Control Buttercup and Poison Hemlock in Pastures Now
Buttercup Control
Pastures that are yellow because of buttercup infestations are a common sight during spring. However, this should not be considered a badge of honor. Do not wait until the pasture is "yellow" with buttercup flowers (as pictured above) to spray. A combination of mowing and herbicides will provide the best management of buttercup species. Mowing fields as low as possible during the early spring before they start to flower can help reduce seed production. Routine mowing can also occur during the rest of the growing season to thwart weed seed production and encourage pasture growth, but a well-timed herbicide application is important for best control. The question about when the optimal time is to spray herbicides --- the short answer is early spring. The use of herbicides during early spring (Mid-March through April) is the most effective time to control buttercup populations. Herbicides such as 2,4-D (2-3 pints/acre), 2,4-D (1 quart) + dicamba (1 pint), metsulfuron/MSM (0.2-0.3 oz), or Crossbow (2-3 quarts) are commonly used to control buttercup. Since herbicide spray coverage is important, it is best to use higher spray volumes (at least 15 gallons/acre, but 20 gpa or more would be better) to allow the application to get into the sward and onto the weeds. Spraying when buttercup is flowering usually does not provide effective control. When spraying in the spring, make sure the air temperatures are at least 50℉ or more for a few consecutive days for effective control. Keep in mind that these treatments will severely injure or kill any legumes in your stand. If you are concerned about keeping white clover in the mix, 2,4-D (1 pint) could be used. However, by using this tactic, buttercup will likely only be suppressed, and clover growth can be temporarily stunted. So be sure to consider all the tradeoffs when using this practice. On a side note, herbicides applied in the fall (mid-September through October) are not as optimal as spring applications, but they can still provide some control over buttercups.
Regarding buttercup species that are common to PA, these include: bulbous buttercup (Ranunculus bulbosus), creeping buttercup (Ranunculus repens), tall buttercup (Ranunculus acris), and small flower buttercup (Ranunculus arbortivus). Most of these have a perennial lifecycle, however some can behave as a winter annual. Also, be aware that another weed called lesser celandine (Ficaria verna) can exist in pastures and in locations similar to buttercups, and it looks very similar.
Keep in mind that pastures with dense populations of buttercup and other weed species, in most cases, are lacking proper management. Often it is a sign of over-grazing and a poor stand of desirable forage. Good agronomic practices are key to a healthy, persistent forage stand and should include proper fertility and soil pH levels and grazing and mowing management, along with effective and properly timed herbicide applications.
Poison Hemlock Control
Similarly, now is a good time to go after poison hemlock. However, keep in mind that it might not be poison hemlock but wild chervil.
Poison hemlock (Conium maculatum) and wild chervil (Anthriscus sylvestris) are in the carrot or Umbelliferae family and the leaves and foliage resemble carrot and parsley. Both are very invasive and spread rapidly if left unchecked.
Lifecycle:
- Poison hemlock germinates from seed and is a biennial plant.
- Wild chervil grows as a biennial or a short-lived perennial.
- Both species begin with a basal rosette of leaves during its first year.
- Once they overwinter, in late April/early May, they bolt into an erect, branched plant, producing prominent white flowers in an umbel, generally in June and July. They set and drop seeds soon after.
- Poison hemlock only reproduces by seed, and its taproot dies when the main plant desiccates.
- Wild chervil mostly originates from seed; however, it can sometimes produce a crown and thus regrows from that structure.
Characteristics:
- Both have fern-like, glossy green, lacy leaves in the rosette stage and can be difficult to distinguish from each other.
- Poison hemlock has a hairless, hollow main steam with purple blotches/spots which branches. Stems may turn purple as they mature. Its large flower structures are composed of many smaller white flowers. Plants typically grow 2 to 6 feet tall and have a parsnip-like odor when the leaves are crushed.
- Wild chervil also has a hollow stem, but its stems are deeply grooved and have velvety hairs, especially on the lower stem. Chervil ranges from 18 inches to 4 feet tall. It also has a large umbel with many small white flowers, which eventually produce stubby, finger-like seed clusters.
Poisonous traits:
- In general, poison hemlock is more toxic than wild chervil. The sap of poison hemlock has the potential to cause dermatitis (skin irritation) in some people. So be sure to wear protective clothing and gloves when handling the plant or when weed-whacking.
- Poison hemlock contains toxic alkaloids. It is poisonous when ingested by humans and livestock. The plant contains several closely related pyridine alkaloids, the main one being coniine, a colorless, volatile, and strongly alkaline oil. All parts of the plant are poisonous, and some studies have shown toxicosis at 0.25% fresh weight (of the animal’s weight) for horses and 0.5% for cattle. That would be 2.5 to 5 lb. of material per 1000 lb. animal. Mature seeds are the most poisonous. Significant poisoning can result in muscle paralysis and suffocation.
Habitat:
- Both typically grow along roadsides, fencerows, fallow areas, and waterways. Poison hemlock can also infest pastures and no-till fields.
Control:
- Individual plants can be easily dug out with a shovel.
- Larger infestations can be cut with a mower or string trimmer or may require the use of a herbicide.
- Several herbicides are effective for control. Herbicide applications are most effective when they are sprayed in the fall when poison hemlock is in the rosette stage or before it bolts in the spring. Effective herbicides include 2,4-D + dicamba (1 quart + 1 pint, respectively), Crossbow (2,4-D+triclopyr), NovaGraz, or glyphosate (spot treatment).
