By now, most of you should have received a new copy of Extension Bulletin 237, Pest Management Recommendations for Field Crops. The spiral binding was a hit last year so we decided to keep on using it. While we are selling hard copies of this bulletin, we are also making it available on the web. At first, it will be somewhat difficult to navigate. You will have to download large sections. Printing may also be a problem. However, we are working on making it more user friendly in the future.

Let me outline some of the changes made to the Weed Control Section. I've updated the Guide to prepackaged mixes. Leadoff is no longer available so it was deleted. All of the FOE-5043 designations have been changed to Define. We also added a number of new package-mixes which I will outline below.

In the Guide to single active ingredients, I've changed FOE-5046 to flufenacet, added Amplify next to FirstRate, eliminated ZA-1296 and added Option.

In the Rain-free requirements I made similar changes by dropping older products and adding newer ones such as Option and Yukon.

In the Corn herbicides and restrictions table, Corn effectiveness tables and the Grazing and forage restrictions table I also deleted the older herbicides and added the newer ones. Similar changes were made in the Approved tank-mix tables as well.

Throughout the entire Weed Control Section take note of the following change;

Roundup Ultra Max has been changed to Roundup Weather Max and rates adjusted to reflect the newer formulation. I'll discuss this change later.

Syngenta is introducing two new package-mixes this year. One is called Lumax and the other one is called Camix. Lumax is a combination of Callisto, Dual II Magnum and atrazine. Camix is a combination of Callisto plus Dual II Magnum. This product will be targeted to areas of the country where there are groundwater concerns with atrazine. Here, Lumax will be promoted especially for control of triazine-resistant weeds. Use rate will vary according to soil organic matter. Use 5 pints per acre for soils with organic matter less than 3% and use 6 pints per acre for soils with organic matter greater than 3%. More atrazine may have to be added for large-seeded broadleaf control since the package-mix contains minimal amounts. I did add Lumax to EB 237.

While Syngenta will still be selling Dual II Magnum and Bicep II Magnum, so will DuPont. DuPont will be buying these herbicides from Syngenta and selling it under their own trade names. Cinch will be DuPont's brand of Dual II Magnum and Cinch ATZ will be their brand of Bicep II Magnum. There will also be Cinch ATZ Lite which is equivalent to Bicep Lite II Magnum.

Dow will be introducing two new blends of acetochlor plus atrazine. The product for our area is called Keystone. At 2.65 quarts per acre, you get the equivalent of 2.0 lb ai/acre acetochlor plus 1.5 lb ai/acre atrazine. A low atrazine formulation called Keystone LA is also being introduced.

Last year, a preemergence grass herbicide called Define was being sold in the mid-west by Aventis. The product was actually a Bayer herbicide which they put in Axiom. With the buyout of Aventis by Bayer, Define will now be sold by Bayer. I added Define to the corn section as well.

In the postemergence section, I added two new products. Yukon, by Monsanto, is a blend of Permit plus Distinct. Use rate is 4.0 ounces per acre which gives you 2/3 ounce per acre of Permit and 4.0 ounces per acre of Distinct. The other new herbicide I added is called Option. Option was actually an Aventis product. Once again, with the buyout by Bayer, Option will be sold by Bayer. It is a postemergence grass control material similar to DuPont's Accent. It is a sulfonylurea herbicide. Use rate is 1.5 ounces per acre and you do have to add oil and a liquid fertilizer. I've tested Option for several years. It looks very similar to Accent. However, to get it to work, especially under drought stressed conditions, you definitely need to add a methylated seed oil plus UAN (urea ammonium nitrate) or AMS (ammonium sulfate). As with Accent, it does not have activity on bermudagrass and is weak on crabgrass. Do not apply overtop of corn that has been treated with Counter, Dyfonate or Thimet.

While I'm on the subject of Accent and Option, two years ago DuPont had a big push for the use of Basis Gold on corn. Last year they were promoting Steadfast. What exactly are these products? Basis Gold contains atrazine + Accent + Matrix; Steadfast contains Accent + Matrix. However, how much Accent do you really get?

If you were going to utilize Steadfast for johnsongrass control, you would have to spike it with additional Accent. As for Basis Gold, it is rumored that DuPont may be discontinuing its production.

As mentioned earlier, Monsanto has changed their formulation of glyphosate. Here is a table on Monsanto's glyphosate changes;

The use rate of Roundup Weather Max runs from 16 to 32 ounces per acre. However, when utilizing it in Roundup Ready corn, single in-crop applications are not to exceed 22 ounces per acre. Sequential in-crop applications of this product from emergence through the V8 stage or 30 inches must not exceed 44 ounces per acre per growing season. Allow a minimum of 10 days between in-crop applications, and 50 days between application and harvest of corn forage.

