Landau
ActiveLactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
Diseases
Viral mosaic diseases are a group of systemic infectious plant diseases manifesting in variegated leaf coloration, tissue deformation, and reduced productivity. These diseases are caused by various pathogens, spread by pests and through contact, and are virtually untreatable.
Mentioned in descriptions 22 022 varieties reference book.
Viral mosaic diseases are characterized by the appearance of alternating spots of different colors on plant organs, including light rings, star-shaped spots, or stripes. In addition to specific variegated coloration, affected plants often exhibit leaf blade curling, wrinkling, and crinkling, as well as stunted overall growth and deformation of fruits and flowers. Sometimes the infection is latent, where visual symptoms are absent, yet crop productivity is significantly reduced.
Pathogen dissemination occurs through vectors such as aphids, true bugs, mites, and nematodes, as well as through mechanical transfer of sap from diseased plants during care, pruning, or physical contact. Infection is possible via seeds, planting material, soil, and crop residues. The intensity of infection development depends on weather conditions, particularly temperature regimes, and crop density, which facilitates rapid virus transmission.
Varietal resistance to mosaics is determined by the presence of specific or recessive genes affecting translation initiation. During breeding and variety testing, resistance is evaluated under artificial inoculation on infectious disease plots. Modern diagnostics for controlling viral load include enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR), while field resistance is determined by a variety's ability to not accumulate the pathogen throughout the growing season.
Selection based on the description text, not official resistance ratings: such data is not available in registers. Mention indicates that the trait is discussed in the variety's sources; see the variety's profile for details on what is specifically stated.
Lactuca sativa L. · Lettuce
Rijk Zwaan Zaadteelt en Zaadhandel B.V.
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