Why should you avoid pruning when the sap is running?

Avoiding pruning when the sap is running is important primarily because it can cause excessive bleeding and stress to the vine. During the sap-flow period, the vine is actively transporting nutrients and water, and any cut made during this time can lead to excessive sap loss, often referred to as "bleeding." This loss of sap not only affects the vine's ability to stay hydrated and nourished but can also result in stress, making the vine more susceptible to disease and weakening its overall health. Healthy pruning practices emphasize timing, and avoiding cutting during the sap run helps maintain the vigor and long-term productivity of the vine.

While other factors may relate to pest introduction or difficulty in the process, the primary concern during sap flow is the health of the vine and the excessive bleeding that results from pruning at this vital time.