C.O.R.N. Newsletter 2010-12

Dates Covered: 
May 11, 2010 - May 17, 2010
Editor: 
Glen Arnold

New Look for AgCrops Webpage

You’re noticing a new look to the OSU Extension Agronomic Crops webpage. We are working on a new website that will have different content and updated functionality and we will announce when that is complete over the next couple weeks.

We took many of your suggestions and also borrowed from some of our other related newsletter producers to add features that will take us a long way into the future. The newsletter is still on the same address http://corn.osu.edu and the Agronomic Crops Team website is still the same – https://agcrops.osu.edu, so some things we are leaving the same.

Patience please. As we continue to update our new webpage please be a little patient with us. We have a great team in Communication Technology at the college who are helping us with this rollout - and then those of us who are content editors will follow up and build on their framework.

 

Mid-May crop weather outlook

The outlook this week is for below normal temperatures and normal to above normal rainfall. Expect 0.50 to 1.50 inches on average with a few higher totals.

Next week will see near normal temperatures and below normal rainfall once we get past about Monday.

Longer range outlook into summer is warmer than average with below normal rainfall in the northeast to normal or slightly above southwest. However, great uncertainty with the change from El Nino to La Nina.

Transition warm to cold

 

 

Low Temperature Effects on Corn and Soybean Survival

The low temperatures that much of Ohio has experienced in recent days have led to questions about the impact of frost and freezing injury on the corn and soybean crop. Many of the major corn producing counties are reporting that nearly all their corn is planted. Soybean acreage planted is also considerably ahead of normal.

Although it’s too early to determine how individual corn fields will respond to the recent weather, the effects of the low temperatures on corn survival will probably be negligible for the most part. In past years, we have observed that early planted corn that was in the process of germinating or as far along as the V1 stage (one leaf collar visible) survived freezing soil temperatures in late April with little impact on crop performance or plant stand. Agronomists generally downplay the impact of low temperature injury in corn because the growing point is at or below the soil surface until V6 (six leaf collars visible), and thereby relatively safe from freezing air temperatures. Moreover, the cell contents of corn plants can sometimes act as an "antifreeze" to allow temperatures to drop below 32 degrees F before tissue freezes, but injury to corn is often fatal when temperatures drop to 28 degrees F or lower for even a few minutes. Soybean plants are more vulnerable than corn to damage by frost or cold temperatures because their growing points are above ground as soon as the crop emerges. Auxiliary buds develop at each leaf axial of a plant, including the cotyledons. Following freeze or frost damage, recovery is possible if any of these buds remain viable. However, soybean seedlings will be killed if freeze damage extends below the cotyledons.

To assess the impact of these freezing temperatures on emerged corn, check plants about 5 days after the freezing injury occurred (and preferably when growing conditions conducive for regrowth have occurred). New leaf tissue should be emerging from the whorl. You can also observe the condition of the growing point (usually located ½ in to ¾ in below the soil surface) by splitting seedlings lengthwise. If the growing point appears white to light yellow and firm several days after the frost, prognosis for recovery is good.

Subsequent rainy weather can cause problems to freeze damaged corn. Bacterial soft rots can destroy the corn growing point and this often occurs when rains splash bacteria into frost damaged leaf whorls. If growing conditions are favorable, i.e. warm and dry after the freezing event, plants typically outgrow bacterial damage, but if weather remains cold, wet and cloudy following the freezing event, the potential for bacterial damage increases. Injury from freezing can also prevent the leaf from unfurling normally resulting in tied leaf whorls. This frost damage sometimes resembles the "buggy whipping" and tight leaf rolling associated with certain herbicide injury. Generally plants exhibiting such symptoms resume normal growth when growing conditions improve. Mowing fields to cut off the tied leaf whorls, and thereby allowing normal expansion of undamaged leaf tissue is usually of limited benefit. 

Spring Insects

As we are now into crop emergence and early plant growth, we are receiving reports from all the field crops that we concern ourselves with of various insects that are beginning to make their presence known.  We would remind growers that it is the time to begin scouting early crop growth, and taking necessary action when warranted.

