C.O.R.N. Newsletter 2007-27

Dates Covered: 
August 20, 2007 - August 28, 2007
Editor: 
Harold Watters

Sudden death syndrome – why so much?

Authors: Anne Dorrance

Calls, samples and reports have come in from across the state this week on the development and early dying of soybeans due to sudden death syndrome (SDS). There has been a lot of research on this pathogen over the past five years via a SDS working group sponsored through the check-off from the North Central Soybean Research Program. The following is a brief review of this soybean disease but also some of the more recent research findings. More information can be found at http://www.planthealth.info/sds_basics.htm.

The pathogen is now known as Fusarium virguliforme but was previously called Fusarium solani f.sp. glycines. In the US, there is very little variability across the regions, so the isolates in Missouri are very similar to isolates in Ohio.

Infections can occur at any time from planting through the reproductive phases, and cool temperatures and high moisture conditions favor disease development. Thus early planting of soybeans, followed by cool temperatures and high moisture in late April 2007 probably played a significant role in the disease development this year. The dry weather that occurred through most of June and July most likely delayed further development of this disease.

SDS is often found in areas of fields with the greatest compaction. This may be an association with the areas of fields that retain water the longest. Most of the reports this year indicate that SDS is on the edges of the fields where there tends to be high levels of traffic. We’ve had several challenging years in a row for both corn and soybean planting and harvest and SDS may be pinpointing those areas of the fields that have compaction problems.

SCN—while we continue to be in denial about soybean cyst nematode in Ohio…the reality is that it is here and it is spreading. To compound this fact, in some fields the SCN populations are adapting to the PI88788 source of resistance. In addition, from controlled inoculation studies, the folks at Purdue confirmed earlier studies that showed when SCN and SDS are both present, the foliar symptoms and root rot levels are more severe (worse) than when SDS is by itself. We’ve seen this a few times, where whole fields appear quite dramatic, but in these cases SCN is present. The take home message here is if you want to reduce the impact of SDS – then reduce the SCN populations.

Tillage – several recent studies have explored the impact of tillage on symptom development of SDS in moderate to heavy soils. While this is not a favorite practice among many producers, deep tillage or sub-soiling have both reduced the severity of foliar symptoms and reduced yield losses associated with SDS. This disease is favored by high moisture levels, which may be why it is not as prevalent in Ohio compared to other states. Many of our soil borne diseases do favor poor drainage, so I think that this is something that Ohio producers do focus on.

SDS is Ohio has always been a good indicator of fields with problems, either high SCN populations or areas of the field with poor drainage. For some producers it is time to begin to choose varieties with resistance to this pathogen.

Bean Leaf Beetles in Late Maturing Soybeans

Authors: Ron Hammond, Bruce Eisley

Over the past few years, we have received numerous reports of extremely large bean leaf beetle populations in late maturing soybeans in September; subsequently the fields end up having high levels of pod feeding. These soybeans can be late planted fields, double-cropped soybeans, relay-intercropped soybeans, and in some instances, full season soybeans being grown in areas further north than they are usually grown. What ever the reason, these still-green soybeans act as trap crops for second generation bean leaf beetles, providing a food source prior to overwintering.

Because of past problems, we felt it important to caution growers of potential bean leaf beetle pod feeding. Growers with fields that are in the pod development stages that will remain green well into September are advised to continue monitoring those fields until they begin to mature in mid to late September. Although defoliation will not be a major worry, injury to the pod is of great concern because of yield loss potential and seed quality issues. This concern is especially important with food grade soybeans and soybeans being grown for seed, both situations where seed quality is of critical importance. However, remember that regular fields that are still filling pods are at also risk. If beetle populations are high, still active and continuing to feed, and pod injury has reached 10% and is relatively new, an insecticide treatment is warranted to prevent further pod injury. Also, growers should be careful with their insecticide choice because of the shorter time period from application to harvest. The need to choose an insecticide with a short time period to harvest is critical.

Options for Drought Stressed Soybeans

Authors: Bill Weiss

Severely drought stressed soybeans can be left in the field, harvested as silage, harvested as hay, or harvested as beans. If the plant has lost leaves and has little seed development, leaving the crop is probably best option (i.e., nutrient value of the harvested crop will not pay for the harvesting costs).

