C.O.R.N. Newsletter 2011-31

Dates Covered: 
September 13, 2011 - September 20, 2011
Editor: 
Justin Petrosino
Bean Leaf Beetle Pod Feeding

Bean Leaf Beetle Pod Feeding

With soybeans reaching the R6 growth stage, full seed, the primary insect we still need to concern ourselves with is the adult bean leaf beetle. This true second generation (although the third group of adults observed this season) is the group that will overwinter to become active again in 2012. Prior to that happening, these insects will feed on the most tender part of the plant, that being the pods. In fields where the pods have started turning yellow and brown, the pod feeding is stopping and the adults will be leaving in search of “greener pastures”. However, they will enter other fields that are still green, where they have the potential to cause significant injury. Growers should maintain a watch on those fields to prevent pod feeding from reaching high levels. See our fact sheet on bean leaf beetles at http://ohioline.osu.edu/ent-fact/pdf/0023.pdf for more information on this insect and when to spray. Treatment is usually indicated when pod feeding reaches 10-15% and beetles are still present and actively feeding. If an insecticide spray is necessary, remember the pre-harvest interval. There is not enough time to use many of the pyrethroids that have long pre-harvest intervals.

Other Insects of Note this Fall

Other Insects of Note this Fall

There are two other insects either in or coming from field crops that we should be aware of. A few weeks ago, we mentioned the brown marmorated stink bug (C.O.R.N. 2011-29, Aug 30-Sep 6). This new pest will also feed on pods. Although we do not expect to see a lot of them, growers should keep a watch for them. In that article, we presented a picture of the adult. What we failed to show is the nymph which is perhaps the stage that would be present in fields if the stink bug is there. See our web page on soybean insect images to see the various stages of this stink bug, including the nymph http://entomology.osu.edu/ag/pageview3.asp?id=1152 . It is a dark color from the top, and is white on its underbelly. It has broad white stripes on its legs.

The other insect of interest is not a concern for soybean growers, but it might cause problems for fruit growers, especially grape and wine producers, and then in homes where it goes to overwinter. This insect is normally considered a beneficial predator. It is the multi-colored Asian lady beetle. This beetle has been building to large numbers in soybean fields where soybean aphids have provided a good food source. Everyone should be forewarned that this lady bug will again be at high numbers this fall.

 

“Abnormal Corn Ears” Poster Available

A reduced 11 x 14 inch version of the poster is available online from:

https://agcrops.osu.edu/specialists/corn/specialist-announcements/AbnormalCornEarsPoster_000.pdf/view

The full sized poster is available online from:

http://estore.osu.edu-extension.org/productdetails.cfm?PC=2625

The OSU College of Food Agriculture and Environmental Sciences Communications & Technology section (contact information below) has 26 x 33 inch copies of the poster available for distribution. The poster is printed on plasticized coated paper for durability. Poster cost is $11.25 plus shipping.  Ask for “Abnormal Corn Ears” poster” ACE-1.

The Ohio State University

College of Food Agric. & Env. Sci.
Communications and Technology
Media Distribution
216 Kottman Hall, 2021 Coffey Road
Columbus, OH 43210-1044
E-mail: pubs@ag.osu.edu

Order Online: http://estore.osu-extension.org/
Phone 614-292-1607
Fax     614-292-1248

Important Wheat Management Guidelines: A 2011 Update

Important Wheat Management Guidelines: A 2011 Update

The 2011/2012 winter wheat season is fast approaching and as growers make preparations for planting, we would like to remind them of a few management decisions that are important for a successful crop. Nearly every farm in Ohio has a field or two that could benefit from planting wheat, if for no other reason than to help reduce problems associated with continuous planting of soybeans and corn. Consistent high yields can be achieved by following a few important management guidelines. Below are listed the most important management decisions that Ohio wheat producers need to make at fall planting time to produce a crop with satisfactory economic returns. Here we also address several issues related to late-planted wheat.

