NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
June 6, 1999
NDSU Agronomist Offers Seven Tips to Reduce Weed Control Expense
Some farmers may be pouring more money than necessary into their spray tanks for weed
control. That fact equates to bad news for those who're spending money they needn't be.
The good news is that there are many ways for producers to spend less on herbicides
without turning their fields into weed patches. An agronomist with the North Dakota State
University Extension Service offers seven money-saving tips.
"The first thing producers can do is to purchase no more weed control than they'll
need," says Duane R. Berglund, extension agronomist at NDSU. "Often treatments
with the most advantage are also the most expensive, but there's no reason to purchase a
product that controls a tough weed you don't have, or that you have only in very limited
numbers. Herbicide selection should be based on which weed species are likely to cause the
most problems and cause crop yield loss."
The following six tips include both chemical and cultural considerations:
- Look for the most economical formulation. As a rule, granules cost most, wettable
powders least, and the costs for emulsifiable concentrates and dry or liquid flowables lie
somewhere in between. Also, some pre-plant incorporated (PPI) herbicides cost less than
pre-emerge or postemergence chemicals. "There is some argument about the lower costs
of PPI herbicides," Berglund says, "since they require tillage for
incorporation. If you are already making two tillage passes for seedbed preparation and
early season weed control, then there's no additional cost for PPI products. They lose
their price advantage quickly, however, if you make a tillage trip to just incorporate
chemicals."
- Consider fuel bills, which can be reduced at least 25 percent by using a field
cultivator rather than a disk. Field cultivators and heavy harrows are lighter than disks
and allow for a faster tillage operation.
- Band herbicides in row crops instead of broadcasting them to reduce herbicide costs by
one-half or two-thirds. But remember that incorporation of banded herbicides can be a
problem. Pre-emergence banded herbicides usually need rainfall or irrigation to activate
the chemical. Banded postemergence herbicides seem to work well in most North Dakota-grown
row crops. "Of course," Berglund says, "you do have to cultivate and have
to be more timely with this operation. Cultivating takes time and money, but it can be
cheaper than some herbicide treatments. You can get additional savings with cultivation if
you band spray postemergence chemicals at the same time. The downside of this practice is
that it is quite slow, and if you have large acreage to cover or wet weather sets in, the
weed infestations can overtake the crop and potential yields are greatly reduced."
- Tailor herbicide rates to the season and growing conditions. If everything is working
right, with good soil moisture and with actively growing weed seedlings, farmers can use
the lower label rates. But there are times when full label rates are necessary. "If
you have difficult-to-control weeds, taller weeds, high weed populations, cloddy seedbeds,
marginal incorporation or delayed application, you're better off going with the higher
rates," Berglund says.
- Buy chemicals in bulk. Many farmers consider themselves too small to buy herbicides in
bulk, but farmers who use only 100 gallons (or even less) of a chemical can probably
qualify for bulk rates, depending on the product. Bulk rates can help cut costs by 5 to 10
percent compared to the costs of buying in smaller containers, and there are then fewer
containers to dispose of later.
- Harrowing a few days after a spring-sown crop has sprouted, but before it has emerged,
is effective in reducing stands of foxtails, wild oats, mustard and other weeds. But the
weeds must be emerging or in the white-sprout stage. Since foxtails are shallow rooted and
easily controlled, set the teeth back on light spring-tooth harrows to minimize crop
injury. Small grains can be harrowed after they have emerged and have two or three leaves,
but before tillering. Soil moisture should be good but with a dry solid surface. Wheat can
be harrowed one to three times, but barley only once. Oats normally are not harrowed
because injury is more likely to occur than with wheat or barley. A light spring-tooth
harrow or rotary hoe can be used for weed control in soybean, corn and sunflower, but
don't use these tools when the seedlings start to emerge because injury can be severe at
this time. Soybeans with the first true leaves (unifoliate stage), sunflower in the
four-to-six-leaf stage and corn beyond the spike stage to three-leaf stage can safely be
harrowed. Tines should always be slanted back when harrowing for weed control. Trashy
conditions which result in trash buildup in the harrow should also be avoided. Use of
harrows and rotary hoes has been most effective at midday or on afternoons when
temperatures are warmer and soil surfaces are dry, since these conditions promote weed
drying and better kill. Also, less physical crop injury has been observed compared to
early morning field operations. Sunflower can be harrowed two to four times during the
four- to six-leaf stage of development. If this type of weed control is planned, sunflower
should be planted at rates 5 to 8 percent higher than normal.
###
Source: Duane Berglund (701) 231-8135
Editor: Dean Hulse (701) 231-6136