Farmers are faced with several challenges throughout a growing season especially with weather related difficulties like we had last year. One growing issue that farmers have to deal with is weeds that are resistant to herbicides.
The weeds of interest to farmers include those in the pigweed family and marestail. The pigweed family would include Palmer amaranth, common waterhemp, and redroot pigweed. Palmer amaranth has lance to diamond shaped leaves with a long petiole. They will not have any hair on the plant. The female form of palmer amaranth is extremely tall.
Common waterhemp has long lance shaped leaves. The upper surface of the leaves will have a waxy appearance. There will be no hair on the plant.
Redroot pigweed has round to oval leaves. The leaves will appear to be rough in texture. This plant has fine hairs on stem, especially towards newest growth.
Here are some helpful cultural practices to adopt to help manage weeds found in the pigweed family. Start by scouting your fields and identifying what species you have. Deep tillage will help reducing the number of weed seeds that emerge. If you don’t want to till, then try crimped cereal rye as a cover crop. When properly managed, crimped cereal rye can provide mulch that will help suppress emerge.
Although not fun, hand weeding a field can help control these weeds and has been used in Southern U.S. cotton fields. If you would decide to go to the extreme of hand weeding, then make sure to remove the weed completely from the field and not just lay it on the ground where it is pulled.
It is important that you not only manage the pigweed species in your field, but also those located in the drainage ditches and field borders. If not managed, the seeds from plants located there will end up in your fields resulting in problems.
Marestail was the first glyphosate resistant weed in Indiana. Marestail plants remain in the low-growing rosette stage through late April, followed by bolting. It will eventually become 3 to 6 feet tall. It can be a real issue in no-till soybean fields because it competes with the soybeans throughout the growing season and reduces crop yield. It can also interfere with soybean harvest. Currently, it is recommended that you do a two shot burn down approach to control marestail in years that we have a mild winter. This two shot approach would involve a spring burndown and then a residual (PRE) herbicide control another 6 to 8 weeks later.
Please remember that if you would use a herbicide to control any weeds that it is always important to read and follow all label instructions. As always, if you have any questions or would like information on any agriculture, horticulture, or natural resource topic, then please contact your local Purdue Extension Office at 448-9041 in Clay Co. or 829-5020 in Owen Co. or reach me directly at email@example.com. Purdue University is an equal opportunity/equal access/affirmative action institution.
Upcoming opportunities available to you through Purdue Extension include:
April 6 Area V Gardening Workshop 9:00 a.m.-12:00 noon Wabash Valley Fairgrounds
April 6 Clay County 4-H Fish Fry Clay County Fairgrounds
April 9 Area V HHS Educator Leader 4:30 p.m. Cloverdale, IN - Knoy Center
April 11 Pond Field Day 1:00-3:00 p.m. Roachdale, IN
call 812-448-9041 to register
April 25 Area V Pond Management 5:30-7:30 p.m. Terre Haute, IN - Fowler Park