Variety and Seed Selection. Select high-yielding varieties with high test weight, good straw strength and adequate disease resistance. Do not jeopardize your investment by planting poor quality seeds or by planting anything but the best yielding varieties that also have resistance to the important diseases in your area. Depending on your area of the state, you may need good resistance to powdery mildew, Stagonospora leaf blotch, head scab, and/or leaf rust. Plant healthy, wholesome, clean (remove shriveled kernels), and disease-free seeds, and make sure that the entire seed lot is treated, whether or not the seeds appear to be diseased. In Ohio, seed-borne wheat diseases such as common bunt and loose smut are rarely ever major concerns because growers routinely plant seeds treated with fungicides. Problems with these diseases usually appear in isolated areas where poorly treated, bin run seeds are planted. Seed treatments can play an important role in achieving uniform seedling emergence and giving seedlings a good head start under certain conditions. In addition, the selective use of seed treatments can protect seeds or seedlings from early-season diseases. More information on seed treatments can be found on the field crops disease website: http://www.oardc.ohio-state.edu/ohiofieldcropdisease/.  

Avoid varieties with susceptibility to Fusarium head scab. Unlike foliar diseases that are relatively easy to effectively control with a single foliar fungicide application, fungicide alone will not provide adequate control of head scab and vomitoxin if the variety is highly susceptible. A fungicide application at flowering must be combined with variety resistance to achieve the best results in terms of scab and vomitoxin reduction. Therefore one of the very first, and probably the most important, steps in a scab management plan is variety selection. In the past, producers have been reluctant to plant scab resistant varieties because some of the varieties did not yield as well as some of the more susceptible varieties. However, we now have scab resistant varieties with very good yield potential to choose from. A list of these varieties can be found in the 2011 Ohio Wheat Performance Trial (http://oardc.osu.edu/wheattrials).

Rotate wheat with Soybean. Wheat should be planted after soybean not after wheat or corn. However, with soybean harvest likely to be late again this year, many producers are considering planting wheat after wheat to avoid having to plant late. Indeed, timely planting is critical for good stand establishment (more tillers per foot of row) and to reduce the risk of winter kill, however, planting wheat after wheat has several disadvantages.

Diseases are a big concern in wheat after wheat. One such disease, and by far one of the most important, is head scab. The head scab fungus survives in wheat stubble left in the field after harvest. Wheat planted into this stubble is more likely to have head scab and vomitoxin problems next year. This is especially true if late-spring, early-summer conditions are wet and humid. Our studies have shown that when wheat (or corn) residue is abundant (more spores of the fungus present), only a few days of wet and humid conditions during flowering are needed for head scab to develop and vomitoxin to exceed critical marketing thresholds (2 ppm). For the same reasons, planting wheat after corn is just as bad as planting wheat after wheat. The scab fungus survives equally well in both corn and wheat stubble.

In addition, growers who plant wheat after wheat usually have more problems with diseases such as Cephalosporium stripe and Take-all root rot. Plants severely infected in the fall and winter will become weak and discolored in the spring and often die prematurely without producing grain. In addition, foliar diseases such as Stagonospora leaf blotch, Septoria leaf blotch, powdery mildew, and tan spot become more problematic when wheat follows wheat. These diseases are all caused by fungi that survive in wheat stubble left in the field, and as such, can readily attack the new crop and spread shortly after germination or early in the spring. When diseases become established early, growers are more likely to suffer higher yield and quality losses  

Planting Date. Plant after the Hessian Fly Safe date for your county. The Hessian fly free dates can be found at (http://ohioline.osu.edu/iwy/flydates.html). These dates vary between September 22 for northern counties and October 5 for the southern-most counties. Planting within the first 10 days after the recommended fly-safe date minimizes the risk of serious problems with the Hessian fly. This is because on the dates indicated on the map, the weather conditions, especially temperature, are unfavorable for the Hessian fly. As a result, damage caused by this insect will likely be less if wheat is planted after the specific date. However, in Ohio the Hessian fly-safe date is not only about the Hessian fly. Another excellent reason to plant wheat after the fly-safe date is to minimize problems with diseases, especially barley yellow dwarf virus (BYDV). BYDV is transmitted by aphids and tends to be most severe when transmission occurs in the fall. Research has shown that due to unfavorable weather conditions, the aphid population tends to crash after the fly safe date, leading to fewer problems with BYDV. Planting date studies conducted here at OSU a few years ago showed that BYDV problems and yield loss associated with this disease are much higher when wheat is planted well before the fly-safe date. Planting after the fly-safe date also minimizes early establishment of other diseases such as Stagonospora blotch and leaf rust.

