Tag Archives: pythium

Review Your season 2017

After the summer what was I hope everyone takes a well deserved break sooner rather than later..

I have written pieces to this similar to this in the past. i do believe writing this every year helps my readers with making better decisions for the coming year..

One thing I hope everyone has done this year in some way is to document the summer. With temperatures the way they were photo evidence is key not just for yourself but show stakeholders of your facility. The NSWGCSA has done just this to help turf managers work with facilities. A copy can be found here.2017-GMA info sheet

Pleas download the article above it is well written and can be ustilised for any turf facility not just golf courses.

I also have some slides from the GCSAA when they went through drought back a few years ago which may come in handy.

GCSAA drought and himidity stress

Now I also want you to download the weather data from BOM website (click on this link to find your closest weather station)  if you don’t have accurate records somewhere.This will show everyone and remind yourself on how much pressure your turf was under. In our job we watch the weather all the time. What i noticed and many of you know this is that the day temperatures were not the issue. We can deal with 40C days. It was the nights that caused the bulk of the issues. Night temperatures did drop all that much at night. Typically in January and February we saw a day of 35C-40C and night temps drop down to 25C only and that was only after midnight. Many posts I saw on Turf Management Australia Facebook page that guys were still at 30C at midnight and soil temps around the same amount.. How can we expect the turf to survive that whether it’s cool season or even warm season grasses.

These are the questions you need to ask yourself:

  • What were my issues
  • When did they start occurring
  • Did I expect them to occur then
  • Could I of dealt with the issue earlier
  • Did I have outside issues to deal with
  • Were the issues caused by nature or by putting the turf under undue stress
  • Was there anything you could have done better
  • Were you more proactive or reactive with the summer i.e did you have a preventative program or just deal with the issues when they arose
  • Did your program stack up

Come March we had a big change in weather up until that point it was hot humid March added rainfall. Temperatures were still high though.

One thing for sure was that spray intervals were greatly reduced. Where commonly 21-28 intervals were the norm this was being reduced to 7-14 days at times as the pressure was very high.

Did you utilise a broad range of control options for the issue (e.g different products, cultural practices, fertility). Specifically for fungicides did you rotate resistance groupings enough What can you do next season to reduce the issues

Does the course need to be altered in any way to help (i.e does drainage have to be put in or fixed, is building a new green/tee possible) There is alot more of a list which I could write but this is just to give you an idea on topics to think about. Keep in mind with the disease pressure this year fungicides you used had to deal with high pressure situations and where expected residual was normally 21-28 days you may have only got 10-21 days control for systemic products or even less with contact fungicides. The fungicide had not failed but more so the pressure was too high to give you control expected. If you would like some help with reviewing your specific situation please do not hesitate to contact me either via this blog or email

zreikat@campbellchemcials.com.au

Regards Nadeem Zreikat

GIS 2017 Orlando Florida summary

I’m back from the US from the Golf Industry Show (GIS) in Orlando. I attended as usual the education conference on Monday and Tuesday and then the trade show the other days. My week concluded with a visit to the University of Florida to visit Dr Phil Harmon and Dr Carrie Harmon along with their lab technician Jeremy. I visited the university as we have done some disease diagnosis and resistance testing in the past with them (where I showed resistance in Sydney to the DMI class of fungicides to dollar spot). We discussed issues in the area and compared to Australia QLD is similar with all the warm season grasses.

I was shown around the lab where they take extra protocols with international samples. Everything has to be spot on especially receiving foreign materials. The process is the same as the local samples but the extra care has to be done.One thing I was impressed with is that a simple test is not so simple when the diagnosis becomes difficult and further analysis is done to get an accurate diagnosis for the client. I was also intrigued by all thre parts of the world where samples have been sent from, they truly are an international diagnosis lab.

Myself and the University of Florida team (Phil, Carrie, myself & Jeremy). Thank you so much everyone for taking out the time and look forward to working with you in the future.

I was very active on social media and many of you may have seen the videos of each day I did. If not here they are which give a good summary of the week. I will post more on the education seminars down the track. However if you have any question please don’t hesitate to contact me.

zreikat@campbellchemicals.com.au

 

 

 

 

Stats from the show:

13,600 people attended across the week

5800 people went to the education seminars

Whats new?

