CMEG Crop Management Extension Group

Field Crop News

Website Address: http://fcn.agronomy.psu.edu/

June 29, 2006    Vol. 06:10 Extra

IN THIS ISSUE:

Ponding/Flooding Effects on Corn — Peter Thomison, Ohio State Extension Corn Specialist

This article first appeared in the new Mid Atlantic Regional Agronomist newsletter available at: http://www.nrsl.umd.edu/extension/crops/newsletter/home.cfm)

The recent rains have been beneficial for many corn fields across Ohio and the Mid-Atlantic region.  Dry soil conditions were raising concerns about the efficacy of preemergence herbicide applications, and delayed emergence and uneven stands.  However, in some areas, heavy rains resulted in localized ponding.  If this ponding is limited, the injury resulting from the saturated soil conditions should be minimal given the relatively cool conditions we are currently experiencing.  The following are some tips to consider when evaluating possible damage from water saturated soil conditions.

The extent to which ponding injures corn is determined by several factors including: (1) plant stage of development when ponding occurs, (2) duration of ponding and (3) air/soil temperatures.  Prior to the 6-leaf collar stage (as measured by visible leaf collars) or when the growing point is at or below the soil surface, corn can usually survive only 2 to 4 days of flooded conditions.  The oxygen supply in the soil is depleted after about 48 hours in a flooded soil.  Without oxygen, the plant cannot perform critical life sustaining functions; e.g. nutrient and water uptake is impaired, root growth is inhibited, etc.  If temperatures are warm during ponding (greater than 77° F) plants may not survive 24-hours. Cooler temperatures prolong survival.  Once the growing point is above the water level the likelihood for survival improves greatly.

Even if ponding doesn’t kill plants outright, it may have a long term negative impact on crop performance.  Excess moisture during the early vegetative stages retards corn root development.  As a result, plants may be subject to greater injury during a dry summer because root systems are not sufficiently developed to access available subsoil water.  Ponding can also result in losses of nitrogen through denitrification and leaching.

If ponding in corn lasts less than 48 hours, crop injury should be limited.  To confirm plant survival, check the color of the growing point.  It should be white to cream colored, while a darkening and/or softening usually precedes plant death.  Also, look for new leaf growth 3 to 5 days after water drains from the field.  Sometimes the growing point is killed by bacterial infections during and after ponding, but plant growth continues in the form of non-productive tillers (suckers).

Disease problems that become greater risks due to ponding and cool temperatures include pythium, corn smut, and crazy top.  Fungicide seed treatments will help reduce stand loss, but the duration of protection is limited to about 10-14 days.  The fungus that causes crazy top depends on saturated soil conditions to infect corn seedlings.  There is limited hybrid resistance to these diseases and predicting damage from corn smut and crazy top is difficult until later in the growing season.

Sprouted Wheat? — Greg Roth, Penn State Extension Grain Management Specialist and Bob Leiby, Lehigh County Extension

There have been reports of sprouted wheat fields in the southeast and southcentral counties caused by our extended wet weather.  Identifying markets for the sprouted wheat will be an issue. Later planted fields appear to have less of a problem.

Sprouting causes the starch level to decline, the falling number to drop significantly and the value of the wheat for milling is decreased.  Sometimes the falling number has caused wheat to be rejected even though sprouts are not visible, so the marketability of sprouted wheat will likely be an issue.

Harvest suggestion: if you have both sprouted and unsprouted wheat still out in the field, harvest the unsprouted first and keep it stored separately from any sprouted wheat.  Expect a MAJOR price difference between sprouted wheat and unsprouted wheat.

Comments From Gene Gantz (Risk Management Agency, USDA) About Crop Insurance and Damaged Small Grain:  About 2,500 small grain crop insurance policies are in effect in PA and provide some protection against poor grain quality. If your insured grain may have quality damage, contact your crop insurance agent before you begin to harvest (or immediately upon discovery) and ask to talk to a crop loss adjuster to determine how to proceed to obtain maximum policy benefits.  If your insured grain has poor quality, the insurance company may require that two tests be determined by the Federal Grain Inspection Service (FGIS/USDA) laboratory, a U.S. grade and toxin identification/amount (i.e. vomitoxin PPM).

Flooding Injury to Soybeans — Anne Dorrance, Ohio State

(This article first appeared in the June 26 Ohio State CORN newsletter available at: http://corn.osu.edu/index.php)

Several past studies have evaluated the effects flooding on soybeans. In one study, soybean plants at the V2 and V3 stages were flooded naturally due to excessive rainfall, something we are all familiar with. Two 9-m wide transects across the flooded area within each field were divided into plots of 9 m by 9 m according to flooding duration: no flooding, 1 to 3 d, 4 to 6 d, and 6 to 8 d. Yield was reduced primarily due to reduced plant populations, shorter plants and fewer pods developing per plant. Other studies showed yield losses of 20% when soybean fields were flooded for greater than 2 days, but it should be noted they still had a yield. Some varieties can tolerate flooding more than others. For those fields with greater than two days of total saturation, ponding, can expect to see some long term effects. Secondary factors, such as root rots, will also contribute to the damage. Growers should note the varieties and compare varieties that were flooded for the same length of time. Some varieties will be impacted to a greater degree than others.

Did This Storm Move Soybean Rust Into PA? — Erick DeWolf, Penn State Extension Plant Pathologist

During the last few days I have received a number of questions about the potential impact of the recent weather system on the movement of soybean rust.

Penn State is fortunate to have one of the leading experts on soybean rust transport, Dr. Scott Isard.  My conversation with Scott indicates that this storm system is the type of system that could move the fungus from the south to PA.  However, he feels, and I agree, that the pathogen population is too small in the south to allow for significant movement north.  We looked at a number of spore transport models that are part of Scott's research on soybean rust, and all the models suggest the probability of movement is low.

The bottom line…it is very unlikely that this weather system moved soybean rust from the south into Pennsylvania.

Making A Crop Insurance Claim — Gene Gantz, Risk Management Agency, USDA and Craig Williams, Tioga County Extension Educator

If a farmer has flooded fields and crop insurance he is covered just like a drought or other disaster.  Below are some tips for getting the most from your crop insurance.

  1. Call the insurance policy seller and report what fields are flooded within 72 hours of discovery of loss or damage.
  2. If the farmer plans on plowing down the crop then he needs to have an adjustor evaluate the field before plowing. Do not destroy evidence of damage until a loss adjuster evaluates it!
  3. If the farmer is going to let the crop go to harvest, then call the Insurance Company, make a report and then document the yield at harvest.

If fields could not be planted due to wet/flooded conditions, then make sure you file a prevented planning report as soon as possible.

See Table 1 for estimated crop insurance protection in counties with flood damage.

Contributors: University Park Faculty/Staff:  Erick DeWolf, Greg Roth.  Extension Educators:  Bob Leiby (Lehigh), Andrew Frankenfield (Montgomery), Dave Messersmith (Wayne), Mark Madden (Sullivan), Craig Williams (Tioga), Mena Hautau (Berks), Dwane Miller (Schuylkill), John Rowehl (Cumberland) and Scott Graybill (Lancaster).

Editor: Dave Messersmith, Penn State Extension, Wayne County

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