Bo­rer beet­le thre­at: pu­blic as­ked to help

George Herald - - VOORBLAD -

The Ge­or­ge Mu­ni­ci­pa­li­ty is con­si­de­ring ur­gent me­a­su­res to sa­ve local trees from a new bo­rer beet­le in­fe­sta­ti­on and is ap­pe­a­ling to ci­ti­zens to help report signs of in­fecti­on.

Ge­or­ge Mu­ni­ci­pa­li­ty Di­rec­tor of Com­mu­ni­ty Ser­vi­ces, Wal­ter Hen­dricks, said re­ports of the Po­lyp­ha­gous S­hot Ho­le Bo­rer (PSHB) or Eu­wal­la­cea for­ni­ca­tus and its as­so­ci­a­ted fun­gus kil­ling trees in ot­her parts of the coun­try s­par­ked an in­ves­ti­ga­ti­on in­to a pos­si­ble local in­fe­sta­ti­on. "Our fe­ars we­re con­fir­med and ad­van­ced in­fecti­on was de­tected in se­ver­al lar­ge trees in Do­ne­rai­le S­qua­re, Van Rie­beeck Garden and Camphers­drift. This was just a cur­so­ry in­ves­ti­ga­ti­on to con­firm the thre­at, but we ex­pect to dis­co­ver mo­re. Ge­or­ge is a tree-rich ci­ty and we are con­cer­ned for our re­si­den­ti­al trees as well as sur­roun­ding farms and fo­re­stry," said Hen­dricks.

The PSHB beet­le is re­la­ti­ve­ly new to South A­fri­ca and a pos­si­ble vi­a­ble com­mer­ci­al che­mi­cal fun­gi­ci­de is cur­rent­ly on­ly a­vai­la­ble w­ho­le­s­a­le. The Ge­or­ge Mu­ni­ci­pa­li­ty and ot­her local ro­le play­ers are meet­ing with U­ni­ver­si­ty of P­re­to­ria Pro­fes­sor Wil­helm de Beer of the Am­bro­sia Beet­le Wor­king Group next week to dis­cuss con­t­rol stra­te­gies. "The mu­ni­ci­pa­li­ty will al­so be con­sulting with ot­her local aut­ho­ri­ties to in­ves­ti­ga­te all op­ti­ons," said

Hen­dricks.

A­si­an beet­le

The PSHB and its fun­gus we­re first dis­co­ve­r­ed in South A­fri­ca du­ring a rou­ti­ne sur­vey for tree pests at the K­waZu­luNa­tal Bo­ta­ni­cal Garden last y­e­ar. It is a 2mm-long am­bro­sia beet­le na­ti­ve to Sout­he­ast A­sia and car­ries se­ver­al fun­gal spe­cies with it. It bo­res through the bark in­to the sap­wood of trees and in­o­cu­la­tes the fun­gus in­to li­ving wood. The fun­gus grows in the beet­le tun­nels and ser­ves as food for its lar­vae. In suscep­ti­ble trees, the fun­gus can spre­ad through the sap­wood, cau­sing di­se­a­se and e­ven de­ath.

All trees vul­ne­ra­ble

The si­tu­a­ti­on is wor­se­ned by the fact that the beet­le and fun­gus is not host spe­ci­fic, but seem to be af­fecting a wi­de ran­ge of in­di­ge­nous and exo­tic trees, in­clu­ding C­hi­ne­se and Ja­pa­ne­se maple, pla­ne trees, ka­pok trees, pa­per­bark a­ca­cia, wild

plum, dwarf co­ral and com­mon co­ral. Sur­veys ha­ve al­so in­di­ca­ted suscep­ti­bi­li­ty of im­por­tant crop trees such as a­vo­ca­do, ma­ca­da­mia, pe­can, pe­ach, o­ran­ge and gra­pe­vi­ne.

So far symp­toms most seen on trees in Ge­or­ge are small e­le­va­ted blue-black le­si­ons on the bark re­sem­bling shot­gun wounds or ci­ga­ret­te burns. Ot­her symp­toms include pa­t­ches of w­hi­te po­w­de­red wood on the bark sur­roun­ding en­tran­ce ho­les of beet­le tun­nels and blot­ches of oozing re­sin on the bark. The mu­ni­ci­pa­li­ty ap­pe­als to the pu­blic to in­spect the trees on their pro­per­ties as well as in parks and si­de­walks and to report back to parks@ ge­or­ge.gov.za

First re­ports

One of the first re­si­dents in Ge­or­ge to spot the beet­le in­fe­sta­ti­on was Jo­han­na Ver­meu­len, who re­por­ted it to the Ge­or­ge Mu­ni­ci­pa­li­ty. Se­ver­al trees in her garden ha­ve died and a fa­vou­ri­te shade tree got the axe, but this has not hal­ted their acti­vi­ties in her garden. P­ris­cil­la Bur­goy­ne, Garden Route Bo­ta­ni­cal Garden her­ba­ri­um cu­ra­tor, said se­ver­al keur­boom trees s­how all the symp­toms of beet­le in­fe­sta­ti­on, a cau­se for gre­at con­cern as it would be tra­gic if the garden lo­ses all its beau­ti­ful trees to the in­fe­sta­ti­on.

Re­si­dents in W­rig­ht Street in Camphers­drift may not ha­ve no­ti­ced, but the PSHB beet­le has been hard at work. The Ge­or­ge Mu­ni­ci­pa­li­ty hopes to sa­ve the to­wn’s trees with im­me­di­a­te in­ter­ven­ti­ons.

The re­sin run­ning do­wn the bark of this keur­boom tree in the Garden Route Bo­ta­ni­cal Garden is a tell-ta­le sign of pe­ne­tra­ti­on by beet­les. In­fe­sta­ti­on of trees by the PSHB beet­le was al­so found in Do­ne­rai­le S­qua­re, w­he­re trees are dying.

Pho­tos: Pau­li­ne Lou­rens

This stump is all that re­mains of a gi­ant ash tree that u­sed to pro­vi­de shade in Jo­han­na Ver­meu­len’s Camphers­drift garden. Af­ter in­fe­sta­ti­on was dis­co­ve­r­ed it was fel­led and tre­a­ted with che­mi­cals, but new spots keep ap­pea­ring.

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