Forages, Pastures, Grain Sorghum, Small Grains and Soybeans

Similar changes were made in these sections such as adjusting the glyphosate rates for Roundup Weather Max. However, I did make a few changes that I would like to discuss.

Raptor by BASF was labeled for alfalfa last year. I added it to the alfalfa section. Use rate is 4.0 to 6.0 ounces per acre. For established alfalfa it can be applied in the fall, winter, or in the spring to dormant, or semi-dormant alfalfa, or between cuttings. For seedling alfalfa, apply Raptor when the seedling alfalfa is in the second trifoliate stage or larger. While I've often felt that both Pursuit and Raptor are stronger products for summer weeds, Raptor may have a fit for winter annuals as well. It does have activity on chickweed, small henbit, mustards, shepherdspurse, and a number of winter grasses such as brome and Italian ryegrass. It will also suppress small dandelion at 6.0 ounces per acre. There is a 20 day wait between application and cutting or feeding of alfalfa forage or hay.

In the permanent pasture section, Ally is still listed as Ally. However, DuPont will be changing the name of Ally and repositioning this product for our area. The new name will be Cimarron. There will also be another product called Cimarron Max which contains Ally + Banvel + 2,4-D. Cimarron Max is considered a two part product of Cimarron Max Part A (Ally) + Cimarron Max Part B (Banvel + 2,4-D). Cimarron rates run from 0.1 to 1.0 oz/acre. It will be promoted for the control or suppression of broadleaf weeds to aid in the establishment of perennial native or improved grasses planted in pasture, rangeland or acres enrolled in the Conservation Reserve Program. There are some new restrictions. For instance, the minimum time from grass establishment to Cimarron application varies across species. Some are listed below.

As you can see from the table, grasses like tall fescue have to be established for 2 years before Cimarron can be applied.

In the permanent pasture section we added a product called Grazon P + D for use only in Virginia. Grazon P + D is a mixture of picloram (Tordon) + 2,4-D. Virginia has a problem with bladder campion and this is the only product that will suppress it.

Once again, in the grain sorghum, small grains and soybean sections, minor changes were made. Most of the changes were reflected in the changes of going from Roundup Ultra Max to Roundup Weather Max. Rates were adjusted accordingly, especially in the soybean section where we list weeds, postemergence herbicides, and rates needed for control. As with Roundup Ready corn, there are certain restrictions for in crop applications to Roundup Ready soybeans. The combined total application from crop emergence through harvest must not exceed 64 ounces per acre. The maximum rate for any single in-crop application is 44 ounces per acre. The maximum combined total of this product that can be applied during flowering is 44 ounces per acre.

Herbicide Resistant Weeds

Herbicide resistant weeds aren't a new phenomena to Maryland the following table illustrates some of the problems we have.

Of the above weed problems, the one that has a lot of people worried is the lack of horseweed control with Roundup (glyphosate). In roughly 2 years, we've seen glyphosate resistant horseweed spread from a couple of farms to just about the entire Eastern Shore. What makes matters worse is that the only tool we have to clean it up postemergence in soybeans is FirstRate or Amplify (same product) which are sulfonylurea or ALS inhibiting herbicides. Unfortunately, there are marestail in the mid-west that are ALS resistant. If those plants cross with our plants, we will not have anything to control them in soybeans outside of a sharp hoe!

So, we are stressing the following. If you think you have glyphosate resistant horseweed and are going to plant full-season no-till soybeans;

1. If spraying > 30 days before planting

Utilize Gramoxone Max + 2,4-D (up to 1 quart per acre of 2,4-D ester)

2. If spraying < 30 days before planting but more than 7 days

Utilize Gramoxone Max + 2,4-D (up to 1 pint per acre of 2,4-D ester)

3. If spraying < 7 days before planting

Utilize Gramoxone Max followed by another application of Gramoxone Max

4. Save your glyphosate application for in-crop

5. If horseweed still exist utilize FirstRate/Amplify at 0.3 ounce per acre

6. Treat only as needed

7. Use rotation and/or tillage

8. It is not advisable to use Roundup Ready crops repeatedly in the same fields on an annual basis. As a general rule, do not use Roundup Ready crops in the same field two years in a row.

Until next time,

Ronald L. Ritter

Extension Weed Control Specialist