Why are the leaves on my morning glory plants curling then going brown?

Question

i have fed them and slug pelleted and sprayed with bug gun?

Answer 1

  as the season are changing very fast nowdays ,

i think you will find , that autumn has begun,

look at the other trees around your area,

they change every day .  

Answer 2

When leaves curl and go brown it sounds like a greater amount of water loss from their leaves than can be transported via the roots.  If you're having really dry weather this could contrast with previously wet weather where roots haven't needed to transport as much water as during hot dry weather.

I would ensure that they are well watered regularly,  and potentially [partially shaded for a part of the day, as this will lower the stress on your morning glory plants, whilst root systems develop to be able to transport more water upwards.

Give your plants a general feed too, as this will contain Phosphorous, the nutrient required for root growth, alongside the other nutrients needed for green growth (Nitrogen) and flowering (Potassium).  

If you need to spray your plants at any time, do this during early evening, when the sun is not so scorching, as water on leaves during intense light can stress plants, and burn them too.

Hope this helps.  Good luck!  Rob