RECENT DEVELOPMENT OF AUGUSTA DISEASE IN THE NETHERLANDS
In the Netherlands there has been a shift in tulip bulb production on sandy soils towards heavy clays. These soils are sensitive to the occurrence and enhancement of Augusta disease. Clay soil was collected from a tulip production field with a history of Augusta. Part of the soil was sterilized by steaming. The clay soil was compared to sandy soil, which were both steamed and not steamed. Two tulip stocks were chosen, based on the observed infection rates in the field during the growing season. The one was heavily infected and the other had a very low disease incidence. Both lots were planted early in October 2002, on the selected soils. Observation in the following spring showed that the tulips with a low incidence stayed healthy on the steamed clay and on both steamed and not steamed sandy soil. The untreated clay resulted in a high infection. The highly infected tulips showed infection on all soils, but the severity was lower on the steamed soils and untreated sandy soil than on the not steamed clay soil. Tulips planted before the middle of October are more susceptible to infection compared to tulips planted in the middle of November. If the precipitation in autumn is high and temperatures are relatively high, the disease is likely to show up in the following spring. This phenomenon might explain why the disease has a cyclic occurrence in time. This is still under investigation. Application of chalk had no effect and the usage of Pseudomonas sp. to control Augusta was not conclusive so far.
Bijman, V.P., Derks, A.F.L.M. and Blom-Barnhoorn, G.J. (2006). RECENT DEVELOPMENT OF AUGUSTA DISEASE IN THE NETHERLANDS. Acta Hortic. 722, 95-102
tulip, Tobacco necrosis virus, Olpidium brassicae, soil type, planting date, pastures