Location: Crops Pathology and Genetics Research2013 Annual Report
1a. Objectives (from AD-416):
1. Develop sustainable disease control practices for grapevines. [NP 303, C3, PS3B] 2. Develop sustainable vineyard floor management practices for vineyards. [NP 305, C1, PS1B.1] 3. Develop sustainable water management practices for vineyards. [NP 305, C1, PS1B.1] 4. Investigate the impacts of vineyard practices on soil microbial ecology. [NP 305, C1, PS1B.1]
1b. Approach (from AD-416):
1. Characterize the infection process of grapevine roots by the fungal pathogen Armillaria mellea, the causal agent of Armillaria root disease; Characterize the significance of riparian areas in the spread of Pierce's disease. 2. Identify differences in regional populations of Conyza canadensis, cover crops that effectively compete with C. canadensis, and the effects of soil resource availability on competition between cover crops and C. canadensis; Identify cover crops that effectively compete wtih problematic weeds. 3. Evaluate the interactive effects of irrigation practices and vineyard floor management practices on grapevine yield, growth, physiology, and nutrition. 4. Examine the effect of cover crop functional type on soil microbial communities and microbially-mediated soil processes; Characterize rhizosphere communities associated with Vitis rootstocks; Examine the impacts of vineyard floor practices on mycorrhizae. REPLACING 5306-21220-004-00D (03/12); 5306-21220-003-00D (01/07)
3. Progress Report:
Winegrapes, table grapes, and raisin grapes grown in California represent over 90% of U.S. production. Maintaining a competitive edge with worldwide producers is crucial. In order to minimize production costs and maximize vineyard productivity, discovery of sustainable vineyard practices for control of trunk diseases, weed management, greenhouse gas emissions, and irrigation is paramount in the grape industry. This need is driven by more stringent environmental regulations, the increasing interface between urban and agricultural areas, and the decreasing availability of water in the western US. In FY2013, our first objective addressed the spread of trunk diseases (Phomopsis dieback and Botryosphaeria dieback), both at the cellular scale and at the vineyard scale. Our findings from objective 1 experiments have applications to the management of trunk diseases, namely regarding the need for pruning-wound protectants in eastern US vineyards. The second and fourth objectives examined biological, edaphic, and management-related drivers of greenhouse gas emissions, soil microorganisms that mediate biogeochemical transformations, and weed establishment, to develop practices that reduce environmental inputs and also the economic costs of grape production. To address objectives 2 and 4, we tracked the energy use and environmental impacts of winegrape production using Life Cycle Assessment, and examined winegrape production areas and the surrounding wildlands for carbon storage capacity. These measurements are critical for the development of national and international environmental policies, which will establish contributions and offsets to global warming potential, energy use, direct water use, and the U.S. Environmental Protection Agency's criteria air pollutants for many different sectors of the US economy. The third objective integrated physiological and genetic approaches to develop grapevines that are resilient in the face of abiotic stresses. To address objective 3, we evaluated drought resistance of grapevine rootstock materials by assessing water uptake potential of fine roots subjected to stress and using high resolution computed tomography (HRCT) to evaluate susceptibility to embolism formation and the ability to repair blocked vessels across grapevine rootstocks. Water use is and will forever be an important priority for US grape growers, particularly in the arid western states, where grape production is dependent on irrigation. Growers require plant material that can better resist drought conditions.
1. Phomopsis dieback, a trunk disease of grape in eastern US vineyards. Phomopsis cane and leaf spot is a serious disease of grape in the northeastern US, which necessitates frequent fungicide applications throughout the growing season. The pathogen Phomopsis viticola spreads with rain; leaves, stems, and fruit are all susceptible to attack. To determine if the pathogen also attacks the woody stem of the vine, causing trunk disease Phomopsis dieback, ARS researchers at Davis, California, and Geneva, New York, examined grapevines with Phomopsis dieback symptoms (dieback, wood cankers) in northeastern US vineyards that also had Phomopsis cane and leaf spot symptoms (leaf spots, shoot lesions, fruit spots). In all such vineyards, they found vines with three species that were pathogenic to the woody stems of Vitis labruscana ‘Concord’ and V. vinifera ‘Chardonnay’, in greenhouse and field inoculations (Phomopsis dieback symptoms, recovered Phomopsis viticola and two related species, Diaporthe eres, Phomopsis fukushii). The current approach to manage Phomopsis cane and leaf spot is with applications of a protectant fungicide after budbreak that may not protect vines from Phomopsis dieback, which attacks the pruning wounds of vines before budbreak.
2. Reducing environmental impacts of winegrape production. Identification of environmental impacts of winegrape production with Life Cycle Assessment (LCA) facilitates targeted improvement in system sustainability. LCA is a tool that helps growers and poli-cymakers understand the full environmental impacts of an agricultural production system, identifying ways growers can improve overall efficiency and use of this tool may open up new “green marketing” opportunities and even lead to reduced overall costs through better utilization of energy, equipment, and agrochemical resources like fertilizer, pesticides, and herbicides. This LCA addressed the environmental impacts of winegrape production across a range of vineyard management regimes in two important growing regions of California. The LCA boundary was defined from ‘cradle to gate’, which spanned resource extraction, manufacturing of raw materials into products used in winegrape production (e.g. herbicide, fertilizer) and their subsequent transport to the vineyard, activities and energy required to grow the winegrapes (e.g. irrigation, harvest), and concluded with final transport of winegrapes to the winery. A number of alternative management practices were discovered, including but not limited to, compost, reduced irrigation, and various cover cropping systems, which will assist growers aiming to improve the energy use and air emissions of their vineyards.
3. Evaluating drought resistance of grapevine rootstock materials. Drought resistance in a cropping system is important as it provides the ability of a plant to continue growth and maintain yield and fruit quality when exposed to periods of water stress. ARS researchers at Davis, California, evaluated the effects of drought on embolism formation and repair in living grapevines by developing a screening technique to evaluate the hydraulic conductivity of fine roots of grapevines and collecting data on numerous grapevine rootstocks ability to withstand embolism spread and repair these blockages once they occur. They found the permeability of grapevine fine roots was significantly reduced by drought and varied across rootstock genotypes. These research efforts will provide a better understanding of the patterns of water absorption in grapevine root systems and greatly enhance the quality of fruit and yield in the grape growing industry.
Baumgartner, K., Fujiyoshi, P.T., Travadon, R., Castlebury, L.A., Rolshausen, P.E. 2013. Characterization of species of Diaporthe from wood cankers of grape in eastern North American vineyards. Plant Disease. 97:912-920.