وضعیت بیماری کوتولگی زرد جو در ایران و بررسی علل شیوع آن در سال زراعی 1402-1403

Barley yellow dwarf disease stands out as one of the most devastating viral infections affecting cereals, particularly wheat, on a global scale. To comprehend the dynamics of this disease and its potential for causing epidemics and damage, a systematic approach involving the epidemiological pyramid is crucial. Understanding the key components of the pyramid-comprising the virus, host, and vector in specific environmental contexts and grasping the intricate relationships among them is essential for proactive disease awareness and effective management strategies.
Primarily caused by multiple serotypes of two distinct viruses, Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV) from the Luteoviridae family, this disease is transmitted by aphids. Approximately 28 aphid species have been identified as vectors, with Ropalosiphum padi being a dominant vector species and the PAV serotype prevailing globally, including in Iran. The interplay among the virus, host plant, and aphid vector in the disease pyramid is intricate, with aphids serving as the sole mode of virus transmission. The spread and epidemic potential of the virus heavily hinge on the behavior, biology, and ecology of the aphid, as well as the environmental factors influencing aphid populations, such as temperature and humidity.
Various climatic factors, including day length, humidity, rainfall, temperature, number of cloudy days, and presence of fog, significantly impact aphid population growth. The movement and establishment of aphids within and around fields, population growth, reproduction, secondary dispersal, diffusion, and migration all rely on the availability of fresh hosts and favorable environmental conditions, such as cool air and high relative humidity. While the sexual form of aphids plays a minor role in virus transmission, the asexual form propagates the virus. The prevalence of mild winters and prolonged, cool springs in regions like Ardabil, Markazi, Razavi Khorasan, Chahar Mahal and Bakhtiari, Lorestan provinces, West Khuzestan, and the northern parts of the country has contributed to disease outbreaks in wheat and rice crops.
Aphids thrive in cooler temperatures, with their activity optimal between 15 and 25 degrees Celsius. Population decline occurs above this range, and sudden cold spells in early autumn, particularly in colder regions, lead to a decrease in aphid populations, subsequently reducing disease prevalence. By leveraging advanced awareness and targeted disease management practices, the impact of Barley yellow dwarf disease can be mitigated effectively.