Hopland Research and Extension Center

Since the middle 1980s, commercial cultivars of annual legumes from the Mediterranean region have been released in Australia for rangeland improvement. This program has released for domestic use and for seed export to other countries. It has been nearly 25 years since the University of California Cooperative Extension has updated annual legumes seeding recommendations. By the late 1980s, these new Australian annual legume cultivars (varieties) were being introduced and marketed at a rapid pace for use on California annual rangelands, but they had not been systematically tested in California. The HREC provides a valuable opportunity to test these annual legumes under controlled conditions on rangelands used for livestock production. A program was initiated in the middle 1980s, by the UC-Davis Dept. of Agronomy and Range Science and the HREC staff, to evaluate these new introductions for their adaptability at the HREC. Our present variety trial was initiated in 1990. Evaluations are made yearly to access the evolution of these cultivars for adaptation in the Hopland zone. Our most recent evaluation of 2004 shows a slow progression of superior adaptation of some of the newer Australian subclover cultivars to those of the earlier commercial varieties that predated the 1980s.

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.  We will determine the impact of grazing by trained and untrained sheep on vine shoot development, floor vegetation, and soil compaction.  We will also compare two methods of administering LiCl and the persistence of the aversion after one year of LiCl treatment.

This project continues research in progress that was initiated by Al Murphy during the 1952-53 growing season at HREC.  It is the only long-term, continuously monitoring study of its kind in North Coastal California.  The only similar study of longer duration in the state is at the San Joaquin Experimental Range.  The herbage production data developed have been used extensively in UC research as well as by various federal, state, and local agencies.