CMEG Crop Management Extension Group

Field Crop News

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

August 23, 2006    Vol. 06:17

IN THIS ISSUE:

Weather Outlook — Paul Knight

The week ahead will offer several opportunities for showers, though the rain is less likely and amounts should be lightest in the southeast sections of the state. Two surges of slightly cooler, drier air will move across Pennsylvania in the next few days. Wednesday will be a smidge cooler with sunshine mixing with clouds. A cool front will move across the state on Thursday preceded and accompanied by some showers (even a few thunderstorms too). Rainfall will be light to moderate with average amounts between 0.10 and 0.25 inches. Some areas will miss the showers, mainly in the southern and eastern sections. Friday will be brighter and a bit cooler, though a band of thunderstorms should move across the northern third of the state late Friday or Saturday morning.

For the first time this summer, a push of marine air from New England will occupy eastern Pennsylvania this weekend with low clouds, drizzle, scattered showers and readings mainly near 70. A new cold front will likely trigger showers in most sections later Sunday and early Monday. Drier, but seasonably warm will return for the first half of next week.

It’s Time to Evaluate Soybeans for Late Season Disease — Erick De Wolf, Plant Pathology

Most full season soybeans in Pennsylvania are now in the R4—R5 stages of growth, and I suspect that some fields are already at the R6 growth stage. Soybeans are most vulnerable to late season diseases while pods are still filling (R3—R5). When the crop reaches the R6 (green seed) stage of growth the risk of yield loss from diseases is greatly reduced because the grain has already developed. This week would be a good time to be out evaluating the disease in soybean fields for late season disease. This is particularly valuable in fields that received a fungicide application in the last month. When evaluating disease check at least 7 to 10 locations in the field and the untreated check strip. At each location note the disease pressure in lower, middle and upper canopy. Reports from around the state indicate that disease pressure is extremely low in most areas, but we have heard reports of persistent brown spot and frog—eye leaf spot in some fields. We have also heard some reports of white mold in the western parts of the state. The bottom line... Check your fields now and evaluate if disease pressure was an issue for your soybeans this year.

Soybean rust has not been reported in Pennsylvania to date, and until this weeks find in South Carolina the disease was limited to just the states bordering the Gulf of Mexico. Our colleagues in in the South indicate that soybean rust has continued to spread in Louisiana and that the disease has reoccurred in Texas. They also indicate the hot dry weather appears to be limiting the spread of the disease North and the disease has not been found in Arkansas and Tennessee. The risk of soybean rust for PA is still very low, and I believe the full season soybeans are far enough along in most fields that they would not be damaged even if soybean rust arrived in the next few weeks. Double crop soybeans are still at risk, and we will continue to monitor the situation in the South closely.

Corn Silage Harvest Observations — Greg Roth, Grain Crop Management

Corn silage harvest is moving ahead rapidly in southeast and south central counties. The crop is drying rapidly there and many fields are being harvested at lower than ideal moisture levels. Moisture levels in the silage are much lower than would be predicted based on the milk line. In one field I checked in Perry County on Friday, corn with a milk line at 1/8 to 3/4 down the kernel was testing at 60 to 63% moisture. Some corn that is not dented has been reported to be in the upper 60’s in some cases. These low moisture levels are due to the extended preharvest dry conditions and lower than anticipated moisture in the stalk.

When chopping test samples, we have noticed that the samples appear to have good surface moisture initially, which is likely due to the wet kernels. This can be deceiving, since the overall sample moisture is lower than it feels. Eventually, when the sample equilibrates, it doesn’t feel so moist and a moisture test confirms this lower moisture content.

Silage harvest does not appear to be progressing as fast as the crop conditions dictate. Fields also appear to have considerable variability due to soil moisture holding capacity and individual loads can vary considerably in moisture content.

Often higher chopping corn will cause moisture levels to be lower in the crop due to the lower moisture in the ear than the stalk. It is uncertain whether that relationship would hold under conditions this year with the relatively wet ears and the dry stalks. Before considering chopping large acreages of high chop corn, you may want to monitor the moisture of the harvested material and see if lower chopping can increase the moisture content.

This year’s crop will likely present some interesting challenges to our dairy nutrition advisors. Dry matters in will be high in some silages, fermentation profiles may be compromised, starch levels may be low due to the shortened grain fill period, and starch digestibility could be high due to the wetter than normal kernels.

For the central and northern counties, the crop looks very good in some areas and corn harvest may still be a week or more away. Based on the experience of those in the other areas of the state, it will pay to make moisture testing a priority and not to rely on kernel milkline as a guide to timing harvest. Careful attention to this issue in the next week or two will ensure that the remaining crop is harvested and stored at the proper moisture to ensure good packing and a good fermentation.

