RESEARCH & EVENTS
Bacterial Spot in Almonds: Is Copper Still Effective?
From page 41 Many were also sensitive at less than the label rate, although this is not a recommended practice in field situations due to the risk of selecting for copper tolerance. All isolates except one were sensitive to Tri-Base Blue ® at every rate. Thirty-eight isolates were sensitive to Copper Oxychloride WP ® 50 % at every rate while 43 were sensitive at the label rate or above. However, there were two isolates that were not sensitive at the label rate. All isolates were sensitive to Blue Shield ® and copper sulphate at the label rate and above with the majority also sensitive at the lower rate( Figure 3). A further 11 isolates collected from Victoria and SA last season are currently undergoing testing. Generally, the Xanthomonas arboricola pv. pruni isolates tested retained sensitivity to copper products at the label rate, although in a few cases the level of inhibition was reduced. In line with best practise the industry should carefully monitor and adhere to recommended application rates and implement good chemical management practises
Figure 3. Number of isolates inhibited by copper products at each rate. ■ no inhibition at 2x label rate, ■ no inhibition at 1x label rate, ■ no inhibition at 0.5x label rate and ■ inhibition at 0.5x label rate.
to avoid the possibility of resistance developing in the future. References 1. Wiechel et al( 2022) AL16005 Integrated disease management in almond Phase I. Final Report Hort Innovation
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