Post-harvest treatment of vines (continued…) Previous reminders have covered post-harvest nutrition and fungicide considerations. The Following are some additional suggestions:
Foliar nutrient sprays:
While some growers choose to apply nutrients post-harvest, many consider the likelihood of nutrient uptake at this stage of the season marginal, at best. Most growers choose to apply nutrition sprays prior to flowering when it is more likely to produce a greater return for the cost. At this stage of the season a sudden bout of cool weather can lead to leaf drop, some leaves may have been damaged by harvesting and the potential uptake of foliar nutrients is greatly reduced.
With the exception of late season appearance of mildews, sprays at this time usually offer questionable benefits. Some exceptions may be a heavy infestation of powdery, or late season downy mildew in patches that use sprinkler irrigation. Application of protectant fungicide may reduce leaf loss and therefore allow greater accumulation of carbohydrates, leading to better bud burst next season.
Selection of fertiliser: With soil temperatures dropping growers may consider using ammonium or nitrate forms of nitrogen post-harvest. These forms of N will have more rapid uptake than urea, which may be limited under these conditions. Care should be taken with the timing of adding nitrate, as it can be leached if it rains soon after application.
Gypsum: With many vineyards now drip irrigated, incorporation of gypsum relies almost exclusively on winter rainfall. In drip irrigated vineyards gypsum application is most often done soon post-harvest to give the greatest likelihood of rainfall incorporation. It is also common practice to concentrate the gypsum in a band over the root zone, rather than across the entire row in drip irrigated vineyards.