Vines & Ovines

Background, rationale, and objectives:
Vineyard floor vegetation is primarily controlled by chemical and mechanical methods.  Both methods are problematic as herbicide applications can potentially impair water quality and mechanical control (mowing and cultivation) can often be delayed by rains.   The cultural practice of grazing sheep in vineyards to control floor vegetation has been used, but cannot be employed after new buds emerge in early spring.  We propose to train sheep to have a dietary aversion to grape leaves by orally dosing sheep with lithium chloride (LiCl) following grape leaf consumption.  LiCl will cause a temporary illness and a negative association with grape leaves, allowing sheep to graze vineyards past budbreak.

Research methods / Creative activity:
Two trials are being conducted at the Hopland Research and Extension Center (HREC).  In trial 1, we test the strength and persistence of the grape leaf aversion in trained sheep.  Aversion testing occurs one day, one week, one month, two months and nine months after the initial aversion training in June 2006.  In trial 2, we will determine the impact of grazing by trained and untrained sheep on vine shoot development, floor vegetation, and soil compaction.