By Sarah Lancaster
Pre-emergence herbicides with residual activity are an important component of high-yielding cropping systems. They are used less frequently in wheat production compared to other cropping systems in Kansas, but residual herbicides applied prior to wheat emergence can be part of a good weed management system in wheat production.
Most residual herbicides labeled for pre-emergence application in wheat are Group 2 (ALS-inhibiting) herbicides, which are associated with herbicide resistant populations of kochia, marestail (horseweed), bushy wallflower, flixweed, henbit, and brome species in Kansas. Products in Groups 14 (the PPO-inhibiting herbicides) and 15 (the long-chain fatty acid inhibiting herbicides) are also labeled; however, they are generally more dependent on rainfall for activation than the Group 2 herbicides.
Herbicides without residual activity may be applied with or without residual herbicides in the weeks prior to planting wheat. Older products include the Group 2 herbicides Amber, Olympus, and Pre-Pare, as well as Group 4 (plant growth regulating) herbicides like 2,4-D, dicamba, or fluroxypyr. It is especially important to be aware of planting interval restrictions for Group 4 herbicides, which range from 10 to 45 days.
One new product is Pixxaro. Pixxaro is a combination of two Group 4 herbicides: fluroxypyr (Starane Ultra, others) and halauxifen (Elevore). It is labeled for control of emerged weeds both before wheat planting and after emergence when wheat is at the 2-leaf through flag leaf stage. The application rate for both timings is 6 fl oz/A.
When selecting pre-emergence herbicides for use in wheat production, keep in mind that many of these products are also labeled for use in emerged wheat. Unless using a planned split-application, avoid repeated use of products from the same herbicide group to slow the development of herbicide-resistant weed populations in your fields.
Table 1. Selected herbicides for pre-emergence or pre-plant applications in winter wheat.
Trade name | Common name | Herbicide group | Application timing* | Comments |
Amber | Triasulfuron | 2 | BD, PRE or POST | Requires tank mix or sequential application of herbicide from different group |
Anthem Flex | Pyroxafulfone + carfentrazone | 15 + 14 | DPRE | Plant wheat 1 – 1.5” deep |
Dicamba | Dicamba | 4 | BD | Apply at least 45 days before planting wheat |
Finesse | Chlorsulfuron + metsulfuron | 2 + 2 | PRE, POST | Suppression only of cheat, downy brome, and Japanese brome |
Kochiavore | Fluroxypyr + bromoxynil | 4 + 6 | BD | Apply at least 30 days before planting wheat |
Olympus | Propoxycarbazone | 2 | PRE, POST | Mix with glyphosate for BD |
Outrider | Sulfosulfuron | 2 | PRE, POST | Apply after planting but before wheat emergence;
If dry, apply POST |
Pixxaro | Fluroxypyr + halauxifen | 4 + 4 | BD, POST | Do not use multiple applications or in successive years at the same site |
Pre-Pare | Flucarbazone | 2 | BD, PRE | Mix with glyphosate for BD;
Rainfall necessary for activation to control PRE |
Scorch | Fluroxypyr + dicamba | 4 + 4 | BD | Apply at least 30 days before planting wheat |
Sharpen | Saflufenacil | 14 | BD, PRE | Rainfall required for activation;
Injury may occur to exposed wheat seed |
Zidua | Pyroxasulfone | 15 | DPRE | Rainfall required for activation; Plant wheat 1 – 1.5” deep |
*BD = burndown; PRE = pre-emergence to wheat and weeds; DPRE = Delayed pre-emergence application after wheat emergence; POST = post-emergence
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 and update use requirements.
Source : ksu.edu