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Controlling tradescantia

Trad is the weed Tradescantia fluminensis (also known as T. albiflora). While the privets are the most important woody weeds, trad a big problem on the forest floor. It covers the ground in a thick mat and prevents the regeneration of rainforest seedlings. It also smothers four native species that are closely-relatedAneilema acuminatum, Aneilema biflorumCommelina cyanea and Pollia crispata

Trad doesn't produce seed. As a result, if you remove the vegetative bits, it doesn't come back unless it's re-introduced, say by floating in on a flood. That said, killing all vegetative bits is difficult, although far from impossible.

Hand weeding
Where trad isn't growing as a thick mat, it can be weeded by hand. Wear gloves (surgical gloves are best for delicate weeding), because trad sap can cause an allergic response. Important points to note:
  • 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, as a pile or even better, in a 'corral'. If you then spray the pile with dilute glyphosate (6 g/l), it will rot down and be invaded by the roots of neighbouring trees. Without follow-up, surviving fragments of stem are liable to resprout. Glyphosate has the advantage over other herbicides in that it is quickly broken down by bacteria in the soil.
  • For effective control by spraying, the trad should be growing. Try to avoid treading on it, because it makes spraying less effective.
  • Be sure to return to the areas that you have sprayed or weeded after a month or two. Tiny fragments that you missed will by then have sprouted and they MUST be removed or spot-sprayed.
  • Kill trad on your own property. Putting it in the garbage, or worse, throwing it over the back fence, is anti-social. By doing so you spread it around and throw away valuable nutrients that help your trees to grow.
Controlling trad effectively is very rewarding, especially when you see the red ash and other species stimulated to germinate once the mat of weed is removed.

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 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 or, even better, the McLeod tool that's used in bushfire control. 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 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 still further, keeping the raked areas absolutely free of regrowing fragments. Keep going...
This may sound complicated, but it's a difficult weed that responds to a consistent and effective strategy. This method removes the weed and leaves a soft bare seedbed in which native seedlings such as euodia (Melicope micrococca) and red ash (Alphitonia excelsa) germinate readily. However, you must continue to revisit the area over the following months. This is to hand-weed or point spray bits that have grown from the tiny trad fragments that you are bound to have missed. Alternating hand-weeding with herbicide treatment is more effective than either by thenselves. All this demands time and effort, but the rewards of success are great. At least, they have been on our site, because native seedlings seem to germinate particularly well in the soft soil from which thick trad has been removed. 

Spot spraying with a water-pistol-like jet of glyphosate is an effective way of controlling isolated regrowths. If you hit a native plant, just wash it with a jet of water - in other words, carry two hand sprays, one with water, one with herbicide (coloured, so as not to mix them up).

The long term method
Trad thrives in partially-shaded, moist and fertile areas - just the kind of places that would, in its absence, regenerate rainforest. But even trad has its limits. It declines in very deep shade, and that's what a mature rainforest provides, where a diversity of vines has helped to close the canopy. So, with good management, your forest will become resilient enough to resist this extraordinary weed.  

weeding tradescantia

This is a trad 'corral'. We have several enclosures like these for putting in hand-weeded or raked trad. A spray with glyphosate herbicide every few months ensures that it rots down. On our site, it needs to be supported by some substantial stakes, because otherwise it would swept away when the flood plain becomes a lake. In between floods, it's sufficient to rake trad into piles for spraying, but then, brush turkeys and lyrebirds can be a problem. They love to rake through the rotting trad for insects, scattering it in the process. Even worse, the turkeys incorporate it in their nest mound, where fragments are likely to regrow. Corrals aren't very pretty, but they do overcome these problems.

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 (cyclosisin this video - worth a visit to see how lively those floral hairs of tradescantia are. The tiny black specks streaming along the strands of protoplasm are the mitochondria.

Our trad is sterile
Don't worry if you see trad flowering, because it won't set seed. This is 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 one. 
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 yet another eats the stems (Lema basicostata),