We are starting to look at late summer pastures weeds. Yesterday, we looked at dogfennel (Eupatorium capillifolium) and mint in a Bahia pasture that is two years old. Dogfennel is normally considered to be unsightly, but research has shone that yield loss can occur in bahiagrass if dogfennel is not controlled before mid-summer. Cows don’t normally eat dogfennel, but will when forage is low in qyaility. Dogfennel has a toxin which can make cattle dehydrated.
Dogfennel bolting in Bahia pasture
The biggest thing with controlling dogfennel is timing or really height. It can grow from overwintering rosettes. Seeds will also germinate and sprout at 65 degree soil temperature. Though a lot about it’s biology is known, treating based on heigh is more recommended.
2,4-D and dicamba do good on dogfennel, but we obviously cannot use from most of April through the fall. In Florida, dogfennel growth will start sooner. For us, germination will occur in late April, after we put out our Weedmaster application. During the summer months, Pasturegard (fluroxypyr + triclopyr) is another option for us. The rate depends on height. When dogfennel is < 36″ tall, use 1 pt / A. When dogfennel are > 36″ tall, use 1.5 pt / A. This rate is effective on large dogfennel, even 5 ft tall.
More of this information can be found at Dogfennel: Biology and Control
General decline of forages in pastures or hayfields can be attributed to many things. Fertility is generally our first thought. Secondary factors are then assessed to see how they might have played a leading role in the reduction of productivity. These secondary factors include drought, diseases, weed pressure, herbicide injury, soil compaction, or insect damage. Producers that have areas declining in the late summer into fall can suspect insect damage from a soil borne insect complex we call grubs.
Miller County Agent Brock Ward wrote a good description of these beetles, and how to deal with them:
Grubs are the larval stage of beetles that feed on decaying organic matter and some of those species also feed on roots as well. Pastures and hayfields that have had chicken litter or other manure applied as a fertilizer are typically the areas where these grubs are the most severe. It is important to also identify the grubs that are causing the damage as control and management of them can be different. Perhaps the most troublesome is the May/June beetle (MJB). The grubs of the MJB have a characteristic “zipper” pattern in the hair on the underside of their “tail-end”. This helps you to distinguish it from other grubs like the Green June Beetle (GJB) or chafer beetles. When faced with the MJB complex of beetles, the larvae burrows deep into the soil for much of its yearlong lifecycle (as many as three years in Northern states), so treatment isn’t an option, because we can’t expose the grubs to an insecticide treatment with any repetitive certainty. In the case that you have grubs from the MJB complex, renovation or replanting after the emergence of the beetles is likely the best management strategy. Chafer beetles are much like the MJB complex of beetles but require many more of them to reduce a stand of pasture grasses. Typically the source of the forage decline in a pasture is linked to other causal agents when chafer beetles are found in heavy numbers.
If the Green June Beetle (GJB) is the source of your damaged forage, treatment can be managed with insecticide use. The GJB has a one year lifecycle and feeds up through the soil surface before burrowing down again. This feeding habit makes it easier to target the pest. Many pyrethroids are labeled for use on the GJB adults, however the larvae have fewer insecticides labeled for their control. It is unlikely that GJB alone is reducing the stand of forage. As with most secondary factors, it is likely a combination of stressors that begin to reduce the stand. An example, I have seen recently is where drought stress, soil compaction, and grubs were leading to stunted areas in a pasture.
We are seeing our second hay cuttings now. We are variable in rain. This pasture has had 0.3 of rain in over a month, whereas more rain is hitting elsewhere. We dealt with some different nutrient issues at the very beginning of the season that seem to have gotten better. I don’t know if it “feels like” 102 degrees or 201 degrees. Since anything above 100 feels no different, we thought it would be a good idea to go ahead and take a forage analysis on hay cut in this field.
