Dandelions and Eclipse

[rook]

This cool wet weather really favours dandelions and there are some monsters in crop. What is better - Eclipse or upping the rate of Roundup? or are there other options

[JoeyPotato]

Isn't Eclipse just Vantage Plus and Lontrel?

If wanted it hotter could a person add some more van
plus?

[Partners]

If your spraying RR canola. Just use the .66 rate and they should be gone...Anything less just gets the weeds mad....

[silverback]

Don't cheap out on dandelions. Use it and add more vantage if you have em bad. You only get to use that product once every 4 years so just do it!

[wd9]

If you check the crop protection book dandelions aren't listed as even suppression for lontrel. Save your money.

[silverback]

Have you ever even used lontrel? If not, you have no idea what it does to dandelions and thistles! It is an incredible yet old product as I used it years ago and I am really old.

Eclipse III will give season long control of big dandelions and if you add more vantage it will kill em dead.

[mcfarms]

we always have a few cases of eclipse on hand it is the cheapest lontrel you can buy and lontrel kicks the crap out of dandelions very very well cetainly removes them as seed producing and competition in this crop, florasulam is real strong too ie prepass or frontline but a little tough on canola.

[mcfarms]

more to this we did trials last year and found as silverback says eclipse plus a little extra maverick is hell on them we reduced the lontrel portion by .25 and .5 and saw still excellent results so much depends on growing conditions.<<
Though think its high time we saw generic lontrel as it has to be off patent and is crazy expensive on its own.

[wd9]

Its suppression only although it "looks" deader with clopyralid, its not. Season long control if small with no regrowth, but it is not dead. Even says so on the label and crop protection book. Dandelions are tough which is why so many fields are a battle. Florasulam and glyphosate post harvest is the best and seems the only true kill method so save your money for that. Kristen Hacault's research is the only and most thorough to have actually done it and was funded by NSERC and Dow for her masters.

Dandelions are a bugger which is why they are everywhere. There are also many biotypes and while some die with a wiff of 2,4D most others do not and we end up selecting the worst and toughest eventually. Vantage may control a few, but you are just going to select a tougher species which will not be controlled and the problem is back.

Some areas it seems dynamite is becoming the herbicide of choice. Certainly my experience. Mileage will vary based on biotype and is my only point.

[wd9]

Not all of it, but a lot of good reading. I will try to find it on the web in completion.

Kristin M. Hacault
Department of Plant Science, University of
Manitoba, Winnipeg, MB R3T 2N2, Canada
Rene C. Van Acker
Corresponding author. Department of Plant Science,
University of Manitoba, Winnipeg, MB R3T 2N2,
Canada; renepvanpacker@umanitoba.ca

In the northern region of the northern Great Plains of North America, the relative
abundance of dandelion in field crops has increased over the past two decades, and
farmers need information to help them to better manage this species and slow its
spread. A study was conducted to determine the emergence timing of dandelion
from both rootstock and seed, and to investigate the efficacy of preseeding (spring)
versus postharvest (autumn) herbicide treatments on dandelion in spring wheat
fields. Emergence of dandelion plants from rootstock was very early (mean time to
50% emergence [E50] of 430 growing degree days [GDD] Tbase 0 C), while seedling
emergence was much later (mean E50 of 980 GDD). Dandelion does not have a
persistent seed bank, and seedling emergence occurred only after dandelion plants
arising from rootstock flowered and shed seed. Herbicide treatments that included
glyphosate plus florasulam, glyphosate plus tribenuron, or higher rates of glyphosate
alone ($675 g ae ha21), provided high levels of dandelion control. Autumn herbicide
applications were more effective than spring applications for reducing dandelion
infestation levels (both aboveground biomass and density). Autumn herbicide applications
came after peak emergence timing for dandelion plants emerging both from
rootstock and from seed. Because dandelion is a simple perennial, population spread
must be limited by controlling seedlings. Autumn herbicide applications provide
control of dandelion seedlings and therefore, should limit dandelion population
spread.

Monitoring Dandelion Emergence
Three permanent 0.25 m2 quadrats were established in
each nontreated control plot and dandelion plants emerging
within these quadrats (and number of flowering dandelion
plants) were counted every 3 to 5 d. Newly emerged dandelion
plants were tagged using colored rings with a unique
color for each assessment date. Plants were deemed to have
emerged from rootstock if cotyledons were absent and there
was a prominent midvein present on true leaves (Stewart Wade et al. 2002). Emergence assessments began immediately
following snow melt, and any dandelion plants present
on the first assessment date of the year were assumed to
have overwintered and were not included in the cumulative
emergence counts. No dandelions were removed from within
monitored quadrats and plants were not protected during
seeding operations, but quadrats were covered with plastic
sheets at the time of in-crop herbicide application. Emergence
assessments continued into the growing season until
dandelion emergence (from either rootstock or seed) ceased
for a period of at least 14 d.

