Pistachio Crops Research Articles

Current status of pistachio diseases in countries of the Mediterranean Basin

AbstractIn the Mediterranean Basin, the pistachio crop is considered an emerging nut crop due to the dependence of the European nut markets on international imports. Consequently, the extension and intensification of pistachio production to nontraditional growing areas has promoted both classic and emerging diseases of this nut tree, which are limiting factors in crop production. Due to the limited interest in pistachio crops, the aetiology and epidemiology of the main pistachio diseases are poorly studied. Thus, this review summarizes the state of pistachio disease research, with particular attention given to the Mediterranean area. The information reported here is based not only on the literature, but also the advancement of our research on pistachio diseases conducted in both Italy and Spain. We describe the main fungal diseases of the tree canopy in Mediterranean countries, such as Botryosphaeria panicle and shoot blight, Septoria leaf spot, and stem, branch and trunk canker diseases, followed by the main soilborne diseases. In addition, we review minor and/or sporadic fungal diseases originating in not only the Mediterranean, but also other pistachio‐producing countries. Another section is dedicated to other diseases caused by bacteria, phytoplasmas, viruses and nematodes. Finally, we summarize the main control strategies adopted in Mediterranean Basin countries against pistachio diseases.

Sporulation and Dispersal of the Biological Control Agent Aspergillus flavus AF36 Under Field Conditions.

Aflatoxins are carcinogens produced by the fungi Aspergillus flavus and A. parasiticus that contaminate pistachio crops. International markets reject pistachio when aflatoxins exceed permitted maximum levels. Releasing the atoxigenic strain AF36 of A. flavus is the leading aflatoxin pre-harvest control method. The product AF36 Prevail, sorghum grains coated with AF36 propagules, has been used in California since 2017. However, a high percentage of grains of the Prevail fail to sporulate in orchards. Here, the effect of soil moisture on the percentage of AF36 product grains sporulating (SG) and the quantity of spores per grain using a sporulation index (SI) was determined. Under controlled conditions, SG was higher than 85% when soil moisture was 13% or more, and SI increased with increasing soil moisture from 8.4 to 21%. The highest AF36 sporulation occurred near the micro-sprinklers when the grains were not impacted by the irrigation water drops. Arthropod predation was responsible for lost product grains, which was more pronounced in non-tilled soil than in tilled soil. Dispersal of the AF36 spores decreased markedly with the height and distance from the inoculum source, following a pattern of diffusion equations. However, AF36 spores easily reached canopies of pistachios located 10 m from the inoculum source. Our results indicate that AF36 Prevail should be applied close to the irrigation line in the moist soil area but avoiding the areas where excess irrigation causes water accumulation. The biocontrol of aflatoxins in California's pistachio production areas was optimized by improving the field realization of the biological control agent.

Survey, Pathogenicity assay, and Molecular Identification of the Pathogenic Fungi Associated with Pistachio in Anbar Province, Iraq

This study was carried out in 6 different locations in the Anbar Province, between January and February 2021. The locations with higher pistachio cultivation, such as Kabisa, Al-Haditha, Al-Baghdadi, Anah, Al-Qaim, and Rawa were selected to study the prevalence of fungal diseases affecting pistachio crops. Twenty-six distinct fungal isolates were identified, and each isolate was examined for the pathogenicity. Although the level of pathogenicity of each isolate varied from high to moderate, they all caused lesions, damaged vascular tissue, signs of root rot and seed rot in pistachio seedlings. The fungal strains were identified depending on ITS marker. Twelve of the isolates belonged to Fusarium solani, 10 of F. falciforme isolates, 2 of F. oxysporum isolates, while 1 isolate of F. vanettenii and Xylaria sp. The most frequently-occurring species were F. falciforme and F. solani in the Anbar Province. Out of all the studied isolates, Al-Qaim and Al-Baghdadi were the highest pathogenic isolates. The pathogenic effects of F. vanettenii and Xylaria sp. on pistachio plants as well as the existence of F. solani and F. falciforme in Iraq were all recorded in this study for the first time.

