Shot hole borer pest found in pecan trees

Shot hole borer pest found in SA pecan trees

The East-Asian polyphagous shot hole borer (Euwallacea sp. nr fornicates) has been discovered in pecan trees in Hartswater, Northern Cape, according to the Department of Agriculture, Forestry and Fisheries (DAFF).

The pest has caused significant damage to hundreds of tree species in California and Israel.

Jan Hendrik Venter, manager of Early Warning Systems at DAFF, told Farmer’s Weekly that while the pest had thus far only been detected in pecan trees in Hartswater, it could also affect avocado and macadamia trees.

He added that the pest was well established in Johannesburg, but had never presented a problem to agricultural areas until now.

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The shot hole borer affects mainly soft-wooded plants such as the London plane tree, Cussonia, oak tree, and some ornamental species.

“It seems that pecan [trees] are a non-reproductive host for the beetle. Although the subtropical industry is conducting surveys together with the Forestry and Agricultural Biotechnology Institute, they have not detected it in commercial avocado production areas,” Venter said.

No losses as a result of the borer had yet been recorded, but it was important that farmers increased their scouting efforts to detect any signs of the pest.

“DAFF needs to be informed of the beetle. The borer is not so much the problem as the fungus [Fusarium euwallaceae] it is transmitting to trees. The fungus blocks vascular tissue of the tree and nutrient flow. Hence branches die back and eventually the whole tree [dies],” Venter said.

Infested trees need to be uprooted and chipped to be used as compost to prevent the spread of the borer.

There is currently no specific product registered for control of the pest. DAFF is thus working with pesticide, fungicide and biological control companies to ensure the emergency registration of a suitable product.