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Pre-emergence Weed Control Trials

NZSTIThis article has been supplied by the New Zealand Sports Turf Institute (NZSTI). NZSTI is New Zealand's leading sports turf consultancy group, recognised by SPARC (Sport and Recreation NZ) as the "standard setting body" for turf maintenance and management. They can offer advice for all natural and synthetic turf surfaces.

Brendan Hannan

The herbicide Foresite 380 (Oxadiazon) has been used for weed control in Leptinella greens since 1993, when Kerry Harrington of Massey University, first identified its use (at 530ml/1340 m2) as a post-emergence herbicide for tillaea (Crassula sp). Since then Oxadiazon has been used on bowling greens (Way, 1997) on a regular basis.

More recently, the rates of Foresite 380 have successfully been reduced with better results. Other potential pre-emergence herbicides have also been identified (Harrington, 1997). Two trials were undertaken by the New Zealand Sports Turf Institute (NZSTI) in order to help answer the following questions:

1. What is the lowest effective rate of Foresite 380?
2. What other benefits/uses are there for Foresite 380 in bowling greens?
3. What other herbicides could be useful in Leptinella and/or starweed bowling greens?
4. What is the best timing of treatments?

TRIAL 1 - Tillaea control in Leptinella dioica "Pahia"

Methods and Materials

On 31 January 2003, Foresite 380 (Oxadiazon) was applied at the equivalent rates of 200, 300 and 400ml/1340m2 to the Pahia nursery at AgResearch, Palmerston North, using a C-DAX jackpot booPic 1m sprayer. Tillaea was the main weed targeted.

Two rubber mats were placed over patches of tillaea in the 200ml and 400ml treatment areas to serve as a control in order to assess the effects of Oxadiazon on tillaea.

Figure 1: Applying herbicide treatments to the Ag Research Pahia nursery


1. Effects were slow, taking three weeks for the first signs of damage to the tillaea (see Figures 2 & 3).

2. There was no yellowing of the "Pahia" dioica.

Leptinella I 3. Tillaea control was achieved for up to ten weeks. Some re-growth occurred after ten weeks, even at the 400ml rate (see Figures 4 & 5).

Figure 2: 31.01.03 Healthy tillaea
Figure 3: 21.02.03 Tillaea damage
Figure 4: 07.03.03 Dead tillaea
Figure 5: 14.05.03 Dioica growth into tillaea

TRIAL 2 - Leptinella Establishment

Methods and Materials Leptinella A

A 25m2 area at NZSTI Head Office plots was killed with Roundup (glyphosate) in April 2003, then mown closely to scalp the foliage off 12 days later. The area was grooved to make a seed bed and further removal of organic matter was achieved by raking. The area was grooved again on the day of establishment.

LeptiWeak Stolonsnella dioica and Leptinella maniototo stolons were harvested from the Hokowhitu Bowling Club and planted on the morning of 16 April 2003. The groovings were produced by a standard bowling green groover that resulted in small stolon fragments (see Figure 6). The stolons were broadcast by hand to completely cover the soil as a 5-10mm layer. The plots were then double-rolled, covered with shade cloth and irrigated by hand-held hose (see Figure 7).

Figure 6: Weak stolons
Figure 7: 16.04.03 Rolling in stolons

That afternoon the shade cloth was removed and Foresite (Oxadiazon) and TribunalRolling in Stolons (Methabenzthiauron) herbicides were applied to 5 x 1m plots, each at three different rates. This left four 1m2 unsprayed plots between the treated plots (see Figure 14). The treatments were:

• Foresite 380 (Oxadiazon) 250ml, 125ml and 90ml/1340m2
• Tribunal (Methabenzthiauron) 200g, 134g and 67g/1340m2
• Foresite 380 250ml applied ten days after sowing (10 D.A.S)

The herbicides were applied with a Cambrian sprayer in four passes, with an equivalent water rate of 75L/1340m2 (600L/ha).

Leptinella B The treatments were not replicated nor randomised.

The fertilizer programme for the 25m2 trial area was:

16 April 03 3kg blood and bone prior to stolonising
1 May 03 450g 31-1-8 slow release nitrogen source (methylene urea)
13 June 03 400g ammonium sulphate
1 August 03 300g ammonium sulphate
17 October 03 450g 31-1-8 slow release nitrogen source (methylene urea)

Note: Ten days after sowing many broadleaf weeds had germinated but were still in the cotyledon (seedling) leaf stage prior to the Foresite 380 at 250ml rate (see Figure 8). Leptinella C

On three occasions the plots were visually scored for:

6 May 03 (3 W.A.S) Leptinella damage (phytotoxicity)
26 May 03 (6 W.A.S) Percentage ground cover and percentage weeds
12 June 03 (8 W.A.S) Percentage ground cover and percentage weeds

Note: W.A.S refers to weeks after sowing


1. No noticeable Leptinella damage occurred from any treatment except for the Foresite 380 at 250ml/1340m2 10 D.A.S.

2. The degree of damage in the F250 10 D.A.S plot was initially severe but it recovered fully after 10-12 weeks. This resulted in one of the best weed controls, equivalent to any other treatment. The degree of damage was surprising, as the delay of 10 days before spraying would normally be beneficial to allow the Leptinella to establish better prior to spraying.

