Issue link: http://winesandvines.uberflip.com/i/66128
GRAPE GRO WING Bud development can be affected by fertilization, temperature, light and cultivar differences. The nitty gritty of bud formation evelopment of the next season's crop depends on genet- ics, environment and management. Fourteen genes con- trol the process in many cultivars. Various genes initiate the flower primordia (cells that differentiate from simple tissue to form flowers), flowering time and, finally, the actual development of the floral organs (stamens, pistils, ovules, pollen) that make up the flowers. This process depends on environmental conditions including light, temperature and nutrients. Plants don't have a central nervous system, so growth is controlled in part by hor- mones including cytokinins, auxins and gibberellins produced by shoot and root tips that affect flowering and shoot growth. The first step in bud development is a group of cells that form known anlagen, which then become primordial. Depending on the hormones present, they may become a shoot tip, a flower or a tendril. Over fertilization and watering have a negative effect on forming flower buds, as these management practices encour- age too much vegetative growth. When vines are vigorous, they produce high levels of gibberellins that inhibit the formation of flower primordia. This is typical when high nitrogen, moisture and low light form dense canopies. Under these conditions, tendrils are produced rather than flowers. On the other hand, when growth is less vigorous, there is a more D favorable ratio of cytokinins (usually produced by roots in the spring) to gibberellin, and flower formation occurs. Warmth and sunshine also contribute to the formation of flower buds. Ideal temperatures range between 80º and 90ºF, and plenty of sunlight also helps (up to 3,000 + foot candles of light). There also needs to be a sufficient amount of RNA present to complete the forma- tion of the flowers. There is still much to be understood about this process, and there are certainly many differences between wine- grape cultivars and how they form flowers and set fruit. G.M. It's lonely out there for a European Grapevine Moth. Thanks to current mating disruption techniques, EGVM can't reproduce because it can't find any mates. And that's just how we like it. KICK THE MOTH OUT • NAPA COUNTY AG COMMISSION Wines & Vines JUne 2012 55 GLENN MCGOURTY