Issue link: http://winesandvines.uberflip.com/i/946131
60 WINES&VINES March 2018 GRAPEGROWING WINE EAST G rapegrowers have long recog- nized that bud burst does not occur on the same calendar date each year. Documentation of bud burst dates for each vine- yard block should be a routine part of every grower's annual management practices. Bud burst dates allow growers to compare the current season with past seasons and pro- vide an estimate for other grapevine growth stages to come. Many growers are good about recording bud burst dates but will neglect to record other important growth stages. All growers need to recognize that collecting data about important phenology benchmarks can help them make better decisions in the vine- yard throughout the growing season. Tracking grapevine phenology Phenology is the study of natural changes or growth and natural development of an organ- ism and its relation to seasonal changes in climate. In viticulture, we are mostly referenc- ing a limited number of key growth stages that are used for benchmarks for implementation of vineyard-management tasks including can- opy management, vineyard nutrient monitor- ing and pest and disease prevention. The growth stages or phenology events most com- monly referred to include bud burst, bloom, fruit set, cluster closure, véraison and fruit maturity (harvest). There are two reasons for recording grape- vine phenology: 1. To implement vineyard-management practices based on current growth stages, resulting in improved efficiency, reduced labor costs and improved vine health. 2. To predict more accurately the onset of growth stages in the current season based on historical data, whereby man- agement practices can be best timed for improving efficiency. Timing is everything in the vineyard Grapegrowers use phenology as the indicator for initializing virtually all vineyard-manage- ment practices. Many growers begin a protec- tive fungicide program when shoots are just 2 inches long. At bloom, growers sample leaf tissue for nutrient analysis and start to intro- duce systemic fungicides into their spray pro- grams. At véraison, growers have a second opportunity to sample leaf tissue for nutrient status and can begin to finalize crop estimates for the winery. Efficiency of vine canopy management is most notably impacted by grapevine phenol- ogy. The task of shoot thinning and positioning is tightly linked to a specific growth period in order to achieve efficiency with labor. If shoots are 2 to 4 inches long, for example, unwanted "sucker" shoots can easily be removed from trunks and non-count shoots from cordons or fruiting canes. However, it may be too early for all shoots to have pushed on the vine, and Grapevine Phenology Revisited Using growth stages to improve vineyard management By Fritz Westover KEY POINTS While the term "phenology" is a broad one; in viticulture, phenology refers to a number of key growth stages. These stages are the bench- marks for certain management tasks. Dr. K.W. Eichhorn and Dr. D.H. Lorenz developed a comprehensive grapevine phenology chart in 1977. The Modified Eichhorn-Lorenz System is more practical for growers and includes eight major stages. Comparison of current phenology events in the vineyard with records of previous seasons can help growers predict the timing of the next stage of growth. Seasonal phenology records can be especially helpful in canopy management such as shoot thinning and positioning as well as pest and disease-control programs. Using grapevine phenology can result in im- proved efficiency and vine health and also re- duced labor costs. A grape bud is on the verge of bud burst, as evidenced by visible leaf tips (Modified Eichhorn-Lorenz Stage 4).