The Use of the System Sys Land Evaluation System in the Evaluation of Gypsum Lands for the Cultivation of Peanut Arachis Hypogaea Irrigated in the Al-Tarrah Region, West of Anbar Province

Land assessment is one of the most important tools for integrated management of sustainable agricultural land use and land use planning. to achieve this, field visits were carried out and, depending on the factors of elevation above sea level and the prevailing land use type, 8 soil troughs and drill holes were dug in the study area with a depth of 120 cm The number of which is (48) so that it is representative of the studied region. The samples were taken in a systematic way, to perform physical and chemical analyzes such as tissue (%rum, %silt, % clay, % organic matter, cation exchange capacity, and others). The results of soil analysis showed the difference in the influence of physical and chemical determinants, and the biggest determinant of peanut cultivation was the amount of gypsum and pH values as an average determinant. The final total estimate of the climate factor is not a determinant of the growth of the field pistachio crop in the study area. The study found that the types of suitability ranged from N1 to N2.

Replacement of Megastigmus pistaciae Walker (Hymenoptera: Megastigmidae) by Eurytoma plotnikovi Nikol’skaya (Hymenoptera: Eurytomidae) in pistachio orchards in southern Italy

Investigating the effect of non-native herbivore species in the new areas is vital for understanding their effects on native crops and the interactions that the newly arrived species have with any natural native herbivores and predatory species. The pistachio-seed wasp Eurytoma plotnikovi Nikol’skaya (Hymenoptera: Eurytomidae) is an invasive species on pistachio groves in Sicily, southern Italy; thus, the current study investigated its effects on pistachio crops and the native pistachio-seed wasp Megastigmus pistaciae Walker (Hymenoptera: Megastigmidae). The results showed that fruits in Pistacia vera pistachio groves were infested only with E. plotnikovi, which had been able to replace M. pistaciae after only a decade. Female E. plotnikovi emerge between May and June, but the males are rarely seen. No natural enemies were detected for E. plotnikovi in the study sites, highlighting an important phytosanitary issue for pistachio nut production in Sicily.

Septoria (Septoria pistaciae Desm.) pathogen infecting pistachio nuts in Uzbekistan and its biological characteristics

This article introduces the results of research on the harmful effects of septoria, a fungal plant pathogen infecting pistachio, on pistachio fruit weight and yield. In recent years, there has been an increase in the negative effects of various diseases on the pistachio crop. Therefore, maintaining their yield and developing modern disease control measures remains one of our main goals. The measures to combat this disease and the effectiveness of the most suitable chemical preparations are presented below.

A Novel Technique Using Planar Area and Ground Shadows Calculated from UAV RGB Imagery to Estimate Pistachio Tree (Pistacia vera L.) Canopy Volume

Interest in pistachios has increased in recent years due to their healthy nutritional profile and high profitability. In pistachio trees, as in other woody crops, the volume of the canopy is a key factor that affects the pistachio crop load, water requirements, and quality. However, canopy/crown monitoring is time-consuming and labor-intensive, as it is traditionally carried out by measuring tree dimensions in the field. Therefore, methods for rapid tree canopy characterization are needed for providing accurate information that can be used for management decisions. The present study focuses on developing a new, fast, and low-cost technique, based on two main steps, for estimating the canopy volume in pistachio trees. The first step is based on adequately planning the UAV (unmanned aerial vehicle) flight according to light conditions and segmenting the RGB (Red, Green, Blue) imagery using machine learning methods. The second step is based on measuring vegetation planar area and ground shadows using two methodological approaches: a pixel-based classification approach and an OBIA (object-based image analysis) approach. The results show statistically significant linear relationships (p < 0.05) between the ground-truth data and the estimated volume of pistachio tree crowns, with R2 > 0.8 (pixel-based classification) and R2 > 0.9 (OBIA). The proposed methodologies show potential benefits for accurately monitoring the vegetation of the trees. Moreover, the method is compatible with other remote sensing techniques, usually performed at solar noon, so UAV operators can plan a flexible working day. Further research is needed to verify whether these results can be extrapolated to other woody crops.

