Berry shrivel, a physiological disorder, adversely affects ripening of grape (Vitis vinifera L.) berries; however, its causes are unknown. We adopted a holistic approach to elucidate symptomatology, morphoanatomy, and osmotic behavior of grape berry shrivel. Berries from healthy and afflicted vines were analyzed compositionally and with various techniques of microscopy. Healthy berries developed all physical and compositional attributes desirable for wine-making. Conversely, berry shrivel berries were grossly metamorphosed manifested as shriveling of the pericarp, which paralleled with loss of membrane competence in the mesocarp cells causing its collapse and a loss of brush. The most intriguing observation was the presence of non-druse crystals. These berries had high osmotic potential (ψS) as a result of low accumulations of sugar and potassium. Nonetheless, the seed morphology, structure, and viability were similar to healthy seeds. Berry shrivel grotesquely modified grape berries both compositionally and structurally, which was paralleled by their inability to accumulate sugars followed by cell death in the mesocarp. Although the mechanisms of berry shrivel remain uncertain, our study provides valuable background information for generating suitable guidelines to minimize the incidences of berry shrivel and also to design future studies toward unraveling the mechanistic basis of berry shrivel.
The juice grape (Vitis labruscana) cultivar Sunbelt has been reported to ripen more uniformly than the cultivar Concord in warm climates; thus, ‘Sunbelt’ might be useful as either a blending partner with or replacement for ‘Concord’ as global climate change intensifies. We conducted a 4-year field trial to evaluate ‘Sunbelt’ alongside ‘Concord’ in arid southeastern Washington. ‘Concord’ yields were on the average 57% higher than ‘Sunbelt’ yields because ‘Concord’ vines produced more shoots of higher fruitfulness and consequently had more clusters. The 31% larger berries of ‘Sunbelt’ were insufficient to compensate for its lower cluster number. Conversion from hand pruning to minimal (machine) pruning had no consistent influence on yield in either cultivar. Juice soluble solids, titratable acidity (TA), red color intensity, and color hue were significantly higher in ‘Sunbelt’ than ‘Concord’, whereas pH and potassium were often similar. Both cultivars cold acclimated in autumn and deacclimated in spring, but hardiness varied during winter depending on prevailing temperatures. With some exceptions, the two cultivars had similar bud, phloem, and xylem hardiness. When differences were significant, ‘Sunbelt’ was 1 to 4 °C less hardy than ‘Concord’ and also tended to deacclimate more readily in spring. The results from this study indicate that ‘Sunbelt’ shows promise as a blending partner with or an alternative to ‘Concord’ for warm vineyard sites or growing seasons even in regions with cold winters.
Although the inland Pacific Northwest has a warm climate during the growing season, grapes grown in this region may be exposed to colder than optimal temperatures at several times during the year. In addition to damage from spring and fall frosts, intermittent winters with little to no snow cover and subzero temperatures can cause vine dieback and death. Temperature patterns in the recent past indicate that both fall and midwinter are times when risk of bud damage from cold events is probable, making proper site selection and cultivar choice critical. Water is not used for frost protection in this climate, but wind machines have proven to be useful. In frost-prone sites, annual sucker growth with cane burying is practiced as an insurance strategy. Modifying pruning strategies has not been shown to be advantageous after fall cold events. If rootstocks are used, research has shown greater scion survival with higher graft positions.
The accurate prediction of winter injury caused by low-temperature events is a key component of the effective cultivation of woody and herbaceous perennial plants. A common method employed to visualize geographic patterns in the severity of low-temperature events is to map a climatological variable that closely correlates with plant survival. The U.S. Department of Agriculture Plant Hardiness Zone Map (PHZM) is constructed for that purpose. We present a short history of PHZM development, culminating in the recent production of a new, high-resolution version of the PHZM, and discuss how such maps relate to winterhardiness per se and to other climatic factors that affect hardiness. The new PHZM is based on extreme minimum-temperature data logged annually from 1976 to 2005 at 7983 weather stations in the United States, Puerto Rico, and adjacent regions in Canada and Mexico. The PHZM is accessible via an interactive website, which facilitates a wide range of horticultural applications. For example, we highlight how the PHZM can be used as a tool for site evaluation for vineyards in the Pacific northwestern United States and as a data layer in conjunction with moisture-balance data to predict the survival of Yugoslavian woody plants in South Dakota. In addition, the new map includes a zip code finder, and we describe how it may be used by governmental agencies for risk management and development of recommended plant lists, by horticultural firms to schedule plant shipments, and by other commercial interests that market products seasonally.