Reemerging Weed Problem in Wisconsin

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Reemerging Weed Problem in Wisconsin

  1. 1. Reemerging Weed Problem in Wisconsin -or-What was Old is New Again<br />Tim Trower, Mark Renz, Bryan Jensen and Larry Binning<br />University of Wisconsin<br />
  2. 2. The Culprits<br />
  3. 3. Why the Resurgence?<br />Both weeds are perennials<br />Shift to reduced and no-till tillage systems favors both weeds<br />Changes in herbicide programs may favor survival<br />Glyphosate not always the most efficacious program<br />Application timing may not be optimum<br />
  4. 4. Dandelion- Taraxacum officinale“Built to Last”<br />Deep-rooted perennial<br />Tap root can reach six feet in length<br />Early riser in the spring<br />Are some of the first weeds to green-up in the spring<br />Early seed production<br />Begins in late April or early spring at the Arlington Research station<br />Seeds are viable and can germinate the same year<br />
  5. 5. Dandelions“Application timing, what is best?”<br />Weed biology can make optimum application timing difficult<br />Fall applications traditionally are the most efficacious<br />Translocating herbicides such as glyphosate and the synthetic auxins move into the tap root<br />But application timing is limited by harvest and weather<br />
  6. 6. Dandelions“Application timing, what is best?”<br />Spring applications have been less effective<br />Application timing can be delayed by weather and planting interval<br />Trials conducted at the Arlington Research Station in 2009 and 2010 to determine dandelion control with fall and spring applications<br />Application information:<br />RCB, four replicates, 10’ X 25’ plots<br />20 GPA, XR8003 tips, 23 PSI, 3 MPH<br />
  7. 7. Dandelion ControlFall compared to Spring Applications<br />
  8. 8. Percent Dandelion ControlFall Compared to Spring<br />
  9. 9. Dandelion ControlFall applied and evaluated the following spring<br />Canopy EX @ 1.1 oz/a +<br />2,4-D @ 16 fl oz +<br />PowerMax @ 21 fl oz<br />2,4-D @ 32 fl oz +<br />PowerMax @ 21 fl oz<br />Synchrony @ 0.375 oz/a +<br />2,4-D @ 16 fl oz +<br />PowerMax @ 21 fl oz<br />Enlite @ 2.8 oz/a +<br />PowerMax @ 21 fl oz<br />
  10. 10. Conclusions<br />Fall-applied Canopy EX, Synchrony and Enlite tank mixes all provided better dandelion control at spring green-up that 2,4-D/glyphosate.<br />All fall-applied treatments gave better early-season dandelion control which coincides with normal corn planting.<br />Conversely, spring-applied 2,4-D/glyphosate, Synchrony and Enlite tank mixes provided better late-season dandelion control which coincides with normal soybean planting.<br />
  11. 11. Conclusions<br />Fall-applied Canopy EX followed by an in-season glyphosate application provided 93% dandelion control at harvest.<br />Dandelion growth stage is important<br />Seedlings much easier to control than mature plants<br />Spring applications of contact herbicides generally do a good job on the seedlings<br />No yield differences were observed. <br />
  12. 12. Percent Dandelion Control:Fall-applied treatments<br />
  13. 13. Conclusions<br />Autumn, Canopy EX, Synchrony, Express and Sharpen tank mixes all provided 90% or greater dandelion control at spring green-up.<br />Dandelion control decreased with most treatments at the mid and late evaluations.<br />The Canopy EX tank mix was the best overall treatment, followed by Autumn and Express tank mix.<br />No yield differences were observed. <br />
  14. 14. Field Horsetail- Equisetum arvensePlant Biology<br />Perennial <br />Spreads by rhizomes and spores<br />Tan-colored stalks are the first to emerge in the early spring-<br />Followed by the<br />vegetative stage-<br />
  15. 15. Field Horsetail<br />Competitive plant that can cause yield reductions.<br />Generally starts at the edge of the field and slowly spreads.<br />Favors low spots<br />Three trials were conducted in 2009 and 2010 in grower fields.<br />Application information:<br />RCB, four replicates, 10’ X 25’ plots<br />20 GPA, XR8003 tips, 23 PSI, 3 MPH<br />
  16. 16. Field HorsetailAddition Information<br />With the exception of two treatments, Dual II Magnum plus atrazine was applied preemergence to reduce competition from non-target weeds.<br />Postemergence herbicide treatments were targeted for corn at the V3 growth stage.<br />Plots were hand-harvested in 2009 and machine harvested in 2010.<br />
  17. 17. 2009 Monroe County Percent Ground Cover<br />Means followed by same letter do not significantly differ (P=.05)<br />
  18. 18. 2009 Columbia County Percent Ground Cover<br />Means followed by same letter do not significantly differ (P=.05)<br />
  19. 19. 2010 Sauk County Percent Ground Cover<br />Means followed by same letter do not significantly differ (P=.05)<br />
  20. 20. ConclusionsField Horsetail<br />Results between years and locations were variable.<br />Steadfast/Status applied postemergence provided the best field horsetail control in two studies.<br />Steadfast/Hornet applied postemergence was effective in one study.<br />Soil-applied programs provide varying degrees of suppression but were generally ineffective after mid-season.<br />Python applied preemergence provided acceptable control in only one trial.<br />Significant yield decrease in one study.<br />
  21. 21. Summary<br />Both weed species are favored by reduced tillage.<br />Both species require a system approach to provide best results:<br />Scout fields often, don’t let the weed increase in the “background”<br />Crop rotation<br />Sequential herbicide applications<br />Application timings<br />Fall compared to spring<br />Tillage?<br />May be required under severe weed pressure<br />

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