Pasture Dieback (a problem now affecting millions of acres of grazing land across Qld & NSW) has been blamed on all sorts of things- even Mealy Bugs. I’d like to go out on a limb now and share why I think that theory is largely ridiculous.
Keeping in mind that “Dieback” is not unique to Australia with many versions appearing throughout the world in different climatic conditions and production systems. Interestingly some of the quoted solutions internationally actually come from Australians, however these don’t seem to have filtered down locally.
The following images are taken at our farm at Amamoor in the Mary Valley, QLD. The 5ha paddock in this drone shot on the left was hit quite hard again this year with Pasture Dieback. The remnants are clearly visible (image taken late January) however as you will see in the shot on the right from 3-months prior, the issue has largely been overcome- down from acres to just square meters.
Two paddocks in this image.
Left ‘the crop paddock’ affected by die back.
Right paddock has no issues, but only a barb wire fence between them.
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Large area affected by dieback
Interestingly, last summer nearly the entirety of the 5ha was covered in pasture dieback. The paddock is now covered with pioneer plants like our friend the scotch thistle, Cotton Bush, Johnson Grass and most other weeds in existence! But amongst them are also the legumes we’ve planted and good stands of grass coming back in too.
Pioneer weeds
Both seasons our treatment was the same- get lignified material (weeds) down by trampling and mulching/slashing then applying microbes (particularly fungi) in the form of extended ActivFert Soil Life. We planted some legumes and did what we could to increase nutrient cycling. We also added micronised lime. This “treatment” had a product cost of about $16/ha plus $8 for the lime and a similar amount for a contractor to spread it.
Although the jury is still out, I believe the symptoms of pasture dieback are closer to a disease or fungal attack than
an insect attack. Like everywhere in nature, there’s good and bad microbes continually competing. Poor soil health pushes the balance one way too far, so a particular type of fungi proliferates attacking unhealthy pastures growing in an area. If there’s a monoculture, their job is all the easier.
Don’t shoot the messenger!
Mealy bugs may be a carrier for a fungi, they may be there just doing their job as a scavenger (as they are definitely present), however the 6ha paddock on the right of the affected paddock has had no symptoms of Dieback with only a barb wire fence for protection (non-Mealy bug proof). In fact the rest of the farm hasn’t been touched!
So why the difference?
The badly affected paddock has always been called “The Crop Paddock”. When we were looking to buy this little farm the advertisement showed a picture of this paddock with a beautiful corn crop ready for harvesting. The history of this paddock is one of tillage – offset discs and synthetic fertilisers producing an annual crop. The rest of the farm was only used for cattle grazing. This all happened over a decade ago, long before our time as the managers of this land. For the last 10 years, all the paddocks on this farm have been treated the same with no tillage, synthetics or chemicals.
I believe our farms’ current microbial regime, further increasing stock densities (beyond 100AE/HA) with longer recovery periods and continuing to capitalise on any recurring “dieback areas” as opportunities to establish legumes will see an end to this problem. We are certified organic, do have very good dungbeetle populations, we feed biochar, paloganite and other soil amendments out through our lick for our cattle to spread (activating it with gut microflora in the process). The farm is on a floodplain in a high rainfall, very moist microclimate. Changes (good & bad) happen quickly – so it’s a great place to test things out!
I guess the message is: Please think about the tillage you do now and the synthetics you use as it’s possible you’ll be living with consequences for a long time to come. Even in our extremely “Non-Brittle” 1200mm rainfall environment problems are manifesting themselves a decade on. Imagine the effect on more marginal country! Thanks to Pasture Dieback for teaching us this valuable lesson. (PS- Although we’ve used Soil Life and mulched up weeds as our main microbial source & food, any measure that improves soil health and microbe levels- particularly fungal diversity is probably beneficial (or definitely can’t hurt). We just looked at bang for buck and scalability as we also have customers on larger holdings needing economical solutions- but please yourself- it’s all good!)
by Tim Scott