When it was cut, the producer felt hay looked better on one side than another. It is not a bad idea to separate samples where soil or some environemtal condition is different. Forage samples are good to do so we know what quality of hay we are feeding.We want to make sure to take samples by “lots” of hay or silage. This is hay from the same cutting, field or stage of maturity. Most cattleman purchase hay, and it is more difficult to differentiate “lots” in these samples. We separate it as best we can, and not represent more than 200 tons of dry matter.
Another important procedure is bale sampling. We need to get as much from the middle or core of the bale that we can. A hollow probe is best to use for this. I have a probe here in the office with a drill I can bring out to help sample. Here is a more detailed write up of Taking a Good Forage Sample.
We have certainly been spraying for bermudagrass stem maggot. In many cases, we are getting in the two sprays following cutting. This maybe why reports of armyworms are not high, and are not significant now.
We are also seeing some leafspot. Helminthosporium (Leaf Blight) and leaf rust is what we usually see. However, we can also have dollar spot (Sclerotinia). In either case, management is cultural. We must first have adequate nutrietion – especially potash. UGA Extension Pathologist Dr. Alfredo Martinez says, “Soil potassium is critical for leaf spot resistance. Most reported leaf spot cases are directly related to low soil potash. Nutrients are removed from bermudagrass hay fields in approximately a 4-1-3 ratio of N, P2O5, and K2O with hay harvest. That means that 75 percent as much potash as nitrogen should be applied each season. Potash can be applied in single applications in the heavy soils of north Georgia or in split applications in any portion of the state. Split applications are particularly helpful in sandy soils.”
All of GA has seen some level of drought this summer. Down here, we have been fortunate to get recent rains from afternoon thunderstorms recently. In any case, drought affects hay producers by not having pastures to graze and also not being able to harvest hay. With the ebbs and flows of cattle industry, UGA Extension Animal Scientist Dr. Lawton Stewart has some information on managing to minimize effects of drought on farm’s finances. It is important to maintain the nutrient requirements of the herd through a drought so animal performance is not compromised in upcoming seasons.
What if hay is not available? The key is to develop a ration that meets the nutrient requirements of the cows.
- The stage of production of your herd is critical to knowing exactly what to feed. Table 1 lists some example rations to use for different stages of production.
- Consider early weaning to reduce the nutrient requirements of the brood cows.
- Utilize a roughage source such as wheat straw, conttonseed hulls, crop residue, grazing drought stressed crops, gin trash.
- Examples of energy and/or byproduct feed include: grains such as corn, oats, etc., soybean hulls, citrus pulp, wheat midds, hominy.
- Examples of protein feed include: soybean meal, cottonseed meal, corn gluten feed, dried distillers grains, whole cottonseed.
Is buying hay the economic choice?
- ALWAYS, ALWAYS, ALWAYS ask for a forage analysis and/or test the hay before purchasing it. If not, you may be paying a premium for something that will not meet the requirements of your cows.
- Take into consideration the cost of the supplement AND hay.
- Also, take into consideration the method of feeding hay. If hay is not fed in a ring or other way to minimize lost, hay losses can be as high as 30%, or more.
- Table 2 compares the cost of buying hay versus feeding a hay replacement diet
- Note that if hay is being wasted, it is more economical to buy a replacement ration. This is point is not necessarily to steer you towards the feed, more so, to show the value of proper handling of purchased hay.
We have been looking at recently sprigged pastures this past month to determine weed control needs. We can use Diuron immediately after sprigging, but for most everything else, the pasture needs to be established. So, when is it established?
There are a few ways to look at this. One way to look at it is, if you can pull on the plant and it snaps off – rather than pulling up roots and all – then it is “established.” There are other definitions of establishment based on runner length. Many of our herbicide labels answer this question. The label may say it is considered established when runners reach 8 – 10 inches. Sometimes labels describe establishment with days after sprigging and say, “use only on bermudagrass established for 60 days.”
