Trunk disease management in California.

Delayed pruning

Schedule hand or mechanical pruning in late winter, before bud break. Pruning wounds made in early winter

Figure 5 (click for larger view)

(December & January, sometimes even in February) are more susceptible to infection than wounds made later in the dormant season (March) because: 1) winter rains induce spore release and there tends to be more rain (and more spores) in early winter, and 2) cold temperatures are thought to lengthen the wound-healing process and early winter tends to be colder (Figure 5).

When compared to pruning in December, pruning in January and, in some studies, in February, has not been shown to significantly reduce pruning-wound infections or to reduce the susceptibility period (Table 1). If you cannot prune your entire acreage in March, therefore, we recommend using a pruning-wound protectant after pruning or to use double pruning (see below).

Table 1 (click for larger view)

Double pruning

Figure 6

This is a modification of delayed pruning for cordon-trained, spur-pruned vineyards and involves two passes:

Pass 1 ( December & January, sometimes February) – Often with a mechanical-pruning machine (Figure 6, left), canes are ‘prepruned’ to approximately 10 to 12 inches above last year’s spurs (Figure 6, right). No cuts are made down to the cordon. Pruning debris is pulled off the trellis wires by hand.
Pass 2 (March ideally) – Canes are pruned to 2-bud spurs by hand. This removes the section of the cane that may have been infected via pruning wounds after Pass 1. This is a relatively rapid pass when the labor-intensive step of pulling the pruning debris off the trellis wires is done during pass 1.

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