Waikato re­gion tus­sles with tut­san

South Waikato News - - Your Paper, Your Place - WAIKATO WEED WATCH

Tut­san is a ma­jor pest plant with po­ten­tial to be the ‘‘new gorse’’ in the Waikato. It is spread­ing rapidly.

Un­der new rules in Waikato Re­gional Coun­cil’s pest man­age­ment plan, landown­ers are re­quired to con­trol it wher­ever it oc­curs on their prop­erty.

Tut­san, which orig­i­nated in south­ern and western Europe, is related to or­na­men­tal hy­per­icums (St John’s wort) and looks very sim­i­lar.

It forms a semi-woody, 1.5 me­tre tall shrub with red­dish stems and small, pleas­antsmelling, oval leaves that of­ten turn red in au­tumn.

Clus­ters of small, bright yel­low, five-petalled flow­ers with prom­i­nent sta­mens ap­pear from Novem­ber to Fe­bru­ary.

Th­ese are fol­lowed by fleshy, round, red berries, which ripen to black and dis­in­te­grate, spread­ing large amounts of long-lived, dust­like seed far and wide.

You will find tut­san grow­ing along road­sides and wa­ter­ways, and on scrub­land and farm­land. It is dif­fi­cult to con­trol once es­tab­lished.

A great sur­vivor, this tough plant is tol­er­ant of shade and all tem­per­a­tures, poor soils and phys­i­cal dam­age.

That dust-like seed is widely dis­persed into nat­u­ral ar­eas by wind, birds and agri­cul­tural machin­ery.

Tut­san can take hold in ar­eas of hill coun­try farm land and dis­turbed for­est where it forms dense stands and pre­vents the es­tab­lish­ment of pas­ture and na­tive seedlings.

Her­bi­cides are most ef­fec­tive on tut­san dur­ing spring and early sum­mer while the plants are still fresh and haven’t formed a wax coat­ing.

Shaded ar­eas can be sprayed later if the plant is still fresh and hasn’t formed a wax coat­ing to the same ex­tent.

Use her­bi­cide de­signed to kill gorse.

Once tut­san is erad­i­cated, the area it has oc­cu­pied can be at lev­els re­planted with na­tive co­pros­mas or corokia, ex­otic Chi­nese sa­cred bam­boo and other suit­able shrubs to help stop it getting reestab­lished.

For more in­for­ma­tion, visit

An­other ma­jor pest plant lo­cally is yel­low flag iris - a pretty, eye catch­ing but de­struc­tive plant.

Yel­low flag iris is preva­lent in gar­dens through­out the Waikato.

This na­tive to Europe, Asia and North Amer­ica was in­tro­duced to New Zealand as an or­na­men­tal gar­den plant.

It has also been de­lib­er­ately planted around wa­ter­ways and wet­lands in many ar­eas.

The plant’s seeds and rhi­zomes are spread by wa­ter move­ment and machin­ery to in­fest new ar­eas.

Yel­low flag iris is tol­er­ant of many cli­matic ex­tremes and grows hap­pily in any open, sunny swampy ground, fresh or brack­ish wa­ter mar­gins, lakes, salt marsh, and wet sandy ar­eas – even in pad­docks near wa­ter­ways or wet­lands.

The rhi­zomes form dense float­ing mats, dis­plac­ing na­tive plants and po­ten­tially caus­ing flood­ing and wa­ter level changes in swamps. Poi­sonous seeds may also af­fect na­tive birdlife.

Iden­ti­fy­ing fea­tures in­clude yel­low flow­ers up to 120 mil­lime­tres across, typ­i­cally in an iris like form, flow­er­ing in spring and early sum­mer. Leaves are broad (20-30mm wide), flat and sword shaped.

Be­cause seeds float in wa­ter, yel­low flag has spread seed down the banks of the Waikato River, with small in­fes­ta­tions from Hamil­ton to Ngaru­awahia, and large in­fes­ta­tions from Ngaru­awahia to Port Waikato.

One plant can pro­duce 1000 seeds, cre­at­ing a large seed bank.

Tut­san orig­i­nated in south­ern and western Europe.

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