Unfortunately, producers will be making difficult decisions on what to do with their failed wheat acres! Producers are also faced with needed feed for their livestock as the pastures are slowly greening up so they can be used soon. So, at this point in the season, viable crop options are still corn, soybeans, sorghum along with forage or cover crops for livestock.
Regardless of which crop you choose to plant, weed control will likely be needed. Despite insufficient precipitation to produce a crop, many fields will still have emerged weeds and all fields will have a weed seed bank likely to emerge and compete with the summer crop. In addition, any remaining wheat will need to be terminated. Burndown of summer annual weeds present at planting is essential for successful double-cropping . Glyphosate will be effective for terminating wheat, but if glyphosate-resistant kochia and/or pigweeds are present, alternative treatments such as paraquat may be required.
A very important component to double-cropping will be herbicide carryover so weed management for each of the crop options is very important. Here are some recommendations from K-State Research and Extension agronomists: Let’s start with corn. In the last few years, producers in northcentral Kansas have planted corn later to move critical corn growth stages around pollination to later in the growing season, after the most intense heat. Fertilization focusing on nitrogen (and other nutrients as needed based on soil testing) is still a critical practice to increase the likelihood of high yields. If planting is delayed, longer maturity hybrids will be a good option to produce biomass for silage and grain, if they can reach maturity before a hard freeze.
According to Dr. Sarah Lancaster, K-State Research and Extension Weed specialist, depending on application date, herbicide rate, and soil and environmental conditions, carryover of Group 2 herbicides such as chlorsulfuron (Glean, others), metsulfuron (Ally), sulfosulfuron (Outrider, others), triasulfuron (Amber, others) will be a concern.
Lancaster stresses if grassy weeds such as downy brome have become established in wheat, control prior to planting will be very important. However, they will likely be controlled by glyphosate or atrazine used to terminate the wheat. Using a Group 1 herbicide such as clethodim (Select, others) or quizalofop (Assure, others) to terminate wheat will prevent corn planting, as these products have rotation restrictions. In addition to atrazine, residual herbicides such as mesotrione (Callisto, others) and Group 15 products (Smetolachlor, Dual; acetochlor, Harness; dimethenamid-P, Outlook; or pyroxasulfone, Zidua) should be used and can be included in the burndown application.
Soybeans are also a very good alternative crop. A dense soybean canopy may reduce herbicide costs compared to leaving the field fallow. Still, a residual herbicide should be applied at or before planting time. According to Dr. Ignacio Ciampitti, K-State Research and Extension, Farming Systems specialist, planting a variety with the same or perhaps even slightly later maturity rating (compared to a typical planting date) will allow the crop to develop a larger canopy before flowering. The goal is to maximize the length of the crop’s growing season. The earlier you can plant, the higher the yield potential of the crop if moisture is not a limiting factor. From a fertilization standpoint, a soil test before wheat termination is recommended. Seeding rate can be similar to that for early planting dates, and row spacing could be narrower (15-inch or less), if this is an option with the available planting equipment.
If an herbicide such as chlorsulfuron (Glean, Finesse, others) or metsulfuron (Ally) has been used, the most tolerant double crop will be sulfonylurea-resistant varieties of soybean (STS, SR, Bolt). Chemical control of pigweeds at or before planting is especially important for soybeans. Dicamba (XtendiMax, Engenia, or Tavium) or 2,4-D (Enlist) can be used to control emerged pigweeds if soybean varieties with corresponding herbicide resistance traits are planted. Dicamba may also provide a bit of residual activity for pigweeds and kochia.
Sorghum is another crop option with optimal planting time usually around late May and early June for late-maturing hybrids. Seeding rate and row spacing are similar to those recommended in normal planting dates. It is important to consider potential residual N from the wheat crop, mainly under the current conditions of very low production for wheat, so soil testing is critical.
Sorghum will also have rotation restrictions to Group 2 herbicides. Igrowth hybrids are tolerant of imazamox (Beyond); however, current herbicide labels do not address rotation restrictions for these hybrids. Weed control before planting is critical for successful grain sorghum production. Both a thorough burndown program and an effective residual herbicide program is needed for both grasses and pigweeds to preserve doublecrop sorghum yields.
Lastly, is the option of cover crops . Lancaster points out that less information is available regarding the herbicide carryover potential of wheat herbicides to cover crops. There is little or no mention of rotational restrictions for specific cover crops on the labels of most herbicides. However, this does not mean there are no restrictions. Generally, there will be a statement indicating “no other crops” should be planted for a specified amount of time, or that a bioassay must be conducted before planting the crop.
For more detailed information about herbicides, pick up a copy of the KState Research and Extension, “2023 Chemical Weed Control for Field Crops, Pastures, and Noncropland” guide at any of our Post Rock Extension District Offices in Beloit, Lincoln, Mankato, Osborne or Smith Center. If you have further questions on planting options, give me a call.
The use of trade names is for clarity to readers and does not imply endorsement of a particular product, nor does exclusion imply non-approval. Always consult the herbicide label for the most current use requirements.
Post Rock Extension District of K-State Research and Extension serves Jewell, Lincoln, Mitchell, Osborne, and Smith counties. Sandra may be contacted at [email protected] or by calling Smith Center, 282-6823, Beloit 7383597, Lincoln 524-4432, Mankato 378-3174, or Osborne 346-2521. Join us on Facebook at “Post Rock Extension” along with our weekly “Ag News” that is emailed to our ag listserv. If you would like to be included, simply email me. Also remember our website is www.postrock. ksu.edu and my twitter account is @PRDcrops.
