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Weed Trials: Summaries

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Weeds - General

Effect of Alternative Control Products on the Reduction of Dandelion in Turf (2011)

J.B. Ross and M.A. Anderson

A number of alternative weed control products were tested at three sites throughout western Canada.  Two applications of each of the products were applied in July and August, 2011.  Killex 500 was the only product that gave consistent control of dandelion.  At the Lethbridge site the Fiesta appeared to provide good control three weeks after the second application of product.  Label recommendations state that two or more applications of this product may be necessary to achieve weed control.  The non-selective herbicides and the compost did not reduce dandelion counts in these trials.

Effect of Velocity SP Herbicide on Annual Bluegrass Populations in Creeping Bentgrass (2010)

James B. Ross

This trial was established to assess the effectiveness of Velocity SP for the removal of annual bluegrass in creeping bentgrass turf.  A second objective was to evaluate the use of a backpack sprayer for application of the product.  Applications commenced July 8, 2010 and were applied weekly for a period of six weeks.  Product applications did not result in the reduction of annual bluegrass spots or overall percentage.  It was thought that the rate of application of the product may not have been insufficient to reduce the annual bluegrass populations.  Application to small plots with a backpack sprayer was not an effective method to apply this product.

The Effects of Fall Applied Velocity SP Herbicide on Annual Bluegrass Reduction (2010)

James B. Ross and Mark A. Anderson

The objective of this trial was to test the effectiveness of the herbicide Velocity SP when applied in the cooler fall period.  Small reductions in annual bluegrass populations occurred following four applications of the product at the highest rate of application.  However, there was also a high level of turf injury, which would likely be unacceptable to a Golf Course Superintendent.  Results of this trial would indicate that Velocity SP applied in the fall is not effective and that applications need to commence and be complete prior to the onset of cooler temperatures.

Effect of Alternative Control Products on the Reduction of Dandelion in Turf (2010)

J.B. Ross and M.A. Anderson

Three registered weed control products, that are marketed as alternatives to traditional chemical herbicides were tested on Olds College campus.  Two applications of each of the products were applied under warm and sunny conditions.  Sarritor proved to be ineffective and at no time over the eight week trial period was there any mycelium formation or damage to the dandelion.  For both the Weed B Gon and Adios Ambros, an initial discolouration and distortion of the dandelion leaves occurred.  However, by day 14 new shoots were observed growing from the crowns of the dandelion.  By day 56 after the first application there was only a 10% reduction in dandelions.

Recovery of Dandelion from Sub-Lethal Doses of the Herbicide, Killex

J.B. Ross, M.A. Anderson and D.K. Tompkins

The objective of this study was to determine if there was re-growth from the root stock of dandelion following the application of the herbicide, Killex.  This trial commenced in 2007 and will be completed in the fall of 2008.  Results are preliminary at this time.

Literature Review: Non-pesticide Control Options for Dandelions in Turfgrass

Darrell K. Tompkins

Turfgrass refers to the use of grasses for functional, recreational and ornamental purposes (Beard, 1973).  Since these grasses are mowed, particularly for recreational use, their ability to resist the encroachment of weeds is reduced.  Consequently, controlling weeds, such as dandelions, in turf using herbicides has become a common practice in the management of turfgrasses.

About 44 tonnes of herbicides were applied for weed control on home lawns and gardens in Alberta in 1998 (McLean, 2000).  Several additional tonnes of herbicides were applied to other urban and suburban settings such as school grounds, municipal parks and golf courses.  In Calgary parks alone, about 3.5 tonnes of herbicides, accounting for 98% of pesticides used, were applied for weed control in 1998 (Alberta Environmental Protection, 1998).  The intensive use of synthetic chemical herbicides in urban and suburban areas has resulted in concerns about environmental sustainability and other societal concerns including public health. 

Some municipal governments in Canada and other countries have proposed a ban on pesticide use in residential and other public areas. In some areas, these bans have already been implemented.  Therefore, the development of alternative tools for weed control in home lawns and gardens, school grounds, and municipal parks is needed. Dandelion control is a particular problem.

