Fundamentals of vigour management
Understanding the cause of your vigour in each block is key to establishing the most effective, cost-efficient management tool.
Back in 2018, the late John Wilton was concerned about the level of vigour seen in intensive plantings having a consequence on bud quality and fruit quality (colour and poor carbohydrate partitioning). 8 years on, and we are having the same conversations! In saying that carbohydrate balancing is key and vigour reduction can be taken too far. Ranking blocks in order of severity can help to prioritise areas for investment.
A useful way to think about vigour management is through the Liebig’s Barrel principle. It reminds us that until the most limiting issue is fixed, everything else is just plugging holes. As an example, fighting vigour using regalis does not fix the underlying issue if the growth is a result of excess Nitrogen. Identifying the cause of excess growth can be tricky with many factors influencing plant growth. To go into them all we would need a few more pages, but to list a few of the most common:
Tree structure –Fruit is the cheapest most rewarding form of vigour management. Does the canopy structure provide enough ’framework’ or ‘metres of fruiting wood’ to comfortably hold the target crop load in singles and/or even doubles (on preferred sites).
Wood texture should also be a consideration. As we have moved to more formal precision systems, the ‘fill a wire’ concept has been followed. This has been absolutely essential to fill the canopy and achieve cumulative yields; however a replacement programme must be implemented to ensure the larger, less fruitful, higher vigour units can be rotated out.
Pruning should focus on balancing carbohydrate. managing excess vigour and setting up high-quality wood for next season. Summer pruning is a highly effective tool for vigour management, but timing and execution will determine the response. E.g. for example, flush cutting when minimal regrowth is required, and stubbing when a stronger response is needed. Summer pruning off a weak/settled/terminated dart is counterintuitive to vigour management, and fruit quality.
Irrigation deficit is an ongoing balancing act that no one has truly mastered. Have your ever heard the saying, “treat ‘em mean keep ‘em keen?”. The first sign of plant stress is vegetative termination. If shoots are still growing, they are more than likely getting sufficient water. This comes back to the fundamentals of irrigation management – where is the active root zone and how is soil moisture behaving at each profile depth.
Combatting the vigour war will not happen overnight, but determining each blocks root cause will aid in making effective, cost-efficient decisions, leading to improved productivity and fruit quality.
Meg Becker
