Plant Pathology Science

Serological and molecular detection of barley yellow mosaic virus in Khorasan Razavi Province, Iran

Mohadese Gerami Nooghabi

Yellow mosaic, caused by the Barley Yellow Mosaic Virus (BaYMV), which is transmitted by the fungal-like organism Polymyxa graminis, is one of the most significant viral diseases affecting barley worldwide. To conduct serological and molecular surveillance of this virus in barley fields across Khorasan Razavi Province, northeastern Iran, a total of 86 leaf samples were collected in late winter of 2022. These samples were either randomly selected or exhibited symptoms such as mosaic patterns, chlorosis, and vein clearing. Upon transfer to the laboratory, the samples were analyzed using serological ELISA tests and molecular reverse transcription polymerase chain reaction (RT-PCR) assays. Using BaYMV-specific primers, an 800 base pair fragment corresponding to the viral coat protein was successfully amplified. Among the RT-PCR-positive isolates, the amplified DNA fragment from the Bajestan isolate was extracted from the gel and sequenced. The obtained sequence was verified using the BLAST program and subjected to phylogenetic analysis alongside other BaYMV coat protein sequences available in the NCBI GenBank database, using DNAMAN-7 and Vector NTI software. The sequenced fragment of the Bajestan isolate shared the highest nucleotide (94.79%) and amino acid (90.59%) similarity with a corresponding fragment from a European isolate. This study represents the first report of BaYMV occurrence in Bajestan County, Khorasan Razavi Province, Iran.

Management strategies for Fusarium crown and root rot disease in tomato

Azadeh Goudarzi

Fusarium root and crown rot disease of tomato is one of the most important and destructive soil-borne diseases of this crop, and one of the factors limiting production of tomato in the world. Disease symptoms include yellowing and necrosis of leaves and petioles, defoliation, formation of brown wounds on the roots and tissues adjacent to the soil surface, necrosis and discoloration of internal tissues of crown and basal stem, reduction in the quantity and quality of fruits, wilting and plant death. Eleven Fusarium species with names; F. solani, F. oxysporum f. sp. radicis-lycopersici , F. moniliforme, F. culmorum, F. commune, F. redolens, F. chlamydosporum, F. semitectum, F. lateritium, F. acuminatum and F. equiseti has been reported as the causatives of the disease in the world. The disease occurrence in farms and commercial greenhouses, if disease management strategies are not implemented, usually leads to great economic losses to the tomato yield and in some cases, complete crop destruction. The disease has been reported from East-Azarbaijan, Semnan, Fars, Hormozgan and Kerman Provinces, in Iran. This article discusses integrated disease management strategies, emphasizing preventive measures such as pathogen exclusion, use of resistant cultivars, prevention of root and crown injuries, sanitation, salt stress management, as well as cultural, biological, and chemical control methods.

Major diseases of date palm and innovative management strategies

Farideh Farahbakhsh

Date fruits are rich in carbohydrates, energy, fiber, vitamins, nutritional elements, and are consumed as a staple or supplementary food in several countries. Iran is the second-largest producer of dates globally, and this fruit serves as a significant source of income for orchard owners and exporters. Numerous limiting factors affect date production, among which fungi, oomycetes, and phytoplasmas are the most critical biological agents causing damage. Effective management of these pathogens requires modern and sustainable approaches. The most important date palm diseases reported from Iran and other countries in the Middle East and North Africa include: Decline, black scorch, Pestalotiopsis and Graphiola leaf spots, spathe rot or Khamj, and yellow stripe disease. The symptoms of these diseases and novel integrated management methods, such as orchard sanitation, optimized fertilization, the use of AI-equipped drones for diseases monitoring, advanced technologies like genome editing to develop resistant cultivars, and biological and chemical control strategies, are illustrated and discussed in this article.

Root parasitic nematodes of sugar beet in Khorasan Razavi Province, Iran

fatemeh Azad Disfani

Plant-parasitic nematodes are considered major pathogens of sugar beet, causing significant yield losses both quantitatively and qualitatively. This study was conducted to determine the distribution and population density of plant-parasitic nematodes in sugar beet fields under the jurisdiction of the Jovain Industrial and Agricultural Company, located in Razavi Khorasan Province, an area playing a vital role in the country's sugar beet supply. A total of 150 soil samples were collected from the rhizospher of sugar beet plants across five regions: Neqab, Azadvar, Rah-Chaman, Hokmabad, and Qazlqarshi, in 2022. The samples were transferred to the laboratory to examine the distribution of plant-parasitic nematodes. Nematodes were extracted using the sieving and centrifugation method, while cyst nematodes were extracted using the Fenwick can method. Identification of cyst and root-knot nematodes was carried out based on morphological characteristics of juveniles and the shape of the vulval cone of females. Twelve nematode species belonging to eight genera and seven families within the superfamily Tylenchomorpha were identified: Heterodera schachtii, Meloidogyne javanica, M. incognita, Pratylenchus thornei, P. neglectus, Merlinius brevidens, Ditylenchus myceliophagus, Scutylenchus rugosus, Tylenchorhynchus annulatus, Helicotylenchus sp., Aphelenchoides sp., and Aphelenchus avenae. Cyst and root-knot nematodes were found at frequencies of 38.3% and 17%, respectively. The Neqab region showed the highest prevalence of cyst nematodes (93.3%), while Azadvar had the highest prevalence of root-knot nematodes (60%) among all surveyed areas. Given the widespread distribution and high population densities of cyst and root-knot nematodes in certain regions, the implementation of management strategies is recommended to prevent their further spread and reduce their populations in sugar beet fields.

