Thrip Damage - UPDATE 17/10/2008
Bright yellow leaf spotting can be seen in many vineyards - above.
This is caused by thrips, small sap sucking insects. This is not a concern, although the spots can be confused with Powdery Mildew spots or occasionally other faults like herbicide spray drift. Powdery has grey growth on the underside of the leaf. Thrip damage is a bright yellow spot only.