More or less fruit next season?
Two weeks ago I attended a workshop, run by AHA Viticulture, on “Bud Fruitfulness & Bud Dissection” with a view to understanding how having buds dissected at this time of the year can assist with a grower’s decision on pruning method as well as how many buds to leave.
We all know that next seasons yield has pretty much been determined by the weather conditions experienced the previous spring. Temperature and light conditions at that time play a pivotal role in setting the potential number of infloresences (bunches) and hence help determine what the final yield will be.
The spring of 2005 was one of if not the coolest experienced in the Margaret River region and it would be expected that these conditions will have impacted on bud fruitfulness. I recall that back in November/December flowering was erratic and spread out - usually an indication that conditions have not been ideal. It is the temperature and light conditions two weeks before and through flowering that is critical in maximising infloresence development. Last spring the temperature rarely got above 20 C with many cool, cloudy days.
It has long been known that if you dissect buds at this time of the year it is possible to count developiing bunches and therefore calculate the potential crop level for next season. This procedure was demonstrated at the workshop to good effect using a dissection microscope.
Results presented indicated that of buds already surveyed Cabernet Sauvignon showed a decrease from the previous season of one bunch at bud number two along the cane. Shiraz on the other hand showed no difference for the first two buds but decreased significicantly from bud three onwards. A high number of necrotic primary buds in Shiraz was also observed.
These facts can have serious implications as to whether one canes or spur prunes this season. It would appear that if you were spur pruning it could be expected that fruitfulness will be reduced due to the second bud being less fruitfull. If cane pruning Shiraz, fruitfulness towards the middle of the cane may be reduced. The other issue noticed at this early stage was the significant number of primary buds showing necrosis. The reasons at this stage are unclear.
In summary, yields could well be down next season for reasons other than the coming season and that while this may not be a bad thing in red varieties, it could be rather serious for white wine production. Only time will tell I guess.
Vineman
Technorati Tags: buds, necrosis, Shiraz, Cabernet Sauvignon, Margaret River, infloresence