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September 2017 WINES&VINES 29 VIEWPOINT One of the key practices has been to re- duce pruning costs with mechanical or mini- mal pruning. A 12-year study of normal versus minimal pruning effects on Concord grapevines revealed minimal pruning gener- ally led to higher yields and lower Brix, sug- gesting over-cropping. Yet minimally pruned vines gave more sustainable and consistent cropping year-to-year (always 10 tons per acre or more) than normal pruning. A great deal of data was collected on yield as well as seasonal canopy development and fruit growth, gas exchange and water rela- tions. This data allowed us to integrate all these factors into the VitiSim model. The model is able to point out that the very rapid canopy development in minimally pruned vines gives a more rapid attainment of can- opy photosynthesis and much lower demand from shoot growth by bloom. The improved carbon balance coincided with the period of fruit set and flower bud development and likely explains the ability to maintain high yields over many years. In contrast, by véraison normally pruned vines had developed similar canopies giving similar vine carbon supply. However, the larger crop on minimally pruned vines then led to lower Brix at harvest. The practical solution for minimal or mechanical pruning, developed by colleagues Bob Pool and Terry Bates, has been to wait until fruit set is done and 50% of final berry size is achieved before estimating potential yield and then mechani- cally thinning the vines to a crop level that can be ripened. This practice takes advantage of the benefit of minimal pruning for yield but overcomes the limitation of excess crop during ripening. Monitoring of grapevine water status The importance of water status for regulating vine growth, fruit composition, wine charac- ter and expression of terroir has been recog- nized. Optimal patterns of water stress at key times to improve wine quality are evolving, but we do not have the tools to monitor the dynamic behavior of vine water status in the field. The pressure chamber gives good results but has limited value as a manual tool giving only spot readings. Cornell engineering colleague Abraham Stroock and I collaborated to develop an elec- tronic microchip version of a tensiometer for soils and also to insert into the trunk of vines to monitor stem water potential continuously. In initial tests in our lab and the vineyard, we found that the sensor is effective and the re- sults correlate with the standard pressure chamber estimate of stem water potential. We believe this will give the grower much more information to optimize water management for grape quality. It is being commercialized by a spin-off company from our research called FloraPulse. Lessons learned Many years of research and learning from col- leagues have taught me some lessons: • Be careful of interpreting correlations as cause and effect. Even those that seem logical may be correlations due to both factors being correlated to a third factor. • Grapevine roots do not grow in con- sistent patterns and can vary each growing season. Despite many years of detailed studies, we could not re- late patterns of root growth to behav- ior of the top of the vine, which has very consistent behavior. The reasons why are not clear, and the lack of co- ordination is puzzling. • The effects of stress (low light, water stress, foliar pests, etc.) are generally stronger if the crop load is larger. Heavily cropped vines al- ready struggle to ripen a crop, so any additional stress will have a strong effect. • The corollary is that the effect of crop load on vegetative growth is stronger if there are other stresses. In the absence of stress, the grape- vine can support a surprisingly large crop and strong vegetative growth. • Nelson Shaulis (the late Cornell Uni- versity viticulture professor) empha- sized that we need to be much more precise in our thinking and language than we normally are, especially about important but often poorly de- fined concepts such as "competition," "crop load," "quality," "vigor," "resis- tance versus tolerance" and "vine balance." A great question to im- prove precision is, "What are the units of these terms?" • In research we often have to accept that we were wrong and must try again. The words of Sir Winston Churchill are apt: "Success is the ability to go from one failure to an- other with no loss of enthusiasm!" • We tend to treat our hypotheses like our babies. They must be protected and defended. Too often experi- ments are conducted or data se- lected to support our hypotheses, when instead we must be strongly skeptical and do experiments to dis- prove our hypotheses. Philosopher Karl Popper beautifully described science: "The method of bold con- jectures along with ingenious and severe attempts to refute them." If we do our very best to find any pos- sible condition or experiment to dis- prove our hypothesis and cannot, then the hypothesis is likely much more sound than the other way around. Be your harshest skeptic. • Complex problems require team re- search. Find excellent team members with enthusiasm and expertise and treat them as equal colleagues. The future • Understanding crop physiology to im- prove practice will continue to be im- portant. Models will be an increasingly important tool for envi- ronmental footprints for the industry and climate change estimation. • Genomic information generally does not translate directly to field perfor- mance. Better integration of genom- ics and whole-plant physiology is needed as a link between genomics and viticulture. • Physiology will be needed to: • Ground-truth remote sensors, • Develop new measurement pa- rameters for sensing, • Provide models to integrate im- pacts from sensed data with geo- graphic information systems (GIS) to display outcomes for management use. Dr. Alan Lakso completed a Ph.D. at the University of California, Davis, in 1973 on "Effects of Temperature on Malic Acid Metabolism in Grapes" with Dr. Mark Kliewer. He moved to Cornell University's New York State Agri- cultural Experiment Station in Geneva, N.Y., to begin a program on grape and apple physiology and retired in 2014 and is a Cornell professor emeritus. EDITOR'S NOTE The following is an excerpt from Dr. Alan Lakso's Honorary Research Lecture, which he gave June 28 dur- ing the 68th annual conference of the American Society for Enology & Viticulture in Seattle, Wash. "Too often experiments are conducted or data selected to support our hypotheses, when instead we must be strongly skeptical."