Injury to Turf and Weeds Following Application of Mustard Products

M.A. Anderson, J.B. Ross and D.K. Tompkins

This test was established to determine if there were any injury effects on turfgrass and weeds following the application of two mustard products.  Two forms of yellow and oriental mustard were tested at three different rates of application.  Injury symptoms were rated on a weekly basis for four weeks following application.  There was a small amount of injury to the turf and the dandelions 21 days after application of the product.

Impact of Glucosinolates on Dandelion Germination and Survival

D.K. Tompkins, J.B. Ross and M.A. Anderson

The objectives of this series of experiments were to determine the impact of mustard by-products on dandelion germination, seedling survival when applied at various stages of growth and on mature plants.  For the initial germination study, the treatments included four sources of glucosinolates: yellow mustard, oriental mustard, wasabi and screenings of oriental mustard as well as corn gluten and soybean meals.  All of the agricultural by-products tested in this experiment reduced dandelion seedling counts relative to the control.  The mustards and the wasabi were somewhat better than either the corn gluten and soybean meals.  Once germination had taken place, the corn gluten and soybean meal were generally ineffective.  However, the mustards and wasabi had post-emergent control and as the dandelions aged, the oriental mustard and wasabi continued to have control, while the yellow mustard became less effective.  When attempting to control mature dandelions the effects of the products were much reduced.  Wasabi, which was incorporated into the rootzone, was the only product that had a significant effect.

Use of Mustard By-Products for the Control of Weeds in Turf

D. K. Tompkins, J. B. Ross and M. A. Anderson

This trial was initiated in the summer and fall of 2007.  The objective of this study was to test mustard by-products for their pre and post-emergent herbicide effects on dandelion in turf.  Data collection will commence in the spring of 2008.

Use of Mustard By-Products for the Control of Dandelion in Turf (2008)

D. K. Tompkins, J. B. Ross and M. A. Anderson

Summary

This study was initiated in the summer and fall of 2007. The objectives of this study were to test mustard to determine glucosinilate levels, test mustard by-products for their pre and post-emergent bioherbicide effects, test rate and timing of application, and to compare mustard with corn gluten meal as a pre-emergent herbicide. Yellow mustard had high levels of benzyl glucosinilate while oriental mustard had high levels of allyl glucosinilate. In the pre-emergent study, dandelions re-established on the site and the untreated control averaged 11 dandelions per m2. Those treatments that showed control of dandelions were the spring herbicide application, the oriental mustard foots at 120g/m2, and the corn gluten meal at 240g/m2. For the post-emergent study, only the spring herbicide application and the Sustane 5-2-4 had significantly fewer dandelions than the control plots that received no treatment. From both the pre and post-emergent studies, it appeared that the mustard products were ineffective for control of dandelion. The spring herbicide application was the only treatment that gave consistent, effective control.

Control of Dandelions with Mustard Meal or Extract (2008)

J. B. Ross, M.A. Anderson, D Lopes-Lutz and D. K. Tompkins

Summary

A growth chamber study, conducted by the PTRC, identified oriental mustard as having an ability to control dandelion seed germination and also the ability to kill dandelion seedlings for at least 4 weeks after germination. This past spring, a field experiment was initiated to determine if mustard could be used to control dandelion seed germination and dandelion seedlings in a field situation. Unfortunately, there was no control. Therefore, a series of non-replicated screening studies were initiated to determine why the mustard was effective in the growth chamber, but not in the field.

These screening studies showed that a greater effect was achieved if the mustard product was watered in. However, it was determined that much of the active in oriental mustard was tied up in the thatch layer of turf. It was also determined that the active was very volatile and that recovery of the active peaked at two hours following application and then declined after that. These results illustrated the need for re-formulation of the product in order to reduce volatility and improve its effectiveness.

Evaluation of the Herbicide Velocity for Selective Removal of Annual Bluegrass from Creeping Bentgrass (2008)

James B. Ross and Mark A. Anderson

Summary

The herbicide Velocity SP was tested for its effects on annual bluegrass removal from a Penn A-4 Creeping Bentgrass nursery maintained at putting green height. At the double rate (62g/ha), complete eradication of the annual bluegrass was obtained. At the single and half rate, control was also achieved (greater than 80% reduction). Some discolouration, which was an indication of toxicity to the plants from the product, was evident at all three rates of application. However, there were no long term toxic affects as colour ratings were unaffected four weeks after the final application. Eight weeks after the final application of product, cold hardiness levels were assessed. There were no significant differences between the three treatments and the untreated control.

