With new products becoming available, it is important to consider all of the options and obtain the right product for your operation.  Bt hybrids have been around for a while and new Bt hybrids and products are available, but does that mean it will pay in your operation.

Yield is the biggest factor in determining which hybrids to grow.  In general, Bt hybrids for European Corn Borer yield well, usually at or above average.  The new corn rootworm Bt technology is relatively new and to make it pay you need a very specific situation where there is continuous corn or there have been significant problems with corn rootworm in the past.

In the first year of testing, the Bt rootworm event in general yielded average to below average in university tests across the Midwest.  A hybrid can only yield as well as its parents genetics.  For farmers with high-rootworm pressure, a rootworm Bt may be a good buy.  In trials in Iowa in 2003, a yieldgard rootworm Bt hybrid yielded an average 34 bu/acre over the untreated check crop with similar genetics.  In a high-rootworm pressure, high-heat, low moisture stress situation the difference was even greater at 44 bu/acre.  However in a field trial where there was only low to moderate pressure, the Yieldgard rootworm Bt hybrid showed no statistical difference from the check hybrid.

In order to avoid spending extra money on non-existent problems on your corn field, you need to study your fields.  If the field is below threshold levels, then no insecticidal treatments, soil insecticides or rootworm Bts are required.  If the field is above threshold, the best approach is to use a soil applied insecticide or a Bt rootworm hybrid.  For light to moderate rootworm pressure, the higher rate seed treatment would probably be sufficient.  In three decades of three independently conducted studies in corn on corn in three different states – Iowa, Illinois and Indiana – 50 % of the fields did not show enough rootworm pressure to cause economic damage to offset the cost of control.

If you are growing corn on corn and noticed a lot of rootworm beetles this summer you may want to consider these options.  If you are not sure you can check for rootworm populations in the spring and adjust your planting plans then.
 

Many weed scientists have attributed this increase to the widespread adoption of glyphosate-resistant soybeans and to the concurrent decreases in the use of residual, soil-applied herbicides that have occurred since 1996.  Glyophosate is very effective but has no residual activity to provide control of winter annual weeds that may emerge after application.

By applying herbicides in the fall, corn and soybean producers are able to eliminate these stands of winter annual weeds that are often present prior to planting in the spring.  In Missouri, some of the most common winter annual weed problems are henbit, purple deadnettle, chickweed, shephard’s purse, field pennycress and horseweed (also known as marestail).

These fall herbicide programs can save producers valuable time in the spring by eliminating spring burndown treatments.  Additionally, some evidence suggests that certain winter annual weeds serve as hosts for soybean cyst nematode and that black cutworm infestations are more likely in areas where dense stands of winter annual weeds persist.

Some of the most popular fall applied herbicide programs used in fields that will be planted into soybean are Canopy XL, Valor, Python, Aim and Scepter.  Express is often included with either of these herbicides because this product is particularly effective on common chickweed.  Valor, Python, Aim and Express have the added flexibility of being able to be applied on fields that will be planted to either corn or soybean.  In research conducted in Missouri over the past several years, Canopy XL plus express has proven to be one of the most effective fall herbicide programs for fields that will be planted into soybeans.

In corn, some of the most popular fall-applied herbicide programs are Princep, Basis, Valor, Python and Aim.  Express or 2,4-D is often included as components in one of these programs.  In research evaluations, most of the fall herbicide programs have provided similar results.  Some have demonstrated an enhanced ability to delay the germination of certain early-emerging summer annual weeds as well.  For example, fall herbicide programs that contain either Princep or Basis have provided at least some degree of common ragweed suppression at the time of corn planting compared to any of these other products.
 

With Diplodia ear rot of corn, the ear leaf and husks on the ear may appear prematurely bleached or straw-colored.  When the husk is peeled back, dense white to grayish white mold growth will be matted between the kernels and between the ear and the husks.  The entire ear may be grayish brown, shrunken, lightweight and completely rotted.  Diplodia ear rot is favored by wet weather just after silking and is more severe when corn is planted following corn.

Penicillium rot is usually evident as discrete tufts or clumps of a blue green or gray green mold erupting through the pericarp of individual kernels or broken kernels.  Gibb ear rot usually begins as a reddish mold at the tip of the ear.  Although mold growth usually has a pinkish to reddish color, it can appear yellow to yellow orange or yellow red.  Gibb ear rot typically begins at the tip of the ear but under favorable conditions, it can move down the ear causing extensive damage.

Black corn occurs when any of a number of saprophytic or weakly parasitic fungi grow on corn plants in the field.  These sooty molds or secondary fungi tend to develop on plants when wet or humid weather occurs as the crop is maturing or if harvest is delayed because of wet weather.  Stressed or lodged plants may be more severely affected.  It is possible that these secondary fungi could contribute to stalk deterioration or stalk rot.

Little can be done to prevent or reduce the invasion of corn by fungi.  If ear and kernel rots develop in the field, it is important to harvest in a timely manner and to store the grain under the best possible conditions.