Well not alot to be honest, but the most exciting thing was the GPS spray units now commonly available. Hopefully we will see these at our show from Jacobsen and Toro.These units will make spaying more efficient and changes on the go will be done in an instance- which will reduce the need to change your nozzles or water pressure all of it is done automatically.

I have been getting a few messages on digital job boards. I was at a presentation during the show from Jason Haines form Canada who i speak to regularly on twitter. He is an expert in this field and runs one for his 9 hole course for 3 staff. It is very simple to setup. For more information visit his digital job board blog www.turfhacker.com

Thank you to everyone who enjoyed my social media posts while I was over there. As well it was great to catch up with friends and make new ones.

 

i will post on the education seminars lately but in the meantime enjoy the pictures form the show.

 

 

 

 

 

 

 

 

 

 

 

 

Heat wave, humid, rain birings on pythium- January 2017

Happy new year everyone I hope you had some time to enjoy with family and friends.

What a start to the year heat waves in Victoria, WA, SA NSW. Storms in QLD and everything in between.

 

Non disease Issues you may face

I have been seeing quite a few sick started to see a few sick turf surfaces around the place just due to sheer pressure from the heat, lack of rain and too much rain. One thing to keep in mind when there has not been alot of rain like especially here in Sydney is to look sodium levels. i have seen this season and in the past poa really going off colour and t

Generally speaking this may not be an issue every year or your water source might be quite low in sodium generally speaking. However this does change over time and has to be monitored. As well having low levels is good but bare in mind putting on a little all the time will build up in the soil and the plant and cause the plant to suffer. Keep this in mind this season, look at an few applications of a product that will reduce sodium levels. Talk to your local rep on this as this issue can be the underlying cause of disease especially pythium..

Another issue you may see is nematodes. Again you may not have a history or testing for them numbers have come back low. However I remember a talk I heard on nematodes from David Westall he always said that the numbers don’t tell the whole story and your threshold may be different to the person down the road.

If your turf is stressed and the root system has shrunken you are more prone to an attack as the plant can’t fight them off naturally.so keep an eye out.

With these conditions you need to look at for the remainder of the summer is your spray program.Normally 3 week intervals are working but with this much pressure you need to look at shortening intervals to 2 weeks. On top of that a in between spray may be needed just to top things with the onset of heavy rains.

The week ahead

Pythium

Pythium is one disease that will be present now.

Water logged greens are a perfect environment for Pythium root rot. You can see Pythium as patterns in greens that follow the drainage lines. Equipment use also spreads the disease. If you have a short root system with compacted soil and poor drainage, your turf will need extra light watering to keep it alive. This will increase Pythium pressure, due to plant wetness. On the other hand, deep infrequent watering can increase Pythium pressure as well as the roots and the soil are being completely soaked which is conducive to Pythium outbreaks. Very hard to win in this situation. That is why it is important to maintain healthy turf and to use specific Pythium fungicides on a preventative basis.

Apply your fungicide (use Proplant here) down past the leaf and crown do not leave on the surface with application (water in slightly after your boom application)

Proplant image

As always we do recommend a broad spectrum tank mix partner with Proplant (as its is specific to pythium only) as when we were anyalysing the samples in the trials we always found other diseases namely brown patch. So have a look at partnering Proplant with Ippon, 250GT, Protak, Monstar,

Also be aware of algae with all the wet surfaces. A good mix is Dacogreen + Liquid Dek here.

Cultural Controls of Pythium:

  • Avoid too much N
  • Aerate the area slightly to allow more oxygen to penetrate the soil
  • Utilise pentrant wetting agents to push the moisture through the profile-I don’t tend to recommend to use with Proplant as it may push past the plant where you need to target the spray
  • Keep plants healthy as possible with using root stimulants and other biological products
  • Avoid mowing in moist hot weather
  • Raise mowing heights
  • Avoid verti cutting, top dressing if greens are infected  as it puts more stress on the plant
  • Reduce leaf wetness
  • Increase air flow and sunlight to Pythium prone areas
  • Reduce sodium levels
  • Monitor for insects

For more information see the brochure here Proplant Brochure Also have a look at our guide to managing pythium not just from a chemical point of view but from a cultural view. Disease guide rhizo eri pythium 2014

I hope this post helps understand the disease a little better and how to manage it.

