There are still some tough burndown situations in the state due to weeks of less than ideal weather conditions. Controlling large marestail is probably the biggest challenge, especially when there’s not much time between herbicide application and soybean planting. This situation is discussed in the video below. We realized too late however that while we showed examples of areas where marestail were still alive following an early burndown, we didn’t cover what the options were for a second burndown to control these and newly emerging plants where soybeans have yet to be planted. Options here depend upon what was already applied earlier in spring. Where a mixture of glyphosate, 2,4-D and residual herbicides was applied early, a follow up burndown of Sharpen plus glyphosate or glufosinate or Gramoxone would be adequate to control the marestail and small grasses and ragweeds that have emerged. It’s probably possible to just apply Gramoxone or glufosinate in these situations, along with a few ounces of metribuzin. Where residual herbicides were applied early, it may also be beneficial to include another reduced rate of residuals in any second burndown. This can improve the chances of: 1) controlling marestail until the soybean canopy can take over and provide late-season control; and 2) controlling giant ragweed, grasses, and other weeds until soybeans get somewhat established and the POST herbicides can be applied.
Results of a national survey of weed scientists and practitioners conducted by the national and regional weed science societies are in. Probably no surprise to all of us here in Ohio that marestail was identified as the most troublesome weed in soybeans. The other four weeds mentioned most frequently as hard to control in soybeans were Palmer amaranth, waterhemp, and giant and common ragweed. Nationally, over all crops, weeds designated as most troublesome, starting with the one listed the most times, were: Palmer amaranth, morningglory, lambsquarters, waterhemp, marestail, nutsedges, kochia, giant ragweed, Canada thistle, and foxtails.
Link to the WSSA newsletter that contains a summary of the survey – http://wssa.net/wp-content/uploads/WSSA_April_2016.pdf.
The amazing marestail plant – is there anywhere it can’t grow?
Our latest video covers pigweed identification. We compare four aspects of pigweed biology that we use to differentiate between redroot pigweed, waterhemp, and Palmer amaranth – pubescence, petiole length, leaf shape, and inflorescence (seedhead) characteristics.
Yes I know – it’s not officially spring yet. Here are some poems about the resilient and adaptable dandelion anyway.
The Dandelion’s pallid tube – Emily Dickinson
The Dandelion’s pallid tube
Astonishes the Grass,
And Winter instantly becomes
An infinite Alas —
The tube uplifts a signal Bud
And then a shouting Flower, —
The Proclamation of the Suns
That sepulture is o’er.
The First Dandelion – Walt Whitman
Simple and fresh and fair from winter’s close emerging,
As if no artifice of fashion, business, politics, had ever been,
Forth from its sunny nook of shelter’d grass–innocent, golden, calm
as the dawn,
The spring’s first dandelion shows its trustful face.
From “A Rhapsody” (excerpt) – John Clare
Tis May; and yet the March flower Dandelion
Is still in bloom among the emerald grass,
Shining like guineas with the sun’s warm eye on–
We almost think they are gold as we pass,
Or fallen stars in a green sea of grass.
They shine in fields, or waste grounds near the town.
They closed like painter’s brush when even was.
At length they turn to nothing else but down,
While the rude winds blow off each shadowy crown
As of late 2015, Palmer amaranth had been found in at least 11 counties in Ohio. A “find” can consist of a few plant or a few fields depending upon the county. Populations are increasing in some counties, but in others the eradication of the few plants that were found has occurred. Current information on the status of Palmer amaranth in Ohio, along with a brief summary of the properties that make it a “super weed” and a heads up and the programs needed for management, can be found in this Powerpoint pdf and the video shown here.
Our digital books on weed identification are now available for use on all types of devices via iTunes and GooglePlay. These include “The Ohio State University Guide to Weed Identification“, “Identifying Noxious Weeds of Ohio“, and “Principles of Weed Ecology and Management“. The latter is a combination lab manual and weed ID resource used in the weed science course here at OSU. Links to purchase these can be found under the “Weed ID” menu at the top of the page.
Each fall we provide an article and video on new herbicides to the OSU Pesticide Applicator Training group, for use in recertification by our educators. The article ends up in the annual recertification proceedings book, and can also be accessed at this link – PAT loux 2015-16. Most of this information can also be found in the 2016 edition of the “Weed Control Guide for Ohio, Indiana, and Illinois”, which is available at the link on the right side of this page. The two YouTube videos that contain some of this same information follow:
In-field video of Dr. Mark Loux explaining late-spring options for control of overwintered marestail. A follow up to the recent C.O.R.N. article on this subject.