Groundwater pumping chronically exceeds natural recharge in many agricultural regions in California. A common method of recharging groundwater -when surface water is available -is to deliberately flood an open area, allowing water to percolate into an aquifer. However, open land suitable for this type of recharge is scarce. Flooding agricultural land during fallow or dormant periods has the potential to increase groundwater recharge substantially, but this approach has not been well studied. Using data on soils, topography and crop type, we developed a spatially explicit index of the suitability for groundwater recharge of land in all agricultural regions in California. We identified 3.6 million acres of agricultural land statewide as having Excellent or Good potential for groundwater recharge. The index provides preliminary guidance about the locations where groundwater recharge on agricultural land is likely to be feasible. A variety of institutional, infrastructure and other issues must also be addressed before this practice can be implemented widely.

The seasonal abundance of Botryosphaeriaceae spp. spores was studied in California vineyards by using glass microscope slides covered with petroleum jelly placed on grapevine cordons and Burkard volumetric spore traps at seven and two different locations, respectively. Correlation analysis was used to determine which meteorological variables (precipitation, relative humidity, temperature, and wind speed) influenced Botryosphaeriaceae spp. spore release. Among all variables, regression analysis resulted in a strong relationship between spore release and precipitation. Additionally, a positive relationship between irrigation and spore release was also observed in the Riverside County vineyard. During the study period, spore discharge of Botryosphaeriaceae spp. occurred from the first fall rain through the last spring rains, coinciding with September to April. However, based on the results obtained from the spore traps, most spores (over 60%) were trapped following rain events during the winter months of December, January, and February, which coincides with the grapevine pruning season. Botryosphaeriaceae spp. spore release was much lower in fall and early spring (22%) and very few or no spores were trapped in late spring and summer (3%). This work suggests that a delay of pruning time in California may be warranted to reduce grapevine infection because the current timing coincides with the greatest period of spore discharge.

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We consider the adoption of biologically integrated agricultural practices from the perspective of farm management style. Adoption decisions for farming practices must fit into a broader farm decision-making context that incorporates economic, environmental, social, family and personal considerations, as well as use of agricultural information sources. Drawing from a study of California almond and winegrape growers, we demonstrate that management styles differ substantially among farmers, these differences affect use of information sources and adoption of biologically based practices on the farm, and such adoption does not negatively affect crop performance. We used Q-methodology, a method for eliciting qualitative data using a variant of factor analysis, to identify three distinct management styles among a purposive sample of 40 growers. The Environmental Stewards' management style places higher priority on conservation of natural resources than on getting the highest possible yields or profits. Production Maximizers, with a different style, prioritize more traditional goals of producing the highest possible yields and quality and focusing resources on the farm rather than on outside concerns. Networking Entrepreneurs, on the other hand, value learning about innovative techniques in social contexts such as informational field days, evaluate new information with a business-like attitude and enjoy off-farm interests. A two-season mail survey of farming practices and information sources demonstrated that differences in management styles affect the adoption of practices. Environmental Stewards were more likely to practice biological pest control and encourage wildlife and less likely to use the most toxic chemicals. Production Maximizers had a greater tendency to use prophylactic and broad-spectrum chemicals, while Networking Entrepreneurs preferred more innovative biological pest controls but tended to avoid time-consuming cultural practices. Production Maximizers were distinguished by less use of more social forms of communication, such as attending field days and talking with other growers. Crop health and quality indicators showed that almost all growers were managing their crops very successfully, regardless of management style or choice of practices. These results hold important implications for efforts to increase the adoption of sustainable agriculture, especially by showing that contents and methods of outreach efforts must vary to accommodate diverse farm management styles.

Grafting joins two distinct plant parts: a scion (shoot system) from a donor plant and a rootstock (root system) from a second plant to which the scion is attached. The practice of grafting chiefly enables clonal propagation but can also have many other benefits, such as reducing the juvenility period (increasing precocity) or size (dwarfing) in fruit trees (Fazio et al., 2014; Warschefsky et al., 2016;Webster, 1995).In grapevines (Vitis vinifera L.), widespread use of grafting began in the late 1800s, following the introduction of phylloxera (Daktulosphaira vitifoliae Fitch) to Europe from North America. While