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.

Almond canker diseases are destructive and can reduce the yield as well as the lifespan of almond orchards. These diseases may affect the trunk and branches of both young and mature trees, and in severe cases can result in tree death soon after orchard establishment. Between 2015 and 2018, 70 almond orchards were visited throughout the Central Valley of California upon requests from farm advisors for canker disease diagnosis. Two major canker diseases were identified including Botryosphaeriaceae cankers and Ceratocystis canker. In addition, five, less prevalent canker diseases were identified including, Cytospora-, Eutypa-, Diaporthe-, Collophorina and Pallidophorina canker. Seventy-four fungal isolates were selected for multi-locus phylogenetic analyses of ITS1-5.8S-ITS2 (ITS), and part of the translation elongation factor 1-α (TEF1- α), β-tubulin (TUB2), and glyceraldehyde 3-phosphate dehydrogenase (GPD) gene sequences, which identified 27 species including 12 Botryosphaeriaceae species, Ceratocystis destructans, five Cytospora species, Collophorina hispanica, four Diaporthe species, two Diatrype species, Eutypa lata, and Pallidophorina paarla. The most frequently isolated species were C. destructans, Neoscytalidium dimidiatum and C. californica. Pathogenicity experiments on almond cv. Nonpareil revealed that N. parvum, N. arbuti and N. mediterraneum were the most virulent. Botryosphaeriaceae cankers were predominantly found in young orchards and symptoms were most prevalent on the trunks of trees. Ceratocystis canker was most commonly found in mature orchards and associated with symptoms found on trunks or large scaffold branches. This study provides a thorough examination of the diversity and pathogenicity of fungal pathogens associated with branch and trunk cankers of almond in California.

There is an urgent need to develop climate smart agroecosystems capable of mitigating climate change and adapting to its effects. In California, high commodity prices and increased frequency of drought have encouraged orchard turnover, providing an opportunity to recycle tree biomass in situ prior to replanting an orchard. Whole orchard recycling (WOR) has potential as a carbon (C) negative cultural practice to build soil C storage, soil health, and orchard productivity. We tested the potential of this practice for long term C sequestration and hypothesized that associated co-benefits to soil health will enhance sustainability and resiliency of almond orchards to water-deficit conditions. We measured soil health metrics and productivity of an almond orchard following grinding and incorporation of woody biomass vs. burning of old orchard biomass 9 years after implementation. We also conducted a deficit irrigation trial with control and deficit irrigation (-20%) treatments to quantify shifts in tree water status and resilience. Biomass recycling led to higher yields and substantial improvement in soil functioning, including nutrient content, aggregation, porosity, and water retention. This practice also sequestered significantly higher levels of C in the topsoil (+5 t ha -1 ) compared to burning. We measured a 20% increase in irrigation water use efficiency and improved soil and tree water status under stress, suggesting that in situ biomass recycling can be considered as a climate smart practice in California irrigated almond systems.

B rown marmorated stink bug (BMSB), Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), has a native range that includes China, Japan, Korea and Taiwan. Its host plant range extends to more than 170 species, among which are valuable ornamentals and agricultural fruit, nut and vegetable crops (Lee et al. 2013;Rice et al. 2014). BMSB can cause direct injury to crops while using its piercing-sucking mouthparts to feed. Characterization of feeding injury to marketable crops such as surface discoloration, depressed areas, deformation or abortion of fruit bodies and internal tissue damage can vary by crop (Rice et al. 2014). BMSB was first detected in the United States in 1996 in Allentown, Pennsylvania. Since then, BMSB has been detected in 42 U.S. states, with establishment (reproduction) confirmed in at least 26 states where nuisance and/or agricultural problems associated with its presence and ensuing economic losses to crops have been reported (NIPMC 2015).Crop losses from BMSB and aggregations in human-made structures have been significant in the eastern United States, where BMSB first established (Rice et al. 2014). The establishment of BMSB in this region confirms its tolerance to climates outside of its home range. Field and laboratory research is needed to characterize the degree to which BMSB can tolerate temperature stresses (i.e., winter cold and summer heat) and how this may influence population dynamics in other geographic locations within the United States (Cira et al. 2016). In addition, the invasion process of BMSB in the United Online: http://californiaagriculture.ucanr.edu/ landingpage.cfm?article=ca.v070n01p15&fulltext=yes doi: 10.3733/ca.v070n01p15Mike Lewis BMSB adult feeding on kumquat fruit. In California, BMSB populations are found mainly in urban locales, but there is risk they will move into agricultural areas.

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