One of my courgette plants has developed a bright yellow powdery coat on the leaves. What is this, and should I get rid of that plant? The neighboring plants seem unaffected so far. It is the only plant that is yellow courgettes. The others are all round green ones. They are in a raised bed, next to some spinach on one side and calo nero on the other. The problem has only occurred in the last couple of days, though the fruits on that plant have not grown very well - some have dropped off when still tiny.
Courgette Plants With Bright Yellow Powdery Coat
Certified GKH Gardening Expert
I have not been able to identify any disease that matches the description 'bright yellow powdery coat'.
Powdery Mildew is the most likely fungus, but would not be yellow.
Is it possible that your leaves have pollen from other plants dropped onto the leaves?
Here are a few links for you.
Treat with Neem Oil as it is both an insecticide and fungicide.