Uptake and assimilation of nutrient resources.

Fruit trees require six macronutrients (N, P, K, calcium, Mg and sulfur) and eight micronutrients (Zn, Fe, B, Mn, Cu, chlorine, nickel and molybdenum) that are taken up through the roots. Many of these occur naturally in the soil as cations bound to negatively charged soil particles, while others are dissolved in the liquid surrounding the soil particles in the form of anions. This chapter discusses the uptake and assimilation of nutrient resources in fruit trees. Tabulated data are given on mean annual N, P and K storage (kg/ha) in perennial organs of mature almond trees that received N fertilizer at 309 kg/ha.

Genetic diversity and potential inoculum sources of Fusarium species causing cankers in bareroot-propagated almond trees in California nurseries

Previous research determined that Fusarium acuminatum and Fusarium avenaceum are important causal agents of a canker disease in bareroot-propagated fruit and nut trees in California that emerges during cold-storage or after transplanting. The disease largely disappeared after 2001, but it reemerged in 2011 in almond trees in at least one nursery. This motivated further study of the etiology and epidemiology of the disease by undertaking studies to determine distribution of the pathogens throughout almond nursery propagation systems and trace possible sources of inoculum. Research initiated in 2013 detected pathogenic Fusarium spp. throughout the almond propagation system, including in healthy trees, in soils, on wheat rotation crops, on equipment, and in the cold storage facility air. In addition to the two Fusarium spp. implicated previously, Fusarium brachygibbosum and a new Fusarium species, Fusarium californicum, were found to be pathogenic on almond trees. Multi-locus sequence typing and somatic compatibility testing confirmed that isolates within a species collected from different materials in the nursery were all highly genetically similar and likely of one clonal lineage. These findings affirm that equipment surfaces, wheat rotation crops, soil, cold storage facility air, and asymptomatic almond tree materials (i.e., rootstock cuttings, budwood, and scions) can potentially contribute inoculum to increase disease prevalence and severity.

Foliar Application of Boron Nanoencapsulated in Almond Trees Allows B Movement Within Tree and Implements Water Uptake and Transport Involving Aquaporins

Nanotechnology brings to agriculture new forms of fertilizer applications, which could be used to reduce environmental contamination and increase efficiency. In this study, foliar fertilization with nanoencapsulated boron (B) was studied in comparison to an ionic B (non-encapsulated) application in young B-deficient almond trees grown under a controlled environment. B movement within the plant in relation to the leaf gas exchange, water relations parameters, and root hydraulic conductance was measured. Also, the expression of aquaporins (AQPs) [plasma membrane intrinsic protein (PIP) and tonoplast intrinsic protein (TIP)] was studied in relation to water uptake and transport parameters to establish the effectiveness of the different B treatments. The obtained results were associated with a high concentration of observed B with nanoencapsulated B, provided by the higher permeability of carrier nanovesicles, which allowed B to reach the cell wall more efficiently. The increases in water uptake and transport obtained in these plants could be related to the role that this element played in the cell wall and the relationship that it could have in the regulation of the expression of AQPs and their involvement in water relations. Also, an increase in the expression of PIPs (mainly PIP2.2) to the applied nanoencapsulated B could be related to the need for B and water transport, and fine regulation of TIP1.1 in relation to B concentration in tissues provides an important feature in the remobilization of B within the cell.

Estimation of Diagnosis and Recommendation Integrated System (DRIS), Compositional Nutrient Diagnosis (CND) and Range of Normality (RN) Norms for Mineral Diagnosis of Almonds Trees in Spain

To ensure good fertilization, it is necessary to know the optimum nutrient levels for each crop. The most common method for obtaining this information for almond trees is to perform a foliar analysis coupled with the use of interpretive tools such as the traditional range of normality. However, currently, there are other, more sophisticated methods such as the DRIS (Diagnosis and Recommendation Integrated System) and the CND (Compositional Nutrient Diagnosis) which take into account the relationship between nutrients. However, little information is available with respect to these methods in the case of almond trees. In the present work, 288 samples of three contrasting varieties of almond were analyzed—Ferraduel, Ferragnes, and Garrigues (Prunus dulcis, Mill.)—corresponding to bi-weekly sampling between the months of May and September. Leaf analysis data, run with different mathematical and statistical models, lead to knowledge of the optimum period for harvesting samples and the determination of the ranges of normality and norms of DRIS and CND for the Ferraduel, Ferragnes, and Garrigues varieties. Data gained from the leaf nutrient content reported that the best season to harvest and interpret leaf samples was July. In addition, Ferraduel and Ferragnes had higher N, P, and K (2.22, 0.14, and 1.04 mg Kg−1 dw, respectively) than Garrigues (2.00, 0.09. 0.67 mg Kg−1 dw). The norms obtained with the leaf mineral data showed similar values between the Ferraduel and Ferragnes varieties but different values for Garrigues variety. Therefore, Garriges had the highest N/P, N/K, P/K, and P × Mg norms in the DRIS method and the highest VN and VCa norms in the CND method.

