Hops have been grown commercially in the Nelson region for more than 100 years. Imported hop cultivars from Europe did not do well in New Zealand, mainly because flowering of the hop plant is latitude sensitive, and they were derived from countries that are much further from the equator than New Zealand. By the 1940s all the hops being grown in New Zealand were of American origin. These cultivars yielded well, as they originated from a similar latitude to Nelson, but they were found to be susceptible to a fungal root-rot caused by Phytophthora citricola . In 1949 the hop growing and brewing industry approached DSIR to initiate some research on the root-rot disease which was devastating growers' properties in Nelson.
Seeds create impurities in the brewing process, and can be a real problem.
In Germany, laws prevent the growing of male hops so accidental pollination and formation of seeds in the hops is avoided. In New Zealand, HortResearch has pioneered the development of naturally seedless 'triploid' hops. Triploid hops contain three sets of chromosomes instead of the usual two, and are infertile so they do not develop true seeds. This ultimate objective was also to be coupled with improved performance under New Zealand growing conditions. Dr Ron Beatson of HortResearch's Riwaka Research Centre has been the leader of the hop breeding programme since 1982.