CMEG Crop Management Extension Group

Field Crop News

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

May 30, 2006    Vol. 06:06

IN THIS ISSUE:

Weather Outlook — Paul Knight

The heat and humidity will persist in eastern sections on Wednesday and much of Thursday, but clouds and more numerous thundershowers will temper the hot weather in the western half of the state those days. Most thundershowers will occur north and west of the Alleghenies on Wednesday, though a few will reach the central valleys later in the evening. On Thursday, all but the southeast corner should notice a shower or thunderstorm. By Friday, temperatures will return to more seasonable levels (upper 60’s northwest, 70’s elsewhere), though clouds and some showers will persist in the eastern third until evening. The weekend will be cooler than average with a few popcorn showers in the western mountains, mainly on Saturday. Warmer air will return on Monday and there should be some overnight or pre-dawn thunderstorms on Tuesday.

There are some indications that a push of rather cool air may arrive late next week (June 9-10).

Fertilizing Forage Crops — Doug Beegle

Even with high fertilizer prices, we need to make sure we are meeting the nutrient needs of forage crops if we want optimum production. Forage crops have a large appetite for nutrients, removing around 50 lb N, 15 lb P2O5, and 50 lb K2O per ton of hay equivalent harvested. Many fields that get a lot of manure in the corn part of the rotation have good reserves of nutrients that can be used by the forage crops, at least for a while. Here is a place to save some dollars and utilize these banked nutrients rather than applying fertilizer. Fields receiving little manure or that are late in the forage rotation can have fairly low soil test levels and thus need fertilization. This is where you need to prioritize your forage fertility dollars. The key is to recognize these differences and fertilize wisely.

As always, begin with a soil test. Even though it maybe the last minute, the Ag Analytical Services Lab at Penn State normally has about 2 day turn-around with soil samples. So if you overnight your samples to the lab and have signed up for free web access to your results, you could sample at harvest and still have your results in time to make topdressing decisions. Other labs have similar service.

The ideal management for forage crops is to build the soil levels at least into the optimum before seeding. Then if the soil test levels are above optimum at that point, you can draw them down for a while until they are in the optimum range and then maintain the soil in the optimum range throughout the remaining life of the stand by replacing crop removal.

Timing of fertilizer applications to forages will depend on the situation. If the soil tests are in the optimum range and the recommendations are relatively small, timing is not very critical. The most common timing is after first cutting. For larger applications on low testing soils, split applications are usually more efficient. Apply some early in the season and the balance in the early fall. This minimizes luxury consumption of nutrients like potassium and the fall application may improve winter survival of the forage.

What about manure on forages? Manure is excellent on grass forages which need N, P, and K. Splitting applications in the spring and immediately after each harvest is recommended for maximum nutrient use efficiency and to avoid problems with injury. Base the rate on the N requirement of the grass forage which is 50 lb/ton of expected yield for the upcoming cutting. Remember that typically manure N will only be about 35% available compared to fertilizer. See table 1.2-14 in the 2005-2006 Agronomy Guide for more specifics.

On legumes, manure is a good source of P and K but since they do not need the N, it will be essentially worthless to the crop. Also, in mixed grass-legume stands or where there is some weed pressure, the N in manure can stimulate the grass and weeds and crowd the legume out of the stand. Old stands that will soon be rotated out of forage are usually the best place to go with the manure rather than newer stands.

Corn Fields for Spotty Germination and Emergence — Don Fretts

In western and northern Pennsylvania some corn fields are exhibiting spotty to very poor germination. In 2005, emergence finally occurred after a three week, cool, dry period that followed planting the week of April 17th. However, this year in May we experienced two weeks of very cool and wet weather, thus providing a more negative climate for emergence.

No-till fields were planted just before the eleven day rain period and cooler temperatures in May and are presenting some frustrating challenges.

In low lying areas where there was standing water, germination is non-existent. On some heavier soils where good ground cover was present, germination and emergence took over three weeks and then an extra week for full emergence. Corn planted on May 10 and 11 still has some seedlings that just emerged within the past several days, even after a significant warm up last week.

Rain induced soil crusting or hard soils apparently have made it difficult for seedlings to break through.

In addition, I have found symptoms of insect feeding. However, since the drier and warmer weather, I have not found cutworm or slugs on the soil surface.

Due to a variety of potential reasons for slow emergence, scout poorly emerged corn fields closely before jumping in to replant.

