The objective of this research project is to evaluate efficacy of various combinations of postemergent herbicides formulations for broadleaf weed control in turfgrass. The research was conducted during the summer field season.Sunco

Carey, Ken C.

Jordan, Katerina S.

Lyons, Eric M.

The Atrium (Univ. of Guelph)

Efficacy of experimental herbicide products – 2015 summer trialE. Lyons, K. Jordan, and K. CareyDepartment of Plant Agriculture and the Guelph Turfgrass Institute, University of Guelph, Ontario.Sponsor: Suncor The objective of this research project is toevaluate efficacy of various combinations of post-emergent herbicides formulations for broadleaf weedcontrol in turfgrass.  MATERIALS / METHODS Plots were located in turf research area at theGuelph Turfgrass Institute, Guelph, ON.   Thesite was an area of established turf (predominantlyKentucky bluegrass and perennial ryegrass, infested with dandelion, clover and other lawn weeds).  Turf was maintained with typical high maintenanceturf regime: 1.5 kg actual N 100 m-2 per year in 3applications (spring, summer, dormant); P and K in a 4:1:4 ratio with N; irrigated to prevent stress prior to treatment application and to prevent dormancythereafter; mowed at 3 inches. The treatments were combinations of different rates and volumes of post-emergent herbicide, aswell as controls for a total of 16 treatments (see Table 1).  Each treatment was replicated four times in 1 x        2 m plots arranged in a randomized complete block design (Figure 1).  Plots were separated by 0.5 m buffer strips.  Treatments were applied in June 11, 2015, and reapplied June 13 (Treatments 10 and 13) and July 2 (all 3 week reapplications).  Broadcast treatments were applied with a compressed air sprayer (Teejet 8001VS flat fan nozzles - 5 ml/sec/nozzle at 20 psi).   Spot treatments were applied with a Chapin Stand’n’spray compressed air sprayer: target weeds were counted and total application amount recorded to give average treatment rate (ml/weed) (Table 2). An anecdotal photographic record of the experiment was kept.Table 1.  Treatments Treatment Broadcast rate Application 1 VNT2015-C1, 2 apps 3 wks apart -2187 ml m  Broadcast 2 VNT2015-C5, 2 apps 3wks apart 187 Broadcast 3 VNT2015-C7, 2 apps 3 wks apart 187 Broadcast 4 VNT2015-C9, 2 apps 3 wks apart 187 Broadcast 5 VNT2015-C10, 2 apps 3wks apart 187 Broadcast 6 VNT2015-C7, 2 apps 3 wks apart See Table 2 Spot1 7 VNT2015-C10, 2 apps 3wks apart See Table 2 Spot 8 VNT2015-C7, 1 app 93.5 Broadcast 9 VNT2015-C7, 1 app 187 Broadcast 10 VNT2015-C7, 2 apps 2 days (48hr) apart 187 Broadcast 11 VNT2015-C10, 1 app 93.5 Broadcast 12 VNT2015-C10, 1 app 187 Broadcast 13 VNT2015-C10, 2 apps 2 days (48hr) apart 187 Broadcast 14 Scotts weed-b-gone (FeHEDTA), 1app 187 Broadcast 15 Scotts weed-b-gone (FeHEDTA), 2apps 3 wks apart 187 Broadcast 16 untreated control — — 1thoroughly wet the weeds till lightly drip  Table 2.  