Continuing the discussion about pruning and basic rules …you should know fungi are one of the several and most common threats to plants.
Remember how mysteriously that plant of yours died even though you did everything by the book regarding taking care of that same plant? Well, overwatering, no matter how little, is a common factor leading to fungi infected plant roots and eventual plant death. But that is for another discussion.
Back to pruning, although many species of fungi have symbiotic relations with plants, thus their existence is beneficial and recommended; many other species of fungi are truly parasitic therefore giving no benefit to their host plants. Interactions between plants and fungi are one of the best studied on plants and fungi are the cause of many plant diseases. It thus important that you be aware that pruning makes a great opportunity to fungi to infect their host plants.
Remember that by cutting a plant part, even a dry branch, you are wounding that plant. Thus, you may create or favour ways through which fungi and other opportunistic agents might enter. As you know, fungi reproduce through spores that are driven by air mostly. However, you can also carry fungal spores on your clothes, your hands, your hair, and eventually the tools that you use to prune your plants. It only takes one single spore to germinate and turn into a serious menace to your plant. To diminish this risk, hygiene is the word you must always have in mind when pruning. Not only for own health, obviously, but most of all for your plants.
Have all your pruning tools always disinfected before you start. Clean them with alcohol or bleach, especially the blades and the all the parts that will contact plant tissue. Let the tools dry from the cleaning and then use them. You would be surprised how many plant diseases and fungi are transmitted this way, by simply using the same tools from plant to plant and not cleaning them after your are done with the task. It may sound silly, but many people are carless in this way when pruning and often complain about the results they are getting. Although, fungi were used as one example of why you should clean your tools, the same principle also applies to other contaminants like rust and dirt that accumulate by using your tools and can seriously affect the cut and exposed plant parts. If you add water or humidity to these, while your pruning and cutting your plants, then you will have the perfect storm, better say nightmare, for your plants in the nearest times. Some plants are more resistant than others and their response to pruning also depends on their own individual status: age; physiological status; and, depending on the species, the time of the year. However, to minimise your part of the risk of infecting your plants when you cut them, get in the habit of cleaning your tools before using them.
One other factor that people forget when pruning is the grow habit of their plants. All branches of a plant have monopodial growth. That is, they exhibited secondary shoots or branches that arise behind the growing apex, tip, and remain subsidiary to it. Often, the apex of the branch will end in flowers that will eventually be fertilised. Whether this happens or not, that branch in particular will no longer growth in length from that tip on and growth resumes in other directions.
When pruning, people often forget about this secondary shoots that most of the time remain as tiny dormant buds on the axils (the junction with the main stem) of leaves or other branches. To ensure that your plant will grow on a particular direction be sure to cut towards the tip after this secondary buds, usually found on nodes. This way although you may have cut a big part of the branch, including the apex, you also have left some secondary buds that will develop after pruning and after the apex has been removed.
People often do not notice this and cut more or less randomly leaving some lengths of branches with no secondary buds remaining. Then surprisingly they notice that that branch in particular not only did not grow but also had eventually died. Well, this kind of “dying” is a natural response of the plant to diminish waist and save resources and ultimately energy.
Special thanks to Dr Pablo Cabrita (Phd. Plant Physiology)