Seminole Crop E News

Agricultural News for Farmers and Agribusiness in SW Georgia

Killing Pigweed with Ignite

Posted by romeethredge on June 30, 2011

Ignite herbicide can kill pigweeds. We’re having trouble killing resistant pigweeds and we’re fortunate to have Ignite as something else in our arsenal to control emerged pigweed. It can only be used on certain varieties however.  In the photo below are Rob Millings, Keith Rucker and Eddie Hatcher with Bayer Cropsciences looking at a dead pigweed in some Fibermax Liberty Link Cotton treated with Ignite.

Here’s some info from Dr Stanley Culpepper, UGA Extension Crop Scientist, concerning Ignite use.

Weed Management in Liberty Link Cotton

Liberty Link refers to transgenic cotton resistant to the herbicide glufosinate, which is sold under the trade
name Ignite 280.

Timing of Application

Liberty Link cotton has excellent tolerance of Ignite 280. Ignite can be applied overtop of Liberty Link cotton
from emergence until the early bloom stage without concern over injury or fruit
shed. On cotton larger than about 10 inches, a semi-directed application may be
preferred in order to obtain better coverage on weeds under the cotton canopy.

The optimum weed size for treatment with Ignite 280 varies, depending on the weed species and growing conditions.
Pigweed species, Palmer amaranth, tropic croton, spurred anoda, velvetleaf, Florida
beggarweed, eclipta, groundcherry, spotted spurge, common purslane, and annual
grasses should be no more than 3 inches tall. Goosegrass should be 2 inches or less. Under dry or other stressful
conditions, Palmer amaranth and all annual grasses should be 2 inches or smaller when treated.

 Application Equipment

Ignite 280 behaves much like a contact
herbicide. Hence, good spray coverage is necessary. The label recommends
flat-fan nozzles, 30 to 60 psi, and a minimum of 15 gallons per acre spray volume.
Drift-reducing nozzles, such as air-induction nozzles that are commonly used to
apply glyphosate, are not appropriate for Ignite 280 applications.
Drift-reducing nozzles produce large droplets which may not give adequate spray
coverage for a contact herbicide.

Glufosinate-based
Systems in Phytogen WideStrike Cotton

Cotton designated as Widestrike
contains two transformation events that express two deltaendotoxins which
confer resistance to lepidopteran pests. Both of these events also contain the phosphinothricin
acetyltransferase (pat) gene which was inserted for use as a selectable
marker during plant transformation. The pat gene confers resistance to
glufosinate.

Tolerance of varieties with the
WideStrike trait to Ignite (glufosinate) is not complete. In contrast to
LibertyLink cotton, which is higly tolerant to Ignite, some injury will occur
when Ignite is applied to WideStrike cotton. The injury is most often leaf
burn, and can range from very minor to rather significant. Research in Georgia
has not shown significant yield reduction of WideStrike cotton from two Ignite
applications at 29 fl oz applied twice at 1- to 3-leaf cotton and again at 5- to
7-leaf cotton. Rates in excess of 29 fl oz should not be applied, and ammonium
sulfate or any other adjuvants should not be included. Additionally, it is critical that applications after 8 leaf be avoided
as yield loss will likely occur
from applications near bloom.

Most Phytogen varieties with the
WideStrike trait also contain the Roundup Ready Flex trait. Hence, Ignite and
glyphosate can be applied to these varieties. However, tank mixing Ignite and glyphosate
is not recommended. Glyphosate does not impact the activity of Ignite, but
Ignite can antagonize glyphosate.

According to the recent EPA
interpretation, Ignite 280 herbicide can be applied to WideStrike cotton.
However, the grower is liable for any crop injury resulting from the
application. Neither Bayer Crop Science nor Dow AgroSciences/PhytoGen recommend
or warrant the use of Ignite on WideStrike cotton.

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