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July 31 - August 6, 2000
C.O.R.N. 2000-24
In This Issue:
A) 2000 Ohio Wheat Performance Test Results Are Now Available
B) Bean Leaf Beetles In Soybean
C) Als-Resistant Ragweed Screening
D) "Silk Balling" And Poor Kernel Set
E) Don't Be Fooled, Soybean Cyst Nematode Is Out There!!
F) Fees For Soybean Cyst Nematode Testing For 2000-2001
The Ohio Wheat Performance Test is now available at your county OSU Extension offices and it will be posted on the Ohio State University Ohioline web page soon http://www.ag.ohio-state.edu/~perf. The publication reports the yield and performance characteristics of 53 varieties from 22 seed suppliers grown at five different locations in the state. Sites of the performance tests were: Hoytville, Bucyrus, Wooster, Greenville, and Circleville. Wheat yields were very good across all locations. The average yield for all varieties across locations was 82.6 bu/A or 3 bu/A above last year's record yield. The location with the highest average yield was again Bucyrus with 93.0 bu/A and the lowest was Circleville with 72.8 bu/A. The varieties are listed in order of maturity, with the earliest varieties listed first. There is a tremendous amount of other information available in the report including: heading dates, test weight, plant height, lodging, disease reactions, flour yield, and flour softness rating. The Wooster site had environmental conditions very favorable for disease development. This gave us an opportunity to evaluate the varieties for resistance to powdery mildew and Stagonospora nodorum leaf and glume blotch. These are the most common diseases in the state and resistance to these diseases is very important. Results of the trial indicated that varieties ranged from highly resistant to highly susceptible for the various diseases.
Variety selection is one of the most important steps growers can take to insure yields and performance of a wheat crop. Growers should use the report to help select varieties for growing this coming fall planting season by comparing varieties for different characteristics, not just yield. Many varieties are high yielding, but some of these are also disease susceptible or lodging prone. Use this years data to update the information you have on the varieties you currently grow and see how they stack up to new varieties available to you. The tables listing two and three year performance summaries will be most helpful in determining varieties with proven performance in Ohio. There is a lot of information presented in this five page report. Spending half an hour looking over the data and comparing variety performance characteristics will help you choose the best varieties available to help insure those top yields. Make a list of the varieties that you are interested in and get additional information about these varieties from the seed companies. If you are looking to try a new variety ask the seed representative for information on straw strength (lodging), winter hardiness, and resistance to other diseases, like wheat yellow mosaic virus, wheat soil borne mosaic, leaf rust and head scab. Also ask about the seed treatment used on the seed. Raxil -Thiram or Dividend XL are two of the better seed treatments available today. Taking the time to review performance data now will help you select the right variety for your farm. The most expensive seed does not necessarily produce the most yield or profit. Consistent performance, high test weight, straw strength, disease resistance and grain quality are the factors that pay for themselves.
We are observing and hearing about reports of ALS-resistant common and giant ragweed in fields throughout Ohio. The only way to verify the presence of ALS-resistant weeds is to collect seeds and grow them out in the greenhouse. If you want to have common and giant ragweed tested for ALS-resistance, we will be willing to test some samples. We will accept up to 4 samples per person and will make sure that at least two samples per person are tested in the event that too many are sent to us.
The procedure for collecting seed is as follows: 1. Harvest 6 HEALTHY (no injury) plants, 2. Harvest at least 80 % of each plant, 3. Harvest the plants when at least 75 %, preferably 100 %, of the seeds are completely brown in color (the seeds are located at the nodes of stems), 4. Harvest plants that were definitely sprayed and not from the field edge, 5. Harvest plants by cutting them into pieces and placing them in large grocery-sized paper bags (2 bags per sample), 6. Label the bags with farmer name and/or field name, size of field and date of harvest, 7. Keep the bags open to dry, but do not allow seeds of one location to get mixed with another location. Once the samples have dried for at least 3 days they may be shipped to Jeff Stachler, The Ohio State University, 223 Kottman Hall, 2021 Coffey Rd., Columbus, Ohio 43210. If you have questions you may contact me at 614-292-1393.
Relatively cool night temperatures during pollination this year may have resulted in "silk balling" in some Ohio fields. Although I have not observed any silk balling yet, I have received reports of some abnormal silking that sounds like silk balling could be involved. The following is a recent article by Dr. R.L. (Bob) Nielsen, corn extension specialist at Purdue University, that addresses this abnormal silking condition:
This article is admittedly fearmongering on the part of your friendly neighborhood corn specialist, but I figure it is my prerogative and responsibility to do so when I believe conditions are ripe for the development of a potential crop problem. If the problem does not occur, then growers will be relieved and they will forget I said anything about it. If the problem does occur, then I will look pretty smart for having forecast its development.
The potential problem of which I speak is a phenomenon traditionally called 'silk balling'. I prefer the name 'scrambled silks' because I think it is more descriptive. The problem is one in which silk elongation, prior to their emergence from the husk leaves, is interrupted or altered, resulting in a mass of scrambled silks near the tip of the cob that never fully emerge from the husk. Obviously, any silks that fail to emerge from the husk will not exposed to any pollen and consequently will not contribute to the formation of kernels on the cob. The net result is some degree of barrenness on the cob and, consequently, lower yield.
