A horticulturist notices that several of their prize rose bushes have developed dark purple or black spots on their leaves, which are turning yellow and dropping off prematurely. This indicates an infection of rose black spot (a fungal disease). They decide to prune and remove the infected leaves and stems.
State one practical precaution the horticulturist should take during or after this process to prevent the fungal spores from spreading to the healthy rose bushes in the garden.