For more information relative to corn population if considering a re-planting decision, view Table 1.4-8.

Change in Yield and Quality of Alfalfa — Marvin Hall

Many growers are asking about the tradeoffs in yield and quality of alfalfa as they enter quality pricing contracts for hay or haylage. The situation is that premiums are paid for quality but some of the premium for increased forage quality is offset by lower yields when fields are cut earlier for higher quality. The table below is a summary of data collected in Pennsylvania, Wisconsin and Idaho during 2004 and 2005.

Alfalfa forage change in yield and quality during the growing season
Cutting Yield (lb) RFV RFQ
--- Daily Change ---
1 100 -5 -5
2 100 -2 to -3 -5
3 100 -2 -4
4 100 -1 -4

The average yield increase of alfalfa near harvest was about 100 lbs per acre per day if growing conditions are ‘average’. The daily yield increase will be less in cool, cloudy weather, and if insects, disease or drought occur. It may be greater in periods of good moisture, sunshine and 75 to 85 degree weather.

Quality of first cutting changes at the fastest rate. Later cuttings decrease in fiber and digestibility at a slower rate. We found that first cutting decreases about 5 pts RFV per day, second cutting decreases 2 to 3 points per day and third and fourth cutting during the growing season decline 1 to 2 points per day. The late fall growth may change little in forage quality during mid to late September and early October. Remember that the change in quality is on the total forage harvested for the cutting (usually 1.5 to 2 t/a per cutting).

Red Clover Underseeded Into Small Grain — Sjoerd Duiker

In the quest for more sustainable agriculture, leguminous cover crops loom large. They help improve soil quality, fix nitrogen for the following crop, take up nitrates that might otherwise leach to groundwater, and offer soil erosion protection. With the need to reduce our dependence on fossil fuel, nitrogen fixing cover crops can play an important role, because about 1/3 of fossil fuel needs in agriculture are to produce nitrogen fertilizer. Integrating these cover crops into our production systems can help us meet some of the challenges of the future.

Red clover is a dependable, low-cost leguminous cover crop that is a short-lived perennial or biennial. Red clover is adapted to a great variety of soil conditions, and is winter hardy in all of Pennsylvania. It does well in somewhat poorly conditions as well as in well drained soils. Full season, over wintered red clover can produce 2 to 3 T of dry matter per acre and fix up to 150 lbs N per acre. A more realistic number is probably 50 lbs/A as the nitrogen contribution of red clover to the following crop.

A great way to establish red clover is to frost seed it in winter wheat, barley or rye. It is recommended to do this in February. It was a normal way to establish red clover a few decades ago, but it has become less common. One counts on freezing and thawing cycles to obtain improved seed-to-soil contact. In tilled ground there is more freezing/thawing action than in no-till, so success with this practice might not be guaranteed in no-till.

Although a little late, we decided to spin 10 lbs/A red clover on winter wheat in March in Centre County. The field had been no-tilled continuously for a number of years. Previous crops were soybeans last year and corn the year prior to that. Although it didn’t look like much in April there is a fair number of red clover plants sitting under the wheat now.

We are hoping that after wheat harvest there will be a fair cover of red clover. We may cut the red clover late in the summer for hay or just so it creates new growth to augment the nitrogen reserve in the soil. If the stand is good, it may be possible to make more red clover hay next year. We may also decide to kill the red clover and plant another crop such as corn into it.

First Cutting Orchardgrass Quality In Northwest Pennsylvania for 2006 — Joel Hunter

The timing of first cutting orchardgrass in northwest Pennsylvania is always of great interest as the window for quality forage harvest is generally rather narrow compared to legumes or mixed mainly legume (mml) stands. Historically, first cutting orchardgrass often comes off the first week of May or soon there after in our area. With the early dry spell and cooler temperatures this year, production was delayed until after rains arrived early the second week of May. Yields on the May 8th sampling date were estimated to be very limited (less than 1 ton of dry matter per acre). However, by the mid-month sampling date, most areas had received several inches of rain and the growing conditions were improving. Production was more typical at closer to 1.5 tons of dry matter per acre by the end of the 3rd week of May.

The actual first cuttings took place the weekend of May 20. Although a little additional yield had accumulated and some heads had emerged by this time, quality of the forage remained high with NDF values in the low 50’s. (Recall that the quality benchmarks for alfalfa are 20% CP, 30% ADF, and 40 % NDF compared to quality grass benchmarks of 20% CP, 30%ADF, and 50% NDF.)

