Question
Hi
 I am try to grow a patio lemon tree for the first time it is in my greenhouse the  leaves going yellowish and seem to have sections bit out of them can you help me please
     thanks Adrian

Answer
It sounds like you have a bug on your tree. Without seeing it, I would be guessing to try to tell what it is. Do a close exam of the tree to see if you can see the pest. This is best done at night. It could be a slug or snail. It could be an earwig or caterpillar. But the best time to see them eating is at night. They hide during the daylight. I caution that on fruiting trees, you will want to be careful how you treat the problem. Don't poison your fruit, by putting a toxic bug killer on it. Read the label.