Soybean Rust Update
        Last year it seemed that soybean rust was discussed anytime there was a gathering of more than two people.  This past winter.....not so much.  It’s not that the disease has changed, but rather the reality of knowing we escaped without harm in 2005 and maybe expect the same this year.  That may be the case, but then again it may not be.  This spring there have been more confirmed cases of soybean rust in the south than in 2005.  Most have been on kudzu, an alternate host plant.  Perhaps the greatest concern is the confirmed presence of soybean rust in Texas and Mexico.  Plant pathologists feel that wind currents from Texas, Louisiana, and Mexico are more likely to bring rust spores into the upper Midwest than those from the southeastern United States. 

        Of course a lot of things have to come together for soybean rust to be a problem in Wisconsin.  Environmental conditions such as low humidity and sunlight are known to decrease spore viability.  As was the case last year, there will be an arsenal of fungicide products available for use on soybean rust.  Some that are already approved for use in the state include Bravo, Echo, Headline, and Quadris.  Others will get a special Section 18 approval once soybean rust is confirmed in a neighboring state. 

Clostridial Silage Fermentation
        With the amount and frequency of rain we typically receive during the first crop harvest season, it's sometimes tempting to chop hay at a moisture level higher than optimum.  This can be a cause for concern.  In alfalfa silage that is less than 30 percent dry matter, clostridial fermentation can occur.  Clostridia are anaerobic (no oxygen required) bacteria that convert forage sugars and organic acids to butyric acid, carbon dioxide, and hydrogen gas.  The result is excessive dry matter and energy losses in a silage with a high pH (typically over 5.0).  After fermentation, the silage is easily recognizable by its rancid milk or sour odor.  

        The feeding value of silage that has undergone clostridial fermentation is greatly reduced.  The high butyric acid level can be harmful when fed to transition cows as it can lead to subclinical or clinical ketosis.  Clostridia also degrade proteins, releasing ammonia and amines.  They also produce high levels of acetic acid.  Normally, we like to see a lactic acid to acetic acid ratio of at least 3:1.  That won't be the case with clostridial silage. 

        Some forage testing labs offer a fermentation profile test.  It provides the levels of volatile fatty acids (lactic, acetic, butyric, and propionic acids), ammonia, nitrogen, crude protein, and pH.  This can be a good tool to assess silage quality.  

Timothy Has Lowest DCAD Levels
        In a recent edition of Agronomy Journal, Quebec researchers reported on a study comparing the dietary cation anion difference (DCAD) of several forage grass species.  The study compared timothy, orchardgrass, smooth bromegrass, meadow bromegrass, and tall fescue.  Timothy had significantly lower DCAD levels than the other grasses while orchardgrass was the highest.  Often it is potassium that causes the high DCAD levels.  The results were consistent across three different locations.  High DCAD diets have been linked to milk fever in dairy cattle when fed prior to calving. 

Speed Kills
        When it comes to operating a rotary hoe, don’t be bashful about ground speed.  Best results are obtained in the 7-10 mph range.  It is also important that soils be relatively dry so when weeds are “flipped out” they do not reestablish.  Hoe in hot, sunny, windy weather during the warmest part of the day.  As you hoe, start and stop abruptly so that weeds are effectively controlled at field ends.  Also, do not make sharp turns unless the hoe is raised completely out of the ground.  This will save both on the implement and reduce crop seedling loss.  Generally, figure on about 10% crop seedling loss with rotary hoeing.

Certified Weed Free Hay and Mulch
        Each year, we get several requests for information or sources of certified weed-seed free hay and/or mulch. The Wisconsin Crop Improvement Association (WCIA) has initiated a new program to certify hay and straw as weed free.  The purpose of the program is to stop the spread of certain noxious weeds.  Certified weed free hay and/or mulch is a growing market.  People taking their horses to specific areas in western states (most notably National Parks) are required to have certified weed free hay.  Further, some state Departments of Transportation are requiring certified weed free mulch to establish grasses on road medians and shoulders.

        For hay and straw to be certified noxious weed seed-free, the pre-harvested crop – and areas where it is stored – cannot contain the seed of 67 invasive weeds.  The WCIA representative inspects the crop during the growing season.  Labels are attached to each bale that is harvested as certified weed free.  As you might expect, there is a cost for certification.  Conversely, certified weed free hay and mulch sell at a considerable premium. To learn more about the program, the North American Weed Management Association has established a web site at http://www.nawma.org/   For more details on the Wisconsin program, contact the WCIA at 1-800-892-1341.