Also I am heading to to the USA to GIS again and will be attending a few lectures that i will post about later on. You will be able to follow what is going on through my twitter feed.

As usual if you need any help feel free to contact me

zreikat@campbellchemicals.com.au

Disease and Mite Seminar 2016

In November ourselves and K&B Adams had the pleasure of presenting two of the top turf minds in Australia. Dr Percy Wong and Professor Peter McMaugh in Adelaide.

The day started off with a supers forum with Percy where new diseases that have been identified were discussed. A number of these had been seen in South Australia and are a concern that not much is known about them and research fund are needed to learn more as well as come up with plans to combat them. Percy also spoke about the need for accurate diagnosis. Just because it has certain symptoms its doesn’t mean that that disease is present and a good disease turf testing lab can help here.

I went on and spoke about a new fungicide we have coming in March next year. This is a brand new active ingredient with a broad range of disease control including dollar spot, anthracnose,algae and helmo and grey leaf spot.. More information to follow in the new year.

As well Monstar update is for full registration February 2017

Afterwards Peter spoke about mites and the work he has done and the work he is doing in correct identification of the mite as there are number of mites out there which effect different grasses. Alot of research has been done by Peter and counterpart Don Loch but plenty of work needs to be done and research dollars are needed.

I’d like to thank the following of helping with the day. Without associations and passionate individuals we would not be able to put these  pure education days:

  • SAGCSA

  • K&B Adams (Sam Sherriff) in partnering with us to put this on and make it all possible

  • Turfwise Consulting

All notes have been sent out to the delegates.

The day has been nicely summed up form Ivan Swinstead from Tea Tree Gully Golf club

“ Listening to Dr. Percy Wong and Peter McMaugh, two of our industries leading experts, talk about fungal diseases and Couch Mite in turf, demonstrated to me the issues that we can potentially face in maintaining Couch playing surfaces at our facility. Having Wintergreen Couch fairways at our club for twenty plus years now, Couch Mite and fungal disease are problems that our club has to deal with each year. It was interesting in hearing the options for control in both areas.”

photo-10-11-2016-12-30-55-pm-copy photo-10-11-2016-8-02-37-am-copy photo-10-11-2016-8-47-17-am-copy photo-10-11-2016-10-37-40-am-copy photo-10-11-2016-10-45-01-am-copy photo-10-11-2016-11-02-20-am-copy photo-10-11-2016-12-00-49-pm-copy photo-10-11-2016-12-01-05-pm-copy

Kicking it in to high gear- Grand Final Weekend 2016

I apologise for the lack of posts since the AGCSA conference. I have been traveling around the country getting to a bunch of seminars where we have sponsored them and given talks at some.

To give you an idea after the AGCSA conference I attended the following:

  • STA ACT
  • VGCSA Country meeting at Rich River
  • VGA Bendigo annual seminar
  • TGAA Corowa annual seminar
  • TGCSA annual seminar
  • SAGCSA conference
  • STA NSW Cricket Wicket 101 course (where i was an assessor for the day)

So as you can see it was fairly full on and the airline and rental car companies know me on a first name basis now. If you are on Twitter or a couple of the Facebook turf pages you would have seen a few pictures I posted as well. Let me just say if you haven’t had a chance to get to any turf turf seminars this year JUST DO IT. The information is first class and networking opportunities are endless.

Enough of that and onto the season. Well a wet start for most. Can someone turn the taps off please for a week or so. Plenty of weeds have been coming up as well and germinating quicker than usual. Get on top of this sooner rather than later.

One thing with the wet weather at least you can identify drainage areas that need to be worked on. If this is something you have in the back of your mind map it on paper so you can easily come back to it when you can.Skitch is a great app here where you can draw on pictures taken from your tablet.

