CORN
Crop Observation and Recommendation Network

July 14-20, 2003
C.O.R.N. 2003-22

In This Issue:

A) Delayed Wheat Harvest Problems and Recommendations for Saving Seed
B) Recovery and Yield Potential of Root Lodged Corn
C) Impact of Weather on Crops
D) Time to Check for Corn Rootworm Larval Feeding
E) Soybean Defoliators
F) Bean Leaf Beetle
G) Foliar Fertilization for Soybeans
H) Too Late to Double Crop Soybeans?
I) Field Days and Events

A) Delayed Wheat Harvest Problems and Recommendations for Saving Seed - Pat Lipps and Dennis Mills CORN Questions

Wet weather has kept the wheat crop wet for nearly two weeks delaying harvest in most areas and causing continued deterioration of the grain. The wheat heads are extensively discolored due to sooty mold fungi growing on the dead tissues of the heads. Since Saturday July 12 the combines have been at work whenever moisture levels were reasonable in an attempt to harvest the crop quickly to limit further quality loss. Several issues have come to the forefront concerning the grain including light test weights and shattering of grain in the field. Growers understand that the wheat crop has gone through extensive weathering over the past two weeks and the previous problems with moderate amounts of head scab and Stagonospora glume blotch have contributed to the overall quality problems. The heads are extremely fragile due to the rotting and weathering. Growers will likely find differences in varieties for shattering problems so check fields as you start harvesting to see if shattering has already occurred. Growers may find it helpful to slow down reel speeds to avoid shattering loss of grain during combining. We also suggest adjusting the combines to blow out as much lightweight seed as possible in an attempt to reduce dockage. This will help improve test weights and reduce the amount of scabby grain with the potential of having the mycotoxin DON (also known as vomitoxin) in the grain.

Because of the problems associated with the harvested grain this year, wheat producers are encouraged not to save their own seed for planting this fall. With the proper equipment, conditioning facilities and seed treatments this grain can be processed into quality seed for planting. This means that any grain that is harvested for seed will have to be dried as soon as possible to below 15% and kept dry until it can be cleaned. The wheat seed processors will then have to clean this grain thoroughly to remove all lightweight seed using air cleaners and gravity tables. In some cases this may mean that clean out losses may be as high as 20 to 30% on some seed lots. Once conditioned the seed will need to be treated with a seed treatment fungicide to eliminate pathogenic fungi on the seed. Both Fusarium, from scabby seed, and Stagonospora, from glume blotch affected seed, are present on the seed and if left untreated could cause seedling emergence and disease problems next season. All seed should be treated with Dividend XL, Dividend Extreme, Raxil - Thiram, or Raxil XT. These materials are highly effective in controlling Stagonospora on the seed and also provide good control of Fusarium on scabby seed. If the seed lot had noted problems with scab, it is recommended to combine the product LSP (available from Gustafson, Inc.) with one of the previous products to improve efficacy against Fusarium. The LSP product will add about 25 cents more to the overall cost of the seed, but it is highly effective against Fusarium and well worth the extra cost. Lastly, have all seed lots tested for germination after the seed treatment fungicide has been applied to determine the overall germination level of the seed.

B) Recovery and Yield Potential of Root Lodged Corn - Thomison CORN Questions

Strong winds and heavy rains associated with severe thunderstorms can lodge or knock corn plants over, especially if the nodal root system is not fully developed. Cool wet soil conditions in May and June may have inhibited good nodal root formation and predisposed plants to such wind injury. Strong winds can pull corn roots part way out of the soil; a condition referred to as root lodging. The problem is more pronounced when soils are saturated by heavy rains accompanying winds. If root lodging occurs before mid-grain fill, plants usually recover at least partly by "kneeing up." This results in the characteristic gooseneck bend in the lower stalk with brace roots providing above ground support. If this stalk bending takes place before pollination, there may be little effect on yield. When lodging occurs later in the season some yield decrease due to partial loss of root activity and reduced light interception may occur. If root lodging occurs shortly before or during pollen shed and pollination, it may interfere with effective fertilization thereby reducing kernel set. Hybrids differ in their ability to resist root lodging.