The Use of Turf Colourants to Reduce Discolouration of Creeping Bentgrass Following Application of the Herbicide Velocity SP (2007)

James B. Ross and Mark A. Anderson

A trial was developed to determine if turf colourants could reduce the discoluration caused by applications of the herbicide Velocity SP.  Green Lawnger, the heavier pigmented product, was better at concealing turf discolouration caused by the Velocity SP herbicide than the Indicator Green.  Over the course of the trial the level of concealment of both products was affected by regular mowing.  It was thought that a portion of the colourant was removed with each mowing.  Irrigating the turf also reduced the masking ability of the Indicator Green WSP as the colorant was washed off the treated plants.

Recovery of Dandelion from Sub-Lethal Doses of the Herbicide, Killex (2007)

J.B. Ross, M.A. Anderson and D.K. Tompkins

Summary

The objective of this study was to determine if there was re-growth from the root stock of dandelion following the application of the herbicide, Killex.  This trial commenced in 2007 and will be completed in the fall of 2008.  Results are preliminary at this time.

Injury to Turf and Weeds Following Application of Mustard Products (2007)

M.A. Anderson, J.B. Ross and D.K. Tompkins

Summary

This test was established to determine if there were any injury effects on turfgrass and weeds following the application of two mustard products.  Two forms of yellow and oriental mustard were tested at three different rates of application.  Injury symptoms were rated on a weekly basis for four weeks following application.  There was a small amount of injury to the turf and the dandelions 21 days after application of the product

Impact of Glucosinolates on Dandelion Germination and Survival (2007)

D.K. Tompkins, J.B. Ross and M.A. Anderson

Summary

The objectives of this series of experiments were to determine the impact of mustard by-products on dandelion germination, seedling survival when applied at various stages of growth and on mature plants.  For the initial germination study, the treatments included four sources of glucosinolates: yellow mustard, oriental mustard, wasabi and screenings of oriental mustard as well as corn gluten and soybean meals.  All of the agricultural by-products tested in this experiment reduced dandelion seedling counts relative to the control.  The mustards and the wasabi were somewhat better than either the corn gluten and soybean meals.  Once germination had taken place, the corn gluten and soybean meal were generally ineffective.  However, the mustards and wasabi had post-emergent control and as the dandelions aged, the oriental mustard and wasabi continued to have control, while the yellow mustard became less effective.  When attempting to control mature dandelions the effects of the products were much reduced.  Wasabi, which was incorporated into the rootzone, was the only product that had a significant effect.

Use of Mustard By-Products for the Control of Weeds in Turf (2007)

D. K. Tompkins, J. B. Ross and M. A. Anderson

Summary

This trial was initiated in the summer and fall of 2007.  The objective of this study was to test mustard by-products for their pre and post-emergent herbicide effects on dandelion in turf.  Data collection will commence in the spring of 2008.

Evaluation of Two Agricultural By-products for Control of Dandelion in Turf (2006)

J.B. Ross and M.A. Anderson

Summary

This trial was initiated in four cities throughout western Canada in order to test corn gluten and soybean meal for the control of dandelion in turf. Application rates were lower in this study than in a previous study which showed high levels of control. In addition, turfgrass quality was measured in order to measure the growth effects of the products on the turf.

Both rates of corn gluten showed a dandelion reduction for the spring and summer rating period, when compared to the untreated control. However, control was not considered to be acceptable (80% or better). There was no significant weed control with the application of soybean meal when compared to the untreated control. For the herbicide treatment, the spring and summer ratings were also considered unacceptable with the highest level of control only being 50%.

Turf quality was only statistically different on one of the four rating periods. At that time, the high rate of corn gluten and soybean meal applied in the fall only, or in spring and fall, had significantly better quality than the untreated control or the herbicide treatment.

