C.O.R.N. Newsletter 2011-17

Dates Covered: 
June 7, 2011 - June 13, 2011
Editor: 
Jon Rausch

The weather outlook has changed little for the next two weeks.

The weather pattern is behaving as forecast last week. The outlook has changed little for the next two weeks.

Week of June 6-10 - Temperatures 5-10F degrees above the normal of about 80/60. Rainfall generally below normal except far north where scattered storms will occur this were and rainfall will be closer to normal. Rain chance will increase late week but will be scattered.

Week of June 11-17 - Temperatures near normal of about 80/60. Rainfall above normal. Normal is 1 inch with widespread 1-3 inches with isolated higher totals especially in the western and north. Main rainfall will be this weekend into early next week and again late next week.

Week of June 18-24 - Temperatures 3-5F above normal and rainfall at or above normal. Normal is 1 inch.

In summary from the week by week forecast above for June is as follows: June will be a warmer than normal month. Rainfall will be near normal but large fluctuations will occur. Normal is about 3-4 inches. Some places will be below and some above.

Outlook for summer is for above normal temperatures and rainfall normal to above normal trending to below normal by August.

Western Bean Cutworm Trapping Should Begin Soon

Western Bean Cutworm Trapping Should Begin Soon

Thankfully, many Ohio corn producers caught a break in the weather which allowed a lot of acres to be planted in the past week.  Late planted corn has its own challenges to get as much yield as possible before harvest, but there is an additional threat that may impact our corn this year.  We have been monitoring western bean cutworm since 2006, and have seen large increases in adult trap count every year.  In 2010, we caught over 2,600 adult moths, and saw damage to corn ears for the first time.  While this damage was non-economic, it still demonstrates the potential for yield loss this year when there is little margin for error.  What is the connection between western bean cutworm and late-planted corn?  Observations from other states have shown an ovipositional preference for pre-tassel corn.  Pre-tassel corn is at its highest risk before or during peak adult flight which can occur anytime from mid-July to mid-August.  The later corn remains at pre-tassel, the more vulnerable it is to western bean cutworm

Predicting peak flight is difficult, but can be estimated using common adult trapping methods.  Trapping is done using a simple lure and either an empty milk jug (with 4 windows cut on the sides, and filled with 4 parts water: 1 part environmentally safe antifreeze, see figure) or a “bucket trap.”   Lures and bucket traps can be purchased from Great Lakes IPM (http://www.greatlakesipm.com/).  Traps are placed on the edge of a corn field, and monitored at least weekly.  Given the cool spring we have had, we do not expect flight to begin until the 2nd or 3rd week of June, so traps should be placed by June 18th

Once again, OSU-Extension will be running traps in Ohio cornfields across the state, and will publish weekly maps at the Agronomic Crops Insect webpage (http://entomology.osu.edu/ag/).  Here, you will find other western bean cutworm information including past years’ maps, fact sheet and identification guides.  Additional information can be found in the October 2010 issue of the Journal of Integrated Pest Management (http://www.entsoc.org/Pubs/Periodicals/jipm), a free journal designed to provide detailed pest information.     

 

Soil crusting from rapid drying may cause emergence issues

Soil crusting from rapid drying may cause emergence issues

Tim Boring, Michigan State University Extension

After all the rain and cold weather during the end of May, the forecast calls for us to turn a corner and finally get some warm temperatures moving into June. The increase in temperature will certainly be welcomed to help dry soils out and get planters back in the field, but this rapid warm-up may cause some issues for crops already in the ground.

When planting into wet soil conditions, a big concern is the effect secondary tillage operations, double disk openers and packing wheels have on soil structure. It’s understandable that with such a wet and delayed planting season, there are going to be some field operations performed under less than ideal conditions. When soils are worked or manipulated wet, water within pore spaces lubricates soil particles and makes it easier for them to pack together. When these soils rapidly dry, such as in the full sun, high 80 degree conditions forecasted for the week of May 30, water is removed from the soil and particles are left compacted against one another. When this occurs on the soil surface, we call the phenomenon soil crusting. Soil crusting can also result from heavy rainfall events when the raindrops cause soil arrogates to break apart and splash, realigning in a denser configuration. Sounds a lot like the conditions we’ve seen over the last days of May, huh?

The extent to which soil crusting may occur depends on how easily soil particles can become compacted. Low levels of organic matter, high silt content, low surface residue and small soil aggregate size can all lead to soil particles packing together. Some of these factors can’t be influenced much by management, but maintaining surface residue and minimizing tillage can help reduce the chances of soil crusts forming.

The most apparent effect of soil crusting is difficulty in crop emergence. Soybeans tend to struggle with emergence issues to a greater extent than corn. As the soybean hypocotyl swells to increase pressure on crusted soils, the hypocotyl can snap off. Cotyledons can also be torn off as the plant pushes through crusted soils. Shawn Conley and John Gaska of Wisconsin illustrate these effects in a newsletter article, Delayed Soybean Emergence and Cotyledon Loss, discussing these challenges in their state last year. Read the article online at http://goo.gl/d40Mh.

Rotary hoes are the most effective tools for eliminating soil crusts that are hindering crop emergence. When operating these tools, it’s important to periodically stop and access crop damage. Soybeans are especially sensitive to damage as the crook emerges. Rotary hoes can also snap off the hypocotyl or rip off cotyledons, similar to the damage that can be incurred by the crop struggling to get through a soil crust in the first place. Operating speed may be slightly adjusted to reduce this damage, which will be a process of trial and error. Damage can also be minimized by operating rotary hoes later in the day when plants are more pliable rather than early in the morning in cool conditions when plants can be brittle. Crop damage incurred from operating a rotary hoe often appears worse than it really is, but severe damage can occur at some growth stages. If the rotary hoe is resulting in damage, you’ll likely have to make a determination if more damage is occurring from the rotary hoe or the soil crust and act accordingly. Some damage from the rotary hoe is expected and acceptable, but specific site conditions will have to dictate where the line crosses into unacceptable.

As soils dry this week and we rush to finish planting, it’s important to remember to monitor the crop already in the ground. Conditions may be right to lead to soil crusting issues, so be ready to pull out the rotary hoe and give struggling seedlings a little help emerging.

Flood Damaged Wheat

The damage left by above-average rainfall is now showing up in parts of Ohio. Wheat fields that were under water for several days are now dying. Wheat can recover from a few days of excess water, once the water dries out quickly. But the frequent and heavy rains we have had left the crop under water for close to a week in some locations. Excess water replaces the air in the soil and deprives the plant roots of much-needed oxygen. Roots that are deprived of oxygen for an extended period will die. This is soon followed by death of the stems, and eventually, the entire plant, and the dead plant tissue is quickly invaded by opportunistic organisms. While wet, saturated, and poorly aerated soils do favor some plant pathogens such as Pythium and could lead to root rot, the problems we are seeing in most of the flooded fields are not caused by diseases. In fields affected by root rot, dead plants or groups of dead plants are usually found among health-looking plants. What we are seeing in these problem fields are huge sections of fields or entire fields with dead or dying plants, which indicates that this is caused more from an abiotic or stress-related situation. In this case it is most likely due to flooding.

So, whether or not the entire crop is lost and should be abandoned to plant corn depends on the length of time that there was standing water and the size of the area of the field that was affected. It is easy to tell whether wheat plants were flooded for too long; they either die or become rotted and stunted, with a chlorotic appearance (light green-yellow discoloration). These plants will eventually lodge and will not recover. If this occurred in a small section of the field, then you may still be able to get a decent crop, but if the majority of the field was affected, then the crop may not be worth keeping.

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About the C.O.R.N. Newsletter

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.