Impact of Bacillus subtilis and Trichoderma harzianum on rice blast disease severity

Aboulfazl Yahyavi Azad

Rice blast, caused by Pyricularia grisea, is a highly destructive fungal disease that affects rice crops worldwide, annually inflicting significant damage on this crop and leading to a reduction in its yield. Considering that the use of chemical pesticides has become widespread for controlling this disease, and that these chemicals can have destructive effects on the environment, the present study was conducted with the aim of investigating the potential of Bacillus subtilis and Trichoderma harzianum for the biocontrol of this disease in the Hashemi rice cultivar. In this study, the effects of T. harzianum and B.subtilis, individually or in combination, were investigated using three methods: seed coating, seedling impregnation, and irrigation. The results showed that for all growth parameters examined, including shoot fresh weight, dry weight and length, root fresh weight, dry weight and length, as well as disease indices such as percentage of leaf surface infection, disease severity and percentage of disease reduction, the use of B. subtilis alone or in combination with T. harzianum as a seed treatment showed the best performance. Therefore, the application of the B. subtilis alone or in combination with T. harzianum, especially when applied by seed coating, has the greatest impact on reducing and controlling rice blast and improving the growth parameters of this crop. Consequently, it can be used by farmers as a practical method for the biocontrol of this disease.

Fungi causing root rot and leaf sheath blight diseases in rice from Golestan Province, Iran

Mojtaba Keykhasaber

Rice is a major food crop in Asia. Fungal diseases such as root, collar, and stem rot, as well as leaf sheath blight, are common in most rice-growing regions of Iran and cause significant economic losses. This study was conducted to identify the fungal pathogens responsible for these diseases in Golestan Province, which ranks third in rice production in the country. Identifying these pathogens provides a foundation for implementing effective management strategies and improving crop yield. Samples showing symptoms of root and stem rot and leaf sheath blight were collected from rice fields across various locations in Golestan Province. Fungi were isolated from diseased tissues using water agar and potato dextrose agar media and then purified. For precise molecular identification, the polymerase chain reaction (PCR) was used to amplify the tef1-α and ITS-rRNA gene regions with the primers EF1728F/EF1-986R and ITS5/ITS4, respectively. Pathogenicity tests were conducted on rice seedlings under greenhouse conditions. Based on morphological, molecular, and pathogenicity analyses, the following fungal pathogens were identified in the diseased samples: Ceratorhiza hydrophila, Fusarium andiyazi, F. incarnatum, and Rhizoctonia solani. This is the first report of C. hydrophila, F. andiyazi, and F. incarnatum occurring in rice fields in this province.

The role of humic acid as a biostimulant in plant disease management

zahra Amjadi

Humic acid (HA) is the most important and widely used biostimulants in agriculture. As a powerful, multifaceted tool in increasing soil health and plant resistance, HA has significant effects for sustainable agriculture and plant disease management. This safe organic compound controls diseases through direct and indirect mechanisms. In the indirect dimension, HA creates an unfavorable environment for the development of pathogens by improving the physical structure of the soil by increasing porosity and ventilation, enhancing the cation exchange capacity and chemical fertility of the soil, as well as stimulating the population of beneficial soil microorganisms. In addition, HA strengthens the plant by stimulating the development of the root system, facilitating the absorption of water and nutrients, and especially by activating the mechanisms of inducing systemic resistance in the plant, leading to the production and accumulation of defensive metabolites increasing the activity of defensive enzymes, and the proteins associated with pathogenesis. This article provides a summary of the effectiveness of HA as a plant stimulant on plant pathogens and the prospects for its use to reduce the use of chemical pesticides or even replace them in controlling plant diseases. A good understanding of the function of biostimulants, including humic acid, will help farmers and agricultural scientists in their better use.

The Role of Artificial Intelligence-Based Software in the Diagnosis and Management of Plant Diseases

Mehdi Sadravi

Diseases are a serious threat to the sustainable and healthy production of plant yields and the food security of the world's people, and annually reduce a significant part of their production in terms of quantity and quality. Classical methods of diagnosing plant diseases based on pathogen isolation in the laboratory and visual field monitoring of disease progression and implementation of management methods are very time-consuming, require specialized personnel and expensive. Artificial intelligence-based software uses image analysis, environmental sensors and disease forecasting modeling to quickly diagnose diseases at the farm level, integrate meteorological data, soil and crop parameters to predict the time of disease outbreak, provide appropriate suggestions for disease management based on previously available data and implement management methods quickly and accurately using the Internet of Things, drones and robots. Artificial intelligence-based softwares, help to quickly and accurately diagnose plant diseases before they cause damage, establish predictive systems for diseases, predict the exact time of their occurrence and spread, and implement timely and correct management methods, enabling increased production of healthy plant products, while reducing costs to ensure food security for the world's people.

The Role of Vermicompost and Its Derivatives in Plant Disease Management

Maryam Mirtalebi

The management of plant diseases using eco-friendly approaches has gained particular importance in sustainable agriculture for reducing dependence on chemical inputs. Vermicompost and its derivatives, including vermicompost tea and vermiwash, improve soil health and plant growth through bioactive compounds derived from earthworms and large populations of beneficial microorganisms, which effectively suppress plant pathogenic fungi, bacteria, and nematodes. Research evidence has demonstrated that these products can reduce the severity of diseases such as Fusarium wilt, bacterial canker, and root-knot nematodes while enhancing seedling growth parameters. The quality of vermicompost and its derivatives is influenced by factors such as raw materials, degree of maturation, and production methods; appropriate selection of these factors enhances their efficacy in pathogen control. The synergistic benefits of bioactive compounds and beneficial microbiota make vermicompost an effective tool for reducing chemical pesticide use and increasing agricultural productivity. Expanding production, farmer education, and supportive policies can further strengthen the role of these products in promoting sustainable agriculture by providing a practical strategy to improve plant health, mitigate diseases, and protect the environment.