Controlling tradescantia

'Trad' (the author abbreviation of John Tradescant) is the weed species Tradescantia fluminensis (also known as T. albiflora). While two privet species are the most important woody weeds, trad presents a big challenge for control on the forest floor. This is because it can cover the ground in a thick mat that prevents the regeneration of rainforest seedlings. It also competes with four species in the same family, Commelinaceae, that are native to Ourimbah Creek. These native species are Aneilema acuminatum, Aneilema biflorumCommelina cyanea and Pollia crispata

Fortunately, our trad does not set seed (it is probably a self-sterile clone) and therefore, once it is removed from any specific area it doesn't come back unless re-introduced. This is the basis for the success of the methods outlined below. 

Hand weeding
Where trad isn't growing as a thick mat, it can be weeded by hand. Be sure to wear gloves (surgical gloves are best for delicate weeding), because trad sap can cause an allergic response. There are also a few points to watch out for.
  • Don't throw fragments of trad on to a pile of sticks (rafting) because it will thrive there.
  • Do segregate the trad from other weeds in a special area, such as the 'corral' as illustrated. If you then spray the pile with dilute glyphosate (6 g/l), with follow-up at intervals of about a month or so, it will rot down and form a good potting compost. Glyphosate has the advantage over other herbicides in that it is quickly broken down by bacteria in the soil.
  • Be sure to return to the areas that you have weeded after a gap of a month or two. Although there will be no seedling trad, tiny fragments that you missed will by then have sprouted and they need to be removed.
  • Kill trad on your own property. Putting it in the garbage, or worse, throwing it over the back fence, is anti-social. In any case, by doing so you throw away valuable nutrients.
Herbicide treatment
Trad grows in damp, shady places as a thick mat. Unless you are fond of lost causes, don't try to hand weed large areas of such thick monocultures. An effective strategy is to attack the mat in the following stages. 
  • Identify any native seedlings that survive and rake the trad stems away from them to leave them within a completely cleared circle.
  • Spray as much of the rest of the trad mat as you can summon energy for, avoiding the native seedlings. Use glyphosate diluted to 6 g/l (~20 ml/l of the 360g/l concentrate). After spraying, it's important to leave the area untouched for 3 - 4 weeks
  • Return after those few weeks armed with a rake, the sort with strong metal tines. Although looking sick, some stems will still retain the potential for regeneration. However, they will be easier to rake back than the original cover was.
  • The sick-looking trad is poorly anchored to the ground. Rake it onto the green and lively area that you didn't get round to spraying. Try to rake in different directions so that you catch all the thick stems that could have survived the herbicide. Again, apart from hand-weeding fragments, leave the area untouched for a further 3 - 4 weeks
  • Return to the area where you dumped the raked trad, now reshooting, and spray again, including another swathe of green trad mat. After 3 - 4 weeks, return to rake it back further, keeping the raked areas absolutely free of regrowing fragments. Keep going...
This may sound complicated, but it's a difficult weed that demands a consistent and effective strategy for its control. This method removes the weed and leaves a soft bare seedbed that seems to be ideal for the regeneration of tree species like euodia (Melicope micrococca). However, you must persist in being vigilant over many months and continue to hand-weed or point spray bits that have grown from the tiny trad fragments you missed. The rewards of doing so are great. At least, they have been so on our site, where the once thick mat of weed is quickly replaced by native seedlings.

The long term method
Trad grows well in partially-shaded and moist areas - just the kind of places that would, in its absence, regenerate rainforest. But even trad has its limits. It does not thrive under the deep shade of a mature rainforest canopy. So, take comfort from the fact that, in the long term, your forest itself will become resilient enough to resist this terrible weed.  

A trad 'corral', in which we dump hand-weeded trad for spraying with glyphosate herbicide. The plastic bags are needed because of male brush turkeys. They will scatter a pile of weed, apparently mistaking it for a nest made by a rival. Alternatively, they will incorporate it into their own nest pile. Fortunately, their instinctive behaviour doesn't seem to cope with plastic tree guards!  

Before you kill it, have a close look at a trad flower. Around the stamens you will see some fine hairs. Under the microscope (photo below), these are seen to be strings of cells, so transparent that you can see mitochondria streaming along strands of protoplasm. 
Photo Michael Reid
You can see protoplasmic streaming in this video - worth a visit to see how lively those floral hairs of tradescantia are.

Our trad is sterile
Fortunately for us, our trad does not set seed. This may be because it was introduced into Australia as a self-sterile clone. There is always the danger that another clone could arrive to pollinate and set seed with our resident clone - seeding forms have been found in the Chatham Islands.
If that happened to us, that would make trad an even more serious weed.  

More information can be found from the following link:
The potential for biocontrol of trad is being investigated in New Zealand. Three beetle species from SE Brazil, where trad is a native plant, appear to show promise. One of these eats the foliage (Neolema ogloblini), another the growing tips (Neolema abbreviata), while another eats the stems (Lema basicostata),