  • Although we have not received many reports of alfalfa weevil causing significant injury to alfalfa, we have had a few calls of treatable populations.  We would remind growers that if the alfalfa is 16 inches in height or taller, they should consider an early cutting rather than making an insecticide application.  When doing so, they should plan on checking the regrowth for possible weevil feeding.

  • We are getting reports of heavier than normal populations of cereal leaf beetle adults from wheat fields, especially from more northern locations.  As we have mention previously, we do not know if this will lead to heavier populations of larvae.  However, with flag leaves starting to emerge, growers should at least check once or twice to make sure larvae do not become a concern.

  • Although bean leaf beetles are not expected to be high, growers who have experienced problems from overwintered before or those concerned with bean pod mottle virus which is transmitted by the beetle should begin checking emerging soybeans.

  • We have received some reports of flea beetles on corn.  Although not expected to be a problem based on average winter temperatures, we would as we always do, suggest that growers scout their early corn growth for unexpected large populations.

  • As mentioned last week in C.O.R.N., slug activity and feeding has begun.

  • As we get into late May and early June, no-till growers especially need to begin scouting for possible black cutworm feeding, which is of special concern on later planted corn that will be smaller when cutworms reach their greatest feeding potential.

For more information on these and other pests, grower should check our web site at http://entomology.osu.edu/ag/ for fact sheets which discuss the need for management and give thresholds where appropriate, and where you can obtain Bulletin 545 which gives recommended insecticides if treatment becomes necessary.

 

New Transgenic Corn Products

The Agrisure Viptera trait from Syngenta has just been deregulated by the USDA.  This new transgenic corn contains a new and different protein, Vip3A, which was also obtained from B.t.   While all previous B.t. proteins are Cry (crystalline) proteins, the new one is a Vip protein, which stands for Vegetative Insecticidal Protein.  The Agrisure Viptera trait will be combined with the Agrisure 3000GT trait stack to form the new Agrisure Viptera 3111 trait stack, which according to Syngenta will offer growers a very broad spectrum of insect control.  For Ohio growers, the new Vip3A trait will provide a wide range of above-ground insect control including fall armyworm, western bean cutworm, black cutworm, and stalk borer.  Of interest, one insect pest that will not be controlled by the Vip3A protein is the European corn borer, which will continue to be controlled by the stacking of the new Viptera trait with 3000GT which has the Cry1Ab gene obtained from Agrisure CB.  Corn borer control will continue to be provided by the Cry1Ab gene.  This new trait should be widely available to growers in 2011.

In addition, EPA has just approved two Optimum AcreMax B.t. corn seed blends from Pioneer, which will be known as OAM1 and OAM RW.  While we have been discussing OAM1 over the past winter, OAM RW is a new product.  OAM1 will contain B.t. traits for both European corn borer and corn rootworm larva control.  The blend will be 90% Herculex Xtra offering control of both insects, and 10% Herculex I which will only offer control of corn borer and serve as a “refuge in the bag” for the B.t. trait for rootworm.  Because the entire bag will have the B.t. trait for corn borers, growers will still need to plant a separate 20% refuge for that insect similar to what had to be done previously.  This refuge, being that it is for corn borers, can be planted up to ½ mile away, and can be a non-B.t. corn hybrid or the OAM RW blended corn discussed below (which will not have the corn borer trait). 

Other refuge requirements will be similar to those in the past.  OAM RW is a totally new blend that we have just become aware of, and it is a true “refuge in the bag” product.  However, it is for corn rootworm control only and as mentioned, will have no B.t. traits for corn borer management.  The OAM RW blend will be 90% Herculex RW and 10% non-B.t. corn.  Because the “refuge”, the non-B.t. corn, is in the bag, no separate refuge is required.  Thus, growers only have to plant a single seed source.  An important attribute of OAM RW is that the 10% non-B.t. corn (i.e., the “refuge”), while being glyphosate (Roundup) tolerant, will NOT BE glufosinate-ammonium (Ignite) tolerant corn, which is also known as LibertyLink corn.  Thus, these fields cannot be treated with Ignite because it will kill the non-B.t. refuge corn which would not only greatly reduce the yield, but also eliminate the refuge corn that is required in the field.  OAM1 and OAM RW should also be widely available to growers in 2011.