Making into silage

If beans are at R6 stage (green seed that fills the pod cavity) or less mature, they should ensile without a problem. If beans have matured beyond the R7 stage (R7 = one normal pod on main stem has reached mature pod color) the plant probably contains too much oil to make good silage. The R7 stage is the grey area. The majority of time the plants should ensile without a problem but there is reasonable risk of a poor fermentation. If you really need forage, it probably is worth the risk but if you are not desperate for forage, waiting and harvesting for beans may be a better option.

Making into hay

Oil content is less an issue for hay than silage but the soybean varieties commonly planted for beans do not make good hay. Leaf shatter will be severe and since the leaves contain a substantial proportion of the protein and energy in the soybean plant, haymaking results in a large loss of nutrients and nutrient value. Soybean hay, made from today’s hybrids will probably not be of adequate quality for lactating dairy cows. If you are feeding beef cows (much lower nutrient requirements than a dairy cow), soybean hay may be an acceptable feed. To make silage, you need to have silage equipment and a silo or have access to custom operators that can chop the crop and then put it into a silo bag. Storage and harvest costs are almost always higher for silage than hay but for soybeans, leaf shatter can be so severe that cost of soybean silage/ton of nutrients is less than cost of soybean hay/ton of nutrients. Even though soybean hay (on a cost per unit nutrient basis) will likely be more expensive than silage it can still be a reasonable option for beef producers that lack silage making equipment and silage feeding equipment. The cost per unit of nutrients for home grown soybean hay may be less than the cost per unit of nutrients for purchased ‘beef quality’ hay

Bottom Line

1. If beans are immature (R6 stage or less) silage is probably best option
2. If beans are at R7 or more mature, waiting and harvesting as beans may be most profitable.
3. Making bean into hay will probably result in lowest return but may still be more profitable than having to purchase other types of hay (for beef cows).

Feeding Corn Stover to Ruminants

Authors: Maurice Eastridge

With the dry conditions this year in many areas of Ohio, the yield of hay has been reduced and corn silage yields are going to be quite variable based on planting time and geographic area. Therefore, forage supplies are going to be quite limited this year, and several areas have been already reporting unreasonably high hay prices. Obviously, ruminants must have forage in their diets to remain healthy. Also with the current hay and grain prices, overall feed costs are going to be elevated for quite some time. With these conditions, alternative forage sources are being considered, including the feeding of corn stover (corn plant after grain harvest). The composition of corn stover is provided in Table 1, and it is compared to the composition of corn grain, corn silage, and wheat straw. The grain and forage components of corn are low in protein, but they especially contribute energy to the diet and fiber for ruminal health. Because of the lower starch and higher fiber, corn stover provides less energy than corn grain or silage. The comparison of the composition of corn stover with wheat straw is made because wheat straw is sometimes fed at low concentrations (2 to 8% of dietary DM) to lactating dairy cattle as a source of effective fiber (fiber that stimulates rumination) and higher concentrations are sometimes fed to nonlactating, nongrowing ruminants. The price for wheat straw is often quite high and the supply often limited caused by the demand for its use as bedding and feed. When you consider that about 50% of the corn plant is stover and that at least 4 times more acres of corn are produced in Ohio compared to acres of wheat, the availability of corn stover is not limited. The composition of corn stover and wheat straw is somewhat similar and are similar in price values at the reported DM (Table 1), but at similar DM (e.g. 90%), corn stover is valued at about 5% more than wheat straw.

Some things that must be considered when feeding corn stover are:

1) Animals can be pastured on a corn field harvested for grain, but their presence in the field must be limited initially because they will eat too much grain that was left in the field. A considerable amount of feed wastage also occurs with pasturing corn fields.

2) Because of the low protein in corn stover and the limited intake that may occur, additional supplementation usually necessary, even for nonlactating, nongrowing animals.