Efficacy Measures
After crop harvest, dandelion plants were counted in three
0.25 m2 quadrats placed randomly in each plot. Dandelions
originating from rootstock or seed were counted separately
using the discriminating characteristics described earlier. At
the same time, aboveground dandelion shoot biomass was
also determined for plants originating from rootstock or
from seed by harvesting aboveground biomass within three
randomly placed 0.10 m2 quadrats in each plot. Harvested
material was dried at 80 C for 48 h and weighed.
Wheat was harvested using a small-plot combine. Harvest
samples were placed in cloth bags at room temperature in a
room with enhanced air flow for a minimum of 3 d before
being cleaned and weighed. For each plot, subsamples of
100 g of clean grain were taken, dried for 48 h at 80 C and
weighed, and harvest sample weights were then corrected to
14.5% moisture content.

Efficacy Measures
After crop harvest, dandelion plants were counted in three
0.25 m2 quadrats placed randomly in each plot. Dandelions
originating from rootstock or seed were counted separately
using the discriminating characteristics described earlier. At
the same time, aboveground dandelion shoot biomass was
also determined for plants originating from rootstock or
from seed by harvesting aboveground biomass within three
randomly placed 0.10 m2 quadrats in each plot. Harvested
material was dried at 80 C for 48 h and weighed.
Wheat was harvested using a small-plot combine. Harvest
samples were placed in cloth bags at room temperature in a
room with enhanced air flow for a minimum of 3 d before
being cleaned and weighed. For each plot, subsamples of
100 g of clean grain were taken, dried for 48 h at 80 C and
weighed, and harvest sample weights were then corrected to
14.5% moisture content.

