Muscling in on vine­yard pests

Marlborough Express - The Saturday Express, Marlborough - - GARDENING - MONIQUE STEELE

Mus­sel shells are al­ready used to con­trol weeds in vine­yards and now may be able to re­pel de­struc­tive grass grubs too, new Lin­coln Uni­ver­sity re­search sug­gests.

Us­ing green­shell mus­sel in vine­yards, al­though not a new prac­tice, could be seen as a win for the aqua­cul­ture and wine in­dus­tries, the study said.

Empty mus­sel shells found around the re­gion, like at ‘‘Shell Moun­tain’’ near Have­lock, could be used to de­ter grass grubs.

That’s ef­fec­tively a sum­mary of the work by Mauri­cio Gon­za­lez-Chang, a Lin­coln Uni­ver­sity PhD stu­dent whose work in Marl­bor­ough us­ing green­shell mus­sels to con­trol grass grub is be­ing seen as a win-win for the aqua­cul­ture and wine in­dus­tries.

Speak­ing from his home in Val­divia in south­ern Chile, Mauri­cio laments the fact that his own na­tion’s wine in­dus­try is show­ing much less in­ter­est in his work than New Zealand’s. He is cur­rently look­ing for more re­search or a wine in­dus­try po­si­tion to con­tinue his work.

Grass grubs emerge from the ground in spring and can cause con­sid­er­able dam­age to vines in a two-to-three hour feed­ing frenzy be­fore they drop to the ground, mate and carry eggs into the soil, which de­velop as lar­vae.

Gon­za­lez-Chang said the ma­jor pas­ture and lawn pests were usu­ally con­trolled by a broad spec­trum in­sec­ti­cide. The in­sec­ti­cides, al­though ef­fec­tive, killed every­thing else in the soil too though. ‘‘It’s a huge prob­lem among wine grow­ers, es­pe­cially if they are or­ganic.’’

Sus­tain­able wine­maker Kono Bev­er­ages was keen to get on board with the study, of­fer­ing up its Awa­tere Val­ley Tohu block for Gon­za­lez-Chang to trial sev­eral vari­ables to con­trol grass grubs, in­clud­ing clay par­ti­cles.

From his re­sults, he be­lieved the light re­flected from the shells dis­ori­ented the fly­ing grubs, mak­ing them land else­where than on vines, which have mus­sel shell beds. They also pro­vided a bar­rier to any bee­tles that did land on the ground. Dur­ing his pre­sen­ta­tion at last year’s Romeo Bra­gato viti­cul­tur­ists con­fer­ence in Blen­heim, Gon­za­lez-Chang showed a video clip of how the use of mus­sel shells re­duced grass grub dam­age to vines by 75 per cent.

Marine Farm­ing As­so­ci­a­tion pres­i­dent and wine­grower Jonathan Large said both in­dus­tries would ben­e­fit if mus­sel shells were more widely used.

‘‘Ev­ery­one has seen the shell moun­tain near Have­lock,’’ Large said. ‘‘We are look­ing at op­tions such as re­turn to the sea but if the shells help con­trol grass grub, I for one am in­ter­ested in putting them on my vine­yard.’’


Chilean re­searcher Mauri­cio Gon­za­lezChang in Kono’s Awa­tere Val­ley vine­yard.

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