It was thought that the herbicide application prior to the initiation of the trial was not sufficiently high to be effective in controlling the dandelion root stock, and only the dandelion leaves may have been ‘burned off’. As a result, dandelions recovered which would explain the ineffective control of the pre-emergent bio-herbicides, corn gluten and soybean meal.

Cultural Control of Established Dandelion in Turf (2006)

M.A. Anderson and J.B. Ross

Summary

This trial was developed in order to study the effects of various cultural practices on the control of dandelion in turf. This trial was conducted over two years and examined aerification and topdressing, as well as mowing height and fertilizer applications. The higher rate of the synthetic fertilizer, Scott’s Contec 21-3-11, showed a reduction in dandelion and improved quality. In year one, dandelion populations increased when plots were aerified and topdressed. None of the other treatments had an effect on dandelion populations.

Dandelion Germination Trial (2006)

Colin A. Clarke, Marilyn Mantei and J.B. Ross

Summary

This objective of this trial was to observe and record the timing of dandelion germination in a creeping red fescue/Kentucky bluegrass turf and also to determine the best method for counting dandelions. This study was conducted in Olds, AB within the black soil zone. In year one, two treatments were evaluated to determine the best method for counting dandelions. In order to facilitate the weekly counting process, four 0.25m2 plots were sprayed with Roundup® (Glyphosphate). This was compared with unsprayed plots that had existing dandelions completely removed. Initial counts of mature dandelion were taken prior to the Roundup application. Following spraying, weekly dandelions counts were taken between June and October 2005. Moisture and temperature data was taken from the Olds College weather station reports. Significantly more dandelions germinated in the untreated plots than the Roundup treated plots and the spraying did not assist in the counting process. Total dandelion emergence for the whole year was 415 dandelions per m2 for the untreated plots and 158 dandelions per m2 for the Roundup treated plots. Trial results indicate that 65% of dandelion emergence occurred between July 7 and August 3 in the non-herbicide plots and 81% in the Roundup applied plots. Moisture was not limiting during the trial.

In year two, two treatments were again assessed. Initial weed counts were conducted on May 23 in one treatment but did not begin until spring seed dispersal was complete in the second treatment. The thought was that there may not be sufficient seed from spring seed dispersal in those plots that were started early. Total dandelion emergence was 429 plants for the early initiated treatment and 331 for the later initiated treatment. There was no need to wait for complete seed dispersal before initiating the study. In the eight week period from May 23 to July 11, 92% of the seed had germinated in the early initiated treatment versus 80% germination over the six week period for the later initiated treatment.

The majority of dandelion germination occurred in early summer and mid-summer in year one of the study and in spring and early summer in year two of the study.

Reduction of Poa annua in Established Kentucky Bluegrass Turf (2006)

J.B. Ross and M.A. Anderson

Summary

Two trials were initiated in late August, 2005 to examine the effects of various herbicides and growth regulators on the reduction of Poa annua in Kentucky bluegrass turf. This trial has commenced at two locations, Windermere Golf and Country Club and an Olds College on existing varietal trial plots. The first application of products took place in late August 2005 and then was applied again in the spring and fall of 2006.

Initial Poa annua percent of infestation was from 66-80% at Windermere. Following the winter of 2005-06 there was a significant reduction in the Poa annua population for the two Betasan treatments. There was also a Poa annua reduction in the Bonzi treated plots, however, the differences were not considered to be significant. When rated in the fall, the Poa annua had recovered completely in the untreated and the Proxy/Primo treatments. However, the effect of the Bonzi and Betasan treatments was still evident. The two rates of Betasan had significantly lower Poa annua infestations and significantly higher Kentucky bluegrass populations.

At Olds, a slight yellowing of the turf was noticed fourteen days after the first application of the Ethrel/Primo treatment in year one. The Proxy/Primo showed a Poa annua reduction at the spring rating, while the Proxy/Primo and Betasan showed lower infestations than did the Bonzi at the fall rating time.

The third trial was initiated on an A-4 Creeping Bentgrass putting green in the fall of 2006 at the Carstairs Community Golf Course. Data collections will begin in the spring of 2007.

