2.3.8.d What leaf thinning methods are there?

Which is more widespread: manual or mechanical leaf thinning?

Manual leaf removal is more common as it is less expensive in terms of equipment investment but it is of course more labour intensive and requires a lot of time on the plot: about 30 to 50 hours/ha. The appeal of manual removal is that, unlike mechanical leaf removal, it can be implemented at any time.

Mechanical leaf removal divides the leaf removal time by about 10 (depending on the plot's characteristics). However, it must be done very early and the machines need to be adjusted beforehand. Leaves or herbaceous parts can be projected and damage the bunches. When carried out on firm, green bunches, mechanical leaf removal will reduce the damage to the bunches after véraison. There are several types of mechanical leaf thinners:

• Air leaf thinners: operate by either blowing or sucking leaves to remove them.

• Thermal leaf thinners: the leaves are dried by infrared radiation.

• Roller leaf thinners: also work by sucking the leaves which then pass between two rollers.

Should one or both sides of the row have their leaves thinned?

Early leaf removal is sufficient when it is preferably done on one side. When carried out later, it can be done on both sides of the row in order to keep the bunches in good health and help the grapes ripen.