Prevention

New Arrivals

Before a new cutting or seedling is introduced into a healthy crop, it should be kept in separate facilities until it has been tested for microbial pathogens. It is recommended to test root material, ideally twice, at intervals of about four weeks. In very young plants, the spread of infection within the plant tissue may be uneven and the infection load too low to provide a reliable result with only a single test.

Introduction by Humans

For HLVd, the risk of introduction by staff (or visitors) is relatively low, whereas for fungal pathogens such as Fusarium spp. or Pythium spp. it can be quite significant. Fungal spores can easily be brought into the facility on clothing and shoe soles. It is therefore important to separate street and work clothing, and to provide visitors with protective clothing and shoe covers.

Introduction via Substrates

If certified pathogen-free substrates are not available, they should be examined and, if necessary, sterilized.

Hygiene

Disinfection of Tools and Surfaces

Most microbial pathogens can be killed with alcohol-based preparations. Viroids, however, have proven to be very persistent and resistant to common disinfectants. Complete inactivation of HLVd cannot be achieved with alcohol or hydrogen peroxide, nor with UV or heat sterilization.

As an effective disinfectant, a solution of approximately 5% sodium hypochlorite is recommended, which can be conveniently prepared by diluting common household bleach (1 part bleach to 10 parts water).

It is important that the tools and work surfaces used are thoroughly wetted with the bleach solution for at least 60 seconds before being used on the next plant. To maintain a smooth workflow, for example, several scissors can be kept in a container with bleach and removed as needed. Since excess sodium hypochlorite can damage plant tissue, tools and surfaces should be rinsed or wiped with clean water immediately after disinfection. Gloved hands should also be disinfected at regular intervals using the bleach solution mentioned.

Plant Waste and Infected Plants

Plant waste is an ideal substrate for fungal (and also animal) pathogens, and should therefore always be promptly and carefully disposed of. Infected plants must be carefully removed from the crop and destroyed to prevent the spread of fungal spores through the air or the spread of HLVd through plant sap.

Irrigation Water

Pathogens can also be easily transmitted by water. Especially in systems where excess irrigation water is collected and reused, the risk of spreading an infection is extremely high. Irrigation water should therefore be tested at regular intervals.

Testing

Which plants should be tested and at what intervals can be found in our testing strategy guide. (Link to the strategy guide)