Evaluation of Two Agricultural By-products as a Control of Dandelion in Turf (2005)

J.B. Ross and M.A. Anderson

Introduction

Recent studies were completed in western Canada that tested various agricultural by-products for their effect on weeds in turf (Anderson and Ross, 2005). Corn gluten meal, soybean meal, mustard meal and sugar beet extract were tested in four western Canadian cities. The three year study examined the effects of the products for their ability to control weeds in turf, particularly dandelion.

Dandelion is the most common turfgrass weed in western Canada and is well adapted to the climatic conditions. Although considerable research has been conducted on control of this weed, the biology of the plant is not well understood. In order for pre-emergent controls to be effective the timing of germination of this plant must be known.

Watson et al (2001) noted that germination could occur between 4-30oC and that the optimum temperature for germination was 23oC, and this was under conditions of adequate moisture. In a recent study conducted in Manitoba, Van Acker and Hacault (2006) found that 96% of plants that germinated in late spring, early summer were from spring seed dispersal. Only 4% of new plants were attributed to the seed bank.

Seed dispersal of dandelion is thought to be greatest in spring in western Canada. However, seed dispersal has been observed throughout the growing season but are thought to be considerably less. Observations of seed dispersal show that it occurs in early April in White Rock, British Columbia, around the end of April in Kelowna and Penticton, and around the middle of May in Olds, Alberta (Clark et al, 2006).

Results of the recent tests showed that high rates of both corn gluten and soybean meal were effective in controlling dandelion populations. Mustard meal was generally less effective, due in part to turf damage which left large voids in the turf that were then colonized by weeds. Sugar beet extract did not effectively control dandelions. However, these high rates of application would make the product cost prohibitive to use and it would not receive wide acceptance at these high rates.

It was also noted in the previous studies that complete eradication of the weeds prior to the initiation of applications of the products was critical in pre-emergent weed control. Products that were applied at sites that did not first of all remove dandelions with a herbicide application did not show effective control.

The objective of this study was to examine corn gluten and soybean meal at rates of application that would more closely approximate normal fertility rates. In addition, the timing of application will be examined in this study.

The Effects of Long Term Use of Corn Gluten and Soybean Meal on Dandelion in Turf (2005)

J.B. Ross and M.A. Anderson

Summary

Evaluation of corn gluten meal and dehulled soybean meal was evaluated for the long term control of weeds in turf at four locations across Western Canada. Three sites (Kelowna, Penticton and Regina) did not receive an initial herbicide application, while the forth site (Calgary) had weeds eradicated prior to the initiation of the study with two applications of the herbicide, Killex. The sites were evaluated for the effect of the products on weed control and turf quality. Applications occurred twice a year over three years at all four locations. Kelowna, Penticton and Regina received applications of corn gluten and soybean meal, whereas the Calgary site received corn gluten only.

At the sites with no prior herbicide application, the high rates of corn gluten meal had significantly lower dandelion counts than the untreated control, while the low and mid rates of application were not significantly different. In comparison to the control, the mid and high rates of soybean meal significantly reduced dandelions populations. There was no difference between the low rate and the untreated control. When considering percent reductions, the soybean meal reduced the dandelion populations the most. However, when considering that there were six applications over the years, it is an expensive control option. There were no differences in turf quality between the treatments and the untreated control.

In the Calgary study where an initial application of herbicide was applied all corn gluten meal treatments had significantly less dandelions than the untreated control (Table 3). Generally, as rates increased the level of control improved. The 63 g/m2 rate of application of corn gluten meal appeared to be insufficient for control. The higher rates of corn gluten produced better turf quality ratings than either the low rate or the untreated control.

Cultural Control of Established Dandelion in Turf (2005)

M.A. Anderson and J.B. Ross

Introduction

Dandelion can be a major weed problem in turf. It forms dense clumps which affects the footing and the overall playability of sports fields and golf courses. The texture and colour of its leaves does not blend harmoniously with the surrounding grasses. When in bloom, its yellow flowers are yet a further detractor from the aesthetics of the turf.

