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Submitted to: Proceeding of International Working Group on Plant Viruses with Fungal Vectors
Publication Type: Proceedings Publication Acceptance Date: 3/20/2003 Publication Date: N/A Citation: N/A Interpretive Summary: A severe soil-borne disease of lettuce has emerged to cause severe losses for lettuce production in the western United States. The disease is caused by a group of tombusviruses, including both Tomato bushy stunt virus and the newly described Lettuce necrotic stunt virus. Fields with sever infections are usually associated with areas near rivers and areas where flooding has recently occurred. Interestingly, disease severity in infested fields varies considerably from year to year. Soil from diseased and adjacent non diseased fields of similar type and texture were analyzed and found to differ in soil salinity. Subsequent greenhouse experiments have confirmed that elevated soil salinity, as measured by soil electrical conductivity, is significantly correlated with elevated incidence of lettuce dieback symptom development and tombusvirus infection. Technical Abstract: A severe soil-borne disease of lettuce has emerged to cause severe losses for lettuce production in the western United States. The disease is caused by a group of tombusviruses, including both Tomato bushy stunt virus and the newly described Lettuce necrotic stunt virus. Fields with sever infections are usually associated with areas near rivers and areas where flooding has recently occurred. Interestingly, disease severity in infested fields varies considerably from year to year. In order to identify factors contributing to variability in infection, soil analyses were conducted on adjacent fields with similar soil type, but differing for tombusvirus infection. These studies identified soil salinity as the predominant factor differing between diseased and disease-free fields. Subsequent greenhouse studies examined the effect of electrical conductivity levels in the soil on virus infection. Results indicated that elevated electrical conductivity (5.5dS/cm3), which exhibited very low disease incidence. |