Spot treatment details. Treatment Application Target weed Application rate count (ml/weed) 6  (C7) Jun 11 84.3±11.1 3.8±0.2 Jul 02 94.5±11 3.8±0.2 7  (C10) Jun 11 77.0±12.8 3.7±0.4 Jul 02 77.5±6.0 4.8±0.4 Guelph Turfgrass Institute 2015 Annual Research Report 1    All measurements were analysed by appropriate statistical analyses (general linear models).Data Collection:  Plots were rated pre-treatment for weed presence by visual ratings of broadleaf weed density and point quadrat measurement of weed cover.  Post-treatment measurements of weeds were taken at 2-3 weeks after treatment and later in the season. Plots were rated visually and using canopy reflectance (normalized-difference vegetation index) 2-3 days after treatment for phytotoxicity of treatments to broadleaf weeds and to grasses.   Environmental conditions were noted at treatment application and for 24 hours following.RESULTSEnvironmental data Daily air temperatures, evapotranspiration demand, and rainfall data for summer 2015 are presented in Figures 2 - 4.-100102030MinimumMaximumJun Jul Aug SepMay OctAir temperature (°C)Figure 2.  Daily air temperatures at GTI, summer 2015.02468Jun Jul Aug SepMay OctEstimated ET (mm)Figure 3.  Daily estimated ET at GTI, summer2015.0204060800200400600DailyCumulativeJun Jul Aug SepMay OctDaily rainfall (mm)Cumulative rainfall (mm)Figure 4.  Daily and cumulative rainfall at GTI, summer 2015.Visual ratings of phytotoxicity.   There was evidence on broadleaf weeds of oil-soaked leaves and necrosis within a few days after treatment (Table 3).  There was little evidence of phytotoxicity on grasses for the first few days, but then phytoxicity (slight browning of leaves) developed.  Patterns of phytotoxic effects on weeds were statistically significant among herbicide treatments, but the differences were not large. Reduction of the broadleaf weed populations in some of the plots/treatments made interpretation of visual estimates of phytotoxicity difficult, as there were few weeds to exhibit the effects.  Canopy reflectance.   Canopy reflectance, which can be correlated with photosynthetic activity and plant health, was reduced by all treatments relative to the control, though the reduction was not statistically significant after the first application (Table 4). Some of the reduction will have been from phytotoxicity to the weed populations, and some from the effects of the treatments on the turfgrasses; because there was not regrowth in the weed populations generally, the recovery in canopy reflectance is mostly due to recovery in the turf.  There were statistically significant differences among treatments on all dates, with the general pattern being similar to the visual phytoxicity data (see Figure 5).  Broadleaf weed control.   Broadleaf weed infestation in the plot area before treatment (May 29) was about 40.8% of the area, as estimated by point-quadrat counts (Table 5).  This is roughly equivalent to a visual rating of 6 (Figure 6 , Table 6).   Most of the weed present 2 Guelph Turfgrass Institute                           2015 Annual Research Report        Table 3.  