2009 weed management in cotton
DESCRIPTION
2009 Weed Management in Cotton. Getting Serious About Herbicide-Resistant Weeds. Managing Herbicide Resistance Attitudes and acceptance Resistance is real It can happen on any farm; It can happen with any herbicide; resistance is not unique to glyphosate - PowerPoint PPT PresentationTRANSCRIPT
20092009
Weed ManagementWeed Management
in Cottonin Cotton
Getting Serious AboutHerbicide-Resistant Weeds
Managing Herbicide Resistance
Attitudes and acceptance
• Resistance is real
• It can happen on any farm;
• It can happen with any herbicide; resistance is not unique to glyphosate
• Far better to prevent it, but learn to deal with it if you already have it
0 20 40 60 80 100 120
No. cases
ALS inhibitors
PS II inhibitors (triazines)
ACCase inhibitors
Glycines
DNA’s
Ureas
Auxins
Arsenicals
Bipyridiliums
Thiocarbamates
PPO inhibitors
Carotenoid biosyn. inhibitors
Nitriles
Herbicide Resistance in US by Mode of Action
ACY 2008
Glyphosate-Resistant Horseweed
Identified in 16 states Initially found in NC in 2003 Slow increase during 2003-2007; less than expected Exploded in eastern NC in 2008
Glyphosate-Resistant Horseweed
Resistant biotype likely will be more prevalent in 2009
Wind-borne seed; easily moves long distances
East of US 1, assume it is glyphosate-resistant and act accordingly;
implement appropriate burndown program Photo by R. Hayes
Burndown Programs for
Glyphosate-Resistant Horseweed in
Cotton, Corn, Full-season Soybean
First choice:
Roundup + Clarity (1/2 pt)* + residual herbicide
Time of horseweed emergence in west Tennessee. Adapted from Main et al., 2006.
0
10
20
30
40
50
60
70
% o
f to
tal
Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug0
10
20
30
40
50
60
70
% o
f to
tal
Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Jackson 2002-03 Milan 2002-03
Burndown Programs for
Glyphosate-Resistant Horseweed in
Cotton, Corn, Full-season Soybean
First choice:
Roundup + Clarity (1/2 pt)* + residual herbicide
____________________________________________
* Waiting intervals required;
Apply mid-February to early March
Waiting Period after Clarity Preplant Application
Corn: no waiting period
Soybean: 14 days (for 8 oz rate)
Cotton: Following accumulation of 1 inch rainfall,
wait 21 days
Burndown Programs for
Glyphosate-Resistant Horseweed in
Cotton, Corn, Full-season Soybean
First choice:
Roundup + Clarity (1/2 pt)* + residual herbicide
Second choice:
Roundup + 2,4-D (1.5-2 pt)* + residual herbicide____________________________________________
* Waiting intervals required;
Apply mid-February to early March
Waiting Period after 2,4-D Preplant Application*
Cotton
Crops listed as use sites on this or other registered 2,4-D labels may be planted within 29 days of application. All other crops (cotton included here) may be planted 30 or more days following application without concern for illegal residues in the planted crop. However, under certain conditions, there may be a risk of injury to susceptible crops. Degradation factors should be considered in weighing this risk. Less risk if conditions following application include warm, moist soils. Under normal conditions, any crop may be planted without risk of injury if at least 90 days of soil temperatures above freezing have elapsed since application.
* Includes some brands of both amine and ester formulations.
Edgecombe Co., NC 2008 8 weeks after burndown
Untreated Roundup only Roundup + Valor
Roundup + Valor + Clarity Roundup + Valor + 2,4-D
Roundup + Valor + Clarity Roundup + Valor + 2,4-D
Untreated Roundup only Roundup + Valor
Edgecombe Co., NC 2008 12 weeks after burndown (and after two in-crop applications Roundup,except check)
Burndown Programs for
Glyphosate-Resistant Horseweed in
Cotton, Corn, Full-season Soybean
First and second choices:
Roundup + Clarity (1/2 pt)* + residual herbicide
Roundup + 2,4-D (1.5-2 pt)* + residual herbicide
Third choice:
Ignite (29 oz), temperature > 75F, at or near planting,
plus a residual
Fourth choice:
Gramoxone + PS II inhibitor (atrazine, Direx, Canopy, Linex)
(may not be adequate)____________________________________________
* Waiting intervals required
In-Crop Control of Glyphosate-Resistant Horseweed
Cotton: Ignite under hood (any variety)Ignite overtop LL variety
Ignite requires GOOD coverage
Ignite hooded on horseweed
(not LL cotton)
Oops!
