Question

N. 'Miranda' leaf   I have been growing a Nepenthes 'Miranda' and recently the middle aged leaves, not the youngest or oldest leaves on the plant, have developed brown dead spots on the leaves that have been increasing in size. My best guess as to the dying leaves is too much sun (In the attached image you can see the vibrantly red leaves), but I have never had this problem before in the five years I have been growing the plant in the same place. Here are some specifics as to the plant and growing conditions.
    The plant is grown on a west facing windowsill that receives (just a guess) around 3-4 hours of direct sunlight a day.
    Since I bought the plant from your nursery in May 2009, the plant has been grown inside on the same windowsill for 9 months of the year and outside for the three summer months, but the problem has developed and I have not put it outside yet.
    The plant was repotted into a mix of peat, orchid bark, perlite and vermiculite about 1 1/2 years ago.
    The plant is watered with filtered water and is flushed every so often.
    The plant is grown in St. Paul, Minnesota.

Answer
Hi James,

If you see these brown spots when you first move your plant outdoors for the summer, it is definitely leaf burn.  It could be, for any number of reasons, the plant is less adapted to the UV light when it first goes outside, so it burns some as it adapts.  If new growth is looking good, and the plant is producing pitchers, it should be fine.  Just cut off any badly damaged leaves.

The other possibility that comes to mind is a particular pest.  These spots look similar to leaf miners.  I've never seen Nepenthes get those before since they are slightly toxic, but take a hand lens and examine the brown patches.  If you have leaf miners, you'll see a little worm in parts of the brown patch.  If that is case, you'll need to treat the plant.  You'll also need to remove any infected leaves.  Be sure and clean up any leaves below the plant outside (tree leaves, etc...) since they can harbor the little nasties.

Let us know if this helps.

Good Growing!

Jeff Dallas
Sarracenia Northwest
http://www.growcarnivorousplants.com