Visual ratings of phytotoxicity in treated plots. Treatment Grass Weed5 DAT 19 DAT 5 DAT 19 DAT C1 0.0 b 0.0 b 2.0 abc 2.0 abc C5 0.0 b 0.3 ab 2.0 abc 1.8 a-d C7- 1 app 0.5rate 0.0 b 0.5 ab 1.3 bc 2.0 abc C7-1 app 1 rate 0.0 b 0.3 ab 2.5 ab 0.3 cd C7-2 app 0.0 b 0.8 ab 1.5 bc 2.5 a C7-48 hr 0.8 a 0.5 ab 3.0 ab 0.5 bcd C7-spot 0.0 b 1.3 a 2.0 abc 1.8 a-d C9 0.0 b 0.5 ab 1.5 bc 2.3 ab C10-1 app 0.5rate 0.01 b 0.0 b 1.3 bc 1.8 a-d C10-1 app 1 rate 0.0 b 0.3 ab 2.3 ab 0.5 bcd C10-2 app 0.0 b 0.5 ab 2.0 abc 2.3 ab C10-48 hr 0.0 b 0.0 b 4.0 a 1.0 a-d C10-spot 0.0 b 1.0 ab 2.3 ab 2.0 abc Control 0.0 b 0.0 b 0.0 c 0.0 d WBG-1 0.0 b 0.0 b 3.0 ab 0.0 d WBG-2 0.0 b 0.0 b 3.0 ab 2.8 a msd p=0.05 0.3 1.1 2.1 1.9  1 Visual ratings 0-10, 10 = most phytotoxicity.  Means of 4 replicates.  Means within columns followed by the same letter are not significantly different (Tukey’s HSD test, p=0.05). Table 4.  Canopy reflectance (NDVI) in treated plots. Treatment pre 0 DAT 4 DAT 13 DAT 14 DAT 18 DAT 27/6 DAT C1 0.5771 0.545 0.492 bcd 0.496 bc 0.480 cde 0.446 def 0.537 cde C5 0.576 0.533 0.495 bcd 0.502 bc 0.476 cde 0.447 def 0.526 def C7- 1 app 0.5rate 0.588 0.563 0.490 bcd 0.529 bc 0.503 b-e 0.442 ef 0.525 def C7-1 app 1 rate 0.588 0.563 0.452 d 0.504 bc 0.515 bcd 0.527 bc 0.581 abc C7-2 app 0.584 0.553 0.456 d 0.479 cd 0.449 e 0.369 g 0.476 f C7-48 hr 0.591 0.540 0.380 e 0.431 d 0.447 e 0.460 def 0.535 cde C7-spot 0.586 0.575 0.524 b 0.551 ab 0.532 bcd 0.481 cde 0.549 bcd C9 0.582 0.546 0.473 cd 0.510 bc 0.491 b-e 0.436 ef 0.533 cde C10-1 app 0.5rate 0.599 0.577 0.511 bc 0.548 ab 0.524 bcd 0.472 cde 0.552 bcd C10-1 app 1 rate 0.575 0.541 0.461 cd 0.528 bc 0.537 bc 0.534 bc 0.594 ab C10-2 app 0.592 0.556 0.481 bcd 0.508 bc 0.471 de 0.405 fg 0.490 ef C10-48 hr 0.583 0.546 0.400 e 0.471 cd 0.483 cde 0.510 bcd 0.574 a-d C10-spot 0.560 0.551 0.496 bcd 0.529 bc 0.508 b-e 0.456 def 0.527 def Control 0.593 0.577 0.583 a 0.608 a 0.611 a 0.605 a 0.614 a WBG-1 0.592 0.561 0.460 d 0.543 b 0.548 ab 0.560 ab 0.600 ab WBG-2 0.577 0.560 0.466 cd 0.521 bc 0.470 de 0.447 def 0.522 def msd p=0.05 NS NS 0.050 0.064 0.064 0.065 0.054 1Normalized-difference vegetation index: mean of 4 replicates; means within columns followed by the same letter are not significantly different (Tukey’s HSD test, p=0.05).   Guelph Turfgrass Institute                      2015 Annual Research Report 3    Table 5.  Total plot area (percent) covered by weed species pre-treatment (May 29, 2015) and post-treatment (July 15, 2015). Treatment Total weed Dandelion Clover Narrowleaf plantain Chickweed 05/29 07/15 Change 05/29 07/15 05/29 07/15 05/29 07/15 05/29 07/15C1 39.31 12.7 a-d -26.7 ab 24.3 4.0 9.7 8.3 ab 0.3 0.0 3.7 0.0 b C5 42.0 9.0 bcd -33.0 ab 19.7 1.3 14.7 7.0 ab 2.7 0.0 4.0 0.7 ab C7- 1 app 0.5rate 40.0 21.7 a-d -18.3 ab 14.0 3.7 21.3 17.7 a 0.0 0.0 4.3 0.0 b C7-1 app 1 rate 37.7 24.7 abc -13.0 ab 12.3 2.3 19.0 21.0 a 0.7 0.0 1.3 0.3 b C7-2 app 40.0 8.7 bcd -31.3 ab 15.7 1.3 20.0 7.3 ab 0.0 0.0 3.0 0.0 b C7-48 hr 42.3 19.3 a-d -23.0 ab 12.3 6.7 23.3 12.3 ab 0.0 0.0 5.3 0.0 b C7-spot 41.7 16.0 a-d -25.7 ab 16.7 2.0 21.7 14.0 ab 0.7 0.0 1.0 0.0 b C9 42.7 12.7 a-d -30.0 ab 12.3 1.7 20.3 10.7 ab 