In a University of Wisconsin study, root lodging was simulated by saturating soil with water and manually pushing corn plants over at the base, perpendicular to row direction. Wind damage was simulated at various vegetative stages through silking (V10 to R1). Compared to hand harvested grain yields of control plants, grain yield decreased by 2 to 6%, 5 to 15% and 13 to 31% when the lodging occurred at early (V10-V12), medium (V13-V15) and late (V17-R1) stages.

C) Impact of Recent Weather on Crops - Thomison CORN Questions

Dr. Bob Nielsen at Purdue has prepared an excellent summary assessing the impact of recent weather conditions (including excessive rain and flooding, wind, hail, etc.) on crops that is available online at http://www.agry.purdue.edu/ext/corn/news/articles.03/RainHailWind-0709.html

See also past issues of CORN (http://corn.osu.edu/archive/)
June 16-22, 2003, C.O.R.N. 2003-18
article B) Weather Stress and Corn Yield Potential
June 23-29, 2003, C.O.R.N. 2003-19
article C) Ear Development in Corn
article D) Flooded or Rotten - What is Happening to These Soybean Roots?
July 7-13, 2003, C.O.R.N. 2003-21
article C) Assessing Corn Root System Development

D) Time to Check for Corn Rootworm Larval Feeding - Eisley and Hammond CORN Questions

Western corn rootworm beetles are beginning to emerge in some areas of the state which indicates that the below ground damage caused by rootworm larvae is almost complete. The next couple of weeks will be a good time to check corn fields (both continuous and first year) to see if any damage has been caused by rootworm. This is especially important if lodging is observed in first year corn fields. Some lodging may be caused by poor root systems due to environmental problems but western corn rootworm larvae may also be the problem.

The root system can be inspected by digging up the plants and carefully removing the soil from the root system by washing with water. Plants should be dug from the soil rather than pulled which will tend to destroy the roots. This will allow you to see if there is any feeding damage from rootworm larvae to the root system. Damage from rootworm larvae appear as either tunneling of the roots or feeding directly on the roots from the root tip toward the plant. If part of the lodging damage has been caused by rootworm we need to know that because it will result in different production practices in the future.

Root damage from rootworm can be rated using the Iowa 1 to 6 scale with 1 equal to no feeding damage and 6 equal to a severely damaged root system. The guidelines in the using the Iowa scale are:

1 = No feeding damage
2 = A few feeding scars present
3 = At least one root chewed to within 1-1/2 inches of the plant.
4 = One entire node of roots destroyed.
5 = Two entire nodes of roots destroyed.
6 = Three or more nodes of roots completely destroyed.

Five to 10 roots should be inspected in each field to get an idea of the amount of feeding damage that is being caused by the rootworm. Economic injury normally occurs when the rating is 3 or above.

E) Soybean Defoliators - Hammond and Eisley CORN Questions

Most early-planted soybeans are now in the R1-2 flowering growth stages. Early reproductive growth stages are where the defoliation thresholds needed for treatment drop to 15%. Observations taken last week throughout Ohio indicate that many of the common defoliators we see on soybeans are beginning to appear, including first generation bean leaf beetle, Mexican bean beetle, Japanese beetle, green cloverworm, and small grasshoppers. Although it would be unusual for any of these single insects to cause significant defoliation alone, a complex of two or more might cause defoliation levels to rise above threshold. Growers are advised to initiate scouting procedures to prevent defoliation from reaching the 15% defoliation threshold during the early reproductive stages, R1-5, later rising to 20-25% during R6. A list of labeled insecticides for control of all these pests is available at http://corn.osu.edu/library/articles/03insectupdate.html.

F) Bean Leaf Beetle - Hammond and Eisley CORN Questions

First generation bean leaf beetles are beginning to occur in soybean fields throughout Ohio. Some growers chose to take action against possible vectoring of bean pod mottle virus by this insect by having applied an early season application of an insecticide after soybean emergence. For those growers only, the suggested practice for best protection against vectoring of the virus, according to Iowa State who developed this protocol, is to apply a second application at the beginning of the first generation. This is now occurring and growers are so advised.

In terms of insect injury, there is evidence that the population size of the second generation of bean leaf beetle that causes pod injury in late August and early September is relative to the size of this upcoming first generation. It is suggested that growers monitor this first generation to give them an insight as to the potential size of the second generation and possible crop injury. If the first generation is large, evident through either sampling large numbers of bean leaf beetles or presence of significant leaf feeding, it will be imperative that the second generation of bean leaf beetle and subsequent pod injury is watched closely later this summer. If the first generation is relative low or non-existent, the probability of later problems is lower (although we will still recommend scouting of all fields through the entire summer). However, determining the relative size of the first generation will offer better insight as to potential problems later in the growing season.

