Thursday, 10 May 2018

10.5.18 Menace of Xylella Fastidiosa Puts Growers on Alert

The pathogenic bacterium Xylella Fastidiosa which is spread by sap feeding insects and can kill over 350 species of wood producing plants including vines, olives, citrus, lavender and rosemary, has been detected in Spain. It causes leaves and fruits to dry up and fall, eventually killing the plant. A forum has therefore been hosted by the Consejo Regulador, the Junta de Andalucía Agriculture Department, the International Organisation of Wine and the Vine and the bank Cajamar Rural to give growers the latest on the risk they face. The forum covered how to detect the presence of Xylella and the devastating economic impact of its arrival which causes Pierce’s Disease in vines.

Glassy winged sharpshooter spreads pathogen (foto:westernfarmpress)

In California the disease has already cost 100 million dollars – half in losses and the other half in research to control the problem, and it is also present in Italy. The disease has been found in olives near Madrid, almonds near Alicante and at a nursery near Almería. The spread of Pierce’s disease is such that it is necessary to uproot the entire hectare surrounding an affected vine. Detection is vital and the Junta has already carried out 9,000 inspections since 2015. The president of the Jerez growers’ association, Francisco Guerrero, said that Jerez can ill afford the uprooting of vines since the vineyards have already been reduced to 7,000 hectares, so without sufficient vigilance, especially in nurseries, the remaining vineyard could be lost.

Damage caused by Pierce's Disease (foto:winesandvines)

There is no cure yet for Pierce’s disease but work on bacteriophages (viruses which can kill bacteria) is offering some hope. The 2018 season in Jerez is already proving difficult as rising temperatures after record rainfall in March are creating ideal conditions for the spread of cryptogamic diseases like oidium and mildew, and most vines have needed to be sprayed twice, costing the growers dear.

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