Summer Annual Grass Control

By Todd Whitney

Summer annual grasses can pose weed problems even in perennial systems like pasture or hay fields. Once foxtail, grassy sandbur or crabgrass are established, these annual grasses can be hard to control in later summer.

For cost-effective weed control, use cultural practices like timely hay harvest or grazing management. In some cases, crop rotation such as rotating out of alfalfa for two to three years may be needed.

Herbicide weed control can be a viable option as well. Since pre-emergent herbicides are usually only effective for six weeks to three months, a second pre-emergent may be needed during this time for yearlong weed control. Follow herbicide labels, since a second application may conflict with maximum annual application rates.

Where alfalfa fields have Roundup Ready® genetics, glyphosate products usually work well — especially when the grassy weeds are less than six inches tall at the time of herbicide application. Also, weed control will improve if applications occur before the alfalfa canopy begins interfering with spray patterns and coverage.

For single species established growing alfalfa, grass weeds may be controlled with Select® or Poast® products. Pursuit® and Warrant® may be options for both grasses and broadleaf control. Warrant® can be applied to established alfalfa within seven days after cutting, but the label does not allow cutting the alfalfa for 20 days following application. Pursuit® is labeled for both pre- and post-emergent applications but rated weak regarding sandbur control. Canopy cover can interfere with spray distribution, so herbicide applications soon after alfalfa harvest are recommended.

For alfalfa/grass mixtures, seedling applications of Prowl H20®, Poast®, Select Max®, Arrow® or Warrant° may be effective controlling foxtails, sandburs and other broadleaf weeds. The Butyrac 200° + Raptor® herbicide combination works well early in the season but is not recommended for sandbur control or when weeds exceed two inches in height.

Summer annual grasses control in forage crops can be a challenge, but using the right product with patience, you can improve the quality of your pastures and alfalfa hay.

Stock Tank Algae

By Ben Beckman

Keeping clean water in front of animals during the summer is important. However, sunlight and warm temperatures can often lead to stock tanks overrun by algae. Let’s look at how we can address these issues.

The first step to stopping algae growth in a tank is preventing a habitat algae will love. Keep animals from getting into larger tanks to limit unwanted nutrient loading. When possible, keep water from becoming warm and stagnant by matching tank size to herd demands. Finally, shade the tank to reduce sunlight, which algae need to grow.  

One control method that often gets lumped in with options that kill algae is barley straw. While studies have shown barley straw does not kill algae, 0.75 oz of straw per square yard of tank area submerged in a loose bag or container should be enough to limit growth up to six months.

Sometimes, algae growth can still become an issue despite our best efforts. If your tank is small enough, a regular scrubbing can keep algae at bay. For larger tanks, commercial algicides, most using copper sulfate, can be effective. Just follow instructions carefully, especially when sheep are involved which are sensitive to copper.

Other often cited control options are goldfish and bleach. North Carolina State researchers recommend up to 2 oz. of bleach per 50 gallons of water mixed well. Keep animals away while mixing to ensure no concentrated areas remain. Or you can try four to six goldfish per 100 gallons of water — just provide them with cover and cool water.

Clean water is vital for animal health, especially during summer. Prevent algae growth through proper tank placement, cleaning, and options like barley straw. If needed, consider copper sulfate, bleach or goldfish.

Heat Effects on Alfalfa

By Jerry Volesky

When it gets hot, alfalfa plants grow more slowly and moisture stress becomes common, even in moist soil. Production of high-quality hay is nearly impossible due to the high temperatures, especially when the heat does not subside at night. High night-time temperatures cause rapid respiration rates in alfalfa, burning off valuable nutrients that plants accumulated during the day.  This often produces alfalfa hay with fine stems that contain high protein, but they also have high fiber and low relative feed value.   

Another problem with heat is how fast alfalfa plants mature. When it is hot, alfalfa may begin to bloom in less than four weeks. If you use blooming as a signal to harvest, this early bloom can be misleading. During hot weather alfalfa plants need more time, not less time, to rebuild nutrient reserves in their roots because they burn off nutrients instead of moving them to the roots when it is hot. So, watch the calendar along with plant maturity to determine when to cut your alfalfa fields. 

Finally, you might adjust the time of day when you cut hay. Some research has shown that cutting in late afternoon produces higher quality hay than cutting in the morning. However, on good drying days, it may still be wiser to cut in the morning. When hay in the windrow stays above 50% moisture, plant cells continue to respire, burning away nutrients. Hay cut late in the day respires all night long, losing yield and quality. On good drying days, plant cells can dry enough to be stabilized before nightfall, reducing respiration losses.  

Getting high quality hay is challenging. Both you and the weather must cooperate and even then, there are no guarantees. 

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