At a recent update provided by Kansas State Extension agronomy specialists, county agricultural agents were provided with the latest research tips for controlling weeds in the winter wheat crop that I'll share in today's column.
Wheat planted in southwest Kansas is in much better shape to date than one year ago, due to occasional moisture events. Last winter, the soil remained extremely dry.
There are several herbicide options for controlling winter annual broadleaf weeds in wheat. Generally, fall applications will provide the best control of winter annual weeds with any herbicide, as long as the weeds have emerged. The majority of winter annual weeds usually will emerge in the fall, although you can still have some emergence in the spring, especially if precipitation after planting is limited in the fall. However, winter annual weeds that emerge in the spring often are not very competitive with the crop, assuming that you have a decent crop.
Some herbicides can work well even when applied during the dormant part of the season, while others perform best if the crop and weeds are actively growing. The key difference relates to the degree of soil activity provided by the herbicide. Herbicides that have good residual activity, such as Glean, Finesse, Amber and Rave, can generally be applied in January and February when plants aren't actively growing and still provide good weed control, assuming you have proper conditions for the application. Most other herbicides, which depend more on foliar uptake, will not work nearly as well during the mid-winter months, when the wheat and weeds aren't actively growing, as compared to a fall or early spring application.
Spring herbicide applications can be effective for winter annual broadleaf weed control as well, but timing and weather conditions are critical to achieve good control. Spring applications generally are most effective soon after green-up when weeds are still in the rosette stage of growth, and during periods of mild weather. Once weeds begin to bolt and wheat starts to develop more canopy, herbicide performance often decreases dramatically.
Huskie is a relatively new herbicide that can provide good control of a variety of broadleaf weeds with excellent crop safety from the two-leaf to boot stage of growth. Huskie is a premix herbicide of pyrasulfatole and bromoxynil. Pyrasulfatole is an "hppd" herbicide, and can be effective to control ALS-resistant broadleaf weeds. Because Huskie has limited residual activity, it works best when applied when weeds and wheat are actively growing and with milder weather.
Another important consideration with herbicide application timing is crop tolerance at different application timings. For example, 2,4-D should not be applied in the fall or until wheat is fully tillered in the spring. On the other hand, any herbicide containing dicamba can be applied after wheat has two leaves, but should not be applied once the wheat gets close to jointing in the spring. Herbicides containing dicamba include Banvel, Clarity, Rave, Pulsar and Agility SG.
There has been some discussion about wheat tolerance to herbicides, especially when applied with fertilizer carrier. The best advice regarding crop safety with herbicide-fertilizer combinations and application timing is to follow the label guidelines. We generally see very minimal crop injury and no yield loss from topdress fertilizer/residual herbicide applications during the winter months. However, these combinations can often cause considerable burn to the wheat if applied when the crop is actively growing and with warmer weather. The foliar burn is generally temporary in nature and the wheat usually will recover if good growing conditions persist.
Research at Hays several years ago found as much as 47 percent injury to the wheat four days after treatment following a late March treatment of Amber plus 2,4-D, but wheat recovered and yields were not reduced. However, research in Nebraska did show some yield loss from Ally plus 2,4-D applications with fertilizer applied in late April to more advanced wheat and with moisture stress conditions. Crop injury with herbicide-fertilizer combinations will depend on the total amount of fertilizer applied, dilution with water and the addition of surfactant. Again, the herbicide label provides the best guidelines regarding if, when and how herbicides can be applied with fertilizer.
Tips for gardeners
Following are several tips that can help home gardeners in growing transplants.
* Use fluorescent lamps, not incandescent bulbs. Often a south-facing window does not provide enough light to grow strong transplants and, therefore, supplemental lighting is helpful. Fluorescent lights produce much less heat than incandescent bulbs. This allows fluorescent bulbs to be placed very close to the plants (two to four inches), increasing the intensity of light received. Additional light produces stronger plants.
Leave fluorescent lamps on long enough. Young plants do not react to day length, so lights can be left on as long as desired. Sixteen hours of light each day usually is sufficient. A timer can be used to automate the process.
* Re-wet a peat-based media with hot water. Though moist peat will absorb cold water easily, dry peat will not. Hot water overcomes the hydrophobic nature of dry peat. Small batches of media can be mixed with water in a sealable plastic bag to cut down on the mess.
* University research has shown that young seedling plants react to movement. Brushing your hand over the tops of the plants each morning and afternoon will cause them to become stockier. Use about 10 strokes each time. Strokes will not compensate for lack of light. Plants grown under inadequate light will be spindly regardless of stroking.
For more information or assistance on this or other topics, please call the Extension office at 272-3670, located at 501 S. Ninth St.