As I write this we are still reasonably cool around Australia besides QLD (I don’t think they had winter this year) but it is about to heat will heat up i Sydney anyway around Grand Final time (Go the Swannies, not sure on NRL as my team is out). So here a few tips to prepare your turf:

  • Use turning boards for mowers, reduce victory lap cuts
  • Maintain adequate soil moisture throughout stressful times.
  • Keep a balanced soil profile (get a soil test do not guess)
  • Improve air flow – cut down trees/branches
  • Communication with the club management and members
  • Promote a healthy growing environment
  • Nutrition (Don’t be afraid to apply N – just know how much and what source)
  • Removing dew to reduce leaf diseases
  • Roll greens instead of mowing – alternate each day
  • Raise mowing heights (even by a 0.5 mm makes a difference)
  • Utilise bio stimulant products during the growing season such as kelp (proven to increase root mass), amino acid (heat stress), humic/fulvic acid products. For any bio stimulant look at what’s inside it and see how each component helps the plant- ask questions to those selling them.
  • Hand water with wetting agent tablets especially for drier areas

Weather for the week coming puts temps higher than they have been so far as you can see:

photo-28-09-2016-11-31-06-am-copyphoto-28-09-2016-11-31-35-am-copyphoto-28-09-2016-11-31-30-am-copyphoto-28-09-2016-11-31-24-am-copyphoto-28-09-2016-11-31-18-am-copyphoto-28-09-2016-11-31-12-am-copyphoto-28-09-2016-11-31-41-am-copyphoto-28-09-2016-11-31-48-am-copy

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lastly 2 things the Monstar permit has been renewed please download the latest permit here

Also I have and event coming up in Adelaide in conjunction with K&B Adams, SAGCSA and Turfwise Consulting featuring 2 great Australian turf professors:

Percy Wong (Plant pathologist)

Peter McMaugh (turf and mite expert)

I will post more later but see all the information here

kb-ccc-sa-seminar-november-2016-main-seminar-invite

Good luck everyone hope you can get some downtime during the weekend. Feel free to contact me with any help needed

zreikat@campbellchemicals.com.au

Cheers

Nadeem

 

Dacogreen WeatherShield “The Ultimate Chlorothalonil”

Some facts you may not be aware of in regards to chlorhthalonil in Australi:

In 1971 (some readers would remember this) Colin Campbell Chemicals introduced chlorothalonil named Daconil into the Australian turf market giving us over 45 years experience. From the initial formulation as a wettable powder, then into a SC (suspension concentrate) and now to the brand new WeatherShield formulation we have always continued research and development into chlorothalonil giving us insight into the working and benefits of this broad spectrum fungicide.

Dacogreen WeatherShield is an evolution of the original Dacogreen/Daconil (chlorothalonil) formulation that been the basis of broad spectrum disease control in the turf industry.

“WeatherShield Technology™”
Dacogreen WeatherShield is a superior surfactant technology.  This technology allows for:

● Improved sticking capability

● Smaller particle size (reduced from 3.5 to 2.5 micron) that spreads evenly for turf protection

● Improved rainfastness over the original Dacogreen 720

● Superior rainfastness over generic chlorothalonil formulations

Two trials were conducted on cucumbers to observe coverage and rainfastness of the following chlorothalanil based products:

  • Dacogreen 720 SC (original formulation)

  • Dacogreen 720 WeatherShield

  • Generic 1 chlorothalonil and

  • Generic 2 chlorothalonil

Cucumber leaves were chosen for the trial as product retention results could be measured more easily than turf leaves. Three replicates were performed for each product

Trial 1 measured the retention of chlorothalonil after simulated rainfall of 40mm of rain over a 2 hour period 1 hour after application. Note, that with this trial the leaves of the plants were not totally dry before rainfall occurred due to slow drying conditions.

Trial 2 measured the retention of chlorothalonil after simulated rainfall of 40mm of rain over a 2 hour period 24 hours after application.  In this instance the leaf of the plant was totally dry before rainfall occurred.

 


 

 

In both trials Dacogreen WeatherShield and Dacogreen original out performed Generic 1 and Generic 2 chlorothaolnil formulations easily for retention of product with more than double the retention. What this means is that using Dacogreen WeatherShield enables you to be confident that Dacogreen WeatherShield will still give you the results desired even with the onset of rain soon after application.

So next time choosing a chlorothalonil product for a broad spectrum disease control have a think about what you are getting and ask for DACOGREEN by Name

Dacogreen WeatherShield is registerd for use in Australia at the following rates

for:

Dollar spot,

13L-20L per hectare

Brown patch (rhizoctonia) 

13L-20L per hectare

Grey leaf spot control. 

24L per hectare

Always read the label before using any product.

