Pro­tect­ing meat and two veg

Tasmanian Country - - NEWS -

WHEN it comes to Aus­tralia’s meat and two veg, car­rots and po­ta­toes re­main in­cred­i­bly pop­u­lar op­tions for our din­ner plates.

No won­der, then, that re­searchers at the Tas­ma­nian In­sti­tute of Agri­cul­ture are help­ing de­ter­mine how best to de­tect soil-borne pathogens that im­pact car­rots and po­ta­toes.

The South Aus­tralian Re­search and De­vel­op­ment In­sti­tute is work­ing with TIA to val­i­date new DNA tests for cav­ity spot in car­rots and pink rot in po­ta­toes, which will be part of the PREDICTA® suite of tests of­fered to grow­ers.

“We’re uniquely po­si­tioned to con­firm if the DNA tests work as in­tended,” TIA re­searcher Dr Robert Tegg said.

“Tas­ma­nia not only pro­duces roughly a quar­ter of Aus­tralia’s po­ta­toes and car­rots, but our soils also con­tain vari­able lev­els of these pathogens that pose a threat to grow­ers.”

Two va­ri­eties of fun­gus, Pythium sul­ca­tum and Pythium vi­o­lae, are the pre­dom­i­nant causes of cav­ity spot in car­rots. A fun­gus-like micro­organ­ism known as an oomycete, Phy­toph­thora ery­throsep­tica, causes pink rot in po­ta­toes.

Dr Tegg said that if the DNA tests are val­i­dated, they may help arm grow­ers by al­low­ing them to pre­dict the like­li­hood of in­fec­tions de­vel­op­ing in their pad­docks.

“It’s not un­com­mon to find pathogens like fun­gal spores at small con­cen­tra­tions in the soil, but when they hit a cer­tain thresh­old, they in­crease the like­li­hood of dis­ease.

“What we’re ba­si­cally con­firm­ing is how much of a pathogen needs to be present to cre­ate an out­break,” he said.

It’s not suf­fi­cient to just know how much pathogen DNA, like that found in fun­gal spores, is needed to flag a po­ten­tial prob­lem for grow­ers.

TIA’s re­search also seeks to un­cover how many tests are nec­es­sary to give a pad­dock the all clear. “If we can say ‘this is a dan­ger­ous level of spores’, we also need to know how many soil tests per hectare are nec­es­sary to be sure that level is ac­cu­rate,” said Dr Tegg. “It’s un­likely the pathogen is in every square me­tre of soil. Do grow­ers need to test 5 or 25 soil sam­ples per hectare? How many tests do they need to be rel­a­tively cer­tain of the soil’s sta­tus? That’s what we hope to find out.” Out­breaks of dis­ease like pink rot or cav­ity spot can have dev­as­tat­ing im­pacts on grow­ers, caus­ing their crop to be dis­carded, down­graded or prevent­ing stor­age. Early test­ing could re­veal po­ten­tially dan­ger­ous con­cen­tra­tions of dis­ease-caus­ing pathogens prior to plant­ing, giv­ing grow­ers no­tice to treat their soil or seed, change va­ri­eties or even crops. Suc­cess­ful tests could re­sult sig­nif­i­cant sav­ings for car­rot in and potato farm­ers not just in Tas­ma­nia, but na­tion­ally and abroad, said SARDI re­search sci­en­tist Michael Ret­tke.

“Car­rots and po­ta­toes are two of the high­est value veg­etable crops in Aus­tralia — and among the most valu­able in the world.

“We need to pre­serve grow­ers’ ca­pac­ity to gen­er­ate in­come, whether they’re pro­duc­ing tonnes of fresh car­rots each year or gen­er­at­ing a bit of ad­di­tional rev­enue from seed po­ta­toes.”

The field tests are be­ing con­ducted at mul­ti­ple com­mer­cial farms statewide and at TIA’s Forth­side Veg­etable Re­search Fa­cil­ity in the state’s North West.

Re­searchers ex­pect to fi­nalise the tests by June of this year.

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