Leaves curling

The top leaves on this plant are starting to curl or cup. Does anyone know why? I don't see the dreaded webs. Tks in advance.

"Leaves curl for a number of reasons" I found this on a website, but no specifics were mentioned.

I found a site, http://hortchat.com/info/brugmansia (Down toward the bottom that says 'cold' will cause leaves to curl.) Some mites are so small you need a 10X magnifying glass to see. Check the underside of the leaves. If the leaves continue to curl and new growth is distorted, it may be broadmites. There are other sucking pests that cause the leaves to curl. If you can't find any evidence of pests, consider other causes, such as the aforementioned cold, or perhaps a nutrient problem.

I'm still learning about problems that Brugs can fall prey to, but nutrient problems can also cause the leaves to curl. Tonny is the expert on those problems.

Thanks bettydee.

There an easy ay to check for mites.

Get you a plain sheet of white paper or a white index card. Place it under the leaves and tap the top of leaves. If you have mites, you will see against the stake white paper little red or black dots. If you foind em then treat with a miticide.