On three farms, orchardgrass varieties were sampled from a total of 6 fields. Sampling was done by hand at 16 random locations across the field. Samples were sent ASAP to a commercial laboratory for NIR Forage Quality Analyses. They were collected over 3 dates. We feel fortunate to have our first cutting of intensively managed orchardgrass off “in great shape” albeit a little later than were used too. Good growing to all.

May 8, 2006 May 15, 2006 May 21, 2006
NDF CP NDF CP NDF CP
Pennlate 41.8 21.3 52.3 24.4 46.6 20.8
Shawnee (GH) 44.8 19.2 49.3 16.9 53.4 15.0
Shawnee (TS) 43.2 21.7 50.3 20.5 50.2 19.9
Bronc 44.6 18.8 52.7 16.2 51.1 16.1
Benchmark+ 45.8 23.0 52.3 18.1 53.3 16.1
Extend 46.2 19.4 54.0 23.1 51.3 18.4
Average 44.4 20.6 51.8 19.9 51.0 17.7

Tough Weeds Breaking Through PRE Programs — Pokeweed and Burcucumber — Bill Curran and Dwight Lingenfelter

This past week, pokeweed started showing its ugly face in many corn fields. This will also start to happen shortly in soybeans. Pokeweed is a simple herbaceous perennial that is commonly found in both tilled and no-till fields in the Northeast. Pokeweed has a large taproot and does not spread vegetatively. It spreads by seed which are consumed and dispersed by birds and other animals. Over the last few years, it is common to see pokeweed that survived the post herbicide application. In some cases, half the plant appears injured or even dies from the application yet a portion of the plant remains healthy and eventually can produce seed. I think that spray coverage is a primary problem with some of these applications. Making sure that the spray boom is above the target species and using spray tips that provide good coverage (e.g. flat fans) are important. This may be a situation where standard flat fans rather than drift reduction tips could make a difference. Also, applying the herbicide in at least 10 gallons of water per acre may improve coverage and help performance.

For pokeweed control in conventional corn, the best post products are mixtures containing dicamba (Banvel or Clarity) and a sulfonylurea herbicide including Beacon (NorthStar, Spirit), Permit or Sandea (Yukon) or Steadfast (Celebrity). Distinct can also be substituted for dicamba. Remember that young corn is the most tolerant to most post corn herbicides and that the risk of injury is greater after the corn is more than 10 to 12 inches tall or beyond the 3 to 4 leaf stage. Callisto and Lightning have been reported to have some activity as well when applied post. Glyphosate post in Roundup Ready corn is also quite effective on controlling pokeweed, but consider boom height and coverage as discussed previously. In Roundup Ready soybeans, adding 1/3 oz of Classic to glyphosate can improve the control. I have heard reports of Harmony GT and FirstRate improving control, but I have not investigated this personally.

Burcucumber is also on the rise. Burcucumber is a summer annual weed that can germinate well into the middle of summer. The seeds are about the same size as a watermelon seed and can emerge from as deep as 6 inches below the surface. Post control in corn is the best approach following the use of a residual soil applied program. A number of herbicides will kill emerged seedlings, but the problem lies in residual control. Including atrazine in the post program on corn less than 12 inches tall will help provide residual control. You can use up to 2.0 lb of active ingredient if none was applied with the pre program or up to 2.5 lb in a combined pre + post program. Remember that atrazine can carryover and injure next year’s sensitive forage or small grain crop. Effective post products with some residual activity include Spirit (and Exceed if available), Beacon, and Callisto. Glyphosate in Roundup Ready corn or soybean will control emerged seedlings, but is not that effective on plants that have begun to vine. Including a residual corn herbicide as mentioned above or 1/3 oz Classic with glyphosate in Roundup Ready soybeans will improve burcucumber control.

Contributors: State Specialists: Doug Beegle, Erick DeWolf, Bill Curran, Marvin Hall and Dwight Lingenfelter, Department of Crop and Soil Sciences. Paul Knight, Department of Meteorology. Extension Educators: Andrew Frankenfield (Montgomery), Don Fretts (Fayette), Kevin Fry (Armstrong), Mena Hautau (Berks), Joel Hunter (Crawford), Mark Madden (Sullivan), Dave Messersmith (Wayne), Thomas Murphy (Lycoming).

Editor: Mena Hautau, Penn State Cooperative Extension—Berks County, CCA

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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