‘A huge chal­lenge is that mu­nic­i­pal­i­ties are not equipped to deal with such out­breaks’

Farmer's Weekly (South Africa) - - Weekly News Wrap -

– As­so­ciate pro­fes­sor at the Univer­sity of Pre­to­ria’s Forestry and Agri­cul­tural Biotech­nol­ogy In­sti­tute, Wil­helm de Beer, be­moan­ing lo­cal mu­nic­i­pal­i­ties’ in­abil­ity to con­trol pest out­breaks such as the cur­rent shot hole borer in­fes­ta­tions

South Africa’s por­ous bor­ders and a lack of com­mu­ni­ca­tion be­tween govern­ment de­part­ments have made it dif­fi­cult to re­strict the spread of the East Asian polyphagous shot hole borer ( Euwal­lacea sp nr for­ni­cates) in the coun­try.

Wil­helm de Beer, an as­so­ciate pro­fes­sor at the Univer­sity of Pre­to­ria’s Forestry and Agri­cul­tural Biotech­nol­ogy In­sti­tute (FABI), told Farmer’s Weekly that the City of Cape Town, Jo­han­nes­burg City Parks, the Stel­len­bosch Lo­cal Mu­nic­i­pal­ity, Kirsten­bosch Gar­dens and the South African Na­tional Bio­di­ver­sity In­sti­tute, as well as stake­hold­ers in KwaZulu-Natal, were work­ing on a strat­egy to stop the shot hole borer in its tracks if it ar­rived in ar­eas in which it had not been pre­vi­ously found.

Com­ment­ing on the lack of con­trol at South Africa’s bor­ders, De Beer said of­fi­cials that checked for th­ese types of pests were only sta­tioned at OR Tambo In­ter­na­tional Air­port, and they were only on duty “dur­ing of­fice hours”.

Farmer’s Weekly had pre­vi­ously re­ported that shot hole borer in­fes­ta­tions had been dis­cov­ered in pecan trees near Hartswa­ter.

The in­sects trans­mit­ted the Fusar­ium eu­wal­laceae fun­gus to the trees, which blocked the trees’ vas­cu­lar tis­sue and thus im­peded nu­tri­ent flow, re­sult­ing in branches dy­ing back and the even­tual death of the whole tree.

“The [stake­hold­ers] are busy with an aware­ness cam­paign [for] mu­nic­i­pal­i­ties, nurs­eries and those who sell fire­wood. Fire­wood is one of the big­gest prob­lems.

“We found a case in Jo­han­nes­burg where some­one bought fire­wood from an in­for­mal seller. This per­son [no­ticed that] the fruit trees in his gar­den were af­fected by an un­known bug.

“When we in­ves­ti­gated, we found that a sin­gle piece of fire­wood of about 500g [con­tained] around 44 fe­males, [each ca­pa­ble of lay­ing] 1 400 eggs,” De Beer said. Stud­ies in the US had found that even wood­chips in mulch or com­post that were smaller than 2cm in size could con­tain fe­male in­sects, as about 5% of th­ese fe­males sur­vived the mulching process.

An­other prob­lem oc­curred when trees bred in nurs­eries were in­fected, as the pest could then be spread across the en­tire coun­try.

To date, shot hole borer in­fes­ta­tions had been found in av­o­cado, guava, plum and peach trees in do­mes­tic gar­dens, as well as grapevines, but thus far it only seemed to neg­a­tively af­fect com­mer­cial pecan nut trees, he said.

“A huge chal­lenge is that mu­nic­i­pal­i­ties are not equipped to deal with such out­breaks. There is also a large com­mu­ni­ca­tion gap be­tween mu­nic­i­pal­i­ties and the de­part­ment of agri­cul­ture, [among oth­ers]. But we are [in the process of en­sur­ing that] lines of com­mu­ni­ca­tion are opened,” he said. – Ger­hard Uys

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