Herbicide Efficacy
For all site-years, the aboveground dry biomass of dandelion
plants originating from rootstock as assessed postharvest
was greatest in the nontreated controls (ranging from
9.2 g m22 at Site 3-03 to 141.6 g m22 at Site 2-04), although
in some instances the control was not significantly
different from all herbicide treatments (Table 8). Aboveground
biomass of dandelion plants from rootstock was
greater in 2004 vs. 2003, perhaps because cool, wet summer
conditions, like that experienced in 2004, favor aboveground
biomass production in dandelion (Stewart-Wade et
al. 2002). For both sites in 2004, all herbicide treatments
significantly reduced dandelion growth as measured by shoot
dry biomass when compared with the nontreated control.
For 4 of the 5 site-years, an autumn application of 675 g
ha21 of glyphosate plus 7.5 g ha21 of florasulam (Treatment
10) provided 100% efficacy, reducing dandelion aboveground
biomass to 0 g m22 (Table 8). The other autumn
applied treatments provided only slightly less dandelion control.
For 2 of 5 site-years (Sites 1-03 and 2-04), Treatments
4, 6, 8, 10, and 12 were significantly more effective when
applied in autumn vs. spring. The largest and most consistent
differences in efficacy between autumn and spring treatments
were observed at Site 2-04. For example, the autumnapplied
rate of 675 g ha21 of glyphosate (Treatment 4) resulted
in more than a 30-fold greater reduction in dandelion
aboveground biomass compared with the same rate applied
in the spring (Treatment 5) (Table 8). In spring canola
grown on the NGP, Froese et al. (2005) also found that
postharvest applications of glyphosate were more efficacious
on dandelion than were preseeding, in-crop, or preharvest
applications. Late-season applications of herbicides to perennial
weeds, such as dandelion and Canada thistle, provide
enhanced control, probably due to enhanced translocation
of herbicides to underground storage organs via the photoassimilate
stream (Stewart-Wade et al. 2002; Wilson and
Michiels 2003).
Generally, herbicide treatments did reduce the density of
dandelion plants from rootstock (Table 9), but the effect on
density was not as pronounced as the effect on aboveground
dry biomass. Similar to the results for aboveground dry bio mass, autumn herbicide applications tended to provide a
greater reduction in density than spring (preseeding) applications.
Again, the most efficacious treatments generally
were glyphosate applied in the autumn at the higher rates
(Treatments 4 and 6) or glyphosate 1 florasulam (Treatments
8, 10, and 12) applied in the autumn. The autumnapplied
treatment of 675 g ha21 of glyphosate plus 7.5 g
ha21 of florasulam (Treatment 10) resulted in a density of
0 plants m22 at 4 of 5 site-years, making it the most consistent
and efficacious treatment in this study. The remaining
autumn-applied florasulam 1 glyphosate treatments
(Treatments 8 and 12) and the highest rate of glyphosate
(Treatment 6) also provided good control, reducing the density
of dandelion plants from rootstock to 0 plants m22 in
at least 2 of 5 site-years. Generally, reduced control was
observed when these same treatments were spring applied.
For example, at Site 3-03 dandelion densities for the springapplied
treatments were not significantly different than the
nontreated control with the exception of spring-applied glyphosate
plus tribenuron (Treatment 15). Although there are
physiological reasons why autumn herbicide applications
provide greater efficacy on perennial species, the reduced
efficacy of spring-applied herbicide treatments on the density
of dandelion plants from rootstock was also related to
emergence timing. Although the emergence of dandelion
plants from rootstock occurred early in the spring (mean
E50 of 430 GDD) (Figure 1), a large proportion of these
plants emerged after the spring (preseeding) herbicide treatments
were applied (mean spring preseeding herbicide treatment
application timing was 280 GDD).
The herbicide treatments in this study had no effect on
dandelion seedlings (density or aboveground dry biomass)
(data not shown) because the herbicide treatments were all
applied before dandelion seedling emergence (treatments
were applied either postcrop harvest in the previous year or
before crop seeding in the given year). Additionally, the incrop
herbicides applied in the spring wheat crop in this
study were applied well before dandelion seedling emergence
had ceased. The mean in-crop herbicide application timing
was 720 GDD, whereas the mean E50 for dandelion seedlings
was 980 GDD (Figure 1). In this region of the NGP,
E50 values for common annual weed seedlings are typically
between 400 and 600 GDD (Bullied et al. 2003), and incrop
herbicide applications are well-timed for control of
emerged seedlings. However, in this study, at 720 GDD an
average of only 10% of dandelion seedlings would have
emerged, and the great majority of seedlings would escape
the in-crop herbicide application. Dandelion is a simple perennial
species and population spread depends on seed
spread and successful seedling emergence and survival (Solbrig
and Simpson 1974). Therefore, controlling dandelion
seedlings is crucial for limiting population spread, but the
timing of in-crop herbicide applications makes them ineffective
for limiting the spread of dandelion populations.
For all site-years, herbicide treatments resulted in significantly
higher wheat yields compared with the nontreated
control, but there were few significant differences in wheat
yield among the various herbicide treatments (Table 10).
There was a strong relationship between wheat yield and
dandelion aboveground dry biomass assessed postharvest
(Pearson correlation coefficients of 20.62 and 20.54 in
2003 and 2004, respectively). These results suggest that
180 x Weed Science 54, January–February 2006
dandelion is competitive in wheat and can cause significant
wheat yield loss. For most site-years, wheat yields tended to
be higher for autumn versus spring applied herbicide treatments,
but these differences were rarely significant.
In summary, the results of this study suggest that for
farmers on the NGP who are experiencing increasing dandelion
populations in annual field crops such as spring
wheat, autumn herbicide applications (postharvest) are more
effective than spring (preseeding) applications for reducing
dandelion infestation levels (both aboveground dry biomass
and density). Autumn application timing is suited to the
developmental physiology of dandelion, which facilitates the
movement of herbicides into the regenerative root structures
in the autumn, and because the autumn timing follows the
peak emergence timing both for dandelion plants emerging
from rootstock and from seed. In this study, herbicide treatments
that included glyphosate plus florasulam, glyphosate
plus tribenuron, or higher rates of glyphosate alone ($675
g ha21), provided the greatest levels of dandelion control.
Because dandelion is a simple perennial species, population
spread must be limited by controlling seedlings. In this
study, the normal timing of preseeding and in-crop herbicide
applications were too early to provide control of emerging
seedlings. Autumn herbicide applications provide control
of dandelion seedlings and should effectively limit population
spread.

[wd9]

So in summary, get the seedlings in the late fall with a shot of roundup high enough, or roundup and sulfons or roundup florasulam and get the little buggers late fall. But it usually snows and we are screwed.

[mcfarms]

I think all apporaches have to be used in the dandelion war, starvation seems to work best keep them sick and they die. The fall prepass with a extra .5 lite of glyphosphate seems to be working well at both reducing populations as well as reducing the need to do a preburn in spring. Dis some last Sept. that still hasn't required attention.
You are right about fall spraying and frosts.

[silverback]

That is a line of crap. We have wiped out HUGE dandelions with eclipse with extra vantage in RR canola.

Just because the book doesn't list it doesn't mean it isn't effective. It means nobody has spent the money to get a claim.

Hoping to go spraying post harvest before it freezes in the fall with a little 24D is the reason that some of these weeds spread across the country.

[cottonpicken]

I hit some that where 12 inches in diameter with that
heat product seems to have done a good job,will know
later

[silverback]

Why do you suppose she didn't try adding lontrel in the trials?