Mite to be used to fight in­va­sive pest

Manawatu Guardian - - NEWS - By ALEXAN­DER ROBERT­SON

One of the coun­try’s most nox­ious weeds might have met its match.

Hori­zons Re­gional Coun­cil (HRC) with the Na­tional Bio­con­trol Col­lec­tive, has been suc­cess­ful in its bid to be the first in the world to use a mite for bi­o­log­i­cal con­trol against the in­va­sive weed Old Man’s Beard.

In a year’s time, the Ser­bian gall mite will be re­leased near Tai­hape in the heart of the Ran­gi­tikei re­gion where the suf­fo­cat­ing plant was first in­tro­duced around 100 years ago.

The seeds spread quickly and the pest was found through­out the coun­try.

Old Man’s Beard is a nasty weed which cloaks veg­e­ta­tion and kills other species such as na­tive trees and plants. The fight against Old Man’s Beard hasn’t been easy or quick. HRC has poured half a mil­lion dol­lars into con­trol­ling the pest by spray­ing, cut­ting and sup­port­ing lo­cal com­mu­ni­ties to do the same each year.

While this work has helped slow the spread of the weed, it was hoped the mite would make a real dent to its growth.

Hori­zons en­vi­ron­men­tal pro­gramme co-or­di­na­tor Craig Davey said the mite would en­able the weed to be con­trolled in places where it was too dan­ger­ous to use pes­ti­cides be­cause of the na­tive flora be­neath the Old Man’s Beard canopy.

“This will be a world first in terms of us­ing a mite against Old Man’s Beard,” Davey said.

“We have at­tempted other forms of bio­con­trol in­clud­ing a sawfly, leaf miner and fun­gus which haven’t been very suc­cess­ful.

“We’re re­ally ex­cited by this new one as we have seen how suc­cess­ful gall mites have been on other pest plants.”

The gall mite was aptly named. Grow­ing galls on the weed, sim­i­lar to a wart or a boil on a hu­man or an­i­mals, it pre­vented the plant from flow­er­ing and grow­ing.

Ex­ten­sive test­ing has been com­pleted as part of the EPA ap­pli­ca­tion to en­sure the gall would will not pose a dan­ger to other plant types.

The mite was ex­pected to be im­ported into the coun­try in au­tumn 2019, for re­lease the fol­low­ing spring.

“We are plan­ning to make the first in­tro­duc­tion of the gall mite to the Tai­hape area.

“Many unique and won­der­ful habi­tats have been rav­aged by Old Man’s Beard,” Davey said.

“As we have a re­ally en­gaged com­mu­nity in the Ran­gi­tikei, we’d like to lo­cate these mites in the places too chal­leng­ing or risky for chem­i­cal con­trol.”

■ www.lo­cal­fo­ Made with Fund­ing by NZ on Air

Hori­zon’s en­vi­ron­men­tal pro­gramme co-or­di­na­tor Craig Davey, who says the in­tro­duc­tion of a mite to con­trol Old Man’s Beard is a world first.

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