If your orchids are not grown under cover, protecting them from wet weather, you should have a fungicide regiment as their leaves tend to develop fungal spots. You will also have to watch for insects. There are many which will attack orchids. These include thrips, aphids, scale and mealybugs, mites and snails and slugs. It is important to follow label directions on the insecticides and fungicides so you don’t damage the plant. Most growers treat as needed when these pests appear. There are many safe, non toxic sprays you can use as well as the usual chemicals like Malathion.