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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2007-10

Dates Covered: 
April 24, 2007 - April 30, 2007
Steve Prochaska

Freeze Injury on Forages is Variable Across the State

Authors: Mark Sulc

In just the past few days I've had the opportunity to observe alfalfa in west central and northeast Ohio, and have been amazed at the variation in freeze injury by location. Near Springfield, our alfalfa plots were severely frosted back, and on Friday there was very little green growth visible. Nearly all the topgrowth has been killed back to the crown, and the plants will have to initiate new buds and start completely over. Given that level of injury, I expect the first harvest will be delayed by 2 weeks at the minimum.

The picture at Wooster today was very different. The alfalfa looked much better at Wooster, and is recoverying very nicely. First harvest has probably been delayed by a week or less. The alfalfa growth at Wooster had many green shoots that were growing nicely, with just the tips frost injured. A week from now I suspect no lasting effects of the frost will even be visible there.

The contrast between those two locations was quite remarkable. I suspect the delayed breaking of dormancy in northeast Ohio resulted in much less freeze injury to the alfalfa compared with further south near Springfield, Ohio. I will be keeping a close eye on the alfalfa near Springfield and providing reports in the coming weeks. Meanwhile, do keep a close eye on the alfalfa, especially regarding weevil feeding (see article in this issue about that).

It was also quite interesting to see the difference between species in freeze injury. At Springfield, where the alfalfa was severely injured, our red clover trial was not and looked just fine. The red clover must have broken dormancy later, and was less susceptible when the cold weather hit. Several perennial ryegrass varieties were severely winter injured in our trial at Springfield. We will report those varietal differences in our annual forage performance trials report in the fall.

Plant Your Forages Now!

Authors: Mark Sulc

I've heard some questions about planting forages, and is it too late to plant? All the way through April is perfect timing for planting most cool-season forages. I hope many have been busy the last few days getting forages planted (as I have). The conditions have been ideal to get the job done. We can plant forages even into early May, but the later it gets after the first week of May, the more stress and weed competition the seedlings will likely encounter. Remember, take time to adjust the planter so seed is placed about one-quarter inch deep to no more than one-half inch deep in a firm seedbed.

Slug Update

Authors: Ron Hammond, Bruce Eisley

Although slug problems are still a few weeks to a month away, it is now a good time to begin determining your chances for slug problems. Population densities continue to be moderate to high in many fields, suggesting that spring populations in some areas of the state will be high this spring. Corn and soybean growers who have had problems with slugs in the past should be sampling their fields over the next few weeks, checking numerous spots in their fields for eggs or newly hatched juvenile slugs. Egg hatch will begin in southern OH within the next week or so and slowly move northwards. Slug eggs are usually laid in batches of 3-5 and are found just at or slightly below the soil surface. Growers should move crop residue aside in an area about a foot square, and scrape the soil with a small knife or other instrument. The eggs will be round, slightly smaller than a BB, and usually clear to slightly opaque. Although there are no thresholds as to what represents an economic problem, finding eggs in the majority of locations suggests a potential problem and a field that needs to be monitored closely. However, not finding any eggs is not a reason to forget that field. All no-till fields will need to be monitored this spring for slug injury. However, egg sampling and knowing which fields have a higher damage potential will aid you in managing your slugs this spring. Keep a watch in this CORN newsletter for further updates. We intend to closely watch numerous fields for egg hatch, growth of slugs, and developing problems.

Alfalfa Weevil and the Recent Cold Snap

Authors: Ron Hammond, Mark Sulc, Bruce Eisley

Last week’s CORN newsletter included an article on issues and concerns related to frost injury to alfalfa. As stated in that article, much of the early alfalfa growth from late March has been killed back by the frigid early April temperatures across most of the state. Some fields still show green leaf material and surviving young shoots in the lower canopy, but the taller stems have collapsed from the cold injury. An issue that was not addressed is injury from alfalfa weevil.

Considering the weevil, the cold temperatures probably only slowed larval development. It is doubtful that any significant mortality occurred. However, what is of concern is the relationship of the pest with the damaged alfalfa. The potential exists for the insect to be more damaging to the alfalfa now because we likely have the same number of weevils feeding on a drastically reduced food source within alfalfa fields.

Fields still need to be scouted when 200 heat units have been accumulated based on a 48 F based temperature. This has already occurred in southern OH (see CORN newsletter from 2 weeks ago), and is now occurring in central and northern OH.

When examining stems for evidence of tip feeding by alfalfa weevil larvae, keep in mind the possible freeze damage that has occurred that might be making that larval injury that much greater. Damage to alfalfa top growth reduces plant height to the point that smaller numbers of weevils can cause damage. Also, freeze injury to the top growth might be causing the larvae to drop further into the plant canopy. If an application of an insecticide is required, pay attention to the pre-harvest intervals of the insecticide.

Adjusting Corn Management Practices for a Late Start

Authors: Peter Thomison, Robert Mullen

As prospects for a timely start to spring planting diminish, growers need to
re-assess their planting strategies and consider adjustments. Since delayed
planting reduces the yield potential of corn, the foremost attention should
be given to management practices that will expedite crop establishment. The
following are some suggestions and guidelines to consider in dealing with a
late planting season.

Although the penalty for late planting is important, care should be taken to
avoid tillage and planting operations when soil is wet. Yields may be
reduced somewhat this year due to delayed planting, but effects of soil
compaction can reduce yield for several years to come.