However, planting too early may not be a concern this year. From all indications, soybean harvest will likely be late again this year in most areas. As a result, some producers may not have the option of planting early. In fact, some may be forced to plant late, well after the Hessian fly-safe date, which is also a concern. Planting late (generally after Oct 20 in northern Ohio) can reduce the number of primary tillers that develop in the fall and increases the risk of cold temperature injury. If planting is delayed by more than three weeks after the Fly-Free date, the seeding rate should be increased to 24-26 seeds per foot of row, which is 1.75 million seeds per acre) to compensate for fewer tillers developing in late-planted wheat.

Seeding Rate and Planting Depth. Optimum seeding rates are between 1.2 and 1.6 million seeds per acre.  For drills with 7.5 inch row spacing, this is about 18 to 24 seeds per foot of row with normal sized seed. When wheat is planted on time, actual seeding rate has little effect on yield, but high seeding rates (above 30 seeds per foot of row) can increase lodging. There is no evidence that more seed is better, it only costs more money. However, as mentioned above, seeding rate should be increased if the crop is planted well after the fly-safe date. Seed size (the number of seeds per pound) and germination rates are critical for determining the proper seeding rate and drill calibrated. That information should be listed on the bag of seed. The table below shows the pounds of seed needed per acre to accomplish various seeding rates using different sizes of seed.

Pounds of Seed Needed to Plant from 1.2 Million to 2.0 Million Seeds Per Acre with Different Size Wheat Seed

 

---Millions of Seed Per Acre----

Seeds per Pound

1.2

1.4

1.6

1.8

2.0

10,000

120

140

160

180

200

11,000

109

127

145

164

182

12,000

100

116

133

150

167

13,000

92

108

123

138

154

14,000

85

100

114

129

143

15,000

80

93

107

120

133

16,000

75

88

100

113

125

17,000

71

82

94

106

118

18,000

66

77

89

100

111

Planting depth is critical for tiller development and winter survival. Plant seed between 1 and 1.5 inches deep and make sure planting depth is uniform across the field. No-till wheat into soybean stubble is ideal, but make sure the soybean residue is uniformly spread over the surface of the ground. Shallow planting is the main cause of low tiller numbers and poor over-winter survival due to heaving and freezing injury. Planting depth is even more important in late planted wheat. Late planting results in plants that smaller than normal when entering dormancy, with smaller and more shallow root systems than normal, making them more susceptible to heaving next March.

Fertilizer Application. Apply 20 to 30 lb of actual nitrogen per acre at planting to promote fall tiller development. Wheat also requires at least 45 ppm of available phosphorus per acre in the soil to produce really good grain yields.  If the soil test indicates less than 40 ppm, then apply 80 to 100 pounds of P2O5 at planting. Soil potassium should be maintained at levels of 135, 165 and 185 ppm for soils with cation exchange capacities for 10, 20, or 30, respectively. If potassium levels are low, apply 60 to 100 pounds of K2O at planting. In Ohio, limed soils usually have adequate calcium, magnesium and sulfur for wheat. Soil pH should be between 6.5 and 7.0.

The key to a successful wheat crop is adequate and timely management. The above recommendations are guidelines that may be fine-tuned by you to fit your farming operation, soils, and planting conditions. They also assume that you are planting wheat in fields that are adequately drained.

 

Burndown Herbicides for No-Tillage Wheat

Burndown Herbicides for No-Tillage Wheat

Herbicide options for burndown of existing weeds prior to planting of no-till wheat include glyphosate, Ignite, Gramoxone, Sharpen, and dicamba.  Dicamba labels have the following restriction on preplant applications – “Allow 10 days between application and planting for each 0.25 lb ai/A used”.  A rate of 0.5 lb ai/A would therefore need to be applied at least 20 days before planting.  We have, as usual, been receiving questions about the safety and legality of 2,4-D use prior to wheat planting.  We do not know of any 2,4-D product label that supports this use of 2,4-D.  There is some risk of stand reduction and injury to wheat from preplant applications of 2,4-D.  

