Phosphorus Fertilization Can Improve Young Almond Tree Growth in Multiple Replant Settings

Young almond (Prunus amygdalus) orchards replanted where old orchards of stone fruits (Prunus sp.) have been removed are subject to physical, chemical, and biotic stressors. Among biotic challenges, for example, is almond/stone fruit replant disease (ARD; formally known as Prunus replant disease), which specifically suppresses the growth and yields of successive almond and other stone fruit plantings and is caused, in part, by a soil microbial complex. During four orchard trials representing different almond replant practices and scenarios in the San Joaquin Valley in California, we examined the impacts of phosphorus (P) fertilization on the growth of replanted almond. During all trials, P was applied to tree root zones just after replanting, and the impact was assessed according to trunk cross-sectional area (TCSA) growth for 2 years. Expt. 1 was performed where a previous almond orchard was cleared using whole orchard recycling (i.e., the old orchard was “chipped” and then turned into the soil). The land was replanted without preplant soil fumigation. We tested separate fertilizer treatments based on various P, nitrogen, micronutrient, and “complete” formulations. Expt. 2 was also performed where an old almond orchard was recycled, but the soil was preplant-fumigated before replanting. Here, we tested only P fertilization. Expts. 3 and 4 were conducted where an old peach (Prunus persica) orchard was removed. Here, P and nitrogen fertilizer treatments were tested among additional factors, including preplant soil fumigation (Expts. 3, 4) and whole orchard recycling chips (Expt. 4). During all four trials, P fertilization (P at 2.2 to 2.6 oz/tree within a few weeks after planting) significantly increased TCSA growth. The growth benefit was nuanced, however, by almond cultivar, date of replanting, rootstock, and other site-specific factors. Although P fertilization did not match the benefit of preplant soil fumigation for the management of ARD, our data indicated that P fertilization can improve the growth of young almond orchards in diverse replant settings with or without preplant soil fumigation and should be considered by California almond producers as a general best management practice

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Fumigation of California Ground Squirrels Revisited: Are Fumigants an Effective Method for Controlling Ground Squirrels?

Fumigation with either gas cartridges or aluminum phosphide is often considered to be an effective method for controlling California ground squirrel populations, although few studies have corroborated their effectiveness. Additionally, utilizing aluminum phosphide in combination with gas cartridges could increase effectiveness of both fumigants by indicating additional burrow openings through escaping smoke from gas cartridges and allowing for treatment of these additional openings with aluminum phosphide, which is a cheaper and potentially more effective material. Therefore, we compared the efficacy of gas cartridges, aluminum phosphide, and a combined treatment on ground squirrel populations from mid-April through early May 2009 to determine which was most effective. We established 4 plots (3 treatments plus control) at each of 2 treatment sites in Madera County, California. All plots were between 1 and 2 ha in size with survey areas of 0.3 - 0.5 ha centrally located within the plot. Ground squirrels were visually counted within survey areas for 3 consecutive days prior to treatment. Following counting, treatments were applied. Forty-eight hours post-treatment, squirrels were again counted within survey areas to determine percent control. These counts were repeated the following 2 days. All treatments were then reapplied for the same plots, with similar surveys again following 48 hours post-treatment. We found that all fumigation methods resulted in marginal to exceptional control of ground squirrels (percent control: gas cartridges = 62 - 86%, aluminum phosphide = 97 - 100%, gas cartridges + aluminum phosphide = 59 - 71%). We suggest aluminum phosphide use could be expanded to increase ground squirrel control in California, given its high efficacy combined with its relatively cheap material cost

New pistachio varieties show promise for California cultivation

California pistachio growers have long relied on a single female (‘Kerman’) and single male (‘Peters’) cultivar. Despite their benefits, these cultivars present important production and marketing concerns. To evaluate new varieties for the pistachio industry, we conducted the first randomized and replicated pistachio variety trials in the San Joaquin Valley, where most U.S. pistachios are grown. After more than a decade of scientific evaluation, several varieties new to California (such as ‘Kalehghouchi’) or the world (such as ‘Golden Hills’) demonstrated commercial potential for the California pistachio industry and would complement the production characteristics of ‘Kerman’

Orchard recycling improves climate change adaptation and mitigation potential of almond production systems.

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