Note: This damage may have been due to:

a) Possible shade cloth effects on growth, etiolating the leaf, making it more susceptible to ForesiteLeptinella E 380 damage. However, an establishment trial on Pahia dioica in September 2003 using shade cloth and Foresite 380 at 120ml and Tribunal 134g ten days after sowing showed no damage. This supports the author's initial expectation that factors other than the herbicide are likely to cause the damage.

b) The combination of Thiodan application for worm control on 29 April 2003 and Foresite 380 increasing the damage from Foresite 380. As Thiodan has been regularly used for many years on Leptinella dioica greens with no adverse reaction, it is unlikely to be the problem in this case.

Leptinella F c) Frost on the morning of 29th and again after spraying, increasing the risk of phytotoxicity, and the damage from Foresite 380. Frost before and after spraying, combined with Foresite 380 being applied to the establishing Leptinella dioica, is the most likely reason for damage.

Figure 8: 25.04.03 F250 10 D.A.S immediately after spraying. Note the broadleaf weed seedlings.
Figure 9: 01.05.03 Same plot as Figure 8 showing damage to Leptinella and weeds.
Figure 10: 22.05.03 Same plot as Figure 8 Leptinella recovery starting.
Figure 11: 05.06.03 Same plot as Figure 8 full recovery.
Figure 12: 24.06.03 Same plot as Figure 8 100% ground cover

3. Good pre-emergence weed control occurred at rates of 125ml and 250ml Foresite, but not at theLeptinella F 90ml rate.

4. Good pre-emergence weed control occurred on the Tribunal 134g and 200g rates, with less weed control (mainly Poa annua grass) at 67g rate. It was clear after 12 weeks that Tribunal at 200g reduced pearlwort and Colobanthus establishment.

5. Excellent weed control was achieved with Foresite 125ml and Tribunal 134g combination 10 D.A.S. It showed good knock down of very young weed seedlings and pre-emergence control thereafter.

Figure 13: 18.06.03 Trial layout and weed control effects Trial Layout

6. Eight weeks after sowing, the best weed control occurred on the following plots in order of priority:

1 Foresite 380 250ml 10 D.A.S
2 equal Foresite 380 250ml + Tribunal 200g
2 equal Foresite 380 250ml + Tribunal 134g
2 equal Foresite 380 250ml + Tribunal 76g
2 equal Foresite 380 125ml + Tribunal 200g
2 equal Foresite 380 125ml + Tribunal 134g
2 equal Foresite 380 125ml + Tribunal 67g
3 equal Tribunal 200g +Foresite 90ml
3 equal Tribunal 200g

Leptinella H The other treatments did not give adequate weed control.

7. By the 24 June 2003 the Foresite 380 at 250ml 10 D.A.S had almost achieved full dioica cover.


The use of pre-emergent herbicides such as Foresite 380 can almost eliminate the need for post-emergent herbicides and/or hand weeding of stolonised areas and new Leptinella greens.

The minimum rate to use should be 125ml Foresite 380; 200-250ml. This should give very good control of most weeds except pearlwort and Colobanthus and partial control of annual mouse-eared chickweed.

Apply Foresite 380 before weed seedlings form true leaves, typically 10-14 days after autumn sowing.

It is possible that frosts before or after an application of Foresite 380 can increase the risk of damage to stolons. However, subsequent re-growth and recovery will occur and the benefit of reduced weed competition will mean the Leptinella stolons will fill in and establish well.

The minimum rate for Tribunal should be 134g; 200g. This is likely to give best results withouLeptinella Gt any increase in risk of damage to stolons.

Do not use Tribunal by itself in autumn, because it does not control a wide spectrum of weeds as effectively as Foresite 380. It will not control toadrush at less than 200g.

Tribunal can be added to Foresite 380 for pre-emergent control of Colobanthus, pearlwort and annual mouse eared chickweed with no additional damage to stolons.


I would like to thank the Hokowhitu Bowling Club for the supply of stolons, Kerry Harrington (Massey University) and Pramda Lallu (Bayer Crop Science) for technical support on this trial. This trial would not have been possible without the funding of Bowls New Zealand and support on the NZ Bowling Greenkeepers Association.


Way B. 1997. New Zealand Turf Management Journal, August Issue, Pgs 10-14, New Zealand Sports Turf Institute (Inc.), Palmerston North

Harrington K. 1997. New Zealand Turf Management Journal, November Issue, Pgs 24-26, New Zealand Sports Turf Institute (Inc.), Palmerston North

NZSTIThe NZ Turf Management Journal is printed quarterly (Feb, May, Aug,
Nov) and is specifically tai lored to the turf industry with a range of topical, technical and research articles, book reviews and trade information


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This article was written

by in Consultancy on 30 Mar 2008

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