WEED OF THE WEEK: QUICK KEYS TO CONTROL*
 
Use a two pass approach for best results.
In corn: Start with Axiom down, and go back with Distinct post-emerge.*

In soybeans: Put Sencor, Authority, Prowl, Treflan, or Sonalan out, follow up with Flexstar or Cobra.*

*Please read transcript below for further explanation of recommendations, or call 1-800-274-3389 (Mon-Fri. 8am-5pm CT, Sat. 8am-12noon CT) with any questions.

B: Well, you've all seen today's weed before, but did you guess what it is?

D: It is kind of tricky, because redroot pigweed looks very similar to several other weeds, most notably waterhemp.

B: During the next few minutes, we'll talk about redroot pigweed, how to control it, and most importantly, how to distinguish it from waterhemp.

D: Redroot pigweed is an annual broadleaf weed. When we talk about small-seeded broadleaves sometimes on the show, this weed falls into that category. It is a very prolific seed producer, and its tiny seeds often show up wherever you spread manure.

B: While pigweed seeds can germinate very early in the spring, you may also see plants emerging almost any time during the spring or summer, which can make it a tough weed to completely control. To identify it, look for rounded leaves to be alternate going up the stem. Also, redroot pigweed has a shallow taproot, typical of many annual plants.

D: Redroot pigweed has a very misleading name. Yes, it is a pigweed, and it does have some degree of red coloring on its root system, but so do many other weeds. A better name for it would probably be hairy pigweed. You see, waterhemp and redroot pigweed are the two most commonly found members of the pigweed family, and they both have that red characteristic to part of their roots and stems. One distinguishing feature to look for is a rounded leaf tip on redroot pigweed, and a pointed leaf tip on waterhemp, but the big difference between them is that redroot pigweed is hairy, while waterhemp is not.

B: Well, I don't know if we'll get the name changed from redroot pigweed to hairy pigweed, but we can help you get it under control on your farm. The big reason why we need to know if you have waterhemp or redroot pigweed is that the ALS chemicals are very good on redroot, but lousy on waterhemp. In fact, many of the waterhemp plants in fields are completely resistant to the ALS products.

D: ALS herbicides include Pursuit, Scepter, Classic, Pinnacle, Raptor, Synchrony, Accent, Basis, and Beacon, as well as many others like Python, which is a component of Hornet. Now, although these products can not be expected to control waterhemp, they all have at least some activity on redroot pigweed. Again, though, you have to know exactly which type of pigweed you have, before you determine your plan of attack.

B: The key to controlling redroot pigweed, just like waterhemp, is to put a good base product down, then follow later on with another herbicide to control any escapes. Let's look at the best corn herbicides first.

D: Pre-emerge in corn, Balance is our number one choice for redroot pigweed. We recommend applying it immediately after planting, but you must spray before the corn emerges. The biggest problem with Balance is that it is not labeled for use in Minnesota, Michigan, or Wisconsin. In addition to that, Balance is not the strongest product on annual grasses like the foxtails. Therefore, many people turn to other products to get redroot pigweed plus kill most of the grass in fields. These herbicides include Surpass, Harness, Frontier, and Dual.

B: Just a reminder with the 4 pre-emerge corn products that Darren just mentioned, don't spray them out after planting and expect great results. As we've said many times before, you get the best results with Surpass, Harness, Frontier, and Dual when you shallow incorporate just prior to planting. If you want to spray these products out and not work them in, you certainly can. They aren't going to evaporate or anything, it's just a question of rainfall. If you spray them out early in the year, like March or early April, you have a pretty good chance to get a couple inches of rain before the weeds emerge. If you spray after you plant, though, your odds of getting sufficient rain get pretty slim.

D: Anyway, as long as you apply these products correctly, expect to kill upwards of 90% of the redroot pigweed. Another pre-emerge product that can give you similar performance in corn is DoublePlay. However, DoublePlay must be INSTANTLY incorporated. If you can't spray it on with your field cultivator, don't use DoublePlay.

B: Regardless of which pre product you use, the idea is to get most of the redroot pigweed under control.

D: Then, you can spray a herbicide post-emerge to get the rest of them. Distinct will again be our number one choice in 2001, but Clarity is also very effective. If you don't have a major problem with pigweeds, both Hornet and Buctril will give you fairly decent suppression, and by adding a half pound of atrazine to any of these products, you'll improve your performance, too.

B: The transgenic products like Liberty and Roundup, plus the Clearfield corn product Lightning, are real good on redroot pigweed, also. If you are concerned about planting GMO crops for this year, remember that Clearfield or IMI corn is not genetically altered. So you can certainly plant it and spray Lightning without any potential problems.

D: By using any combination of these corn products, you should be able to do a pretty decent job on redroot pigweed. In soybeans, there are also many choices that are all very effective.

B: Start by applying either Sencor, Authority, Sonalan, Treflan, or Prowl down. Remember that of these 5 products, only Sencor, Authority, and Prowl can be used in no-till. Also, if you have severe pigweed problems, you might want to consider mixing Sencor or Authority with one of the other 3 herbicides. The standard rates of Sencor and Authority will only cost about 6 to 8 bucks, so even if you mix…say, Treflan…with Sencor or Authority, you could still be under $10 an acre.

D: Post-emerge in soybeans, Flexstar and Cobra are maybe the most widely used products for redroot pigweed, but Pursuit is good, and a Classic/Pinnacle combination is probably even better. In Roundup Ready soybeans, Roundup doesn't have too tough a time with redroot pigweed as long as it is small. The key is to get it before it gets taller than 3 or 4 inches.

B: Once again, there are many chemicals that will control redroot pigweed in both corn and soybeans. The key to stopping pigweed is to use a product pre-emerge, and follow later on with another herbicide post.

D: Above all, when scouting for redroot pigweed, be sure to distinguish IT from waterhemp. To help you out, just think of redroot pigweed as hairy pigweed, and waterhemp as smooth pigweed.