Dacogreen is a registered trademark of Colin Campbell (Chemicals) Pty Ltd

For label and SDS see here

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GF Weekend 2015

I usually write this post saying disease pressure is going through the roof but looking at the forecast for east coast Australia we are going to be getting some really hot temps and this does not go well with long weekends.Don’t get me wrong disease pressure is increasing as turf will be more vulnerable to attacks in this hot weather namely anthracnose and brown patch.

Photo 30-09-2015 9 02 39 pm Photo 30-09-2015 9 02 32 pm Photo 30-09-2015 8 45 14 pm Photo 30-09-2015 8 45 08 pm Photo 30-09-2015 9 02 46 pm

 

 

 

 

 

 

 

 

 

 

 

 

 

Some tips to help you get through the hot weekend

  • •Use turning boards for mowers, reduce victory lap cuts
  • Maintain adequate soil moisture throughout stressful times.
  • •Keep a balanced soil profile (get a soil test do not guess)
  • •Improve air flow – cut down trees/branches
  • •Communication with the club management and members
  • •Promote a healthy growing environment
  • •Nutrition (Don’t be afraid to apply N – just know how much and what source)
  • •Removing dew (use DewCure here or dew brooms) to reduce leaf diseases
  • •Roll greens instead of mowing – alternate each day
  • •Raise mowing heights (even by a 0.5 mm makes a difference)
  • Utilise bio stimulant products during the growing season such as kelp (proven to increase root mass), amino acid (heat stress), humic/fulvic acid products. For any bio stimulant look at what’s inside it and see how each component helps the plant- ask questions to those selling them.
  • Hand water with wetting agent tablets especially for drier areas

Also if you haven’t been notified Monstar permit has been extended while the registration is being evaluated. You can download the permit here

Monstar 2015 permit PER14379

STA GOLF DAY

As well if you are interested in coming along to the STA golf day at Bayview gold club in Sydney all information can be downloaded here.

Overall have a good weekend everyone and enjoy the time off where you can..

Good luck to Graeme and the crew for the NRL GF and Tony and his crew for the AFL.

Cheers

Nadeem

 

 

CCC, K&B Seminar featuring Percy Wong & Gary Demspey August 2015

Last month I was honored to be part of a educational seminar put on by K&B Adams (our Victorian Distributor) and ourselves featuring Dr Percy Wong from the University of Sydney and Gary Dempsey Superintendent NSW Golf Club. Percy and Gary have been in the industry a very long time and their experience really showed as they answered plenty of questions along the way.

Dr Wong spoke on new turf diseases that he has been researching and the impact that this will have in the long term to the industry without adequate funding. We hope here at Campbell’s this has increased awareness to the delegates in what needs to be done as an industry to deal with these diseases..

Gary Demspey spoke about the Aqua Aid Wetting Agents and the new technologies available to turf managers as well as the sunscreen product Turfscreen. For more information see Aqua Aid website.

I was last up and spoke on fairy ring management and updated delegates that Monstar has been submitted to the APVMA for fairy ring and brown patch (rhizoctonia) control.

iphone 180 iphone 186 iphone 177

 

 

Feedback from the day was very encouraging with many delegates learning more than what they expected to. thank you to the AGCSA and Turfmate for attending and writing about the day on their websites.

All delegates received information in their show bags as well as bonus material which has been emailed out as well.

 

 

 

 

 

 

 

 

A big thanks goes to the VGA who helped bring Percy down for their seminar the day before which we were happy to be a part of as well; Thanks to Gary for making the trip down and K&B Adams for getting the the number of turf managers that we had.Lastly thank you to all that did turn up we hope to bring you more education days like this in the future.

 

 

 

Disease Alert Pythium spp update Sydney Dec 2014

As continued from my last post we are experiencing very high pythium levels with all those storms around. It seems if you didn’t get the first 3 the next 3 hit your area. We tend to see Pythium blight and Pythium root rot. Both are very destructive and come in quickly like all Pythium diseases. Controlling Pythium is paramount and all measures should be taken. With these prolonged wet conditions Pythium root rot is most prevalent and is difficult to manage. There is not a lot of information on this type of disease but to say that with water soaked roots and water logged soils this disease runs rampant.

