Plant Pathogens
- Plants can be infected with a range of bacterial and viral pathogens; such as the tobacco mosaic virus (TMV) and rose black spot fungus (see Viral Diseases & Fungal Diseases)
- Plants can also be infested with insects such as aphids
- Aphids have long sharp mouthpieces that pierce the surface of the stem and into the phloem so that they can feed on the sugar filled sap
- They can infest a plant in large numbers and remove large quantities of the phloem sap. This can weaken the plant
- Aphids can also act as a vector for the transfer of diseases
- Biological pest control (using ladybirds, a natural predator of the aphid) to feed on them or using chemical pesticides are the best ways to control infestation with aphids