Scrambled silks is a relatively infrequent problem and its causes are not well understood. Some believe that the occurrence of cool nights (low 60's or cooler) prior to silk emergence plays a role in the development of scrambled silks. Others believe that rapid changes in temperature patterns (e.g., very warm to very cool) prior to silk emergence encourages the problem. Hybrids with naturally tighter husks seem to be more susceptible to developing scrambled silks.
Given these opinions on temperature factors that may contribute to the problem, one could speculate (some would say fearmonger) that recent unusually cool nights throughout the central and northern parts of Indiana, plus the current forecast for more of the same, may lead to an increased occurrence of scrambled silks this year. Unfortunately, there is nothing you can do about preventing or avoiding the problem. Nonetheless, it would be prudent to walk some of your fields during or after pollination and look for evidence of the problem. Typically, the severity of the resulting poor kernel set is low and concentrated near the tip end of the cob. However, I've seen situations in the past where scrambled silks resulted in severe barrenness in nearly 1/3 of the plants in a field.
If you don't have time to walk your fields right now, any affected plants will likely raise red flags later on in the grain filling process. By this, I mean that any plants severely afflicted with barrenness will develop purpling or reddening of leaf midribs, leaf sheaths and other plant parts.
The reasons for this discoloration are similar to those for purple corn earlier in the growing season. An otherwise healthy plant whose ear is highly barren of kernels is a plant that is overproducing photosynthate (source) relative to the demands of existing kernels (sink). The excess sugars in the leaves and stalk trigger the formation of anthocyanin pigments in the plant tissues, especially in those hybrids with quite a few of the purpling genes. The similarity to early season purple corn is in the connection between excess plant sugars and anthocyanin production. Early in the season, excess plant sugars often result when root development is hindered for some reason.
A photo gallery of scrambled silks and their effects on kernel set is available on the Web at http://www.kingcorn.org/news/articles.00/SilkBalling-0718-Gallery.html .
If you think you are seeing early season yellowing caused by either brown stem rot or sudden death syndrome, better look again. Soybean cyst nematode combined with the multiple stresses that this season has put on the beans is causing some plants to pre-maturely turn yellow. Lower leaves have yellow spots which will slowly turn tan to dark brown. DIG the plants up with a shovel and look for the white females. These tiny "pearls" can now be seen easily on the roots. The best management tactics for Soybean cyst nematode are ROTATION, ROTATION AND ROTATION. These fields should be targeted for soil sampling to monitor SCN populations. When populations are very low (<40 eggs/cup of soil) SCN susceptible soybeans can be planted, if populations are between 40 to 2,000 eggs/cup of soil, SCN resistant soybean varieties can be planted. When SCN populations reach levels greater than 2,000, wheat, corn or alfalfa should be planted to reduce the populations. For more information on management of SCN see our fact sheet on Ohioline (http://ohioline.ag.ohio?state.edu/ac?fact/0039.html).
Since the autumn of 1998, 7,674 soil samples have been processed at Ohio State University for growers and consultants interested in soybean cyst nematode (SCN) detection, in a program funded by the Ohio Soybean Council using checkoff dollars. Of these samples, 3,781 or 49% have contained detectable levels of SCN eggs. Populations of the nematode are known to exist in 61 counties in Ohio.
Fields should be sampled in the fall following harvest. How often to sample fields will depend on several factors 1) is SCN present and 2) rotation schedule.
If you are in a 3-year rotation and populations are low or zero, probably once every 10 years prior to a soybean crop will be sufficient. If the field is in 2-year rotation, and populations are low or zero then every five years prior to a soybean crop. If populations were high then sample before each soybean crop to ensure that populations are dropping sufficiently during the years in corn and SCN resistant soybeans. If you are not rotating and relying on SCN resistant beans, which is not advised, then we highly recommend that you sample every fall. SCN populations do develop a healthy appetite for SCN resistant beans and this will need to be monitored quite closely. The end result is a field with extremely high populations in which the beans are severely stunted and produce less than 10 bushels/acre.
The main objective of the sampling program sponsored by the Ohio Soybean Council, to raise awareness of soybean cyst nematode in Ohio soybean fields, has been achieved. The SCN program now moves to the next phase in which soil sampling for SCN before planting soybeans becomes a part of production planning, along with routine testing for fertility needs. Therefore the charges for SCN testing have been re-instated at the C. Wayne Ellett Plant and Pest Diagnostic Clinic. The funds received from the Ohio Soybean Council from the check-off have been essential in identifying the problem in Ohio. SCN will not disappear but with a good rotation schedule, use of SCN resistant varieties in SCN fields and soil sampling to monitor SCN populations should minimize yield losses to this Soybean pathogen.
Beginning October 1, 2000, for a single shipment of soil samples from an individual farm the fee will be: $15.00 for the first soil sample, $10.00 for each additional soil sample in the shipment.
Sampling Instructions:
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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.
Contributors to C.O.R.N. this week include: State Specialists: Pat Lipps & Anne Dorrance (Plant Pathology), Peter Thomison (Corn Production), Jeff Stachler (Weed Science), Ron Hammond (Entomology), Bruce Eisley (Entomology); District Specialists: Ed Lentz (Agronomy) Extension Agents: Roger Bender (Shelby), Ray Wells (Ross), Dennis Baker (Darke), Gary Wilson (Hancock), Greg La Barge (Fulton), Howard Siegrist (Licking) and Glen Arnold (Putnam).Editor: Greg LaBarge Web Editor: Tom Rosati
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.
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