest to make the herbicide application provided 79 to 99% control by early July with the combination of 2,4-D + dicamba providing the best results. By waiting 17 days after harvest when the alfalfa was 10 inches tall, all treatments effectively killed the alfalfa.

Now the bad news; because of dry weather in May, corn yields were severely reduced in all treatments. Yields averaged 8 bu/acre in the untreated checks, 52 bushels in the PRE treatments, 84 bushels in the EPOST timing and 76 bu/acre in the MPOST timings. Yields were fairly similar at the two locations and although we did not include an alfalfa-free check, typical corn yields at both research farms were at or above normal for the regions. So, even with adequate alfalfa control a month into the growing season, we could not recover from the early season competition and the moisture deficit. Although this season is starting out much differently, keep in mind the importance of alfalfa regrowth for adequate control (6 inches is the minimum) and how soil moisture may make the ultimate yield decision.

Alternatively, and still somewhat risky, glyphosate can be used 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 to be 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 POST application should be made to control the legume regrowth. The plant growth regulator herbicides (2,4-D, dicamba, clopyralid - Stinger and Hornet, as well as Distinct or Status), should help control alfalfa post in corn. In Roundup Ready corn, glyphosate can also help suppress the legume and a growth regulator herbicide could be tank-mixed with the glyphosate. This approach should at least insure more timely control of the forage, but will not prevent the negative effects of a dry spell early in the growing season.

Weed Control in Grass Hay and Pasture — Bill Curran and Dwight Lingenfelter, Weed Science

We are starting to get questions regarding herbicide considerations and restrictions for grass hay and pastures. The current options/details are outlined in Tables 2.6-7 through 2.6-9 in the Penn State Agronomy Guide.

For most of the products that contain plant growth regulator type herbicides (2,4-D, Clarity, Crossbow, ForeFront, Milestone, etc.) remember to allow seedling forage grasses to get established (4–5 inches tall, have a good secondary root system, and show good vigor) before making a herbicide application. Cimarron Plus also has some necessary establishment periods for different grass species before herbicide application that should be observed. Also, most herbicide for use in grass forage crops will severely injure or kill legumes. Don’t use these products if loss of legume species cannot be tolerated. In many cases, weed control is very important during the grass establishment period since weeds can become very competitive. Also, remember that perennials should be treated in the bud to bloom stage for best results, biennials in the rosette stage, and annuals as seedlings.

Pest Updates — Del Voight, Interim Grain Crop Specialist

There are numerous pests of corn and as the plants emerge it is important to scout to determine if there any insect issues that need to be addressed. There are two pests that are active that we have received calls this week regarding leaf feeding those being slugs and cutworms.

slug damage on corn showing holes in leaves

Slugs — Slugs are active and small the gray garden slug is measuring about ¼ but can be found easily now under surface residue… They can severely impact the development of corn if prolonged wet weather is occurring. If we get dry windy weather the slug issue will go away as quickly as it emerged with the exception of side wall compaction when they feed under the soil line and are not subject to weather. My experience with slugs is that leaf feeding is not a huge issue provided dry weather returns, however, if the slugs attack the seed due to sidewall compaction they can kill plants and set seedlings back weeks before recovering. To avoid this pest here are some methods.

slugs Effects of Deadline Bullet on slugs Figure 4

Cutworms — Numerous cutworms are active. Perhaps the first to show its feeding is the Eastern Black Cutworm often confused with the dingy cutworm. Dr. Tooker has a tracking network and moth fights were heavy in some areas in Berks and Lancaster while the Lebanon site was low in numbers this indicates that the cutworms could be a problem in some fields and not others. There are more of these cutworms that we will begin to see. The true armyworm and then European corn borer will become active. For this article a focus will be on Eastern Black Cutworm. The damage is from chewing mouth parts and this picture illustrates damage caused by cutworms. Often times when larvae are large they will completely cut the plant off at ground level.

Cutworm damage on corn

Management:

Partial list of Insecticides labeled for black cutworms in corn: Penn State Agronomy Guide 2008
Insecticide Amount/Acre Cost per Acre
*Restricted-use pesticide.
Neemix 4.5 .25–1 pt ???
Bacillus thuringiensis Numerous ??
Capture 2EC 2.1–6.4 ??
Ambush 2EC* 3.2–6.4 ounces 2.94–5.87
Sevin many formulations 9.56
Asana XL* 5.8–9.6 ounces ??
Dimethoate* 1.5 pint 6.32
Lorsban 4E* 1–2 pints 3.34&nash;6.68
Mustang Max 1.28–2.8 ounces ???
Penncap-M* 2–3 pints ???
Permethrin Pounce 3.2EC*numerous others 4–8 ounces 1.835–$4.00
Sevin many formulations @ 9.56
Baythroid XL 1.6–2.8 ounces 1.68–4.71
Warrior*/Pro Axis/Taigra Z 1.92–3.2 ounces 3.78–4.34

Second Annual Northeastern Weed Science Society (NEWSS) Noxious & Invasive Vegetation Management Short Course (NIVM)

This course has evolved to meet the demand and need for training and instruction of professionals involved in the administration and/or application of management strategies for invasive plants here in the Northeastern United States. The short course is designed for public and private land managers (parks, conservancies, preserves, forests, private parcels and farms) from Maine to North Carolina who desire a better understanding of non-cropland weed management. A huge success in 2008, the course has expanded to include even more topics. Pre-registration is required to attend this course and should be submitted before June.

The announcement flyer and pre-registration documents are now posted on the NEWSS Web site. We appreciate your assistance in disseminating this important and exciting information.

Register for the Agronomic Weed Control Twilight Tour at Landisville, June 29, 2009

The Second Annual Twilight Weed Tour, Southeast Research and Extension Center (Landisville). Will be held begin at 4:30 pm on June 29, 2009. This is the evening before the “Farming for Success” Field Day on June 30. We will tour the weed control plots from 5:00 to 7:00 pm. You will have an opportunity to examine corn and soybean weed control trials including some cover crop control studies. The format of the program will allow time to view the various treatments /studies and discuss the results with those in attendance. We will finish the evening socializing with one another and enjoying a hot meal.

This event costs $25 per person and includes dinner and educational materials. To register, fill out and send in the form before June 24. Pesticide and CCA credits will be offered. Please contact John Bray or Del Voight at 717-270-4391 in advance if you need additional information.

Contributors: State Specialists: Bill Curran, Del Voight; Extension Educators: Kevin Fry (Armstrong), Mena Hautau (Berks), Jeffrey Graybill (Lancaster), John Rowehl (York), H. Grant Troup (No-till Specialist- Capital Region), Mark Madden (Sullivan), Joel Hunter (Crawford), Jonathan Rotz (Cumberland).

Editor: Jeffrey Graybill, MS, CCA

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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