The weed science group at U of Missouri has released a new publication, “Weed Identification and Herbicide Injury Guide”. It’s available for $18 at http://extension.missouri.edu – search for “IPM1007”. It’s well done, so consider adding to your library or folder of materials carried around to aid in problem solving and making recommendations. Cover and sample pages shown below.
We are currently in our first year of research to determine the safest and most effective herbicide programs for spring barley in Ohio. This research is briefly described in the video below. We don’t have any prior experience with weed control in spring barley. Summer annual weeds such as ragweeds, lambsquarters, pigweeds, and foxtails are the primary weed problem in spring-planted crops, and the competitiveness of the crop with weeds will be affected by planting date and stand density, among other things. There are a number of herbicides registered for use in barley, but not all labels specifically mention spring barley. Control of foxtails in barley can be obtained only by POST application of an Axial product, such as Axial XL or Axial Star, and labels for these products just mention “barley”. Axial Star controls ragweeds in addition to foxtails, since the premix contains fluroxypyr (Starane) in addition to the pinoxaden (Axial XL). Axial products can be applied up to the pre-boot stage, when grass weeds have 1 to 5 leaves and less than 3 tillers. There is no mention of a need for adjuvants on Axial XL and Star labels, but mixtures with certain broadleaf herbicides may require nonionic surfactant (check labels). Labels for the following broadleaf herbicides specifically mention spring barley: 2,4-D, MCPA, bromoxynil (Moxy, etc), dicamba (Clarity, etc), Huskie, Peak, Pulsar, and Starane. Labels for another group of broadleaf herbicides do not specifically mention spring barley, just “barley”: Aim, Cleansweep, Orion, Widematch, tribenuron (Express, etc), and thifensulfuron/tribenuron premix (Harmony Xtra, etc). We have descriptions and ratings for all of these on summer annual weeds in the “Weed Control Guide for Ohio, Indiana, and Illinois” (page 139-149 of 2016 edition).
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