Pantoea agglomerans-Induced Dieback in Pistachio in Chile

Pistachio crops have a great economic potential, as their global production has increased dramatically over the past few decades. Therefore, it is important to maintain the healthy phytosanitary status of pistachio crops. In a Chilean pistachio orchard, a dieback of the trees was observed, with blighting of twigs and severe necrosis in the trunk and twigs. Bacterial isolation, pathogenicity tests and molecular characterization were conducted to determine the causal agent of the observed disease. The bacterial isolation and analysis of 16S rRNA gene led to the identification of Pantoea genus bacteria. Pathogenicity tests carried out on fruits inoculated with Pantoea isolates induced large necrosis seven days post-inoculation. Further inoculations were carried out on pruning cuttings and on the trunk of 18-month-old pistachio plants. Thirty-one weeks after inoculation, necrotic lesions were observed in the wood of pistachio plants. Sequence analysis of housekeeping genes enabled the isolated bacterium to be identified as Pantoa agglomerans, and to verify its role as the causal agent of the pistachio dieback with necrotic lesions. This is the first report of an occurrence of P. agglomerans inducing dieback in pistachio.

Assessment of aflatoxins in some pistachio cultivars supplied in bulk in Tehran food stores

ABSTRACT Tree nuts, especially pistachio kernels, are highly susceptible to aflatoxin contamination. These substances are produced by certain moulds such as Aspergillus flavus and Aspergillus parasiticus. Release of aflatoxins in pistachio bulks and their sources are the main causes of aflatoxin contamination in pistachio nuts. The aim of this study is the assessment of aflatoxins in some pistachio cultivars supplied in bulk in Tehran Food stores. Iranian pistachio cultivars such as Ahmad Aghaei, Akhbari closed-mouth, half-splitting Akbari, Ohadi, Badami Sefid, Chorouke, Khanjari Damghan, Abbas Ali, Fandoghi 48, Kaleghoochi, and Mumtaz, were randomly collected and sampled from nuts supply centres. Levels of aflatoxins B1, B2, G1, G2, and total aflatoxin were measured in the cultivars using high-performance liquid chromatography (HPLC). The findings showed that aflatoxin B1 contamination was found only in Akbari closed-mouth (0.3 μg/kg) and Ohadi (0.4 μg/kg) pistachio cultivars (p < 0.05). Total aflatoxin levels in these two cultivars were measured at 0.3 and 0.4 μg/kg, respectively (p < 0.05), with no aflatoxin found in the other cultivars. The values measured in the present study are lower than the maximum tolerance established in the national standard for aflatoxin B1 (5 μg/kg) and the total aflatoxin (15 μg/kg) in the pistachio crop. It was concluded that the density of aflatoxin in highly consumed pistachio cultivars supplied in Tehran is within acceptable health and safety standards.

First report of the pest pistachio‐seed wasp Eurytoma plotnikovi (Hymenoptera: Eurytomidae) in France

AbstractThis is the first official report of the pistachio pest Eurytoma plotnikovi in France. Twenty adults were identified after they emerged from a sample collected in South‐Eastern France. A brief description is provided, along with biological, geographical and economic data on the pest. This species should not be considered as a major concern for nut production in France so far, although this might evolve with the development of pistachio crops in this area.

Fungal diseases in pistachio trees caused by cylindrosporium concentricum pathogen: A case study of Uzbekistan

This article discusses the fungal infections of pistachios and the results of the fight against them. On a yearly basis, pistachio diseases have a significant impact on yields. Three drugs were utilized in the research. All of them are drugs recommended for use in agriculture. The drugs were used in the recommended doses and the results were shown. As a result of this research, a large part of the pistachio crop can be preserved. It is also recommended to produce a drug that has shown good results against the disease.

Estimating evapotranspiration of pistachio crop based on SEBAL algorithm using Landsat 8 satellite imagery

