> From: Charles Benbrook <firstname.lastname@example.org>
> To: email@example.com
> Subject: RR Beans, Alfalfa and Plant Back Restrictions
> Date: Wednesday, March 24, 1999 12:37 PM
> There are no crop rotation or plant back restrictions associated
> with any uses of Roundup, whether with a GMO variety or not. Roundup
> down quickly and is not persistent, which is why it must be applied two
> three times in most RR systems.
> The information on restrictions against planting alfalfa (or many
> other rotation crops, cover crops and grasses/legumes) probably was in
> reference to imidazolinone or sulfonylurea resistant corn or beans
> varieties. These products typically have a 12 month or more crop
> restriction, in some cases, much more (see below).
> Some major soybean herbicides by class associated with GMOs and
> of the crop-rotation or plant-back restrictions are briefly reviewed
> Soybean herbicide percent acres treated data are from USDA/NASS, for
> Plant back, crop rotation restrictions are from pages 143 to 168, section
> soybeans, in "Weed Control Manual," Meister publication, Vol. 31, 1998.
> Chlorimuron-ethyl (Classic), 13% national soybean acres treated. Plant
> depends on soil Ph and region, have to see the label, but is surely 12 to
> months or longer for most crops.
> Sulfentrazone+chlorimuron-ethyl (Authority), new product, market-share
> unknown. Canola, beets, 30 months. Alfalfa, sorghum, 42 months. (Recall
> one reason the low doses work is because of the chemical' persistence;
> persistence=longer plant back restrictions, and more undiagnosed (and
> diagnosed) crop injury when, for one reason or another, herbicide
> in the soil take longer to break down than "normal").
> Sulfentrazone (Cover). New product. Alfalfa, 12 months. Many other
> 12-18 months, and rest, 30 months.
> Imazaquin (Scepter), 13% acres treated. Most crops, 18 months (include
> alfalfa). Sugar beets, 24 months.
> Imazethapyr (Pursuit), 38% acres treated (average rate of only 0.05
> a.i. per acre). Potatoes, 26 months. Sweet corn, 18 months. All other
> crops 40 months after application. (So much for cover crops, small grain
> rotations, alfalfa, etc, on 1/3 of soybean acres).
> Clomazone (Command). 5% acres treated. No crop rotation until 16 months
> after planting in Northern U.S., 12 months elsewhere.
> Clearly, some herbicide tolerant plant varieties are going to
> some serious localized problems. Application rates tend to be a bit
> and repeat applications are much more common in herbicide tolerant
> One reason -- herbicide/GMO-seed companies are, in effect, guaranteeing
> "satisfactory" weed control, and give growers the chemical needed for
> season resprays. These extend the crop rotation restrictions, but more
> worrisome, can lead to runoff following an early summer thunderstorm.
> Imagine what a little of these herbicides will do to that nice new
> waterway, or grass filter strip, half or 3/4 paid for with public
> as runoff flows over the newly established grass stand. Also, expanded
> of these technologies will lead to more problems among neighbors when
> drift, runoff, or volatization (and drift) lead to herbicide injury in
> nearby fields.
> Charles Benbrook 208-263-5236 (voice)
> Benbrook Consulting Services 208-263-7342 (fax)
> 5085 Upper Pack River Road firstname.lastname@example.org [e-mail]
> Sandpoint, Idaho 83864 http://www.pmac.net
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