SALEM, Ohio — Having a weed management plan can be beneficial to maximizing your crop yield this year. Mark Loux, Ohio State University weed specialist, and Doug Doohan, weed management expert and professor in the Department of Horticulture and Crop Science, share a few pointers on weed management, equipment preparation and challenging weeds farmers should be on the lookout for this year.
Q. Why is weed management so important?
A. “Weeds rob crops of nutrients, water and sunlight,” said Doohan, and weeds often create conditions that are conducive to disease.
“They are probably the biggest robber of yield,” said Loux. “If we don’t do a good job of weed control we will lose yield.”
Q. What weed species should farmers be on the lookout for this year?
A. Marestail (or horseweed) has been a concern for farmers for a few years, as it has become resistant to many commonly used herbicides, particularly glyphosate. It is easiest to control when it is in its seeding or low-growing rosette stage — through late April. (Marestail will reach a height of 3-6 feet.)
“I spend a lot of time tweaking marestail programs,” said Loux. “A lot more time than any other weed in my 28 years here and I am still tweaking programs.”
Palmer amaranth, an Amaranthus (pigweed) species, is fairly new to Ohio and has resulted in substantial crop losses in affected areas. Originating from the South, the species has most likely made its way to the area through equipment, cotton-derived feed products and cover crop and wildlife seed products that have been transported from infested areas like Kansas and Texas.
Palmer amaranth has prolific seed production and small seeds well adapted to minimum and no tillage. It grows really fast — up to 3 inches a day — and is highly resistant to many common herbicides. Timing is critical when treating for Palmer amaranth and needs to be done when the plants are less than 3 inches tall. Palmer amaranth also has a strong, woody stem that can cause damage to equipment.
Q. How can farmers prepare for weeds now?
A. “They should be evaluating their history of weed control over the last several years,” said Loux. That means, identify what has been working and what areas need to be improved. Certain parts of the field may require more attention than others and may have different species of weeds growing in them. Identify what herbicides have been used and what has been most effective.
“It’s a great time of year to make sure your equipment is cleaned up,” said Doohan, commenting on the milder temperatures this winter. Cleaning equipment prevents the spread of weed seeds that could have been pick up in the fields from previous years.
Check sprayer nozzles and filters to make sure they are working effectively and creating an even spray. Doohan recommends replacing all nozzles if they haven’t been changed in a few years, “even if some are OK, you should bring them all up to spec.” Check hoses for leaks and check storage for old materials that need to be discarded.
How can farmers update their weed management programs and identify what herbicides are best to use?
“One of the most important things a farmer can do is spend some time reading the herbicide label,” said Doohan. Understand how the herbicide works and what the risks are involved with using that particular herbicide.
“You need to know your crop and you need to know your weeds,” said Doohan. Weeds tend to be patchy, meaning one area of a field could be covered in thistle while another area has some viney weeds. “You have to know how to manage those different weeds.”
And those resources are readily available through Extension services with online fact sheets and identification guides. A recently released book, featuring information from both Loux and Doohan, the 2016 Weed Control Guide for Ohio, Indiana and Illinois, also provides management tips and weed identification.
If you are still struggling, call an expert like Loux or Doohan.
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