What’s your “baddest” weed? “The worst weed we continue to get questions about is definitely marestail,” reports Dwight Lingenfelter. “Yes, Palmer and waterhemp are very nasty, and they’ll continue to spread over the next few years. But pretty much every farmer knows what marestail is and is having issues with it.”

Here’s a quick-read version of Penn State University’s 2017 update on newly labeled or expanded label herbicides expected for use this year in most of the Northeast. It comes from Lingenfelter and Bill Curran, Penn State Extension weed control specialists.

New for corn
• Acuron Flexi 3.26SC (Syngenta) is a premix similar to Acuron, but doesn’t contain atrazine. It controls many annual grasses, broadleaves and nutsedge. It’s labeled on all corn types, including sweet corn, and can be applied preemergence or postemergence on up to 30-inch-tall corn and 3-foot-tall annual broadleaf weeds. But it’s inconsistent on emerged grasses.

• Armezon PRO 5.35SE (BASF) is a premix product registered for post use on field and sweet corn. The Armezon component provides foliar control of certain annual grasses and broadleaves. Its Outlook component gives residual control of many annual weeds germinating after application.

• DiFlexx DUO 1.53SC (Bayer CropScience) is another premix that can be used in field corn to control broadleaves and annual grasses. It can be broadcasted from corn emergence to 36 inches tall; drop nozzles can be used thereafter. For best results, apply before annual broadleaf weeds reach 6 inches tall and grasses reach 3 inches tall. It can be tank-mixed with other corn herbicides to broaden the weed control spectrum. Always include spray additives such as liquid nitrogen solution or ammonium sulfate plus methylated seed oil or crop oil concentrate to improve control.

• Resicore 3.28SE (Dow AgroSciences) is a new herbicide premix that can be applied pre or post (up to 11-inch corn) in field and silage corn. It’s not yet labeled for sweet corn. It controls many annual grasses and broadleaf weeds including common and giant ragweed, lambsquarters, annual morningglory, pigweed species and velvetleaf. It may be tank-mixed with atrazine, glyphosate and other labeled corn products.

• Tolpyralate, code named SL573 3.34SC (ISK Bioscience), is a new, experimental HPPD-inhibitor herbicide for use in corn. No details yet about its trade name or when it’ll be registered. It’s similar to Impact/Armezon and Laudis as it has post activity on many annual grasses and broadleaves. It’ll mostly be used in two-pass programs or early post systems.

New for soybeans
• Scepter 70DG (AMVAC) is labeled for soybeans. And you’re right; it’s not exactly new. Scepter was sold from the late 1980s up until a few years ago, then dropped by BASF who sold it to AMVAC. It’s in the same herbicide family as Pursuit and Raptor and is, in general, about 10% to 20% less active than Pursuit on most grass and broadleaf weeds. It’ll likely be tank-mixed with other pre herbicides to broaden the control spectrum and to get a second site of action for control of ALS-resistant weeds. It won’t help with burndown, but does provide residual action.

• Zidua PRO 4.09SC (BASF) is premix labeled for burndown/residual use in soybeans. It controls many annual grasses and broadleaves (including marestail) and can be tank-mixed. Make sure to add MSO plus a nitrogen adjuvant for burndown. It should be available this year.

New for small grains
• Sentrallas 1.5SC (DuPont) is a premix of Harmony SG and Starane Ultra active ingredients. It controls broadleaf weeds in wheat, barley and oats. It’s similar to Travallas 1.58SC (DuPont), a premix of Ally, Harmony SG and Starane Ultra active ingredients for broadleaf control in wheat and barley.

• Talinor 1.77EC (Syngenta) is an experimental premix of Maestro/Buctril active ingredients plus a crop safener. It’s labeled for broadleaf weed control in wheat and barley from two-leaf to pre-boot stage. Include necessary spray additives. It can be tank-mixed to broaden control spectrum.

New multi-species products
• Halauxifen-methyl, dubbed “Arylex Active” (Dow AgroSciences), is a new plant growth regulator similar to 2,4-D and dicamba, but it isn’t a new mode of action. It’s active at very low use rates, rapidly degrades in soil and has no soil activity or residual control. Halauxifen controls only broadleaf weeds such as marestail, deadnettle, pigweed and lambsquarters, but is weak on common chickweed. Penn State hasn’t yet evaluated this product. But reports from other universities claim it has better activity on marestail than 2,4-D and similar control to dicamba. Halauxifen-containing products initially will include:

√ Elevore SC (halauxifen only). It will likely be labeled in 2017 for corn, small grains, pastures, turf and for burndown in soybeans. The initial label will allow a 14-day early preplant in soybean and corn. But this’ll likely be reduced at some point. It may be tank-mixed with glyphosate and other labeled herbicides to broaden the control spectrum.

√ Quelex 20.4WDG (halaxifen + florasulam). It is labeled for wheat, barley and triticale. It controls many common broadleaf weeds in cereals when applied to 2-inch to 4-inch-tall weeds. It can be tank-mixed with other herbicides to widen its control spectrum. Always include necessary adjuvants for effective control. Keep in mind it can be used in liquid fertilizer. There’s a three-month rotation to soybeans.

√ Zidua SC 4.17L (BASF). This is a liquid pyroxasulfone formulation, providing good control of several annual grasses and broadleaves in field and sweet corn, soybeans and wheat. It’ll have the same utility as the dry form and should be available for 2017.

Grass pastures and hay products
• Prowl H2O 3.8CS (BASF) is labeled for used on pastures and hayfields containing cool-season grasses with and without alfalfa — but not clovers or other legumes. It can be applied to established stands and tank-mixed with other forage herbicides during fall, spring or in-season between cuttings. While it controls many annual grasses and some broadleaves, its efficacy is affected by the rate you use. Prowl doesn’t control already emerged weeds. A split-application is recommended versus a single, high-rate early-season application. First application should occur in early spring (March) before weed germination. A second application right after first or second cutting should provide more residual control. While 4 pints of Prowl H2O may run $20 to $23 an acre, it might be worth it if annual weedy grasses are a problem. There are no grazing restrictions. But immediate over-seeding of forage species to thicken a stand might be challenging since the label requires a six-month wait for planting alfalfa and 10 months for grass species.

• Vastlan (Dow AgroSciences) is a new triclopyr-containing product, with a revised label permitting grazing. Also, Dow has reformulated triclopyr with a new choline salt formulation called Vastlan 4L to make it a low-volatile product. It’s on the market, but hasn’t yet been tested at Penn State.

For more details on these products, including active ingredients, control group classifications and suggested use rates, click on extension.psu.edu/pests/weeds. There, you’ll also find instructions for downloading a PDF copy of the 2016 Mid-Atlantic Field Crop Weed Management Guide for $10.

The 240-page guide provides strategies and herbicide tables for managing weeds in corn, sorghum, soybeans, small grains, legumes, grass forages and pastures. Problem weeds — burcucumber, henbit, horsenettle, horseweed/marestail, Palmer amaranth and waterhemp, common pokeweed, common and giant ragweed, and annual/Italian ryegrasses — are covered in detail. This regional guide was produced by Penn State Extension in cooperation with University of Delaware, University of Maryland, Virginia Tech and West Virginia University.