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By David Ormsby in Consultancy on 22nd Feb 2012 10:55
The Verdict - Endosulfan (Thiodan, Thionex, Flavylan) Reassessment
The verdict of the Environmental Risk Management Authority (ERMA) reassessment of Endosulfan was released in December and resulted in Endosulfan being deregistered.
For turf managers (and all other users) this means that from January 16, 2009, it is illegal to import, sell or use Endosulfan. Clubs considering using up existing stocks on their turf should be aware that this is a breach of the Hazardous Substances and New Organisms Act and if caught and successfully prosecuted, could result in substantial fines or imprisonment.
For those clubs or facilities that still have stocks of Endosulfan, you now have 12 months or until January 2010 to appropriately dispose of all stocks of Endosulfan.
Appropriate disposal means either:
i. Contacting your Regional Council to confirm the disposal procedure. To date, Auckland, Waikato, Wellington, Canterbury and Otago Regional Councils have agreed to provide a free service for disposal.
ii. In other areas of New Zealand, clubs will need to employ the services of a professional chemical disposal company.
For more information refer to: www.mfe.govt.nz/issues/waste/special/agrichemicals/index.html
Figure 1: Example of substantial casting created by earthworm activity.
Interestingly there is a wide range of agri-chemicals that have been identified as being damaging if not lethal to earthworms. However to date, the research has not been carried out as to the appropriate rate, timing and recommended procedure for the use of these products. The main products identified included:
# 2,4-D 
# acephate
# captan
# carbaryl
# carbendazim
# copper sulphate
# cypermethrin
# diazinon
# malathion
# phorate
# thiophanate methyl
Research is now required to determine the most effective agrichemical, rate and control programme.
Carbendazim, Thiophanate methyl and Carbaryl
Introduction 
Regrettably all the products (discussed) relative to Endosulfan provide inconsistent and unreliable control. This poorer control is believed to be the result of both the limited persistence in the soil of these chemicals and that they are adsorbed onto the soil colloids, reducing effectiveness. Consequently when managing earthworms it will be important to adopt a comprehensive management approach based around cultural and chemical practises.
Figure 2: Once significant casting occurs and surface sealing is evident, the damage is done and the effectiveness of chemical treatments will be very limited.
Carbendazim & Thiophanate methyl
Both carbendazim and thiophanate methyl have been used to control earthworms and suppress casting. Internationally available lumbricides (e.g. Scotts Turf Clear, Ringer) are based on carbendazim.
The internationally recommended programmes involve:
Applying carbendazim (500gai) at 4L/ha in 1000L of water (530mls/bowling green in 100L of water) when the profile is wet, using flood jets and before significant casting occurs. The product should be washed into the profile immediately after application.
Key points to note which will impact on the effectiveness when using carbendazim and thiophanate methyl are as follows:
i. Results are very inconsistent due to the product adsorbing to the surface organic matter. Overseas, the inclusion of a surfactant has reportedly improved the effectiveness of these programmes. Given the lack of compatibility data for wetting agents and fungicides within New Zealand at present, an option is to pre treat the area a day prior to applying carbendazim with a penetrant type wetting agent.
ii. Follow up applications of carbendazim will typically be required at 10 - 12 weekly intervals.
iii. Carbendazim is more effective when used during warmer conditions as occurs during autumn and spring.
iv. Treatment is required before significant casting occurs in order that:
# The development of excessive surface mud is prevented
# To provide the best opportunity for these products to penetrate into the soil profile. Once the soil/sand surface has sealed these products will largely be ineffective.
Given that within New Zealand we can still use Carbaryl (at least presently) NZSTI's preference is to use this product. The basis for this preference and despite carbaryl being more toxic, is to reduce potential issues associated with disease resistance that can occur with the repeated use of carbendazim or thiophanate methyl and which are presently well documented within the turf industry.
Carbaryl
Carbaryl was last registered for the control of earthworms on turf within New Zealand during 1987. Results at the time were generally variable, with the best results being achieved with spring applications. It was presumed that spring applications were better as younger earthworms were being targeted and soil microbial activity was slower, thereby improving the persistence of carbaryl within the soil.
The half life of carbaryl (2008 Novachem manual) in soil is stated as:
# Sandy-loam - 7 - 14 days
# Clay-loam - 14 - 28 days
# Sands - would be substantially less than these stated values
The programme when using carbaryl involves:
Applying carbaryl (500 gai) @ 10-40L/ha in 800L (1.5-5.5L/bowling green in 100L of water) of water via floodjets, when soil profile is moist and prior to significant casting occurring. The product should be washed in immediately following application.
Key points to note which will impact on the effectiveness when using carbaryl are as follows:
i. Relative to other insecticides, carbaryl has a comparatively low dermal rating (i.e. Acute LD50 Dermal Carbaryl is 500mg/kg rats compared to 2000mg/kg rats for chlorpyrifos). Consequently and given the high application rates of carbaryl required; effectiveness and the highest level of safety for turf users will be achieved where the product is washed in immediately after application. Furthermore and in the absence of any definitive research, serious consideration should be given to closing the facility until as a minimum, the product has been washed in.
ii. Given its comparatively short half life in the soil, it is likely that multiple applications at 8-10 week intervals will be required to provide control. As a guide trial an initial application at 20-30L/ha (2.7-4L/bowling green) and follow up 8 weeks later at 15L/ha (2L/bowling green).
iii. Turf managers should remember their compliance requirements under Hazardous Substances & New Organisms Act. Where you hold more than 100L (in total) of 6.1A, 6.1B, 6.1C, 9.1A substances, which is likely given the high rates of carbaryl required:
# Level 3 emergency plan
# Secondary containment is required.
Cultural Pactises
Cultural practises are covered in more detail in the NZ Sports Turf Institute fact sheet, see http://www.nzsti.org.nz/news-briefs html
The main cultural control strategies are based around:
# Acidifying the surface in late autumn 
# Greater consideration will need to be given when liming turf. Liming rates should be based on soil test results. Managers need to differentiate between manipulating the pH within the turf surface as opposed to raising the whole profile pH as is typically adopted in agriculture. The timing of lime applications can also assist in reducing earthworm activity. Generally the preferred time for liming will be during spring.
Figure 3: Illustrates the effect of a bunker splash with a calcareous sand (same as liming) encouraging earthworm activity.
# Avoiding the use of organic based fertilisers during autumn - early winter as they typically act as a food source, encouraging earthworm activity.
# Greater emphasis is required on the management of irrigation and most importantly ensuring the profile has been "dried down" by winter. The basis for this is that saturated soil conditions are believed to be one of the contributing factors that force earthworms to the surface and require them to vent their burrows, i.e. cast.
Endosulfan is no longer an option when controlling earthworms; hence greater emphasis should be placed on a management approach based around cultural practises and the alternative agrichemicals, carbaryl, carbendazim and thiophanate methyl.
The NZ Turf Management Journal is printed quarterly (Feb, May, Aug,
Nov) and is specifically tailored to the turf industry with a range of topical, technical and research articles, book reviews and trade information
www.nzsti.org.nz
Read more articles in Consultancy, by David Ormsby or from February 2012.