Hail Damage in Wheat Fields

Strong thunderstorms last weekend across northern Ohio caused resulted in hail damage in wheat fields. Wheat is in the boot stage in northern Ohio with head emergence expected soon.

Joe Lauer, University of Wisconsin Corn Agronomist has an information sheet on hail damage in small grains  at http://corn.agronomy.wisc.edu/WCM/W075.aspx

Joe Lauer writes “The kind of damage and amount of loss due to hail is determined in part by the crop growth stage. Before jointing, small grains are least susceptible to hail damage. The spike is still below ground and protected from injury. Hail damage occurring during jointing or the boot stage is difficult to assess. Spikes can still pollinate and fill, and regrowth from new tillers can occur. The greatest yield reduction from hail damage occurs in the milk stage near Zadoks 75 (Busch, 1975). Hail damage occurring at other growth stages from boot to ripe kernels (Zadoks 45 to 90) is variable and further influenced by environmental conditions following the hail damage (Afanasiev, 1967).

Let the crop recover for 5 to 7 days before assessing the remaining small grain stand. Adequate time does remain for planting soybeans or some other alternative crop, if the small grain stand is no longer economically viable.”

Wheat for Hay

Some farmers have asked about harvesting hail damaged wheat for a hay or haylage crop before planting the field to corn or soybeans. Here are some thoughts from Steve Boyles and Maurice Eastridge, Ohio State University Extension animal nutritionists.

Steve Boyles, Ohio State University Extension Specialist, Animal Sciences
Wheat cut in the boot to very early head-emergence growth stage is suitable for calves or other livestock needing relatively high nutrient content feedstuffs.  Hay yield can be increased by waiting until early milk stage of the grain. This wheat hay is lower in nutrients but is suitable for dry beef cows.

Many varieties of wheat are being bred to have rough awns for harvesting in areas where small grained must be swathed to dry prior to combining.  Rough-awned varieties may cause soreness and irritation to the mouth, lips, gums, and lower surface of the tongue in cattle.  A crop with rough awns should be ensiled rather than baled to minimize this occurrence. Harvesting at the late-boot stage rather than the dough stage reduces palatability problems caused by rough awns.

When harvesting small grains for hay in the late-boot stage, a crimper or crusher attachment will help speed the drying, but when harvesting in the milk or dough stages, these attachments increase kernel-shattering losses. If the crop is harvested in the dough stage, plants will not contain excess moisture, so crimping or crushing m ay not be beneficial.

Occasionally, nitrates accumulate in small-grain cereals.  Nitrate accumulation in small grains is more of a concern with hay than with silage. Oat hay is more likely to have a high nitrate level than other small-grain cereal hays. 

Maurice Eastridge, Ohio State University Extension Specialist, Animal Sciences
1) The wheat harvested at boot stage will be high in quality (high protein, lower in NDF) but yield will be lower than early head to milk stage.
2) There is a risk for high nitrates, especially if the farmer used high application of N fertilizer. However, with the rather warm temperature prior to this week, there should be good growth and if harvested as silage, the nitrate concentration will drop during fermentation. So I think the risk is low if harvested as silage or balage. However, fermentation should be for at least 30 days before feeding. Harvesting as hay increases risk for nitrates and drying time is somewhat difficult due to hollow stem.
3) Other than nitrates, there should be no other risk of using this crop as feed. Just make sure crop is dried to proper DM of respective storage method for silage; else there will be an excessive amount of seepage.

Read the Label:

Farmers thinking of using wheat for livestock feed should also note the labels on any fungicides, insecticides or herbicides applied prior to the hail damage. Harmony and Harmony Extra labels state "do not graze or feed forage or hay from treated areas to livestock".  Quilt has a 30-day restriction.  Warrior has a 21-day restriction.

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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.