Which organisms can cause infectious diseases in plants?

Infectious plant diseases are caused by a diverse array of organisms and biological agents, collectively known as pathogens. These agents can be grouped into the following categories:

• Fungi: A major group of plant pathogens responsible for numerous diseases, including rusts, mildews, wilts, and rots.1
• Bacteria: Prokaryotic microorganisms, including mycoplasma-like organisms (MLOs), that cause various blights, cankers, and wilts.123
• Viruses and Viroids: Submicroscopic infectious agents that cause systemic diseases such as mosaics and curly top.12
• Nematodes: Microscopic, wormlike organisms that feed on plant tissues, often weakening the plant and facilitating secondary infections by fungi or bacteria.24
• Parasitic seed plants: Higher plants that derive nutrients from other plants.2
• Funguslike organisms: This includes groups such as Oomycota (e.g., the cause of late blight) and Plasmodiophoromycota (slime molds), which are distinct from true fungi but act as significant plant pathogens.56