As part of our recognition of UC Cooperative Extension's centennial year, throughout 2014 the research articles in California Agriculture will be paired with short historical sidebars. Some sidebars may draw from the same broad research area, while others may discuss earlier studies of a problem still being investigated or challenged by contemporary scientists. Research that was genuinely new and enlightening at one time may now be taken for granted or even proved wrong. This was the case in our January–June 2014 issue, page 21 .

There, a research article on the economic impact to California of Pierce's disease in grapevines was accompanied by a sidebar on one of the most challenging aspects of Pierce's disease at the time: the identification of its causal agent. In 1974, Auger, Shalla and Kado identified a Gram-positive bacterium as the organism causing the disease. Their report was incorrect, as demonstrated 3 years later by Alexander Purcell and collaborators. One year later, in 1978, UC Berkeley graduate student Michael Davis, together with UC professors Purcell and Sherman Thompson, correctly demonstrated that a bacterium now called Xylella fastidiosa was the causal agent of Pierce's disease in grapevines (Davis et al. 1978).

In running historic material we aim to place the university's scientific endeavors into a larger context and remind readers how today's science builds on previous knowledge — not confuse people. We regret the latter.

Also in the January–June 2014 issue, the timeline on page 8 listed the year for the founding of the University of California incorrectly. The correct year is 1868.