If you originally planned to apply nitrogen and herbicides pre-plant,
consider alternatives so that planting is not further delayed when favorable
planting conditions occur. Although application of anhydrous N is usually
recommended prior to April 15 in order to minimize potential injury to
emerging corn, anhydrous N may be applied as close as a week before planting
(unless hot, dry weather is predicted). In late planting seasons associated
with wet cool soil conditions, growers should consider side-dressing
anhydrous N (or UAN liquid solutions) and applying a minimum of 30 lb/N
broadcast or banded to stimulate early seedling growth. This latter approach
will allow greater time for planting. Similarly, crop requirements for P and
K can often be met with starter applications placed in bands two inches to
the side and two inches below the seed. Application of P and K is only necessary with the starter if they are deficient in the soil, and the greatest
probability of yield response from P and K starter is in a no-till

Keep time expended on tillage passes and other preparatory operations to a
minimum. The above work will provide minimal benefits if it results in
further planting delays. No-till offers the best option for planting on time
this year. Field seedbed preparation should be limited to leveling ruts left
by last year's wet, problem harvest - disk or field cultivate very lightly
to level. Most newer planters provide relatively good seed placement in
"trashy" or crusted seedbeds. Final tillage passes just before planting can
be beneficial in suppressing weeds, but may not be practical this year. In
many cases, it will be more profitable to complete planting first and
control weeds with post planting applied herbicides. Planting into seed-beds
which contain emerged weeds will make post planting weed control critical.
Herbicide resistant corn including Roundup Ready and Liberty Link hybrids
may offer definite advantages in these situations. Effective burn-down
applications will help minimize the potential for major weed problems developing later in the season.

Don't worry about switching hybrid maturities unless planting is delayed to
late May. If planting is possible before May 20, plant full season hybrids
first to allow them to exploit the growing season more fully. Research in
Ohio and other Corn Belt states generally indicates that earlier maturity
hybrids lose less yield potential with late plantings than the later
maturing, full season hybrids.

With no-tillage or reduced tillage, increase seeding rates 10% over those
used with conventional tillage. Consult seed company recommendations for
specific hybrid planting rates under reduced tillage. Lower yields in
no-till can sometimes be related to sub-optimal plant populations at

Rust Update

Authors: Anne Dorrance

Soybean rust has stalled in development this spring. Late frosts (April 7/8th) in Florida and dry weather have not been favorable for new infections in Florida, Southern Georgia and Alabama. Kudzu is leafing out across the south, sentinel plot plants have been planted and scouting has started. Dry weather during the early spring also stalled rust development during 2006.

Common Seedling Diseases Found in Ohio

Authors: Anne Dorrance

Cold wet soil conditions favor many of Ohio’s seedling pathogens. Many of these corn and soybean pathogens, common residents in the soil in many areas of the state, are there waiting for favorable conditions to infect plants. We have found a large number of Pythium spp. as well as Fusarium causing these diseases. Conditions that favor development include: cold (<65oF) and saturated soils for long periods of time. To minimize the impact that these pathogens can have on corn and soybean production; plant when soil temperatures are closer to optimum for seed germination and growth.

Admittedly, this may be a challenge in many areas of the state this year as soil temperatures hover in the low 40’s. Correct drainage issues in fields with a history of stand establishment problems. A poorly drained field is especially prone to these types of conditions. Tillage doesn’t always solve this problem if a hard-pan develops. Check tile lines to be sure that they are still draining. Finally, use seed treatments to protect the seed. We have found these to be highly successful when heavy rains occur shortly after planting and can protect the stand and avoid a replant issue. Seed that has been treated with a fungicide (insecticides don’t count) are best to put in poorly drained fields. Seed treatments can not protect against severe flooding and they don’t work miracles, but they may be able to protect the stand and avoid a replant situation.


Managing a Dual Crop of Soybeans and Wheat

Authors: Jim Beuerlein

We have received questions about planting soybeans into wheat fields in early May and trying to produce both crops at the same time. There are two production systems for the successfully production of two crops in a wheat field the same growing season, and we refer to them as double cropping and relay intercropping.

Double cropping is the planting of soybeans immediately harvesting wheat. Relay intercropping is the planting of soybeans between rows of wheat spaced twelve to fifteen inches apart when the wheat is at the boot to head emergence stage of growth. Both systems are productive when managed properly and there is adequate water to produce the second crop. Procedures for both production systems are discussed in the Agronomy Guide, 14th edition and are on the Internet at: . Major deviations from the recommended procedures for either production system usually results in failure.

Planting soybeans into wheat fields in early May with the intent of maintaining and harvesting both crops is a flawed plan with a high probability for economic disaster. Once the soybeans emerge, any attempt to control weeds will damage either the wheat or the soybeans. Even if there are no weeds in the field, the soybeans will grow as tall as the wheat by the time the wheat is harvested and the top part of the soybean plants will be destroyed during wheat harvest. The soybeans will not be able to produce branches because they will have reached the reproductive stage of growth by that time. There will be only a few nodes where pods can develop resulting in a very poor soybean yield.

If the wheat crop has a poor yield potential, then it should be destroyed and another crop planted. If the wheat is to be maintained and a second crop is to be produced, then double cropping is a very acceptable plan with a good probability on economic success.

Archive Issue Contributors: 

Mark Sulc (Forage Production), Jim Beuerlein (Soybean and Wheat Production), Anne Dorrance (Plant Pathology), Robert Mullen (Soil Fertility), Peter Thomison (Corn Production), Ron Hammond and Bruce Eisley (Entomology). Extension Educators: Roger Bender (Shelby), Howard Siegrist (Licking), Glen Arnold (Putnam), Keith Diedrick (Wayne), Todd Mangen (Mercer), Mark Koenig (Sandusky), Jonah Johnson (Clark), Mike Gastier (Huron), Ed Lentz (Seneca), Harold Watters (Champaign), Steve Bartels (Butler), Wes Hahn ( Logan), Jim Lopshire (Paulding), Allen Sundermeier (Wood) and Steve Prochaska (Crawford).

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.