Herbicide Resistance Pigweed 5: Prevention and Disposal
- [Instructor] Parts one through four of this five part learn now series covered how to identify resistant Palmer amaranth and waterhemp, and the best management practices for controlling them.
Of course, the easiest way to manage these pigweeds is to prevent them from ever entering the field.
They can be introduced to fields by various means, some of which a grower may not realize would bring in weed seed, and some of which allow the seed to spread for several hundreds of miles.
One common way Palmer and waterhemp are introduced to fields is through livestock feed and manure.
When fields containing these weeds are harvested, the weed seeds end up in the harvested crop.
If that crop is used as livestock feed, then the weed seeds remain in the feed.
Some common cases of pigweed contamination have been in hay and cotton seed for dairy rations.
When an animal consumes the contaminated feed, the weed seed easily survives digestion.
And when the manure is spread onto a field, the weed seeds go with it.
Poultry litter from chickens fed contaminated feed is also a way that Palmer seeds have spread to new fields in the mid-Atlantic.
A second area of dispersal is through specialty seed mixes that were grown in fields with the weeds, and then were not completely controlled for pigweed seeds after being harvested.
In certain counties in the mid-west, specialty seed mixes were found to be the cause of Palmer amaranth introduction to new counties because they contained even just a few Palmer seeds that made it through the screening process.
When possible, make sure that specialty seeds purchased were not grown in areas where Palmer amaranth and waterhemp are common.
However, one of the main modes of transfer is from farm equipment that's recently been in a field containing these weeds.
The seeds can easily hitch a ride on equipment, and stay on it as it travels to the next field.
Custom harvesters are common modes of spread because the time of year they go into the field coincides with the time when Palmer and waterhemp have millions of mature seed to drop, and combines have lots of nooks and crannies where seeds can get stuck.
Harvest infested fields last, so that the weed seeds picked up in the combine do not spread to more fields.
In extreme cases, it has been necessary for growers to forgo harvesting heavily infested fields.
If the combine that a grower plans to use has recently been in a heavily infested field, they should explore alternative options.
If equipment such as a combine or mower may have been in contact with Palmer or waterhemp, inspect equipment for contamination before and after use.
Know where the equipment has been and whether or not the weeds are prevalent in that area or that field.
Then, clean all farm equipment that comes in contact with Palmer or waterhemp before using it again.
Using an air compressor, clean tillage and harvest equipment before leaving the infested fields to prevent weed seed from spreading along the way out.
When cleaning the combine for small Palmer or waterhemp seeds, it's important to flush out the small spaces of the combine where seeds can hide.
Using an air compressor and a vacuum, start at the front of the combine with the header, feeder and rock trap, then move to the grain tank and unload the auger and sump.
Finally, clean the shoe and the back of the machine.
An air compressor or a vacuum are good tools for this job, but avoid using water.
To prevent Palmer and waterhemp spread via livestock feed manure, avoid applying manure that could contain the weed seed, as this could spark a serious infestation throughout the field.
Ensile crops containing Palmer or waterhemp, and do not feed contaminated grain to livestock unless it is first ground, roasted or ensiled.
Avoid purchasing feeder hay from infested areas, and inspect all feed and hay that is purchased for signs of Palmer and waterhemp such as the leaves, stems and seeds.
If livestock is fed grain from infested fields, compost manure to destroy weeds seeds before spreading it onto the field.
When you find a Palmer or waterhemp plant at a field, there are certain ways that they should be disposed of so that they don't spread or drop their seed.
Employ a zero tolerance policy.
This means not letting any Palmer or waterhemp plant survive, and destroying 100% of them before they produce seed.
The most reliable option for large plants is often to remove them manually with hand-pulling or hoeing.
In Pennsylvania, it's not uncommon for producers to hire out crews to remove vast numbers of plants in a single field.
Because the plants you pull may re-root if left in the field, remove them to the field's edge and bury or burn them there.
Don't transport the removed plants to other parts of the farm, as this will spread the infestation.
Penn State has released pigweed paper bags that you can take in a truck or tractor and use it to remove and dispose of stray Palmer or waterhemp plants that are spotted on a field edge.
If infestations get so large that they can't be controlled with hand-pulling, the farm may have to resort to more drastic measures such as mowing the crop down or burning the field.
If burning is a viable option in your area, burning can help destroy those seeds.
Mowing can greatly slow the growth of Palmer and waterhemp, and may be the only viable option in the late season.
But mode plants will regrow from the stumps and quickly form seed heads, so frequent, repeated mowing is necessary.
There is a new piece of equipment on the market from Australia that's capable of pulverizing weed seeds as it harvests the crop.
It's called the Harrington Seed Destructor.
It's another potential solution for tackling Palmer and waterhemp seeds.
The first version of the HSD trails behind a combine, grinding the shaft containing weed seeds into a fine powder, destroying the seeds.
Then it shoots the powder back onto the field.
There's the newer version that's integrated into the combine and is a more affordable option.
It's currently being tested for use in US fields by USDA agricultural research stations in Maryland and Illinois, and at the University of Arkansas.
Go to this link to see a video of the HSD in action at the University of Illinios and hear more about how it works.
Thanks for watching our five part learn now series on controlling and preventing herbicide-resistant pigweeds.
If you missed any of our previous episodes, feel free to go back and watch.
For more information on identifying and managing Palmer amaranth and waterhemp, contact your county extension educator.
You can also visit our website.
Thanks for watching.
Frequently Asked Questions