Planting Date, Controlling Volunteers and Variety Selection are Keys to Successful Disease Management in Wheat — Erick DeWolf and Greg Roth

The time to plant wheat is just around is just around the corner, and some of the most important decisions we make in our small grain production will be made in the next few weeks. Variety selection, controlling volunteers and planting date are important factors that determine the productivity of our small grain production in Pennsylvania. Specifically, these factors can profoundly influence the winter survival, the amount of time for spring tillering and vulnerability to disease.

The recommended planting dates for wheat in most parts of Western and Central Pennsylvania range between September 20— October 8. Counties in Southeastern PA have slightly later recommended planting dates (Oct. 1 — Oct. 15). In most years, planting within these recommended dates helps to ensure good stand establishment in the fall, improves winter survival, and helps the crop avoid insects and diseases. Planting before the recommended dates often does not translate into improved yields, but it does increase the risk the crop will exposed to several important diseases including barley yellow dwarf virus, wheat streak mosaic virus, and powdery mildew and several insect pests as well.

Producers wanting to plant wheat this year should consider eliminating the volunteer small grains at least two to three weeks prior to planting, especially in fields adjacent to those planned for winter wheat or barley this fall. These volunteers are the result of grain that is blown out of the combine during grain harvest and these plants can be an important green bridge for many diseases and the insects that vector them. Controlling these volunteers several weeks prior to planting provides enough time for these plants and associated pests to decline before the new crop emerges. The next few weeks is the ideal time to control volunteer small grains in Pennsylvania.

From a disease management perspective, variety selection is extremely important part of small grain management in Pennsylvania. For example, using varieties with resistance to powdery mildew may help producers avoid input costs associated with fungicide sprays in May. Another important development in the disease management is the release of several varieties with moderate levels of resistance to head scab including Truman, Bess, Cecil, and McCormick. Of these, Truman, Bess and McCormick had above average yield at the Rock Springs location of the Penn State Wheat Performance Trials. I would suggest small grains producers keep an eye on these varieties as they are likely to be an important part of an integrated management program for head scab in the near future.

You can check out the Penn State Wheat Performance Trials on line at: http://smallgrains.psu.edu/ These reports provide valuable information about yield, test weight, and disease reactions. The report also includes observations of important traits like winter survival, lodging and heading date that can help you evaluate whether a variety is adapted to Pennsylvania conditions. Remember, as with any variety test information it is best to look at data averaged over multiple years or locations if possible and to consider both independent performance data and variety characteristics supplied by the seed company in your decision.

Grain Harvest Supervisor Training — Greg Roth, Grain Crop Management

It’s rewarding to document the high yields that many of our producers are achieving in some of their production fields. It’s also rewarding to recognize producers for achieving top yield with good management. Agronomists and other professionals are often called upon to act as a harvest supervisor to document yields for national, state or local yield contests programs. It’s important to pay careful attention to details when performing these checks and to carefully following the harvest guidelines of the sponsoring organization. Several of our extension educators have considerable experience performing these yield checks under high yield conditions.

We have developed a program to train potential harvest supervisors to document yields and complete the appropriate forms for programs like the National Corn Yield Contest, the Pennsylvania Soybean Contest and the Pennsylvania Five Acre Corn Club. The program this year will be hosted by our extension educator, Del Voight in Lebanon County. Del has considerable experience conducting yield checks in the field and will be sharing some of his procedures with us. The program will be conducted Wednesday, September 20th from 10 to 12 pm at the Lebanon Valley Ag Center, 2120 Cornwall Road, Lebanon, Pennsylvania. Registration is $5. Contact the Lebanon County Extension office (717—270—4391) for more information or to register by September 15. The program will include an in field demonstration of a harvest yield check.

If you are a rookie or an experienced veteran, consider joining us to sharpen your skills on performing yield checks for our producers. If you are a producer, you may want to consider encouraging one of your crop consultants to join us.