Stationary actual evapotranspiration (ET) estimation methods deal with some issues such as maintenance problems, the point data recording for a particular location, the complex hydrological process calculation, and requiring the expert workers. To solve this, ET estimation methods like Surface Energy Balance Algorithm for Land (SEBAL) method can be used based on the satellite images. However, the efficiency of the SEBAL model varies in ET estimation for different products and environmental conditions. On the other hand, pistachio is an important crop of Iran which little investigation were accomplished to estimate its ET using the presented models. Therefore, the purpose of this study is to investigate the efficiency of SEBAL algorithm in estimating ET of pistachio crop. In this regard, actual ET of a 100 hectares pistachio farm, located in Safaeieh region in the Semnan province, Iran, was selected as the study area. Implementations were performed using 29 Landsat 8 Operational Land Imager (OLI) images during the 2013–2017 period. The results were verified and compared with the results of evapotranspiration in standard condition estimated by the Intelligent Meteorological instrument (iMetos-Pessl) as the ground truth. The results of this study indicate the determination coefficient and Root Mean Square Error (RMSE) of the estimated actual ET for pistachio plant as 0.8 and 2.5 mm, respectively. Moreover, the results indicate the high spatial variability of ET in the pistachio growth period and the need to use a satellite data analysis method, like the SEBAL method, to prepare the ET map. Overall, the results show the good efficiency of the SEBAL model for estimating the actual ET of the pistachio product.

Effects of calcium salts in controlling Phytophthora pistaciae, the causal agent of pistachio gummosis

The ability of calcium chloride and calcium sulfate to control pistachio gummosis caused by Phytophthora pistaciae was evaluated both in vitro, on solid and liquid media, and in vivo, on broad bean, a potential annual host of the pathogen, and seedlings of three pistachio cultivars. In vitro, all concentrations of the salts (1.5, 4, 8 and 15 mM) reduced mycelial growth, dry weight of mycelial mats, and sporangial production of the pathogen. Calcium chloride reduced the size and volume of sporangia, antheridia and oogonia. Calcium sulfate also reduced the size and volume of sporangia, but it had less impact on the volume of oogonia and increased the size of antheridia and the volume of oospores. Moreover, concentrations of both calcium salts higher than 1.5 mM reduced zoospore discharge and induced cyst germination. In vivo, application of calcium salts before and after inoculation of sterilized soil with P. pistaciae reduced the mortality of broad bean plants and different cultivars of pistachio trees compared to the respective controls. Analyses using atomic absorption showed calcium concentrations to increase in the foliage of Ca-treated broad bean and pistachio plants. Based on the results, the application of calcium chloride to P. pistaciae infested soils could be more advantageous than calcium sulfate to control P. pistaciae gummosis in commercial pistachio crops.

Aflatoxin Regulations and Global Pistachio Trade: Insights from Social Network Analysis

Aflatoxins, carcinogenic toxins produced by Aspergillus fungi, contaminate maize, peanuts, and tree nuts in many regions of the world. Pistachios are the main source of human dietary aflatoxins from tree nuts worldwide. Over 120 countries have regulations for maximum allowable aflatoxin levels in food commodities. We developed social network models to analyze the association between nations’ aflatoxin regulations and global trade patterns of pistachios from 1996–2010. The main pistachio producing countries are Iran and the United States (US), which together contribute to nearly 75% of the total global pistachio market. Over this time period, during which many nations developed or changed their aflatoxin regulations in pistachios, global pistachio trade patterns changed; with the US increasingly exporting to countries with stricter aflatoxin standards. The US pistachio crop has had consistently lower levels of aflatoxin than the Iranian crop over this same time period. As similar trading patterns have also been documented in maize, public health may be affected if countries without aflatoxin regulations, or with more relaxed regulations, continually import crops with higher aflatoxin contamination. Unlike the previous studies on maize, this analysis includes a dynamic element, examining how trade patterns change over time with introduction or adjustment of aflatoxin regulations.

Taxonomic Revision of the Genus &amp;lt;i&amp;gt;Pistacia&amp;lt;/i&amp;gt; L. (Anacardiaceae)

Pistacia is an economically important genus because it contains the pistachio crop, P. vera, which has edible seeds of considerable commercial importance whose value has increased over the last two decades reaching an annual value of about $2 billion (harvested crop). The taxonomic relationships among its species are controversial and not well under- stood due to the fact that they have no genetic barriers. The taxonomy of this genus is revised in detail through our re- search. It includes the following taxa: Pistacia atlantica Desf., P. chinensis Bunge subsp. chinensis, P. chinensis subsp. falcata (Bess. ex Martinelli) Rech. f., P. chinensis subsp. integerrima (J.L. Stew. ex Brandis) Rech. f., P. eurycarpa Yalt., P. khinjuk Stocks, P. lentiscus L. subsp. lentiscus, P. lentiscus subsp. emarginata (Engl.) AL-Saghir, P. mexicana Humb., Bonpl., & Kunth, P. X saportae Burnat, P. terebinthus L., P. vera L., and P. weinmannifolia Poiss. ex Franch. The genus is divided into two sections: section Pistacia and section Lentiscella. A key to the 14 taxa that have been recognized by this study is included. The new combination P. lentiscus subsp. emarginata (Engl.) AL-Saghir is made, and the names P. chinensis subsp. integerrima (J. L. Stew. ex Brandis) Rech. F., P. terebinthus L., and P. vera L. are lectotypified.

