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Ohio State University Extension


C.O.R.N. Newsletter 2012-08

Dates Covered: 
April 10, 2012 - April 16, 2012
Steve Prochaska

Strip Intercropping Corn and Soybean

Strip intercropping corn and soybean usually involves growing the two crops  in narrow, adjacent strips within a field during the same growing season. It’s a practice that’s been receiving more attention recently as a means of boosting corn yields and profits. Strip intercropping systems have also been promoted as a means of enhancing conservation of soil and water resources, and increasing crop rotation and spatial diversity across the landscape.  The concept is not new. In the U.S. strip intercropping is often used in conjunction with contour farming in hilly, rolling areas.

The response of corn and soybeans to strip cropping is strongly influenced by the width of the strip in which they are grown. Earlier planted and taller corn intercepts more sunlight at the border  with soybean and produces greater yield (the “edge effect”). However, yield of soybean are reduced at the border due to shading, water competition, and nutrient depletion by the adjacent corn. This tradeoff may limits the potential of strip intercropping .

In trials conducted in 1996 -1990, Purdue researchers reported that strip intercropping  (involving eight row strips) increased yield of outside corn rows by an average of 25.8% and decreased yield of outside soybean rows by 26.6%. Corn strips with extra population and N in outside rows yielded 20 bu/A more than nonstripped corn with regular management. Stripped soybean averaged 5.9 bu/A less than unstrapped soybean.  These finding are similar to the results of most published university research regarding relative yields of the outer rows of corn and soybean in strip intercropping. 

Proponents of strip intercropping believe new technologies, such as autosteer, RTK, variable rate seeding, and herbicide resistant crops, make it easier to plant and manage strips. For example, to optimize the border row effect on yields of corn, farmers with variable-rate planters have increased outside row corn populations as high as 60,000 plants/A. They are also interested in changing row spacing and planting hybrids that respond better in the “light rich” border rows. However some university agronomists question whether the negative impact of adjacent corn rows on soybean yields has been adequately addressed, especially under dry conditions and whether strip intercropping is logistically feasible or practical in large scale crop production.

According to Iowa work, strip intercropping benefits are maximized when strips run north–south rather than east –west.  Also north-south strips tend to yield more in the east than the west border rows. This is attributed to the higher rate of photosynthesis during cooler mornings when sunlight is striking the eastern edge than during the hot afternoons when sunlight striking the western border rows may not be fully used due to moisture stress and wilting. Ultimately the direction of strips is determined by topography and other field conditions.


Ghaffarzadeh, M. 1999. Strip Intercropping. Iowa State University Extension Pm 1763, Ames.

Nafziger, E. 2011. The devil is in the details. Strip Intercropping  Feedback. Letters. Corn and Soybean Digest. Dec. p. 46 

West, T.D. and D.R. Griffith. 1992. Effect of strip intercropping corn and soybean on yield and profit. J.Prod. Agric. 5:107-110. 

Winsor, S. 2011. Farming on the edge. Corn and Soybean Digest. Nov.p. 6-8.


Spring Insect Pest Problems

Black cutworm - We have had heavier weed growth because of earlier warm weather, especially chickweed growth.  With this extra growth comes the potential for greater black cutworms problems.   Added to this is that adult cutworms are already being collected in the Midwest.  When corn gets planted and starts to emerge, cutworms might already be at damaging stages.  Thus, there is a greater need to pay extra attention in those fields conducive to cutworms problems, namely no-till and/or weedy fields. 

Slugs - Warmer weather and soil temperatures will be causing slugs to hatch earlier and will result in slugs beginning their heavier feeding earlier.  If planting times are normal, slugs will be a bigger and larger threat than normal.  If planting early, perhaps the slug feeding will be more similar to normal conditions.  If planting is late, slugs will be relatively larger and capable of even heavier feeding. 

Bean leaf beetles – Based on studies at other universities, we might seed more bean leaf beetles because of the warm winter.  However, we believe that if most fields are planted and emerged about the same time, beetles should disperse themselves over all those fields and not be major problems. However, if only a few fields have emerged, those will still get them all and as usual, potentially be problem fields that would need extra monitoring. 