Dandelion seed is spread on the wind, and as this seed can be carried great distances, prevention of new infestations is difficult. Once a dandelion becomes established and supported by its large taproot, they are even harder to control.

The foundation of cultural dandelion control in turf has always been to create a growing environment in which the turf has the competitive vigor to repel the establishment of new dandelion seedlings. However, when it comes to dealing with established dandelion, many of the cultural methods are abandoned, opting to solely rely on chemical control. As concerns over the use of herbicides for aesthetic purposes increases, the turf manager must explore new strategies and rethink the whole dandelion control process.

In a previous study conducted by the Prairie Turfgrass Research Centre, mowing various species of grasses at a higher height was thought to reduce weed populations. A number of grasses resisted the development of weeds when mowed at 3” and there was virtually no weed development over the duration of the study.

Aeration and topdressing are cultural practices that improve gas diffusion in soil which in turn helps to promote root growth. In addition, aeration physically removes thatch from the turf which also helps to improve the turf quality.

High quality turf as promoted by adequate fertility has also shown to reduce weed infestations. In addition, the two organic fertilizers, soybean and corn gluten meal, have shown to have weed suppression properties.

This study was developed to determine the effects of various cultural strategies for the control of dandelion in turf.

Dandelion Germination Trial (2005)

Colin A. Clarke and J.B. Ross

Summary

This trail was performed in order to determine the best method for counting dandelions and also to observe and record the timing of dandelion (Taraxacum officinale) germination in a creeping red fescue (Festuca rubra) / Kentucky bluegrass (Poa pretensis) turf. This study was conducted in Olds, AB within the black soil zone. Two treatments were evaluated to determine the best method for counting dandelions. In order to facilitate the weekly counting process, four 0.25m2 plots were sprayed with Roundup® (Glyphosphate). This was compared with unsprayed plots that had existing dandelions completely removed. Initial counts of mature dandelion were taken prior to the Roundup application. Following spraying, weekly dandelions counts were taken between June and October 2005. Moisture and temperature data was taken from the Olds College weather station reports. Significantly more dandelions germinated in the untreated plots than the Roundup treated plots and the spraying did not assist in the counting process. Total dandelion emergence for the whole year was 415 dandelions per m2 for the untreated plots and 158 dandelions per m2 for the Roundup treated plots. Trial results indicate that 65% of dandelion emergence occurred between July 7 and August 3 in the non-herbicide plots and 81% in the Roundup applied plots. Moisture was not limiting during the trial.

Control of Dandelions with Mustard Meal or Extract (2004)

J. B. Ross, M.A. Anderson, D Lopes-Lutz and D. K. Tompkins

A growth chamber study, conducted by the PTRC, identified oriental mustard as having an ability to control dandelion seed germination and also the ability to kill dandelion seedlings for at least 4 weeks after germination.  This past spring, a field experiment was initiated to determine if mustard could be used to control dandelion seed germination and dandelion seedlings in a field situation.  Unfortunately, there was no control.  Therefore, a series of non-replicated screening studies were initiated to determine why the mustard was effective in the growth chamber, but not in the field.

These screening studies showed that a greater effect was achieved if the mustard product was watered in.  However, it was determined that much of the active in oriental mustard was tied up in the thatch layer of turf.  It was also determined that the active was very volatile and that recovery of the active peaked at two hours following application and then declined after that.  These results illustrated the need for re-formulation of the product in order to reduce volatility and improve its effectiveness.

Use of Mustard By-Products for the Control of Dandelion in Turf (2004)

D. K. Tompkins, J. B. Ross and M. A. Anderson

This study was initiated in the summer and fall of 2007.  The objectives of this study were to test mustard to determine glucosinilate levels, test mustard by-products for their pre and post-emergent bioherbicide effects, test rate and timing of application, and to compare mustard with corn gluten meal as a pre-emergent herbicide.  Yellow mustard had high levels of benzyl glucosinilate while oriental mustard had high levels of allyl glucosinilate.  In the pre-emergent study, dandelions re-established on the site and the untreated control averaged 11 dandelions per m2.  Those treatments that showed control of dandelions were the spring herbicide application, the oriental mustard foots at 120g/m2, and the corn gluten meal at 240g/m2.  For the post-emergent study, only the spring herbicide application and the Sustane 5-2-4 had significantly fewer dandelions than the control plots that received no treatment.  From both the pre and post-emergent studies, it appeared that the mustard products were ineffective for control of dandelion.  The spring herbicide application was the only treatment that gave consistent, effective control.

