Pasture and Forage Minute: Managing Grasshoppers, Pasture Weeds and Wet Hay
Late Summer Grasshopper Management
Areas of the state are beginning to dry or continue to suffer from drought conditions after the recent hot and dry weather, which has created an environment conducive to grasshopper movement into crops from field edges. Alfalfa and grasses seeded this late summer can be especially susceptible to grasshopper feeding damage.
Frequent scouting of fields is critical for maximizing grasshopper control. By conducting visual counts or using a sweep net, you can determine if the threshold of 15-20 nymphs or eight to 10 adults per square yard has been reached in your field.
If grasshopper levels have reached threshold, treatment with an insecticide may be feasible as long as pre-harvest intervals are considered. Many insecticides used for other insects in alfalfa and other forages are also labeled for grasshoppers. Please be especially careful to avoid injuring bees and other important pollinating insects when using insecticides and carefully read and follow all label directions.
It's also important to remember that our goal isn’t to completely eradicate grasshoppers from our fields, but to reduce their numbers to below threshold levels and give our crops a chance to “win the race” against pests until the first hard freeze of the season.
Late Summer Pasture Weeds
Late summer always seems to be a time when weeds can become quite noticeable in pastures. This is especially true this summer because of the abundance of annual weeds like sunflowers, lambs quarters, or snow-on-the-mountain that are a result of last year’s drought conditions.
Perennial weeds like western ragweed, ironweed and verbena can be plentiful in some pastures as well. In areas of pastures that have relatively thin grass stands, in areas where animals congregate or if some overgrazing has occurred, they can be very visible.
Spraying weeds now does little good. Many weeds are too large to kill. On both annual and perennial species that produce seed, herbicides might only reduce some seed production. If the goal is to improve appearance, shredding areas that have an abundance of weeds might be the best option and may reduce some seed production too, if it’s not already too late.
Two other approaches are better for long-term weed control. First, focus on the grazing management of your pastures. This includes using the proper stocking rate and developing a good rotational grazing plan. An important objective is to increase the health, vigor and density of your grass. Healthy, competitive grass stands are essential to reduce weed populations economically over time.
Second, target herbicide applications for when they will do the most good. Both perennial and annual species can be better targeted with a spring application when plants are smaller and able to be controlled. For perennials, if a second application is needed, waiting closer to a killing frost is best. These fall applications can be more effective as more product is translocated down to the roots of the weeds.
Pasture weeds may look unsightly now, but hold off on spraying. Improve grazing management and time herbicides for the best window of control so herbicides won’t be needed as often in the future. On the bright side, for areas that have had good rains this summer, it is likely that annual weeds will be less abundant next year as pasture grasses had a chance for buildup vigor and reproduce.
Wet Hay Options
Depending on where you are in the state, putting up hay this year may have been a struggle. Dry conditions were prevalent early on and continue to plague some areas, while too much rain has been an issue for some.
Rainy forecasts make deciding when to mow hay difficult. The more hay is raked and tedded, the more leaf shatter occurs, resulting in quality that may be less than harvesting overly mature hay.
With low hay supplies from last year, getting more growth and delaying cutting may be the best option, especially if hay quality will end up being equally low if harvested earlier and raked several times to dry.
Wet hay that needs to be removed may be better wrapped as baleage rather than risking fire, mold growth and declining quality that occurs when hay is put up too wet. If bales are slightly wet, make sure to put them outdoors in an area separate from other hay in case of fire. Even if these bales end up cooling down, high temperatures can denature proteins, limiting digestion, but will not be picked up by a normal forage test. If you see signs of high temperatures (sweet smelling, caramel-colored hay that is matted together), be sure to get a heat-damaged protein test when you send samples in for your regular analysis. This will give the true protein value of the hay.
Finally, don’t forget that stressing a field with a late hay harvest, just like grazing, can end up doing more harm than good in an already stressed stand. However, an occasional late cutting can easily be tolerated and may open the door for other forage opportunities.
Regrowth after an early August cutting of Sandhills wet meadows was measured in September and contained 16.5% crude protein. This is a great grazing option for weaned calves or even dry cows when stocked correctly.
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