C.O.R.N. Newsletter: 2015-26
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Don’t Press the Panic Button on Soybean Aphid Yet
As predicted, we have begun to see soybean aphids move into soybean fields over the past few weeks. Coincidentally, this is the 3rd year in a row that we have seen aphids move in relatively late in the growing season. Hopefully, most of our soybean are starting to mature and reaching the R6 stage, but there are some that still have a way to go due to delayed spring maturity.
By now we all should be familiar with the soybean aphid threshold of a rising population of 250 aphids per plant. But keep in mind that this number is the action threshold, it is not the economic injury level (EIL) at which soybean aphid causes yield loss. Yield loss occurs when aphids reach 500-600 aphids per plant. If you soybeans are at R4 and below, then continue to use the 250 threshold. However, the threshold does not apply to beans at R6 and later. The thresholds at these growth stages increase to over 1,000 aphids per plant. So if you are in an R5 stage, and have 250 aphids per plant should you treat? Here is some information to help you guide your decision:
1) Check again in 3-4 days, are the aphids increasing (remember a RISING population of 250 per plant)? At many sites, natural enemies like lady beetles are keeping aphids down or maintaining them at the 250 level.
2) At this point in the summer, you can expect aphids to double in size in about a week. Do you think you will reach R6 stage before aphids get to 500 per plant? If so, then it probably won’t pay to treat. Bottom line is predicting when you can get to R6 when thresholds go up.
3) Do you have to use ground equipment? Then expect a 2-3 bushel loss on yield which might impact whether or not you see a return on the application cost.
Predicting when soybean will reach the R6 stage and frequent scouting will provide the best information on whether or not it pays to treat.
For more information about the soybean aphid, scouting procedures and thresholds click on the following link: Soybean Aphid OSU Extension fact sheet
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Estimating Soybean Yield
To estimate yield, four soybean yield components need to be considered: plants per acre, pods per plant, seeds per pod, and seeds per pound (seed size). A printable worksheet to estimate soybean yield can be found by clicking here. It is difficult to accurately predict soybean yield because of plant variability and fall weather conditions can influence seed size. Estimates become more accurate as the growing season progresses.
To estimate soybean yield:
1. To calculate plants per acre, count the number of pod-bearing plants in 1/1,000thof an acre. In 7.5-inch row spacing, count the number of plants in 69 feet, 8 inches of row. In 15-inch row spacing, count the number of plants in 34 feet, 10 inches of row. In 30-inch row spacing, count the number of plants in 17 feet, 5 inches of row.
2. To estimate pods per plant, count the number of pods (containing one or more seeds) from 10 plants selected at random. Divide the total number of pods by 10 to get the average number of pods per plant.
3. To estimate the number of seeds per pod, count the number of seeds from 10 pods selected at random. Generally, the number of seeds per pod is 2.5, but this number can be less in stressful environmental conditions. Divide the total number of seeds by 10 to get the average number of seeds per pod.
4. To estimate the number of seeds per pound (seed size), assume that there are 3,000 seeds per pound. If the soybean plants experienced stress, seed size will be reduced, and it will take more seeds to make one pound. Use a seed size estimate of 3,500 seeds per pound if smaller seeds are expected because of late season stress.
Using the above estimates, the following formula is used to estimate soybean yield in bushels per acre: bushels per acre = [(plants/1,000th acre) x (pods/plant) x (seeds/pod)] ÷ [(seeds/pound) x 0.06]
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Weather Outlook and El Nino Update
Not much change from previous weeks thinking. Temperatures will average normal to slightly above normal for the rest of August while rainfall will be close to normal or slightly below. Nothing extreme is forecast. See the 8-14 temperature and precipitation outlook maps at the following links:
http://www.cpc.noaa.gov/products/predictions/814day/814temp.new.gif
http://www.cpc.noaa.gov/products/predictions/814day/814prcp.new.gifGoing into autumn and harvest season, climate models continue to suggest a turn to wetter conditions again across the corn and soybean belt including Ohio which would make harvest season a bit tougher. The good news for harvest season is frost and freeze dates could be delayed.
El Nino is well underway in the eastern Pacific Ocean of the equatorial region. This El Nino is shaping up to be a strong one from the second half of 2015 into 2016. The effect will likely extend from winter wheat season into planting season and possibly beyond for 2016. This El Nino of 2015 into 2016 will likely be similar to the years of 1997/98, 1982/83, 1972/73 and 1957/58.
See historical links to El Nino temperatures and precipitation from NOAA National Weather Service Climate Prediction Center here with climate trends adjusted here:
http://www.cpc.noaa.gov/products/precip/CWlink/ENSO/composites/EC_ENP_index.shtml -
2015 Ohio Wheat Performance Test Available Online
A pdf of the 2015 Ohio Wheat Performance Test can be found at the Soybean and Small Grain website at: http://stepupsoy.osu.edu/node/35. A sortable version of the Ohio Wheat Performance Test can be found at:http://www.oardc.ohio-state.edu/wheattrials/regions.asp?year=2015#single. Test results are for 78 soft red winter wheat varieties grown at five Ohio locations (Wood, Crawford, Wayne, Darke, and Pickaway County). Variety selection should be based on disease resistance, average yield across test sites and years, winter hardiness, test weight, and standability.
Overall, grain test weight averaged 56.3 lb/bu (compared to an average test weight of 58.8 lb/bu in 2014). Grain yield averaged between 77 and 92 bu/acre at the five locations in the test. Lower than normal test weight and grain yield may be attributed to wet weather in June and July and delayed harvest.
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FSR Agronomy College coming September 15th
The FSR Agronomy College is September 15th. We will make use of the site and facilities of the Farm Science Review’s Molly Caren Agricultural Center, near London Ohio. We encourage company Agronomists, CCAs and Custom Applicators to attend.
9 a.m. start – our OSU Extension agronomic crop state specialists will meet with attendees in the Agronomy Plots – Plant Pathologists Anne Dorrance and Pierce Paul, with Peter Thomison, Laura Lindsey & her graduate students and Mark Loux from the Horticulture & Crop Science department and Andy Michel from OSU Entomology. We will break into small groups so you get an up close and personal educational experience for the morning.
For the afternoon, we have four sessions, and you will have a choice of three. We will break up into smaller groups here as well.
1) Sprayer setup and nozzle selection for reduced movement – Monsanto & Dow.
2) Tillage and Nutrient Placement Systems for Improved Efficiency and Environmental Consequences in High Yield Corn – Tony Vyn, Purdue University
3) UAV & Remote sensing - John Barker OSU Extension
4) Precision Ag – Using a planter for placing inputs where you want them – seed & nutrients - John Fulton FABE, likely with Scott Schearer
This program is supported by the Ohio Soybean Council. For the noon meal we have a BBQ box lunch. Commercial Pesticide Education credits will be available as well as CCA CEUs. The program this year was planned in conjunction with the Ohio AgriBusiness Association - registration is through their office, for more information:http://oaba.net/aws/OABA/pt/sp/events.
Contact for registration: Margo Long at Ohio AgriBusiness Association, 5151 Reed Rd. Suite 126-C, Columbus, Ohio 43220. Tel: (614) 326-7520 or email:Info@OABA.net. For questions on the program you can contact Harold Watters atwatters.35@osu.edu or at the office 937 599-4227
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.
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