Expansion in Cultivating Almond Trees in Egypt

Egypt spends a lot of hard currency annually to import nut fruits (almond- walnut and pistachio) to apply market needs of these crops especially in Ramadan month. It is known that there are wide uncultivated areas in Sinai despite of its suitability for cultivation. Cultivating nut trees can share in development of Sinai. There are scarcity of these trees in Egypt in spite of the relevance of environmental conditions for growing almond trees in different regions. Since the last 25 years I and a group of scientists studied the possibility of achieving self sufficiency of almond by cultivating in Sinai Peninsula and different regions after carrying out climatic, economical, water requirements, nutrition and genetic studies. Many fruit trees require cold temperatures during the winter to overcome their seasonal dormancy.() Most fruit species that evolved in temperate or cool subtropical climates have such chilling requirements that need to be fulfilled each winter to achieve homogeneous and simultaneous flowering and regular crop yields. Coldness. (). Monthly historical data of minimum temperature from Central laborator for Agricultural climate of four districts were analyzed in order to determine the changes in minimum temperature from October to February during the period from 2001 to 2010. Understanding monthly temperature changes from October to February during the period 2001–2010 was the first step in carrying out this study. The highest minimum temperature was found during 2010 year during the studied period in the October month for all districts except in November and December, the highest minimum temperature was observed in the year of 2009. Saint Catherine district was the lowest minimum temperature in all months during the studied period. Understanding average monthly temperature trends of the studied time serious from 2001 to 2010 was the second step in carrying out this study. October month was the highest values of minimum temperature and January was the lowest value of minimum temperature at the four districts. The highest and lowest values for temperature were found in Ras Sudr and Saint Catherine respectively. The third step in carrying out this study is to understanding the annual trend of minimum temperature for the period 2001–2010 at the Suez, Ras Sudr, El Tur and Saint Catherine districts. Data shows the average annual minimum temperature at the four districts during the years from 2001 up to 2010 and it can be observed that, Ras Sudr district has the highest average annual minimum temperature while Saint Catherine has the lowest one among the studied districts. It can be concluded that the carried out climatic studies, estimate the irrigation water requirements of almond trees and genetic studies help in solving the problem of achieving self sufficiency of almond fruits through expansion of cultivating almond trees in Egypt.

Biochemical and Histological Insights into the Interaction Between the Canker Pathogen Neofusicoccum parvum and Prunus dulcis L.

The number of reports associated with wood dieback caused by fungi in the Botryosphaeriaceae in numerous perennial crops worldwide has significantly increased in the past years. In this study, we investigated the interactions between the canker pathogen Neofusicoccum parvum and the almond tree host (Prunus dulcis L.), with an emphasis on varietal resistance and host response at the cell wall biochemical and histological levels. Plant bioassays in a shaded house showed that among the four commonly planted commercial almond cultivars (cvs. ‘Butte’, ‘Carmel’, ‘Monterey’ and ‘Nonpareil’), there was no significant varietal difference with respect to resistance to the pathogen. Gummosis was only triggered by fungal infection, and not by wounding. A two-dimensional NMR and liquid chromatography determination of cell wall polymers showed that infected almond trees differed significantly in their glycosyl and lignin composition compared to healthy, non-infected trees. Response to fungal infection involved a significant increase in lignin, a decrease in glucans, and an overall enrichment in other carbohydrates with a profile similar to those observed in gums. Histological observations revealed the presence of guaiacyl-rich cell wall reinforcements. Confocal microscopy suggested that N. parvum mainly colonized the lumina of xylem vessels and parenchyma cells, and to a lesser extent the gum ducts. We discuss the relevance of these findings in the context of the CODIT model in almond and its potential involvement in the vulnerability of the host toward fungal wood canker diseases.

Candidatus phytoplasma phoenicium.

Phytoplasmas are wall-less parasitic bacteria living exclusively in plant phloem as consequence of transmission by sap-sucking insect vectors (Lee et al., 2000); they have been associated with several hundred plant diseases. 'Candidatus Phytoplasma phoenicium' (CaPphoe), subgroup 16SrIX-B, is the aetiological agent of almond witches'-broom (AlmWB), a severe disease affecting almond, peach and nectarine trees in Lebanon and Iran. The first epidemics of AlmWB occurred in almond trees in Lebanon in the early 1990s and in Iran in 1995. In Lebanon, the disease rapidly spread from coastal to high mountainous areas, killing almost 150,000 trees over a period of 15 years. CaPphoe was first added to the EPPO Alert List in 2001 and removed from the list in 2006. The more recent rapid spread of CaPphoe in peach and nectarine orchards and in other plant hosts, along with the identification of efficient insect vectors, increased the alarm about the risk it poses for stone fruit production in the Middle East and in all the countries of the Mediterranean basin. Thus it was re-inserted in the EPPO Alert List in 2015.

Candidatus Phytoplasma phoenicium.

Phytoplasmas are wall-less parasitic bacteria living exclusively in plant phloem as consequence of transmission by sap-sucking insect vectors (Lee et al., 2000); they have been associated with several hundred plant diseases. 'Candidatus Phytoplasma phoenicium' (CaPphoe), subgroup 16SrIX-B, is the aetiological agent of almond witches'-broom (AlmWB), a severe disease affecting almond, peach and nectarine trees in Lebanon and Iran. The first epidemics of AlmWB occurred in almond trees in Lebanon in the early 1990s and in Iran in 1995. In Lebanon, the disease rapidly spread from coastal to high mountainous areas, killing almost 150,000 trees over a period of 15 years. CaPphoe was first added to the EPPO Alert List in 2001 and removed from the list in 2006. The more recent rapid spread of CaPphoe in peach and nectarine orchards and in other plant hosts, along with the identification of efficient insect vectors, increased the alarm about the risk it poses for stone fruit production in the Middle East and in all the countries of the Mediterranean basin. Thus it was re-inserted in the EPPO Alert List in 2015.