Volume
4 Issue 9
July 17, 2007
Use Caution When Harvesting and Feeding Ditch
Hay
 Harvesting
ditch hay (grass and legumes growing alongside the roadways) is a
common practice in Minnesota (Figure 1). Ditch hay provides
livestock owners with forage suitable for beef cattle, dairy heifers
and horses, especially in dry years when forage is limited. However,
there have been several cases of significant soybean injury as a
result of manure applications from livestock fed ditch hay that was
treated with picloram or clopyralid. This injury has reduced grain
yields, and in some cases, resulted in total yield loss. There have
also been a number of livestock health issues correlating to
poisonous or harmful plants that commonly grow in ditches that are
harvested for hay.
Soybean Injury
Picloram (commonly sold as Tordon, Grazon, and
Pathway) and clopyralid (commonly sold as Stinger,
Curtail, and Transline) are used to control unwanted broadleaf weeds
on cropland, rangeland, pastures, and along roadways. These
herbicides are especially popular with local, county, and state
highway departments because they control hard-to-kill noxious weeds
like thistles and leafy spurge, but do not kill beneficial or
planted roadway grasses.
Recently labeled herbicides containing the active ingredient
aminopyralid (commonly sold as Milestone, Milestone VM,
and ForeFront R&P) are beginning to replace picloram and clopyralid
in many roadside treatment programs due to increased Canada thistle
control with aminopyralid. Aminopyralid is in the same herbicide
family as picloram and clopyralid, and poses the same potential to
cause injury to broadleaf crops from contaminated manures. However,
sensitive crop injury from aminopyralid contaminated manure has not
yet been reported in Minnesota.
 When
animals are fed ditch hay that has been treated with either picloram
or clopyralid, these chemicals pass quickly through the animal
without significant degradation and end up in the manure via the
urine, usually within a day or two. If sensitive crops (i.e.
soybeans, lentils, peas, legumes, potatoes, tomatoes or peppers) are
planted in fields where contaminated manure has been applied, injury
or crop death can occur (Figure
2). Injured plants can exhibit twisting (epinasty), leaf
cupping, and loss of apical dominance, resulting in short plants and
abnormal side shoots.
Labels of many products containing picloram and clopyralid list
restrictions that ditch hay harvesters and feeders need to be aware
of:
- manure and urine containing these herbicides may cause
injury to sensitive broadleaf plants,
- since plant material containing these products does not
break down more rapidly in compost, treated plant material
containing these products should not be used in or for compost,
and
- picloram and/or clopyralid contaminated manure and/or
compost should not be spread on land used for growing
susceptible crops. Contaminated manure may be spread onto fields
that will be planted to grass crops (i.e. corn, small grains, or
sorghum sudan forage).
Herbicide labels for products containing picloram and clopyralid
may have slightly different warnings or recommendations based on the
product formulation and/or active ingredient concentration. Some
examples of warning and recommendations for these products include:
- do not allow lactating dairy animals to graze treated areas
within 7 days after application;
- meat animals should be withdrawn from treated fields at
least 3 days before slaughter;
- and, do not harvest or cut the forage within 30 days after
application.
Better awareness and communication is needed between local,
county, and state highway departments and farmers harvesting,
feeding and selling ditch hay.
If you are harvesting ditch hay, develop a working relationship
with your county weed inspector or highway department to:
- identify which herbicides are used in the roadside weed
control program,
- determine which roadsides are spot treated and if some areas
have broadcast treatments, and
- dates when roadsides will be treated.
By working together with local, county, and state agencies, hay
harvesters can reduce the risk of harvesting forages with unwanted
herbicide residues. If the harvest and/or grazing restrictions for
the herbicides are communicated to, and followed by farmers
harvesting ditch hay, the forage can be fed to livestock without
contaminating manure.
For more information on picloram or clopyralid
contaminated ditch hay:
http://www.extension.umn.edu/cropenews/2005/05MNCN43.htm
Krishona Martinson, PhD,
Regional Extension Educators
University of Minnesota Extension
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