Effect of harvesting time on nut quality of pistachio ( Pistacia vera L.) cultivars

The appropriate time of harvest is one of the most important factors affecting the quality of pistachio. Cultivars ‘Ahmad-Aghaii’, ‘Kaleh-Ghoochi’, ‘Ohadi’ and ‘Badami-Zarand’ were evaluated for qualitative indices of nut over a period of four years from 2001 to 2004. Nut samples were collected during eight successive weeks from 23 August to 11 October. Splitting, early splitting, hull cracking and hulling percentage continually increased toward the last harvest week while non-splitting, immaturity, number of nuts per ounce and moisture content decreased during the harvest weeks. The increment of splitting and the number of nuts per ounce was not significant from 20 September to the last week of harvest. Early splitting, hull cracking and aflatoxin contamination of kernel progressively increased from 13 September. Total crude fat and sugar contents showed a peak in the middle of September. The concentration of aflatoxins prior or at maturity stage of selected cultivars was lower than the critical level. In general, the appropriate time of harvest for the cultivars studied is the middle of September to avoid contamination of nuts to aflatoxin and to ensure the nut quality. This study emphasizes different quality indices for determining the optimum harvest time of pistachio crop.

Effect of exogenous application of free polyamines on physiological disorders and yield of ‘Kaleh-Ghoochi’ pistachio shoots ( Pistacia vera L.)

Pistachio trees exhibit some physiological disorders such as abscission of inflorescence buds, fruit abscission, the production of blank, non-split, early-split and deformed nuts. Since the occurrence of these disorders is closely related to the yield, the effect of free polyamine treatments on these disorders and the yield was investigated in two consecutive years (“on” and “off” years). Free polyamine treatments were applied one week before and also two weeks after full bloom. Results showed that Spermine (Spm), unlike Putrescine (Put), decreased the physiological disorders of pistachio and also increased the yield. Free polyamine treatments did not affect the percentage of early-split nuts. Spermidine (Spd) decreased the percentage of both fruit abscission and deformed nuts but did not affect the yield. In both the “on” and “off” years the effect of Spm and Spd was greatly dependent on both the time of application and the concentrations used. Results of free polyamine analysis showed that exogenous application of these compounds, especially two weeks after full bloom, increased the free polyamine contents of shoots in both “on” and “off” years confirming the absorption of free polyamines via spray application in pistachio crop. Exogenous application of Spm two weeks after full bloom decreased the abscission of inflorescence buds in “on” year supporting the idea that free polyamines could trigger the abscission process of inflorescence buds. Since Spm decreased the percentage of blank, non-split and deformed nuts, it seems that Spm dominantly plays a key role in the growth and development of pistachio nuts.

Low Cost Real-Time Sorting of In-Shell Pistachio Nuts from Kernels

A simple, low-cost optical system and decision making circuitry for use in high speed sorting devices designed for separating pistachio nuts with (in-shell) and without (kernels) shells is reported. Testing indicates 95% accuracy in removing kernels from the in-shell stream with no false positive results out of 1000 kernels tested. Testing with 1000 each of in-shell, shell halves, and kernels resulted in an overall error of about 3.3%, roughly twice the overall error rate achieved using a commercially available dual band NIR-VIS sorting device. However, the cost of materials for the equipment reported here was less than $500 (U.S.), indicating the potential for economical sorting versus for commercially available equipment. Since existing sorters can be trained to sort a variety of product streams, implementation of the new device in pistachio plants could free up machines for other sorting tasks, thus reducing the overall cost of sorting the pistachio crop.