3) The feeding value of ammoniated corn stover is higher than for unammoniated stover. Ammoniated corn stalks (2 to 3% of DM; increase in CP by 6 to 8 percentage units) fed with 2 lb/day of grain supplement to 525 lb steers increased DM intake, DM digestibility, and N retention compared to unammoniated corn stalks fed with the same amount of supplement (Purdue University). Mature beef cows fed similar diets had higher DM intake and weight gain with ammouniated versus unammoniated corn stover.

4) Because of the large particle size of corn stover, challenges may occur when adding stover to a total mixed ration because cows can readily sort thorough the TMR, leaving the corn stalks in the bunk and having lower fiber intake than anticipated. Therefore, reducing the particle size before or during mixing will be important in reducing the risks for sorting.

5) The corn stover certainly can provide a considerable amount of energy and fiber as a forage source; however, very low inclusion rates in lactating cow diets can help to provide an effective fiber source (95% of the fiber in corn stover is regarded as effective fiber) and may also be used to reduce a small amount of starch from the ration. However, corn stover is not an effective replacement for grain, even if pelleted. For example, in an University of Illinois study reported this year, corn stover was treated with calcium oxide and water, mixed with distillers grains (3:1 corn stover:distillers grains), and then pelleted. Diets fed to lactating dairy cows containing 40% corn silage, 10% alfalfa silage, 5.5% soybean hulls, and either 0, 11, or 22% of the corn stover pellet to replace corn grain. As the amount of corn stover pellet increased, DM intake, milk yield, and milk protein percentage decreased. Thus, even with chemical processing and reduction to a small particle size, corn stover is not a replacement for corn grain as an energy source.

The supply of corn stover is plentiful and it should be evaluated as a source of forage in diets for ruminants during times of limited forage supply and when desiring to provide low amounts of additional effective fiber in diets for maintaining rumen health.

Table 1. Composition (DM basis) of corn-based feeds and wheat straw.

Item(1) Corn Grain Corn Silage Corn Stover Wheat Straw
DM % 88.1 35.1 85.0 90.0
CP % 9.4 8.8 5.0 4.8
TDN % 88.7 68.8 49.0 45.7
ME Mcal/lb 1.42 1.06 0.79 0.65
NEL Mcal/lb 0.93 0.66 0.49 0.37
NEm Mcal/lb 0.98 0.71 0.50 0.38
NEg. Mcal.lb 0.67 0.44 0.19 0.13
NDF % 9.5 45.0 65.0 73.0
ADF % 3.4 28.1 42.4 49.4
Lignin % 0.9 2.6 10.0 8.8
Ash % 1.5 4.3 7.2 7.6

(1)DM = Dry matter, CP = crude protein, TDN = total digestible nutrients, ME = metabolizable energy, NEL = net energy for lactation, NEm= net energy for maintenance, NEg = net energy for gain, NDF = neutral detergent fiber, and ADF = acid detergent fiber.

 

“Tassel Ears” in Corn

Authors: Peter Thomison

During the past week, I’ve received several questions about tassel ears in corn. Corn is the only major field crop characterized by separate male and female flowering structures, the tassel and ear, respectively. However, in most corn fields it is not unusual to find a few scattered plants with a combination tassel and ear in the same structure - a "tassel ear." The ear portion of this tassel ear structure usually contains only a limited number of kernels.

Tassel ears often appear on tillers (suckers) arising from plants with normal ears and tassels. These tassel ears are produced at a terminal position on the tiller where a tassel would normally appear. However, tassel ears may also be produced by individual plants. No specific cause of this condition is known but it often occurs in shorter spindly plants associated with delayed emergence and uneven crop development. Some hybrids may also be more prone to tiller under certain environmental conditions and these tillers may give rise to tassel ears. Tassel ears are frequently observed along the edges of fields where early season soil compaction and saturated soil conditions may have contributed to this abnormal growth and development. Tassel ears are a reminder that the male and female parts of the corn plan are structurally very closely related. Wild progenitors of corn-teosinte spp. have complete flowers tassels and silks together. These can be crossed with Zea mays (normal corn).