Managing Glyphosate-Resistant Palmer Amaranth
Can’t ignore it and hope it goes away; it is not going away
• Prolific seed production
450,000 seed/plant grown in competition with
cotton (Sosnoskie and Culpepper, UGA)
Managing Glyphosate-Resistant Palmer Amaranth
Can’t ignore it and hope it goes away; it is not going away
• Prolific seed production
• Continued selection; can manage this
• Spread of resistance– Seed movement; equipment, gin trash– Pollen-mediated gene flow Pollen from resistant male can fertilize susceptible female at least 1,000 ft away;
resistant offspring (Sosnoskie and Culpepper, UGA)
Managing Glyphosate-Resistant Palmer Amaranth
Considerations in developing a management strategy
• Prevention is the goal; reduce seed bank
Managing Glyphosate-Resistant Palmer Amaranth
Considerations in developing a management strategy
• Prevention is the goal; reduce seed bank
• No POST salvage options in cotton
What is the implication?
Managing Glyphosate-Resistant Palmer Amaranth
Considerations in developing a management strategy
• Prevention is the goal
• No POST salvage options in cotton
• ALS resistance (Staple, Envoke, others) is wide-spread; multiple resistance
Weathermax 88 oz
Staple LX 10 oz
Managing Glyphosate-Resistant Palmer Amaranth
Considerations in developing a management strategy
• Prevention is the goal
• No POST salvage options in cotton
• ALS resistance (Staple, Envoke, others) is wide-spread; multiple resistance
• Increasingly concerned over potential for resistance to PPO inhibitors
PPO inhibitors for the Southeast
Corn Cotton Peanut Soybean
Aim
Cadet
Resource
Valor
Cobra
Reflex
Valor
Blazer
Cobra
Valor
Aim
Authority/Sonic
Blazer
Cadet
Cobra
Envive
Flexstar
Prefix
Reflex
Resource
Valor
Valor XLT
Impacts of Roundup Ready TechnologyOn Cotton Weed Management
1. Reduced or eliminated use of other herbicides
2. Allowed successful transition to no-till
3. Eliminated cultivation
Impacts of Roundup Ready TechnologyOn Cotton Weed Management
1. Reduced or eliminated use of other herbicides
2. Allowed successful transition to no-till
3. Eliminated cultivation
4. Unprecedented selection pressure
for glyphosate-resistant biotypes
Herbicide Resistance Management
(avoidance)
The focus must be on
reducing selection pressure.
Glyphosate Resistance Management (reducing selection pressure)
1. Minimize the seed bank
2. Do not depend entirely on glyphosate
Incorporate other modes of action, specifically residuals, into the program; most effective to do that on the front end
3. Use full rates
4. Start clean, stay clean
5. Take advantage of non-chemical control where practical;
cultivation or cover crops
6. Vigilance! Watch for escapes, do not let them seed out
Is this weed resistant?Want to risk it?
ACY 2008
GR Palmer Amaranth Management in CottonSoutheast Recommendations
• Herbicide program:– Aggressive preplant/preemergence program.
Palmer amaranth control by PRE herbicides; 40 days*
0 20 40 60 80 100
Cotoran
Prowl
Direx
Caparol
Reflex
% control
* Average of 5 locations; 2 in GA, 3 in NC. Very heavy infestations. No other herbicides included.
Staple (susceptible)
PRE herbicides in Palmer amaranth management system. Four locations, NC.*
50 60 70 80 90 100
No PRE
Prowl
Direx
Reflex
Staple
Prowl + Reflex
Reflex + Direx
Reflex + Staple
Direx + Staple
* All with glyphosate/s-metolachlor POST-1, glyphosate POST-2, conventional layby.
Palmer amaranth control by PRE herbicides; 40 days*
0 20 40 60 80 100
Cotoran
Prowl
Valor
Direx
Caparol
Reflex
Staple (susceptible)
% control
* Average of 5 locations; 2 in GA, 3 in NC. No other herbicides included.
Strip-Till After Valor Preplant
Waiting Intervals for Valor Preplant in Cotton
2 oz/acre
14 daysStrip-till, with tillage operation between Valor application and planting
21 days and
accumulation of
1 inch rainfall
No-till, with residue
30 days and
accumulation of
1 inch rainfall
Stale beds, no cover
GR Palmer Amaranth ManagementSoutheast Recommendations
• Herbicide program:– Aggressive preplant/preemergence program.
– Dual Magnum (or other metolachlor product)
early POST; to extend residual control
– Residual herbicide(s) lay-by
– Limit PPO inhibitors to one application/year
Roundup + 2,4-D burndownGram. + Reflex PRERoundup + Dual first POSTRoundup second POSTDirex + MSMA Layby
Glyphosate-resistant Palmer amaranth, Wayne Co., NC 2008;
PRE herbicide followed by Roundup tank mix
Most POST soybean herbicide labels
specify 6-leaf or 4-inch maximum
Palmer amaranth
Harmony SG label specifies 8-inch
maximum Palmer amaranth
ACY 2008
Untreated Atrazine-based program
Herbicide Resistanceand Crop Insurance
• Concern by insurance companies
• Failure to follow good farming practices
is not an insurable loss
• Keep records to document what you did,
and whose advice you followed
Get Serious About
Herbicide-Resistant Weeds