Late Season Stalk Nitrate Test — Jeffrey Graybill, Lancaster County

How was your Nitrogen management on this year’s corn crop? By checking the nitrate levels in the lower corn stalk you can perform a check on the Nitrogen status of the maturing crop. High levels indicate that you may be able to reduce N inputs, while low readings would indicate that you probably did not meet the crops yield potential. If you see areas in which the lower leaves are yellowing the plants may be N deficient. Some yellowing is acceptable and indicates efficient N use; however, significant and early yellowing is undesirable. Consider giving fields in question a “Check up”. Stalks can be harvested beginning at ¼ kernel milk line until to a week or so after the “Black Layer” develops. Visit the following web site for sampling procedures and submission forms http://www.aasl.psu.edu/Corn_stalk_nitrate.html

Cover Crop Options After Early Corn Silage Harvest — Sjoerd Duiker, Soil Scientist

It seems a lot of corn silage will come off early this year. This creates some excellent options for cover crop establishment that we would not have with a late corn silage harvest. The benefits of cover crops include soil tilth improvement, over—winter protection of the soil from erosion, uptake of nitrate—nitrogen, provision of mulch cover for next year’s no—till crop, reduction of weed infestations and fixation of nitrogen. Spreading manure on soil with living vegetation in the fall is sanctioned in nutrient management plans, whereas manure cannot be spread on bare soil in the fall. Conservation plans may call for the presence of a cover crop in no—till systems to meet soil loss tolerance levels. If we get some rain, it is possible to harvest above—ground foliage for forage this fall, which may be a welcome supplement if corn silage harvest is smaller than expected. Here follow some suggestions for cover crops:

Oats

Oats established in August or early September can be harvested for forage later this fall. The recommended seeding rate is 3 bushels of oat seed per acre, seeded at 1—1½ inch deep. You should not have used more than 1 lb/A of atrazine. Manure can be applied early to provide nutrients to the oats. Economical broadleaf control options are available in standing oats, which may be of interest if perennial or winter weeds are prevalent. No burndown is required to kill oats in the spring, although it may still be needed to burn down weeds in no—till production.

Oats and rye mix

If both fall and spring forage is desired, one can seed a mix of 2 bushels of oats and 2 bushels of rye seeded 1—1½ inch deep. The oats produce forage in the fall, while rye gives forage in the spring. If manure is fall applied, nitrogen credits are counted for following crops if no forage is harvested (see Agronomy Guide for more information). If forage production is the goal, N—fertilization is desirable in manure or fertilizer give oats and/or rye a boost.

Oats and hairy vetch

Oats and hairy vetch make a nice mix. The mix needs to be established by the 1st of September in the central part of PA, and by the middle of September in the south. A seeding rate of 20 lbs/A of hairy vetch should be mixed with 1—1.5 bushels of oats, and seeded 1—1½ inch deep. Since hairy vetch is more sensitive to atrazine than small grains, it is preferable to not have used more than ¾ lbs/A of atrazine in preceding corn. It may be better not to harvest the oats to avoid damaging the small hairy vetch seedlings. The seed needs to be mixed regularly in the drill because the hairy vetch seed tends to sink to the bottom of the seed box. Hairy vetch seed is too big to be planted through the small seed box. Give the hairy vetch some time to grow into May and you can count on some substantial nitrogen (100—150 lbs/A of N). The vetch will be the only cover remaining in the spring — it needs to be sprayed with a mix of glyphosate and a broadleaf herbicide such as 2,4—D. An early season nitrogen test in the spring (chlorophyll meter or PSNT) can tell you how much nitrogen you need to sidedress in corn.

Crimson clover

Crimson clover is not as winter—hardy as hairy vetch. It is therefore recommended for the south only, where it needs to be established by the middle of September. We have had some success with crimson established by the first of September in Centre County, but winter survival will depend on how cold it gets in the winter and whether there is snow cover. Herbicide rotational restrictions are similar to those of hairy vetch. Crimson clover grows faster in the fall than hairy vetch, so there is no need to mix it with another cover crop. Seed crimson clover ½ inch deep at about 15 lbs/A. You will have a nice cover over the winter. Crimson matures earlier in the spring than hairy vetch. It does not release as much nitrogen as hairy vetch for the following crop. It is probably reasonable to expect 100 lbs/A of N if crimson is terminated at the beginning of May. Again, use a mix of glyphosate and a broadleaf herbicide for termination of crimson clover. The residue is more stemmy than hairy vetch which may present some challenges in the spring.

Some of these benefits result in an economic return within one year, whereas others result in long-term benefits.

Contributors: State Specialists: Dr. Sjoerd Duiker, Dr. Erick De Wolf, Dr. Greg Roth Extension Educators: Susan Alexander (Jefferson County), Kevin Fry (Armstrong), Del Voight (Lebanon), Dave Messersmith (Wayne), Mark Madden (Sullivan), Dwane Miller (Schuylkill), Paul Craig (Dauphin), John Rowehl (Cumberland).

Editor: Jeff Graybill

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