Field Crops Notes (July 2012)

Assessing Potential Drought Impacts

The dry and hot weather has everyone concerned about corn yields across the state.  With the price of corn and strain on forage inventories, this concern is important. Now is the time to be assessing corn fields for their potential yield and any need to salvage severely drought stricken fields for silage. This year’s crop is early in many places with pollination occurring already in early July. Normally pollination only begins in early July and starts in earnest in mid to late July.

To assess pollination, gently pull back the husk leaves of some representative corn ears and shake the ear. Those silks that remain attached to the ear are likely not pollinated. Often these will be on the ear tip where the last silks to emerge were attached. In severe situations, non pollinated kernels may be scattered throughout the ear or concentrated on the underside of the ear.

You can then do a yield estimate by counting the number of rows and the kernels per row. Multiply the rows by the kernels per row to determine the kernels per ear. Then multiply the kernels per ear by the plants per acre to determine kernels per acre. Then divide this by 90000 to estimate the potential yield in bushels per acre. Estimating silage yields is trickier but often we divide the yield by 6.5 to 7.0 to get a ball park estimate of the yield in tons/acre @ 65% moisture. This is quite variable though since the bushels/ton can vary, especially in years like this when the plants may be shorter than normal.

In general we have been surprised at the success of pollination in a lot of early corn we have looked at so far. This tells us that we have significant recovery potential from the early drought stress in some fields. Getting a good estimate of the yield potential early will provide you some idea of the potential for marketing the crop or future forage needs. Another thing to note is the maturity of the crop. Often corn is ready to chop 35-45 days following silking. With the early maturity of some corn this year and the warmer than normal conditions between silking and the dent stage, we could be looking at an exceptionally early silage harvest this year.

Greg Roth, PSU Grain Crop Management

Consider Herbicide Rotational Crop Restrictions for Late Summer/Fall Planted Crops

If corn harvest begins earlier than normal this year because of drought, herbicide selection can help dictate what rotational crops can be planted. For our dairy farmers, obvious choices might be forage sorghum or sorghum-sudangrass or a spring small grain or perhaps a forage brassica or even a legume.

Most corn herbicides have recrop restrictions that limit what can be planted. The two issues are:
1) Herbicide residues could exceed allowable standards in the forage and end up in milk or meat, and 2) Herbicide residues in soil that impact the growth and success of the rotational crop (i.e. carryover).

The second concern is probably the one we think about most. Let’s discuss a couple of scenarios. You applied Bicep II Magnum (or Degree Xtra or Guardsman Max) at corn planting and came back with Status postemergence. With Bicep II Magnum (or the others) you can plant safened sorghum seed (e.g. Concept treated) anytime and certainly 3 or 4 months after the herbicide was applied, there is no concern for sorghum or sorghum-sudangrass. This is also the case for Lumax and Lexar (Keystone and Harness Xtra do not allow sorghum until the spring following application). However, if you want to plant spring oats late summer, that’s another matter. With many atrazine-containing products, you can only plant corn, sorghum, and soybean (next year) as rotational crops.

Winter cereals, legumes, and other crops are restricted. Winter wheat, barley, and rye (not oats) may be planted 4.5 months after Lumax application (assuming no additional atrazine was added), but not Lexar. Halex GT allows winter cereals and oats 4 months after application (since it does not contain atrazine). Status has a one month recrop restriction for sorghum crops, winter cereals, and oats.

We know that many producers successfully follow atrazine-containing herbicides with all kinds of things including wheat, rye, and oats, but for many of these products, they are off-label.  For other corn herbicides, review Table 2.2-17 in the Penn State Agronomy Guide and check the most recent product label for specific restrictions.

  Bill Curran and Dwight Lingenfelter, PSU Weed Science

New Hazard Communications on the Horizon

The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) is requiring new information on hazardous chemical labels beginning in 2015.  In addition to the previously required signal words (DANGER, WARNING and CAUTION) and appropriate hazard statements, new chemical labels will be required to have pictograms representing distinct human health hazards, such as carcinogenicity, mutagenicity (genetic mutation) and reproductive toxicity.

While the “skull and crossbones” pictogram has been used for decades on chemical labels indicating DANGER or DANGER-POISON and is probably the most familiar of older pictograms, the Exclamation Mark version is very important to farmers and agriculturists.  It indicates exposure hazards on farms and ranches that are common health problems, including skin and eye irritants, skin sensitizers, and respiratory tract irritants.

Other chemical label pictograms that you will most likely find in the future on farm products will be:
     - Flame
     - Gas Cylinder
     - Corrosion

Although the June 1, 2015, deadline for the new pictograms on chemical labels seems far away, OSHA is requiring employee training on the new label requirements by the end of next year—2013.

Creating a higher level of awareness and knowledge among agricultural workers about chemical labels is a good intervention strategy.  OSHA resources are available to help agricultural employers bring their workers up to speed on the meaning of these new pictograms.

To view the pictograms and for more information, go to  http://www.osha.gov/dsg/hazcom/index.html

“Agricultural Safety and Health News” (July/August 2012)