Pythium is always living in the soil and needs the right conditions to cause problems. Water logged greens are a perfect environment for Pythium root rot. You can see Pythium as patterns in greens that follow the drainage lines. Equipment use also spreads the disease. If you have a short root system with compacted soil and poor drainage, your turf will need extra light watering to keep it alive. This will increase Pythium pressure, due to plant wetness. On the other hand, deep infrequent watering can increase Pythium pressure as well as the roots and the soil are being completely soaked which is conducive to Pythium outbreaks. Very hard to win in this situation. That is why it is important to maintain healthy turf and to use specific Pythium fungicides on a preventative basis.

The aim now is to use fungicides on a 7-14 day intervals (no matter what product you are using- hopefully Proplant through). The reason behind this is that your soil will be still very wet and until it dries out it is a perfect environment for the disease. As well as try and reduce the moisture content in your turf to help get the turf to recover. This is the most essential in managing root rot pythium from what I’ve seen over the years with attending various seminars and talking to various turf pathologists and professors.

Apply your fungicide down past the crown do not leave on the surface with application (water in slightly after your boom application)

If you do have an outbreak with any disease, not just Pythium reduce the use of PGR’s until you get recovery. Also look at at tank mixing your fungicide as other diseases maybe present. An Ippon & Proplant tank mix is very effective here.

Cultural Controls of Pythium:

  • Avoid too much N
  • Aerate the area slightly to allow more oxygen to penetrate the soil
  • Utilise pentrant wetting agents to push the moisture through the profile
  • Keep plants healthy as possible with using root stimulants and other biological products
  • Avoid mowing in moist hot weather
  • Raise mowing heights
  • Avoid verti cutting, top dressing if greens are infected  as it puts more stress on the plant
  • Reduce leaf wetness
  • Increase air flow and sunlight to Pythium prone areas

I hope this short posts helps understand the disease a little better and how to manage it.

Any help needed again please don’t hesitate to contact me.

Thank Nadeem

As I sign off another storm is coming past our office at Wetherill Park

High to Extreme Disease Alert Sydney – December 2014

Wow after the driest spring on record and a very dry and hot November December has had a u-turn. high temps high rainfall. This is what I saw yesterday on the radar and on the road. Yes it did get worse after I got home (pic taken by passenger). The red on the radar meant very heavy rain.

 

Radar 3/12 Can't see a thing

 

UPDATED MY CLIMATE DISEASE PREDICTIVE MODEL APP (from livingturf.com.au) SHOWING EXTREME DISEASE ALERT FOR PYTHIUM IN SYDNEY

Photo 5-12-2014 11 05 51 Photo 5-12-2014 11 05 54

As you can see tfrom Monday 1st pythium pressure increased dramatically and is still extreme to high. Recommendation is Proplant as Proplant works in all disease pressure conditions especially known and proven as a strong pythium fungicide

Overnight I was speaking to a few supers on twitter on how much rain they received. There was quite  a difference with western Sydney copping about 45mm of rain while the eastern suburbs only got around 8-18mm which is very surprising since they are the ones who always get a drenching.

What all this means is that disease pressure is very high to extreme (my climate app report) at the moment and will be staying high for the next few days at least. Having a preventative program is the best option however even the best prevention program needs a little fine tuning. Here at Campbell’s we have Proplant available for pythium and is on the of the best products on the market available due to its curative abilities and longest residual over nay other pythium product. Proplant has been a trusted fungicide by meany turf managers for over 10 years now. In our trial work we did with Proplant we compared it against a standard pythium fungicide and found that the standard gave only 7 days residual while Proplant even at both the low and high rates gave 28 days.

For more information see the brochure here Proplant Brochure

Also have a look at our guide to managing pythium not just from a chemical point of view but from a cultural view. Disease guide rhizo eri pythium 2014

Managing pythium is not just use fungicide but use every tool you have at your disposal and make observations on your turf. You need to take a holistic approach from mowing practices, watering practices and inputs you are using. See our guide to find out more.

Proplant image

As always we do recommend a broad spectrum tank mix partner with Proplant (as its is specific to pythium only) as when we were anyalysing the samples in the trials we always found other diseases namely brown patch. So the options we have are:
So have a look at partnering Proplant with Ippon, 250GT, Protak, Monstar,

Again please don’t hesitate to contact me if you have any questions.

 

Nadeem

zreikat@campbellchemcials.com.au