A world-first bio­con­trol agent is go­ing to fight a wan­der­ing pest

NZ Lifestyle Block - - Notebook -

Trades­cantia, also known as wan­der­ing jew and wan­der­ing wil­lie, is an in­sid­i­ous weed that is hard to con­trol. It quickly takes over gar­dens and re­serves, and is known to give dogs der­mati­tis.

Any scrap left be­hind can re-sprout. It thrives in shade, in damp con­di­tions, and in most soil types. Its leaves form large, dense mats that pre­vent na­tive species re­gen­er­at­ing.

But there’s new hope for con­trol­ling it in NZ with the world’s first field re­lease of the trades­cantia yel­low leaf spot fun­gus in Ro­torua.

Chan­tal Probst of Man­aaki Whenua Land­care Re­search says the yel­low leaf spot fun­gus has been ex­ten­sively tested and is host spe­cific. That means it’s highly un­likely to at­tack any other NZ plant life.

It works by in­fect­ing the weed and dam­ag­ing the epi­der­mis, caus­ing the leaves to shrivel and die. It is ‘released’ via the plant­ing of lab-in­fected plants among healthy trades­cantia plants.

Dr Probst says it’s hard to de­ter­mine how long it will take for the fun­gus to be­come prop­erly es­tab­lished as it is the first time it has been released in any coun­try as a bio­con­trol agent.

The fun­gus was ap­proved for use in 2013, but it was not im­ported un­til three species of trades­cantia-eat­ing bee­tles were first given time to es­tab­lish. The bee­tles have shown great prom­ise, but strug­gle in ar­eas that flood, a pop­u­lar grow­ing area for trades­cantia.

The fun­gus will ini­tially be released into ar­eas with­out any bee­tles. In fu­ture, it’s ex­pected the bee­tles and fun­gus will com­ple­ment each other. A mon­i­tor­ing project has been set up to mea­sure their ef­fec­tive­ness.


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