Definition - What does Crown Suckering mean?
Crown suckering is the removal of suckers which grow on the vine itself and not at the roots. The suckers are unwanted growth that emerges on the vine.
During times of extra precipitation, nutrient-rich soils and ideal growing conditions, more shoots may develop than what is needed. These are shoots, which usually have laid dormant, for sometimes years and emerge when conditions are right.
WineFrog explains Crown Suckering
Throughout the annual life of a grapevine, there are necessary times when pruning will have a positive effect on the following growing season.
From the spring and into the summer months, grapevines develop new branches and shoots at a fast rate. In years when winter precipitation has been high and, for instance, the growth of cover crops which will later be mulched in are at higher yields, the grapevine will too develop extra shoots and branches, later creating higher fruit yields.
However, higher yields in vineyards cultivated for wine production means lower quality wine. Therefore, the vine needs to be pruned in order to reduce overall yield. The trimming of such shoots (suckers) which produce more fruit is called "crown suckering."