G) Foliar Fertilization for Soybeans - Lentz CORN Questions

Each year producers read or hear stories about increased soybean yields from foliar fertilization. This is not a new concept for universities. Studies investigating foliar fertilization have occurred throughout the years since the 1970's and most recently, studies completed by Iowa State University and University of Minnesota. These studies have investigated foliar applications of nitrogen and combinations with phosphorus, potassium, sulfur, and micronutrients. Occasionally a site will show a response, but overwhelmingly the majority showed no yield benefit to a foliar fertilization program. The Ohio State University has no formal investigation at this time, but on-farm and small studies have been established across the state to evaluate these programs. Presently, foliar fertilization would not be a recommended practice for soybeans since research has not shown a predictable or consistent yield benefit.

H) Too late to double-crop soybeans? - Beuerlein CORN Questions

It is too late to plant double crop soybeans in Ohio and expect the crop to be profitable. The potential for double crop soybean yield can decrease one bushel for each day that planting is delayed. With the week that has now been lost due to the excessive rains, yields would now be expected to be seven Bu/A less.

I) Field Days and University Events CORN Questions

Hands-on Agronomic Workshop July 17 (Jim O'Brien)

The Fayette County Extension Office, Fayette County Agronomy Committee and the Ohio Agri-Business Association are sponsoring an Agronomic Workshop for all interested agricultural producers and agri-business persons interested in the latest in farm technology, soil, crop and pest management on Thursday, July 17 at the Fayette County Airport, State Route 38, two miles north of Washington Court House.

Topics for this years workshop will include: "Using the New Soil Quality Indicator - A simple field test", K. Rafiq Islam, OSU Soil Scientist, "What you don't know about slugs may hurt your profits", Ron Hammond, OSU Entomologist, "Corn Pollen Drift in Biotech and IP Crops", Peter Thomison, OSU Corn Specialist, and "Hand-held GPS and Light Bar Technologies: You've got to be in it, to win it", Matt Sullivan, OSU Ag Engineering.

The format of this years' workshop will be split into a morning session and an afternoon session. The topics listed above will be covered at both sessions, however the morning session will focus on the application and use for farm activities, while the afternoon session will go into greater depth on topics and will focus on the technical aspect needed for the agri-business person.

The morning session will run from 9:30 AM to 12:30 PM, this session will be geared toward farmers. Cost is $10.00 and lunch will be provided. The afternoon session will run from 2 PM to 5 PM, this session is designed for agri-business and sales persons. Cost is $30.00 and dinner will be provided.

Certified Crop Advisors will find this field day valuable since we will offer the hard-to-find Soil & Water CEU's including a total of 4.0 hours of CCA credits. Pesticide Applicator Credits will also be available.

For more information about Southern Ohio Agronomic Workshop, call (740) 335-1150 or visit the Fayette County Web site at: http://www.ag.ohio-state.edu/~faye/ and download a brochure with location and registration information.

BIOHIO SHOWCASES AGRICULTURE AT OARDC AND ATI - OSUToday

BioHio, a showcase of the many ways agriculture affects the lives of
all Ohioans, returns to the Wooster campus Friday-Sunday (7/18-20).
Last held on the Wooster campus in 1996 and 1998, and on the
Columbus campus in 2001, BioHio features hundreds of displays and
demonstrations about agriculture and horticulture, children's activities, and entertainment. Admission to BioHio, a celebration of the many ways agriculture touches the lives of all Ohioans, is free. Hours are Friday and Saturday, 10 a.m. to 6 p.m., and Sunday, noon to 6 p.m. A complete schedule of events is online.
-- > CONTACT: (330) 263-3700 or biohio@osu.edu
-- > SEE: http://biohio.osu.edu

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Past versions of C.O.R.N. can be found on the World Wide Web at: http:/www.ag.ohio-state.edu/~corn/archive/

C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.

Editor: Harold Watters        Web Editor: Nathan Watermeier

Information presented above and where trade names are used, they are supplied with the understanding that no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Keith L. Smith, Director, Ohio State University Extension.

TDD # 1 (800) 589-8292 (Ohio only) or (614) 292-1868

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