| Passiflora are prone to a number of viruses. They include Chrysanthemum B carlavirus, Passiflora latent carlavirus, Passiflora ringspot potyvirus, Passionfruit woodiness potyvirus, & Purple granadilla mosaic virus. Some are introduced by biting insects such as greenfly but others, especially in hybrids seem to be in the genes in the same way that 90% of us carry the cold sore virus. Their symptoms include leaf distortions, loss of vigour, poor flowering and poor fruiting. Nutritional deficiencies can look very similar and of course are linked. Some can weaken the plant enough to kill it. See comparison shots of P. x belotii before and after treatment above. Each species and hybrid are vulnerable to particular viruses only. They are of most concern of course to commercial growers. Once an individual plant has a virus it will not get rid of it. Cutting an infected plant back and using the same tools to trim another plant will easily transfer the virus in the sap. Typical damage is as above in P. x belotii. Damage is often most notable at the beginning and end of the growing season. When growing quickly the plants can leave the virus further back in the stem and so cuttings can be taken at the height of the growing season to start a new plant without the virus. This can also be done with tissue culture. Plants do have their own immune system and if virus damage is particularly bad I will feed the plant intensively with fertilizer which seems to help suppress the viruses. Many of my plants, especially the hybrids, have virus problems but I just let them live with them. Some people advise pulling any Passiflora with viruses out and destroying them. For amateur growing that is not necessary. I would have few plants left if I did that. Rarely however a plant will be so poorly that it is best pulled out and then burnt. |