The pasture pictured above has 8-10 inch runners in 40% of the pasture and the rest was 3 – 4 inch runners. In terms of safest postemergent application, UGA Extension Weed Scientist Dr. Patrick McCullough says, the 2,4-D and Weedmaster products will be the safest to use on immature bermudagrass during establishment. However, we are too risky to apply these products now, so mowing will be our only option here until we can buy some time on establishment.
Here is some TifQuik Bahia that was drilled in mid April. It’s only at 3/10 of an inch of rain since then, but coming up good. We have a more variety of weeds here, and automatically lose any option with mesulfuron since it’s Bahia. Some seedlings are still emerging, but most of it is 3 -4 inches. The rule of thumb here is when grass is 8 – 10 inches tall, it is considered established and safer to apply herbicides. In this situation, we would mow throughout the growing season, then come in the fall with a phenoxy herbicide to start control.
We are seeing spiderwort in pastures now. I was asked if I knew what this weed was last week. It was actually growing along the roadside where we first looked. It is in both pastures and hay fields. Spiderwort emerges in early spring, flowers in March-April, and then produces seed through mid-summer. It is an issue in grazing forage because cows avoid it. In the situations we looked at, the large, fleshy stem makes spiderwort an issue in hay production. When cut with a grass forage, spiderwort does not dry at the same rate as the grass and can cause spoilage when the hay is baled.
Here are some control options from Dr. Jay Ferrell, University of Florida Weed Scientist found in their blog post: Spiderwort: A Troublesome Weed Invading North Florida Hays & Pasture Fields.
Experiments were conducted in High Springs, Florida to compare the activity of commonly used pasture herbicides on fully emerged and flowering spiderwort. All herbicides were applied with crop oil concentrate (COC) at 1% v/v.
Spiderwort response to all herbicides was similar at 1 week after treatment (WAT) and control was less than 50% (Table 1). Triclopyr resulted in 86% control while very little change was noted from all other herbicides at 4 WAT. Triclopyr exhibited excellent control (95%) at 8 WAT, while the other treatments remained at 50% or less. Control of spiderwort by triclopyr began to decline shortly after 8 WAT (data not shown), and spiderwort re-established in all plots.
No single herbicide application was found to fully control spiderwort. The greatest control was found when triclopyr was applied at 32 fl oz/acre. Canopy growth did not recommence in the triclopyr plots for another 4 to 6 weeks after the initial burn-down. However, the majority of the spiderwort plants did eventually regrow in the triclopyr plots. Therefore, it is important to keep in mind that the results from triclopyr may be temporary. With this timeline in mind, producers should treat infested fields at least a month prior to cutting hay. Fortunately, producers should have at least a month after burn-down to cut and bale their hay without experiencing any issues associated with spiderwort. It will take multiple cycles of regrowth and burn down to reduce the population in a field. When feasible, hand removal is still the most effective control method.
Smutgrass is a non-native, perennial grass that can be a real issue in our pastures and one where management can be difficult. These pics I took a month ago. The seed head is a long spikelike. Leaves are usually folded but can be flat. They are also smooth. Many times the seadhead or spikelet is infected with black smut.
Ccows will graze the smutgrass for some time then they will stop. When the pastures become infested, large areas of the pasture are not grazed.
In terms of chemical control, hexazinone (Velpar, Velossa), is our main option for smutgrass. One issue is injury to Bermuda. Hexazinone will injure bermuda pretty good and can eliminate the first hay cutting. Bahia and Bermuda will recover from temporary burn and yellowing within two to four weeks of application. We need to target smutgrass around between April and July, when humidity is high and air temperatures are over 80 degrees. Hexazinone is root absorbed and requires about one-half inch of rainfall within two weeks of application. Fall applications are not very effective.
Another point to remember is we need to use low rates on coarse, sandy soils and high rates on clay soils. Hexazinone can injure trees (especially oaks). Caution should be used near desirable deciduous trees.
For additional information, visit Smutgrass Control in Perennial Grass Pastures.
…….We can also use something like glyphosate on a wic bar……