Plant disease GapFill

Plants, like animals, can also suffer from  injurythirststressdiseasesocial rejectionhunger, which can be a cause of concern for gardeners. This can be as a result of a viral,  bacterialcellularmitochondrialribosomalchromosomalvacuolar or fungal infection, or due to the action of insects.

Tobacco  mosaicmontagecollagepatchworkleachjigsaw virus and rose black spot both cause discoloured leaves, which restricts a plant's ability to  photosynthesisereproducerespiremoveabsorb waterabsorb nutrients. This effect is similar to a condition called  blightmildewchlorosisbotrytiscancerhypomagnesis, which is caused by a deficiency of magnesium ions, meaning the plant is unable to synthesise enough chlorophyll. Similarly, stunted growth may be the result of a  sulfurlithiumnitratecarbonatecalciumpotassium deficiency, or due to small insects called  tickstermitessilverfishaphidsmosquitoesladybirds, which suck the sap from plant stems.

Plants do have some natural defences against pathogens and predators. Physical defences act to prevent microorganisms from entering a plant, such as tough waxy cuticles on  leavespollenflowersbrancheshairsroots and cell walls made of  glycerolstarchlipidfructosecelluloseprotein. Trees have a thick layer of dead cells called  barkrootskintubersblossomfur surrounding their trunk to resist infection. Many plants also display mechanical adaptations such as sharp thorns or drooping leaves to stop animals from eating them, or they may  defendrepelfeedmimickillattack other organisms or objects to confuse animals. One of the best plant defence responses is the use of chemicals. This can include the production of an antibacterial chemical or  ionglucoseamino acidfatlipidpoison which harms organisms, or the use of stinging  seedshairsrunnersfruitsrootspetals to deter herbivores.