There has been some speculation that a fungal disease called "crazy top" may be responsible for this abnormal ear condition. Crazy top does affect the appearance of tassels and ears but the symptoms are distinctly different from those of the tassel ear phenomenon. Crazy top causes the tassel and/or the ear to become leaf-like. In severe cases, the whole top of a plant and ears are replaced with a mass of leaf-like structures. Visual symptoms and more details concerning crazy top are available online at http://www.oardc.ohio-state.edu/ohiofieldcropdisease/corn/crazytop.htm.

For more information on tillering, check out fact sheet AGF-121-95, "Corn Growth and Development - Does Tillering Affect Hybrid Performance?" It’s available online at:http://ohioline.osu.edu/agf-fact/0121.html.

Dr. Bob Nielsen, extension corn specialist at Purdue University, has an article with excellent pictures of plants with tassel ears – “Tassel-Ears in Corn” available online at: http://www.agry.purdue.edu/ext/corn/news/articles.04/TasselEars-0713.html.
 

Changes in the recent WAAS satellite coverage can affect your GPS performance

Authors: Nathan Watermeier

Before heading to the fields you may want to check to see if your Wide Area Augmentation System (WAAS) capable GPS receiver is accepting the new satellites. As of July 30, the Atlantic Ocean Region West (PRN#122) and the Pacific Ocean Region (PRN#134) satellites were decommissioned by the Federal Aviation Administration (FAA). Taking it’s place on July 11 included a new WAAS Telesat (PRN#138) and an existing reconfigured PanAmSat (PRN#135) geostationary satellite. The new Telesat satellite will provide better WAAS performance for the US east coast. It will also extend WAAS coverage into northeastern Canada. The US will still have dual–WAAS coverage as before.

What does this mean to growers and other users of WAAS capable GPS receivers? It means that many older receivers may not locate the new WAAS satellite signals and you will not get the desired differential correction and accuracy you need for specific field operations. Depending on how old your receiver is, some receivers can be updated with a simple firmware upgrade while others may not. The best advice is to contact your manufacturer about this issue and learn if your GPS receiver can read the new WAAS signals or can accept a firmware upgrade to read the new satellites. When contacting the manufacturer make sure to indicate the model and latest firmware version. Many manufacturer’s web sites provide a list of GPS receivers affected by the change in WAAS satellite signals. Some manufacturers will provide you the necessary instructions to download, install, and setup the firmware for free. Make sure to field test the GPS receiver after installing the firmware to make sure you are picking up the new WAAS signals. If you are in the market for purchasing an older GPS receiver you will want to make sure it accepts the new signal. GPS receivers that are not able to read the new WAAS signals will still read the other GPS satellite signals but will not be as accurate. In addition, other fee-based commercial services like Omnistar can still be used to maintain higher levels of accuracy for specific GPS receivers.

WAAS was first implemented by the FAA to improve reliability and accuracy of GPS for aviation users throughout the US. It is a free signal and provides a level of differential correction for various agriculture, natural resources, and other general applications. It consists of a network of geostationary satellites and 25 ground reference stations around the US. More information on the changes in WAAS coverage and outages for the US can be found at http://gps.faa.gov and http://www.nstb.tc.faa.gov/.

Make sure to join us this year at Farm Science Review, September 18-20, 2007 at London, Ohio. Many of the major agricultural GPS companies and OSU specialists will be available on hand to demonstrate new equipment and handle specific questions related to your GPS receivers and needs. For more information on the Farm Science Review: http://fsr.osu.edu.
 

Archive Issue Contributors: 

Mark Loux and Jeff Stachler (Weed Science), Peter Thomison (Corn Production), Anne Dorrance, Pierce Paul and Dennis Mills (Plant Pathology), Ron Hammond and Bruce Eisley (Entomology), Bill Weiss and Maurice Eastridge (Animal Science) and Robert Mullen (Soil Fertility). Extension Agents: Roger Bender (Shelby), Howard Siecrist (Licking), Glen Arnold (Putnam), Greg LaBarge (Fulton), Jonah Johnson (Clark), Wesley Haun (Logan), Ed Lentz (Seneca), Steve Bartels (Butler) and Harold Watters (Champaign).

About the C.O.R.N. Newsletter

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.