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Pest Profiles - Diseases

Zucchini Yellow Mosaic Virus

  • About

    Photo: Wikimedia Commons
    Photo: Wikimedia Commons
    Virus transmitted by aphids. After feeding on an infected plant, aphids are only able to transmit this virus for very short periods of time (minutes to a few hours). In general, spread of potyviruses in the field occurs when aphid activity is high and is often very rapid and localized.

  • Category
    • Virus
  • Signs/Symptoms

    First symptom is a clearing of veins, followed by development of mosaic patterns or mottling consisting of irregularly shaped, dark green areas alternating with light green or yellow areas. Leaves on some species and cultivars are drastically reduced in size and growth is often retarded.

    Typically causes leaf lobes to become long and narrow and fruit to be malformed.

  • Where

    Wherever aphids are present; this virus is transmitted by many species of aphids.

  • When

    When aphid activity is high and localized.

  • Prevent

    Silver reflective plastic mulches applied at planting have been shown to be effective in repelling aphids from plants, thereby reducing or delaying virus infection. These mulches help plants off to a healthy start and are effective until expanding foliage covers the reflective surface. 

    In the Central Valley and cooler areas, these mulches have not caused plant damage in the summer; in fact, they improve soil moisture and nutrient retention, which may further aid plant productivity.

  • Manage

    Start looking for potyviruses during the vegetative growth stage. Note infections to make management decisions before the next crop because during the season, mosaic viruses are difficult to control. Spraying with insecticides is rarely effective because the insect transmits the virus before being killed by the insecticide. Because their occurrence is erratic and unpredictable, control of these viruses is not attempted.