MARYLAND WEED REPORTER

Most of you receiving this edition of the MARYLAND WEED REPORTER should have received a copy of my annual report titled, "2000 Results of Weed Control Research." We have the results from about 50 field trials we conducted state-wide in 2000. While many are at the Research and Education Centers, a number were conducted on-farm. There are two ways you may want to familiarize yourself with this publication. One way would be to read all of the titles of the studies. If it is something of interest you may want to turn to that study and see what materials were used and the kind of control we obtained. Another way to use the publication is to go directly to the chemical index located in the back of the book. You may find a number of herbicide names you recognize, but you may also find a number of unfamiliar names. If there is a product you want to know about, once again you can turn to the study by using the page numbers listed by each study. If you have any questions please don't hesitate to call or email.

Well, the dust is finally settling on all of the glyphosate formulations we'll have in 2001! The following should give you a pretty good idea of what new names we can expect.

Glyphosate and glyphosate-type products:

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Confused? So am I! Many of these glyphosate formulations are actually manufactured by Monsanto. Monsanto sells the material to another company, they put a new name on it, and pay royalties to Monsanto.

Outside of the Monsanto formulations, most of the products listed above can only be used on Roundup-Ready soybeans, except Touchdown IQ. Touchdown IQ is another salt of glyphosate. Regular Roundup contains the isopropylamine salt, Touchdown 5 had the trimesium salt, and Touchdown IQ contains the diammonium salt. Touchdown IQ just received its registration and is registered for all Roundup-Ready crops. It does not have the odor the old Touchdown 5 had. Use rates will be comparable to Roundup Ultra since both are 4 lb ai/gallon products.

While we're on the subject of knock-down herbicides, Syngenta will be replacing Gramoxone Extra with a new formulation called Gramoxone MAX. The old formulation was a 2.5 lb ai/gallon while this new formulation will be a 3.0 lb ai/gallon product. Griffin will also be introducing their generic brand of paraquat. It will be called Boa and be comparable to the old Gramoxone Extra containing 2.5 lb ai/gallon.

What else is new?

Small grains. Axiom (by Bayer) was given a Section 18 (emergency use exemption) in Virginia for preemergence use in wheat for control of ryegrass. We have been looking at Axiom and Dual II Magnum (by Syngenta) for preemergence control of ryegrass in wheat over the past two years. Both look very promising! The following two tables are averages for 1999 and 2000. We applied Axiom and Dual II Magnum right after planting wheat in the Fall of 1998 and 1999. The data presented were observations made in the Spring of the year.

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Finesse (by DuPont) has also been examined for preemergence and postemergence use in wheat for control of ryegrass. While results have been variable, we have obtained good to excellent control of ryegrass with Finesse applied preemergence at ½ ounce per acre. Finesse is a sulfonylurea herbicide. Carryover to double-crop soybeans is a concern. It is suggested that where you use Finesse, that STS soybeans be used if you are going to double-crop.

Other grassy weeds we have been working on in wheat include the following:

• Annual bluegrass
• Bromegrass
• Bulbous oatgrass
• Roughstalk bluegrass

One new herbicide that we've been looking at for control of grassy weeds in wheat is a product from Monsanto called Maverick. Maverick is labeled for control of a variety of bromegrass species including downy brome, cheat and hairy chess which are common in our region. We have studied its use on annual bluegrass and bulbous oatgrass and have found excellent control of annual bluegrass. Bulbous oatgrass control has varied, but Maverick is the only product that we have found that has any activity on this particular grass.

Maverick is a sulfonylurea and like with Finesse, safety to double-crop soybeans is a concern. The current Maverick label says, "Do not plant to any crops other than winter or spring wheat for a period of one year following Maverick herbicide application." We have two year's data which shows that a planting of STS soybeans, even where Maverick was spring applied, will not show any signs of injury or yield reduction.

While most of us are familiar with Harmony Extra, DuPont will be introducing another product called Harmony GT. Harmony Extra contains Pinnacle and Express. Harmony GT will only contain Pinnacle. Before we had Harmony Extra we had Harmony. It did a nice job in controlling chickweed and wild garlic. Henbit control was average. With Harmony GT we can expect the same thing. Use rate will be ½ ounce per acre, going up to 2/3 ounce per acre for garlic control.

Corn. We are losing all Broadstrike/Dual formulations and also Bicep Magnum TR. So what's left for preemergence control of triazine-resistant pigweed and lambsquarters? Basis (by DuPont) and Python (by Dow AgroSciences) are the only two products left. Python was the herbicide in Broadstrike/Dual and Bicep Magnum TR that provided preemergence control of triazine-resistant weeds. These two products can provide some corn stunting under cool, wet conditions, especially on light, sandy soils.

Ready Master ATZ (by Monsanto) is a new entry this year for use on Roundup-Ready corn. It's labeled from seedling emergence until the corn reaches 12 inches in height. Ready Master ATZ contains 2.0 lb ai/gallon of Roundup and 2.0 lb ai/gallon of atrazine. Suggested use rate is 1.5 to 2.0 quarts per acre.

Pinnacle (by DuPont) has extended its use in corn. It can now be applied to 2 to 6 leaf corn (up to 12 inches tall). Pinnacle can provide excellent control of pigweed and lambsquarters under good growing conditions. If you are in a sensitive area where the Banvel type products cannot be used, Pinnacle could be an alternative.

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Soybeans. We'll probably see a few new products in 2001. Boundary (by Syngenta) is a blend of Dual II Magnum plus metribuzin (Sencor, Lexone). It replaces Turbo which was a blend of Dual II plus metribuzin.

Command Xtra (by FMC) may also be available in 2001. It will be either a co-pack or a blend of Command plus Authority.

Axiom (by Bayer) is a blend of FOE-5043 (preemergence grass herbicide) plus metribuzin (Sencor, Lexone). A new blend may be introduced in 2001 under the trade name Domain (by Bayer).

Harmony GT (by DuPont) will probably be replacing Pinnacle for postemergence use in soybeans. As mentioned in the small grain section, Harmony GT is really Pinnacle. However, Pinnacle was a 25% material while Harmony GT is a 75% material. Use rate for Pinnacle was 1/4 ounce per acre, while Harmony GT will be 1/12 ounce per acre. Under good growing conditions, Harmony GT will provide good control of pigweed and common lambsquarters.

Non-crop areas. This past year, I received a number of phone calls regarding weed control in non-crop areas. This would include CRP and CREP ground. The problem I usually run into is the fact that on some of this land, a legume and a grass are planted. It's hard to achieve weed control in this situation. This past summer we looked at a product called Plateau (by BASF) for use in the control of johnsongrass. Plateau is actually labeled for weed control in plantings of big and little bluestem, indiangrass, switchgrass, blue grama, buffalograss and eastern gamagrass. Plateau is also labeled for a number of wildflower and prairiegrass/wildflower mixtures.

Two other herbicides labeled last year for use in grass pastures and non-crop areas are Remedy and Redeem (by Dow AgroSciences). Remedy contains triclopyr (Garlon) while Redeem contains triclopyr (Garlon) and clopyralid (Stinger). A similar product, also by Dow, is Crossbow which contains 2,4-D plus triclopyr (Garlon). While I haven't tested Remedy or Redeem, I have sprayed Crossbow in fence row areas and obtained good control of perennial weeds such as honey-suckle, poison ivy, poison oak and sumac.

That's it for now! I hope you all have a happy holiday season.

Ronald L. Ritter

Extension Weed Control Specialist

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