The primary targets for a preplant burndown in wheat are the small, emerged winter annual weeds that can overwinter and have a negative effect on wheat the following spring.  This includes marestail (horseweed), chickweed, deadnettle, annual bluegrass, mustards, etc.  Herbicide treatments at this time can also have considerable activity on biennials (wild carrot, wild hemlock), dandelion, and Canada thistle. Although, herbicides are often more effective on these weeds later in the fall.  The larger summer annual weeds (ragweeds, marestail, foxtails, etc) are going to die after the first hard frost, and soybean harvest decimates these weeds to the point that herbicides won’t be effective on them anyway.  Where wheat is planted into a fallow situation, it may be necessary to target the large summer annuals with herbicide in order to ensure that they do not interfere with planting or wheat stand establishment. 

While glyphosate can adequately control small winter annual weeds, it should be combined with Sharpen or dicamba in fields with a history of marestail problems (or in fields downwind of a neighbor’s marestail nightmare).  Due to the late soybean harvest, glyphosate and Sharpen may be the better alternative because of the 10-day waiting period for dicamba.  Ignite or Gramoxone should also effectively control seedlings of marestail and other winter annuals.  Be sure to use the appropriate adjuvants with any of these, and increase spray volume to 15 to 20 gpa to ensure adequate coverage. 

This year’s late-season leaf canopy of soybeans may be suppressing winter annuals and reducing populations that develop into late September, compared with years where soybeans have lost leaves already.  This may reduce the need for a burndown application in wheat, although often a field that appears to be weedfree from a distance does actually have a lot of small weeds upon closer examination.  There are several effective postemergence herbicide treatments for wheat that can be applied in November to control these weeds, in fields where preplant burndown treatments are not used.  Effective postemergence treatments include Huskie or mixtures of dicamba with Peak, tribenuron, or a tribenuron/thifensulfuron premix with dicamba, among others.  Huskie may be the most effective fall postemergence treatment for control of marestail, where the marestail population is resistant to ALS inhibitors.  We discourage application of 2,4-D to emerged wheat in the fall due to the risk of injury and yield reduction.

Farm Science Review Agronomy Plots

Farm Science Review Agronomy Plots

The agronomy demonstration plots at the Farm Science Review will highlight some of the Agronomic Crops Team’s research, and open the door for questions and comments. We’ll have a dozen mini-field days happening all at the same time (it’s actually 13, a baker’s dozen). Extension specialists in weed science, crop production, nutrient management, entomology, plant pathology, bioenergy, cover crops and more will be in the plots and tent to talk with Review visitors. We will be located in the Exhibit area demonstration plots along the gravel path between the parking lot and just outside the main Gate C entrance to the show. 

Some things to see in the Agronomic Crops Team Demonstration Area include: 

Corn manure management – in-crop manure applications save money and the environment.

  • Manure + 28% to cover N needs to 160 lbs of N
  • Manure in-crop sidedress 160 lbs of N
  • Manure on surface 160 lbs of N
  • Manure interseeded with Annual ryegrass 

Cover crops – with prevented planting some of you tried; for others after wheat harvest they planted a cover crop to reduce compaction.

  • Spring planted rye      
  • Late spring planted oats
  • Spring planted sudangrass
  • Summer planted radish
  • Summer planted winter pea
  • Late summer planted oats 

Bioenergy crops – What crop will you be growing? It is not just corn for ethanol.

  • Sweet sorghum (Dale)
  • Corn
  • Sunflower
  • Switchgrass (Blackwell)
  • Poplar trees
  • Willow trees 

Biotechnology in Corn – a thousand years of genetics.                    

  • Teosinte - the original maize crop.
  • Longfellow    
  • Podcorn          
  • Gourdseed     
  • Flint    
  • Reid's yellow dent (an Ohio mistake that led to modern corn)         
  • Wooster clarage         
  • Late Clarage   
  • Mo17 x B73   
  • DKC61-06 a modern traited hybrid 

Along with numerous production and pest management plots, including a population demonstration of Reid’s yellow dent planted from 6,000 seeds/A up to 45,000 right next to a modern “quadstack” hybrid. See the differences. We also have a soybean management demonstration where we threw everything at the crop including the kitchen sink. Well maybe just the table sugar next to the kitchen sink.  Ask us what yields and what is sweet to the taste but not the pocket book. 

So stop and see us, we will be in the plots all three days of the 2011 Farm Science Review, September 20, 21 & 22 at the Molly Caren Agricultural Center, London Ohio.

 

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Crop Observation and Recommendation Network

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.