Rootworms - Although we would expect rootworm larvae to hatch earlier this year, we would not expect to necessarily have more or greater problems.   Because most fields are already transgenic for rootworm control, treated with a soil insecticide if continuous corn, or are part of a rotation, we would still expect good control.  We would not recommend any additional or two-tactic applications be made (for example making soil insecticides applications on transgenic corn). 

Corn flea beetle - we have already discussed this pest in previous C.O.R.N. newsletters (#5, March 5-20).  Seed treatments on most corn should offer control, at least for beetles; we are not sure about its impacts on Stewart's wilt.  Growers should plan on scouting any non-seed treated fields along with popcorn and sweet corn fields that are usually more susceptible to Stewart's wilt, and any field corn hybrids that are more susceptible. 

Cereal leaf beetle – We would expect an earlier presence of cereal leaf beetle larvae, and thus, the need to scout wheat and oats earlier.  Because of the potential for greater survival, perhaps it is more important this spring.   

Mid-summer problems – At this time, we are not sure how the warmer winter will impact populations later in the growing season; thus, the need to monitor will still be there. 

No matter what, as always, remember: IPM - scout, Scout, SCOUT.  If management is necessary, see our Bulletin 545 ( for options. 

Soybean Aphid Prediction for Ohio

We had reported the lack of eggs at most buckthorn sites last fall, but we did find lots of eggs on buckthorn at Mirror Lake on the OSU Campus in Columbus.  We sampled these various sites  over the past few weeks and did not find any aphids following the leafing-out of the buckthorn, including the Mirror Lake buckthorn where masses of eggs were found.  However, in looking at the eggs that were still there, it was observed that the eggs, while still present, were all shriveled.  Having talked with people more in the know, these eggs were perhaps not fertilized last fall, maybe from a lack of males.  Based on these observations and past history, we predict that Ohio, and only speaking for Ohio, will experience a "low aphid" year.  We expect aphids to be hard to find through most of the summer, and will only rise in numbers in late summer/early fall prior to migrating to buckthorn.  In essence, we expect to continue the 2-year cycle of "high - low" aphid years, with 2012 being another low year.  HOWEVER, this cycle, because of unknown reasons, could change at any time.  Thus, we urge you to continue to scout for this insect pest and to read this C.O.R.N. newsletter throughout the summer for updates and possible changes in the situation.

Update on Bees and the Neonicitinoid Seed Treatment Situation

Having commented on the concern of the use of neonicinitoid seed treatments in field crops last week in this newsletter, we were able to view a webinar broadcast on the subject done by Purdue University from where the recent study suggesting a problem had come from.   At the present time, there is still much research needed to determine whether this is a significant concern or not.  Currently, we would recommend that growers, especially those using air-planters, communicate with neighbors who are bee keepers to help keep their hives safe during planting season.  One thing growers can do is to be aware where they clean out their air-sprayers, and doing this when the wind is down to prevent significant blowing and drifting off the farm.  Just like with spraying foliar insecticides to flowering crops, we all need to work to keep bees and hives safe, perhaps now even during the planting season, and we can do this with good communication and cooperation between farmers and bee keepers. 

Weather Outlook

The week of April 9 will be cooler and drier than normal. The week of April 15 will be warmer and wetter than normal. The wet period appears to be from Saturday April 14 to Wednesday April 18. We do expect some minor freezing conditions this week especially for Wednesday and Thursday AM. We can not rule out some additional frost events yet the week of April 22, but they look marginal at best. The trend does not support much in the way of anything significant beyond this week. The overall trend remains in place for above normal temperatures and near normal rainfall in later April into early May. However, it still is reasonable to expect normal to below normal rainfall from May into June, it is just a matter of when the drier pattern occurs. If we miss the rains early next week then we are likely already into the drier than normal pattern with the likelihood of it persisting into May and June.


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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.