fungal disease of rose leaves, causes black spots to appear on leaves

yellow > less chlorophyll > less surface area for PS > less growth

Fungicide can be used, and affected areas can be burned/destroyed to stop the spread

Insects, most notably aphids can destroy plants or spread disease as a vector. They have sharp mouthparts that penetrate into the phloem of the plant and steal the sugar-rich phloem sap. Their mouthparts can have pathogens from other plants and spread it to healthy plants. They can be dealt with chemical pesticides or biological pest control (in closed spaces)

areas of decay or rotting (rose black spot, potato blight)

discolouration (chlorosis caused by magnesium deficiency, or mosaic patterns from TMV)

Some diseases can be treated, and treatment must start quickly, and for those that can't be treated, the diseased plants must be removed to stop the spread

Monoclonal antibodies are used in testing kits to identify plant pathogens

Distinctive mosaic pattern of colouration on the leaves as the virus destroys the cells.

yellow > less chlorophyll > less surface area for PS > less growth

smaller flowers, important cause roses are only wanted for nice flowers

no treatment, farmers grow TMV resistant strains of plant, the spread is controlled by good field hygiene and pest control

There are not many bacterial diseases for plants, but there's one that causes crown galls