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August 4-10, 2003
C.O.R.N. 2003-25
In This Issue:
A) Second Brood European Corn Borer
B) New Weed Threatens Ohio Agriculture
C) Late-Season Weed Control Restrictions
D) Western Ironweed Control
E) Ohio Field Crop Disease web site update
F) Field Day Events - NW Ohio Alfalfa Field Day & Western
Ohio Agronomy Field Day
Second brood European corn borer (ECB) moths are flying in central and southern Ohio at this time. They should be attracted to the later planted corn in the areas to lay their eggs. Late planted corn should be scouted beginning this week for egg masses which are normally laid on the under side of the leaves above and below the ear zone (see picture of ECB egg mass on the WEB at: http://www.ag.ohio-state.edu/~ohioline/icm-fact/images/22.html). Check this area for egg masses and record the number plants with egg masses. Treatment threshold is based on the number of egg masses and live larvae found on the plants. Additional information on ECB is available in a fact sheet on the WEB at: http://entomology.osu.edu/ag/cornpost.htm#linkecb.
In greenhouse tests, apple of Peru was generally very sensitive to glyphosate; yet a few seedlings were still alive several weeks after treatment. Because apple of Peru can germinate late in the season and still produce seed, sensitivity to glyphosate may be of little help in preventing buildup of the seedbank. We saw evidence of this in a Seneca County field last fall. The grower planted bell pepper following ten years of corn and RR soybeans. Dual and Command were applied, the field was cultivated four times and hoed once. Despite the intense weed control, apple of Peru plants were 6 feet tall and reached densities of 12 plants per square yard by late summer.
Scientific literature indicates that apple of Peru is one of the worst weeds in the soybean growing areas of Brazil. Its tolerance to a broad spectrum of herbicides and its damaging effects on crop yield are well established in other countries. We surveyed weed ecologists and crop scouts at over 40 locations in the US and Canada to determine their knowledge of the weed. Most believed the weed to be non-existent in their state or region. However, colleagues in North Carolina and Georgia who described small, but spreading and persistent populations in tomato and peanut producing areas, respectively, shared our alarm.
We hope that apple of Peru will disappear from the landscape as quickly as it has emerged; however, history tells us this is unlikely. Two of the most serious weed problems in the Midwest today, giant foxtail and velvetleaf, were uncommon plants restricted to waste areas only 30 to 50 years ago. Think of the time and resources spent every year in controlling these species, and think of how different things might be if their invasion had been prevented.
We urgently need to 'get a handle' on the distribution of apple of Peru in Ohio. This information is needed to plan containment and eradication schemes. At this time we know of infested fields in Sandusky and Seneca Counties, totaling less than 2000 acres. Apple of Peru, grows faster and taller than most other weeds in the Solanaceae, and last week was approximately 30 inches high in Wooster (Fig. 1a). During August it is easily identified by its light blue flowers and lantern-shaped seed-pods (Fig. 1b). Shirt-pocket laminated ID cards are available from the Horticulture and Crop Science Department in Wooster. Call Joel Felix at 330 202 3591 or email felix.15@osu.edu , if you could make use of these.
If you find any plants that look like apple of Peru call or email the Weed Ecology lab in Wooster or OSU Extension in Sandusky County. We will visit the location, confirm your ID, and map the infestation. Contact us by calling Wooster at 330 202 3591 or OSUE Sandusky at 410 334 6340. Email contacts are felix.15@osu.edu, koenig.55@osu.edu and doohan.1@osu.edu.
Figure 1a. Mature apple of Peru in pepper field in Seneca Co., OH.
Figure 1b. Flower, leaf and lantern-shaped seed fruits of apple of Peru.
We are getting to that time of the season where herbicide applications to soybeans need to stop due to meeting harvest interval restrictions. Many herbicides need greater than 75 days from the time of application until soybean harvest, which means not harvesting until mid-October. Herbicides with these restrictions include Aim, Assure II, Backdraft, Extreme, Flexstar, Fusilade, Fusion, Poast, Poast Plus, Pursuit, Raptor, and, Reflex. Classic and Synchrony STS must be applied 60 days before maturity. FirstRate must be applied 65 days before harvest. Herbicides with a harvest interval of 60 days (Harvest after October 3rd, if sprayed today) include Harmony GT, Resource, Select, and Stellar. Galaxy, Storm, and UltraBlazer require 50 days until harvest. Cobra requires 45 days before harvest. Most glyphosate formulations must be applied at least 14 days before soybean harvest.
