Role of Biotic Factors Inducing Senescence
Besides environmental and endogenous factors, biotic factors also play a role in inducing senescence. For example, due to an attack of mites, insects or even parasitic fungi, the process is hastened. Also, without realising when you walk in a garden and pluck leaves or break branches and twigs, you are also contributing to initiating senescence in those plants. Figure gives a general view of the factors that affect senescence of various plants.
Figure: The role of various physical and chemical factors on the senescence different part of a plant