0.0 0.0 1.3 0.0 b C10-1 app 0.5rate 39.7 14.3 a-d -25.3 ab 19.0 1.0 17.7 13.0 ab 1.3 0.0 1.3 0.0 b C10-1 app 1 rate 38.3 23.7 abc -14.7 ab 20.0 4.0 13.0 18.0 a 0.3 1.0 2.0 0.0 b C10-2 app 42.3 8.3 cd -34.0 ab 16.0 1.7 18.0 6.7 ab 1.3 0.0 5.0 0.0 b C10-48 hr 43.7 21.3 a-d -22.3 ab 19.0 6.0 19.3 13.3 ab 1.3 0.0 3.7 0.3 b C10-spot 31.0 11.7 bcd -19.3 ab 11.0 2.0 12.7 9.3 ab 0.0 0.0 2.0 0.0 b Control 38.3 29.3 a -9.0 a 14.7 5.3 20.7 22.0 a 0.3 0.7 2.0 0.3 b WBG-1 49.0 25.3 ab -23.7 ab 14.3 5.3 29.0 18.0 a 1.7 0.3 2.7 1.7 a WBG-2 44.0 5.7 d -38.3 b 16.0 4.3 21.3 1.0 b 0.7 0.0 2.3 0.0 b msd p=0.05 NS 16.9 26.1 NS NS NS 15.5 NS NS NS 1.2      Birdsfoot trefoil Broadleaf plantain Black medic Bindweed Other  05/29 07/15 05/29 07/15 05/29 07/15 05/29 07/15 05/29 07/15  C1 1.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3  C5 0.7 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0  C7- 1 app 0.5rate 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3  C7-1 app 1 rate 3.7 0.3 0.3 0.3 0.0 0.0 0.0 0.0 0.3 0.3  C7-2 app 1.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0  C7-48 hr 1.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.3  C7-spot 1.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0  C9 5.7 0.0 2.7 0.0 0.3 0.0 0.0 0.0 0.0 0.3  C10-1 app 0.5rate 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3  C10-1 app 1 rate 2.7 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 0.7  C10-2 app 1.3 0.0 0.3 0.0 0.3 0.0 0.0 0.0 0.0 0.0  C10-48 hr 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0 0.0 1.7  C10-spot 5.0 0.3 0.0 0.0 0.3 0.0 0.0 0.0 0.0 0.0  Control 0.7 1.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0  WBG-1 1.3 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0  WBG-2 3.0 0.3 0.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0  msd p=0.05 NS NS NS NS NS NS NS NS NS NS  1Percent cover area estimated by point-quadrat weed counts:  75 points per plot x 4 replicates. 0 1 2 3 40.40.50.60.7Visual rating of phytotoxicity  (weed + grass)NDVI meanFigure 5.  Association between canopy reflectance (NDVI) and visual phytotoxicity ratings (sum ofweed + grass phytotoxicity), June 30, 2015 (19DAT).  Pearson r = 0.77.was dandelion and clover, with smaller amounts of narrowleaf plantain and mouse-eared chickweed . Other sporadic weeds which were included in the total weed counts were birdsfoot trefoil, broadleaf plantain, black medick, and field bindweed. There was significant reduction in total broadleaf weed by 13 days after the first application in some treatments. By two weeks after the reapplication there were significant reductions in visual weed presence in many of the treatments, with the exception of some of the single application and low rate treatments. By 4 weeks after the reapplication most of the treatments had less weed than the control, but the reduction was significant only in the iron chelate repeat application (WBG-2) .   Post-treatment point-quadrat weed counts taken 5 weeks after the first application (2 weeks 4 Guelph Turfgrass Institute                           2015 Annual Research Report   0 10 20 30 40 5002468% weed cover (point quadrats)Visual weed ratingFigure 6.  