Weed Control in Turf with the Bioherbicide Sarritor (2004)

J.B. Ross and M.A. Anderson

A field study was initiated at the Victoria Golf Course in Edmonton that had a low to moderate natural infestation of dandelion.  The objective of the study was to test the product, Sarritor, for its post-emergent effects on dandelions.  Two rates of the product were first applied in July, 2009.  Dandelion counts were recorded prior to the first treatment and then again just before a second application was made in the fall.  Results did not shown any control following the initial treatment.  This study will continue in 2010 to assess application timing, rate and moisture conditions surrounding the application dates.

Evaluation of Agricultural By-Products for the Control of Weeds in Turfgrass (2004)

Darrell K. Tompkins, Carol Bubar, James B. Ross, Mark A. Anderson Prairie Turfgrass Research Centre

SUMMARY

Three studies were initiated in four cities (Calgary, Regina, Kelowna and Penticton) across western Canada in order to evaluate various agricultural by-products for control of broadleaf weeds in turfgrass. The first study, located at two sites in Calgary tested the efficacy of corn gluten in controlling dandelions (Taraxicum officinale). In this study, the dandelions were killed in 2002 with two herbicide applications. In this study, different rates and timing of application of corn gluten was tested relative to spring and fall herbicide applications. The second study was located at two sites in Regina and Penticton and one site in Kelowna. In this study, the weeds were not killed with herbicide prior to the initiation of the study. Varying rates of corn gluten, soybean meal and sugar beet extract were applied to control weeds. The third study was located at one site in Penticton and one site in Kelowna. In this study varying rates of corn gluten and mustard meal were used to control weeds. In each study, data was collected for weed counts, turfgrass colour and density.

In the first study, the pre-trial herbicide applications almost completely eliminated the dandelion population at both sites. In the untreated control plots, dandelion populations then increased from less than 1 weed per m2 on Sept 2002 to 9 weed per m2 by Sept 2004. At the opposite extreme, the application of corn gluten at the 15x rate twice a year effectively maintained a dandelion population of less than 1 per m2 throughout the rating period.

Application of the corn gluten during the fall produced a consistently lower dandelion population although the numbers were not significantly different. Increasing the rate and the number of applications also increased efficacy. The greatest impact on the dandelion population was provided by the use of the corn gluten at the 15x rate applied in both spring and fall. At all rating periods in 2003 and 2004, this treatment exceeded the PMRA criteria for weed control (at least 80% reduction).

In the second study, dandelion populations increased from 14 to 21 per m2 over the period from May 2003 to Sept 2003. In contrast, the use of corn gluten and soybean meal at the 10x and 15x rates maintained or slightly reduced the population of dandelions over the period of the study. At the 1x rate for corn gluten and soybean meal, the dandelion population increased slightly. The sugar beet extract was less effective than the corn gluten or soybean meal at the rates studied. Therefore, if using corn gluten or soybean meal to control dandelions, it would be best to first eliminate the dandelions and use the amendments to control new weeds. Also, the 1x rate may not be effective over a long term.

In this study, there were populations of veronica and clover in Kelowna and plantain at one site in Penticton. There was no significant impact of corn gluten, soybean meal or sugar beet extract in controlling these weeds. However, since there was only data from one site for each weed, and there was a lot of variability within the plots, the true impact was hard to assess.

The third study demonstrated that mustard meal was less effective than corn gluten at controlling dandelions at the rates studied.

