Noxious Weeds
How to Identify Palmer Amaranth
Palmer Amaranth – Remain Vigilant!
As weeds continue to rear their ugly heads above the soybean canopy, it is important to remain vigilant and continue scouting your corn and bean fields on a regular basis. We are seeing many weeds, Palmer Amaranth, Marestail, Waterhemp, Pigweed, Ragweed (Giant & Common), and various grassed, just to name a few.
Marestail, Palmer Amaranth and 19 other weeds are on the Ohio Noxious weed list. This designation requires that the landowner Public or Private MUST control these evasive weeds. See earlier posts in this blog for more information on each of the 21 noxious weeds in Ohio.
Need help to identify weeds? As you scout your fields and you come across a weed that you’re not sure about; Is it Pigweed, Is it Waterhemp, Or is it Palmer. If you are not sure call me at 740-397-0401 and I will be happy to help you with the identification. Visit our Knox County Extension YouTube channel (Click Here) for locally produced videos an how to identify and control this devastating weed. Additional resources for Palmer Amaranth can be found on the OSU Weed Management Blog (Click Here).
Palmer Amaranth may very well be the most devastating pest you have/will ever encounter. Soybean yield losses approaching 80% and corn yield losses exceeding 90% have been reported. A single female plant can produce up to 1,000,000 seeds and these seeds can remain viable in the soil for many, many years. As Dr. Mark Loux states “Waterhemp and Palmer Amaranth will have more impact on the profitability of your farm operation than probably any other weed. Palmer Amaranth, in the south, essentially doubled the herbicide costs in beans.” Remember, weed seeds are easily spread within a field and from field to field during harvest.
It is Your Farm, Your Field, Your Operation, Your Future – Protect it by keeping a watchful eye on your fields!
No Pigweed Left Behind – Late-Season Scouting for Palmer Amaranth and Waterhemp
by: Mark Loux
If you don’t already have to deal with waterhemp or Palmer amaranth, you don’t want it. Ask anyone who does. Neither one of these weeds is easy to manage, and both can cause substantial increases in the cost of herbicide programs, which have to be constantly changed to account for the multiple resistance that will develop over time (not “can”, “will”). The trend across the country is for them to develop resistance to any new herbicide sites of action that are used in POST treatments. Preventing new infestations of these weeds should be of high priority for Ohio growers. When not adequately controlled, Palmer amaranth can take over a field faster than any other annual weed we deal with, and waterhemp is a close second. Taking the time to remove any Palmer and waterhemp plants from fields in late-season before they produce seed will go a long way toward maintaining the profitability of Ohio farm operations. There is information on Palmer amaranth and waterhemp identification on most university websites, including ours – u.osu.edu/osuweeds/ (go to “weeds” and then “Palmer amaranth”). An excellent brief video on identification can be found there, along with a fact sheet. The dead giveaway for Palmer amaranth as we move into late summer is the long seedhead, and those on female seed-bearing plants are extremely rough to the touch.
If you need help with identification, call John at 740-397-0401.
Continue reading No Pigweed Left Behind – Late-Season Scouting for Palmer Amaranth and Waterhemp
Ohio Noxious Weed Identification – Week 21 Palmer Amaranth
Palmer Amaranth
Family: Pigweed, Amaranthaceae.
Habitat: Crop fields, pastures, and roadsides.
Life cycle: Summer annual.
Growth habit: Erect up to 6 ft. high.
Leaves: Prominent white veins on the undersurface unlike redroot pigweed, not pubescent, alternate, without hairs (glabrous), and lance or egg-shaped. Leaves are 2 to 8 inches long and 1/2 to 2 1/2 inches wide with prominent white veins on the undersurface. Leaves occur on relatively long petioles.
Flower: Small, green, inconspicuous flowers are produced in dense, compact, terminal panicles that are from 1/2 to 1 1/2 feet long. Smaller lateral flowers also occur between the stem and the leaf petioles (leaf axils). Male and female flowers occur on separate plants. Each terminal panicle contains many densely packed branched spikes that have bracts that are 3 to 6 mm long; can produce 500 thousand to 1 million seeds per plant.
Roots: Taproot that is often, but not always, reddish in color
Stem: One central stem occurs from which several lateral branches arise.
Similar Plants: Loosely resembles many other pigweed species. Palmer’s petioles are as long or longer than the actual leaf. This plant is hairless and has elongated seed heads. Leaves are typically more diamond shaped than other pigweed species, and occasionally has one hair at the tip of the leaf.
