TRANSMISSION OF PELARGONIUM FLOWER BREAK VIRUS (PFBV) BY RECIRCULATING NUTRIENT SOLUTIONS WITH AND WITHOUT SLOW SAND FILTRATION

In recent years the occurence and infestation levels of Pelargonium Flower Break Virus (PFBV) in geraniums have been increasing.
Nowadays PFBV is the most common viral pathogen of this crop.

Due to the development of new cultivation techniques the conditions for virus infections have changed.
Spread of viral pathogens in recirculating nutrient solutions has already been reported.
One of the questions to be answered is the possibility of a PFBV- transmission via irrigation systems of soilless cultures.
In order to investigate this, PFBV infection trials were carried out with geraniums grown on rockwool cubes in plastic-gullies with drip irrigation.
Plants were inoculated by grafting scions from PFBV-positive geranium shoots.
While no direct root or leaf contact between individual plants occured during the whole experiment, the nutrient supply units of inoculated and healthy plants were connected.
The detection of virus particles in plants and nutrient solutions was carried out by ELISA. The experiment was repeated twice.

The following results were obtained in the second trial:

PFBV spreads easily during the observation period of 15 weeks.
Contamination of the recirculating nutrient solution could be detected two weeks after starting the hydroponic system.
The virus concentration increased continuously reaching a plateau about one month later.
Fluctuations of the virus titer was noticeable until the end of the trial.
Systemic top infection occured after six weeks.
At the end of the experiment 100% of the plants were infected.

In neither of the two experiments were the control units contaminated with PFBV.

To investigate the efficacy of slow sand filtration against PFBV, a small pilot filter device was used.
The filter container consisted of a plastic pipe with a length of 217 cm and an effective filter surface of 279 cm². The filtration rate was 200 1/m²h.

The results of this study show that the virus titer of the filtered nutrient solution was reduced compared with the recirculating solution of the untreated unit.
Infection of geraniums could be retarded by six weeks.
At the end of the observation period the percentage of infected plants had been reduced to about ¼ by slow sand filtration.

IV International Symposium on Soil and Substrate Infestation and Disinfestation

B. Berkelmann, W. Wohanka, G. Krczal

geranium, hydroponic

https://doi.org/10.17660/ActaHortic.1995.382.29