Evaluation of the Herbicide Velocity for Selective Removal of Annual Bluegrass from Creeping Bentgrass (2003)

James B. Ross and Mark A. Anderson

The herbicide Velocity SP was tested for its effects on annual bluegrass removal from a Penn A-4 creeping bentgrass putting green maintained at a height of 3.2mm (0.125”).  Weekly applications were made beginning July 17.  Four applications were made for the two higher rates, while six applications were made for the two lower rates.  At the 1.0x rate (0.31 g/100m2), almost complete eradication of the annual bluegrass was obtained one week after the third application of product.  As well, control of annual bluegrass was almost complete with the 0.75x rate (0.23g/100m2).  However, removal was more gradual and it was six weeks after the fourth application before almost complete eradication was achieved.  Removal rates were even more gradual for the 0.5x (0.15g/100m2) and the 0.25x (0.07g/100m2) rates.  A 90% reduction was obtained three weeks after the final application, while a 70% reduction was obtained with the lowest rate.  Discolouration of the turf was evident for all rates of application.  However, recovery was complete for all rates three weeks after the final application of product.  Cold hardiness levels were unaffected by the product when sampled prior to the onset of winter.

Discolouration of Kentucky Bluegrass from Velocity SP (2003)

James B. Ross and Mark A. Anderson

This test was developed in order to determine whether Velocity SP would discolour Kentucky bluegrass when applied at rates that were safely applied on creeping bentgrass.  Applications of the herbicide at double the recommended rate (0.62g/100m2) caused moderate levels of discolouration to the Kentucky bluegrass which would be considered unacceptable.  This discolouration would happen anytime there was sprayer boom overlap when the recommended rate was applied.  More extensive testing at lower rates is required to determine the effects of this product when applied to different varieties of Kentucky bluegrass.

Prevention of Discolouration of Creeping Bentgrass Following Application of the Herbicide Velocity SP (2003)

James B. Ross and Mark A. Anderson

The product, Velocity SP Herbicide (active ingredient bispyribac-sodium), has been licensed for use in Canada to remove annual bluegrass (Poa annua) from creeping bentgrass that is mowed higher than 9mm.  Unfortunately, the majority of bentgrass grown in western Canada is for use on golf course putting greens, which is typically mowed at a height of 3-5mm.

An accompanying study showed that applications of the herbicide Velocity SP was very effective for reducing annual bluegrass in creeping bentgrass when mowed at putting green height.  However, in order for this product to be widely accepted for use the issue of turf discolouration must be dealt with.  Recently researchers at Rutgers University tested various rates of application of nitrogen prior to the application of the herbicide, Velocity SP.  Their study found that there was a reduction in discolouration when nitrogen was applied prior to product application.

This tested was developed to determine whether discolouration of turfgrass due to the application of the herbicide Velocity SP could be reduced with the application of iron and/or nitrogen fertilizer.

Evaluation of the Herbicide Velocity for Selective Removal of Annual Bluegrass from Creeping Bentgrass (2003)

James B. Ross and Mark A. Anderson

The herbicide Velocity SP was tested for its effects on annual bluegrass removal from a Penn A-4 Creeping Bentgrass nursery maintained at putting green height.  At the double rate (62g/ha), complete eradication of the annual bluegrass was obtained.  At the single and half rate, control was also achieved (greater than 80% reduction).  Some discolouration, which was an indication of toxicity to the plants from the product, was evident at all three rates of application.  However, there were no long term toxic affects as colour ratings were unaffected four weeks after the final application.  Eight weeks after the final application of product, cold hardiness levels were assessed.  There were no significant differences between the three treatments and the untreated control.

Evaluation of Agricultural By-Products for the Control of Weeds in Turfgrass (2003)

Darrell K. Tompkins, Carol Bubar, James B. Ross, Mark A. Anderson

Prairie Turfgrass Research Centre

Summary

Three year studies were initiated in four cities (Calgary, Regina, Kelowna and Penticton) across western Canada in order to evaluate various agricultural by-products for control of broadleaf and grass weeds in turfgrass. Within each of the cities two sites were tested. At the Calgary sites, two pre-trial applications of the herbicide, Killex 500 (active ingredients 2-4D 385.25g/l, mecoprop 75 g/l and dicamba 18.75 g/l) were applied, while the other sites did not receive pre-trial applications. Various rates of four agricultural by-products, corn gluten, soybean and mustard meal as well as sugar beet extract, were compared against untreated and treated controls. Data were collected for weed counts, turfgrass colour and density.