We have noticed lots of western ironweed in pasture fields this season, especially in eastern Ohio. It is starting to flower, which is a good time to control western ironweed with glyphosate. We suggest applying at least 1.5 lb ae/A of glyphosate (44 oz/A Roundup WeatherMax or 64 oz/A of most other glyphosate formulations) plus 2,4-D ester at 1.0 pt/A. Making this application within the next two weeks should provide excellent control of western ironweed. If a broadcast application is not possible due to too much damage to the pasture species, consider a rope-wick application. For a successful rope-wick application use concentrated glyphosate plus 2,4-D ester at a ratio of 3 parts glyphosate to 1 part 2,4-D ester, use a sturdy applicator since western ironweed is very rough, and run the applicator in 2 to 3 different directions for good plant coverage. For small pastures with few western ironweed plants, cut off the plant stems above the soil surface with a sharp pruners and then apply concentrated glyphosate to the cut surface as soon as possible. Some cultural practices to reduce future problems with western ironweed, include proper fertilization and less over-grazing.
A final report of the Fusarium head scab risk forecasting system used in Ohio during 2003 has been recently posted including the results of the forecasting models and County agent survey reports from 30 counties on the Plant Pathology Ohio Field Crop Diseases website. (http://www.oardc.ohio-state.edu/ohiofieldcropdisease/)
Also, we have updated the chart, "Reactions of winter wheat varieties to Powdery Mildew, Leaf Rust, Stagonospora, Head Scab and Wheat Spindle Streak Mosaic." (www.oardc.ohio-state.edu/ohiofieldcropdisease/wheat/wheatreactions03.htm).
Alfalfa Field Day
An Alfalfa Field Day is scheduled for Thursday evening, August 7, 6:00 p.m.
at the Dennis Niese Farm at 15128 Road B-13, Continental, Ohio. The farm is
located 2½ miles north of Miller City on SR 108 and then west 1½
miles on Road B-13.
Topics for the field day include: Alfalfa Establishment; Stand Evaluation; Compaction Problems; Crown Damage; Weed, Insect and Disease Control. Speakers for the field day include: Dr. Mark Sulc, State Forage Specialist with The Ohio State University, Columbus; Glen Arnold and Gary Wilson, Agricultural Extension Agents for OSU Extension in Putnam and Hancock Counties.
Western Ohio Agronomy Field Day
The Ohio State University Extension, Stillwater Watershed and A.C.E. (Agriculture
for a Clean Environment) groups are co-sponsoring the Western Ohio Agronomy
Field Day on August 7, 2003. The field day will be held at the Darke County
Farm located at the southwest corner of St. Rt. 127 and St. Rt. 49, just south
of the Darke County Jail. Register by calling the OSU Extension Office at 937
548-5215.
The program will start at 6:00 p.m. with an early bird diagnostic clinic. Presentations
will be given on; "Managing Dandelions and Other difficult Weeds,"
"Controlled Drainage Systems," and "First Generation Corn Rootworm
Concerns." Following the presentations a walk-around of the on-farm research
plots will be conducted. Some research on the farm include: 30 inch row corn
compared to Twin-row corn, Bt corn test plots, an extensive corn seed treatment
study was also planted with 7 different seed treatments, additionally, a first
year corn rootworm survey study will be on-going.
This educational program is open to the public, and will provide a unique and
hands-on perspective of agronomic production in Western Ohio. For more information
contact Steve Foster at (937) 548-5215 or email foster.99@osu.edu.
Readers can subscribe electronically to this newsletter by sending an e-mail message to: corn-out-on@postoffice.ag.ohio-state.edu. A successful subscription message will receive by an automatic reply from the listserv. Contact your local Ohio State University Extension Office or e-mail labarge.1@osu.edu if you have problems subscribing.
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.
State Specialists: Pat Lipps, Anne Dorrance & Dennis Mills (Plant Pathology), Jeff Stachler (Weed Science) and Bruce Eisley (IPM); Extension Agents: Alan Sundermeier (Wood), Woody Joslin (Shelby), Clark Hutson (Seneca), Gary Wilson (Hancock), Greg La Barge (Fulton), Glen Arnold (Putnam), Mark Keonig (Sandusky), Harold Watters (Miami) and Steve Foster (Darke).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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