Association between point-quadrat weed cover estimates and visual weed ratings post-treat-ment.  Pearson r = 0.81.after reapplication) showed a decrease of about 24 percentage points, from 40% to 16.5% weed cover on average.  All of the treatments showed a decline in weed cover when assessed as the difference between pretreatment cover and post-treatment (Table 5). The weed cover in the control plots declined by 9 percentage points; as with the visual ratings, only the repeat WeedBGone treatment showed a significant decline in weed cover compared to the control.DISCUSSION AND CONCLUSIONS All of the treatments showed some controleffects.  The best effects early (2 weeks after 1application) were the two 48 hour repeat treatments, and later in the trial the 3 week repeat applicationtreatments at full rate.  Overall, only the iron chelate repeat application maintained a significantly lower weed presence than the control by the end of thetrial, though most other treatments had less weed, numerically.    Table 6.  Visual ratings of weed presence. Treatment Total weed Dandelion Clover Narrowleaf plantainBroadleafBirdsfoot plantain trefoil  13 DAT 19 35/14 67/46 35/14 67/46 35/14 67/46 35/14 67/46 67/4667/46C1 3.3 abc 1.8 cd 3.0 b-e 4.5 ab 1.3 2.3 2.5 ab 2.3 ab 0.0 0.0 0.0 0.0 C5 3.0 bc 2.5 bcd 3.5 b-e 4.5 ab 1.3 1.3 2.3 ab 2.8 ab 0.0 0.0 0.0 0.5 C7- 1 app 0.5rate 3.8 abc 3.8 bc 4.5 abc 5.0 ab 1.3 1.5 3.3 ab 2.5 ab 0.0 0.0 0.0 0.5 C7-1 app 1 rate 3.5 abc 5.0 ab 5.0 ab 5.8 a 1.3 1.0 3.8 a 4.5 a 0.0 0.5 0.3 0.3 C7-2 app 2.8 bc 1.3 cd 2.3 cde 4.5 ab 1.0 1.8 1.5 ab 2.3 ab 0.0 0.5 0.3 0.3 C7-48 hr 1.8 c 3.5 bcd 3.8 bcd 4.8 ab 1.5 2.0 2.5 ab 2.8 ab 0.0 0.0 0.0 0.0 C7-spot 4.5 abc 3.5 bcd 3.3 b-e 4.8 ab 1.0 1.3 2.8 ab 3.3 ab 0.3 0.0 0.0 0.0 C9 5.3 ab 2.8 bcd 3.5 b-e 5.0 ab 1.0 1.8 2.8 ab 3.3 ab 0.0 0.0 0.0 0.3 C10-1 app 0.5rate 3.8 abc 3.3 bcd 3.3 b-e 5.3 ab 1.3 1.8 2.3 ab 3.0 ab 0.3 0.5 0.0 0.0 C10-1 app 1 rate 4.3 abc 4.8 ab 5.3 ab 4.8 ab 1.5 2.5 3.5 a 2.5 ab 0.3 0.0 0.0 0.0 C10-2 app 3.0 bc 1.3 cd 2.0 de 4.3 ab 1.0 2.3 1.5 ab 2.3 ab 0.0 0.3 0.0 0.3 C10-48 hr 2.3 c 3.5 bcd 4.5 abc 5.3 ab 2.0 2.0 2.5 ab 3.3 ab 0.0 0.0 0.0 0.0 C10-spot 3.3 abc 2.8 bcd 2.3 cde 4.3 ab 1.0 1.5 2.3 ab 2.5 ab 0.0 0.0 0.0 0.3 Control 6.0 a 7.3 ab 6.3 a 5.8 a 2.0 1.3 4.0 a 3.5 a 0.0 0.8 0.3 0.3 WBG-1 3.3 abc 5.0 ab 5.0 ab 5.3 ab 1.3 1.5 3.5 a 3.5 a 0.3 0.5 0.0 0.0 WBG-2 2.3 c 1.0 d 1.3 e 3.3 b 1.3 2.0 0.8 b 0.8 b 0.0 0.3 0.3 0.3 msd p=0.05 2.8 2.5 2.4 2.2 NS NS 2.6 2.6 NS NS NS NS     1  Visual ratings 0-10, 10 = most weed.  Means of 4 replicates.  Means within columns followed by the same letter are not significantly different (Tukey’s HSD test, p=0.05). Guelph Turfgrass Institute                           2015 Annual Research Report 5

Efficacy of experimental herbicide products – 2015 summer trial

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Efficacy of experimental herbicide products – 2015 summer trial

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