The Problem is……..Palmer amaranth is one of the most difficult weeds to control in agricultural crops. It developed a major glyphosate resistance problem in the southern US from 2006-2010, and has been spreading in the midwestern US since, causing crop loss and increases in weed management costs. Characteristics that make it a successful annual weed include: rapid growth rate; wide window of emergence (early May through late summer); prolific seed production (upwards of 500,000 seeds/plant); tendency to develop herbicide resistance; and tolerance to many post-emergence herbicides when more than 3 inches tall.
Continue reading Ohio Noxious Weed Identification – Week 21 Palmer Amaranth
Ohio Noxious Weed Identification – Week 20 Marestail
Marestail
Family: Composite, Asteraceae.
Habitat: Thin turf, agronomic crops, pastures, orchards, fallow fields, waste areas, and roadsides.
Life cycle: Summer or winter annual.
Growth habit: Seedlings develop a basal rosette and mature plants erect are reaching 6 1/2 ft in height.
Leaves: The mature plant has leaves that are entirely without petioles (sessile). Leaves are 4 inches long, 10 mm wide, alternate, linear, entire or more often toothed, crowded along the stem, and hairy. Leaves become progressively smaller up the stem.
Stem: Erect, solid, hairy, reaching 6 1/2 ft in height.
Continue reading Ohio Noxious Weed Identification – Week 20 Marestail
Ohio Noxious Weed Identification – Week 18 Wild Mustard
Wild Mustard
Family: Mustard, Brassicaceae.
Habitat: Wasteland, roadsides, grain and other fields crops, primarily in northern Ohio.
Life cycle: Annual annual or summer annual.
Growth Habit: 1-2 feet high, branched and erect.
Leaves: Alternate, 2-7 inches long. Lower leaves have petioles and are irregularly lobed and toothed with bristly hairs; upper leaves are smaller and may not be lobed; petioles lacking or short.
Stem: Branched near top, bristly.
Flower: June – October. 1/2 inch, bright yellow, four-petal flowers borne in small terminal clusters.
Fruit: Slender, slightly curved, smooth seedpod about 1 inch long; borne on upper branches.
Similar plants: The yellow rocket looks similar but has rounded lower leaves that are more heart shaped.
Continue reading Ohio Noxious Weed Identification – Week 18 Wild Mustard
Palmer Amaranth
Palmer Amaranth
Palmer Amaranth has been found in Knox County.
Watch this video for more information.
Palmer Amaranth is on the Ohio Noxious weed list.
Check back for more videos discussing identification and control of this devastating weed!
A big thanks to our co-workers in Delaware County for making this video available!
Checkout other videos on our YouTube Channel.
Ohio Noxious Weed Identification – Week 17 Wild Carrot
Wild Carrot
Family: Parsley, Apiaceae.
Habitat: Dry fields, wastelands, pastures, and no-till field crops.
Life cycle: Biennial, forming a rosette the first year and producing flowers and seed in the second.
First Year Growth Habit: A basal rosette.
Second Year Growth Habit: 1-3 feet tall, branched and erect.
Leaves: Alternate, pinnately compound, finely divided and hairy.
Flowering Stem: Tall, hairy, stout, and branched.
Flower: June – October (second year). Small, lacy white 5-petaled flowers in flat-topped, umbrella shaped clusters with one dark reddish-brown flower in the center. Flower closes up and turns brown as it matures.
Root: Fleshy taproot.
Similar plants: Leaves have the appearance and odor of a garden carrot. Wild carrots taproot is not as large as the garden carrot. The plant also resembles poison hemlock (Conium maculatum). However, wild carrot has a hairy stem while poison hemlock has a smooth stem with purple blotches. The dark floret in the center of the inflorescence in second year and a distinctive carrot smell in the first year will also help distinguish this common weed.
Continue reading Ohio Noxious Weed Identification – Week 17 Wild Carrot
Poison Hemlock is in Full Flower and Towering over Fields and Landscapes in Ohio
Orginally posted on Buckeye Yard and Garden onLine- June 1, 2018, By: Joe Boggs
Poison hemlock (Conium maculatum) is one of the most lethal plants found in North America. This biennial weed is now in full flower throughout much of Ohio. So, the clock is ticking on preventing seed production by this non-native invasive plant.
Continue reading Poison Hemlock is in Full Flower and Towering over Fields and Landscapes in Ohio