February (No. 493)
Case study: Nutritional treatment of a Margaret River vineyard following acute herbicide damage
Ken Bailey, Tim Quinlan, Anthony Quinlan , Era Farming Company, PO Box 411, Leederville 6903
Wetting agents or adjuvants are frequently included in vineyard canopy sprays from budburst (E-L stage 04) to pre-flowering (E-L stage 17). These agents are designed to increase adherence and coverage of spray droplets early in the growing season when targeted shoots are smaller. In mid-October 2003 an ERA Farming Company consultant was called to assess the damage to a vineyard after herbicide was accidentally substituted for a wetting agent during a fungicide application.
The most-extensive damage occurred in a 2.2 hectare block of five-year-old Semillon vines. These vines were pruned to between 16 and 18 buds per metre on 3.6m row spacings. A cropping level of 6.4t/ha (2.3kg/m) was achieved in 2003 with a block yield of 14 tonnes. The target yield for 2004 was 8.3t/ha (3kg/m) with a potential block yield of 18 tonnes. This yield target allowed for the removal of bunches from low-capacity shoots of less than 50cm in length.
On 16 October 2003 the herbicide Oxfluorofen was inadvertently added, at a concentration of 0.1%, to a tank mix of wettable sulphur before being sprayed over the vineyard at a water rate of 400l/ha. The sulphur was mixed at label rates and there was no risk of leaf burn with ambient temperature at less than 25 degrees centigrade. Vine shoots were at E-L stage 12, with 5-6 leaves unfolded and clearly visible inflorescences.
Oxyfluorofen is generally applied as a pre-emergent barrier herbicide which binds to the soil particles and kills weeds as they emerge. Oxyfluorofen can also be included as a ‘spike’ with systemic and contact herbicides to increase the spectrum of weeds controlled.
NOTE: The complete article can be found in the February issue of The Australian & New Zealand Grapegrower & Winemaker.