Brown Curly Spots on a Marantha Plant

Helminthosporium Leaf Spot

• This fungal infection causes small dead spots initially, but these spots eventually merge to become light brown, large and irregular. Dead spots in leaves, when bounded by living tissue can cause distortion and wrinkling. Penn State University cautions against overhead watering as it may spread the pathogen. The university also recommends applying chlorothaonil to protect unaffected foliage.

Tip Burn

• Tip burn, crinkly, curled, brown or scorched looking leaves, actually has a few causes, but the primary cause is over fertilizing, according to the University of Wisconsin. Houseplants do need fertilizer because they don't have natural soil from which to draw nutrients, but too much of a good thing can damage your plant. Look for a fertilizer recommended for your marantas and follow the manufacturer's directions carefully. Fertilizing once every couple of months should be just the right amount.

Pests

• Pest infestations can cause a wide variety of symptoms and brown, curled leaves are among them. Aphids can cause distorted or deformed growth. Severe infestations can cause these distorted leaves to turn brown and die. Spider mites, white flies, thrips and leafminers are all common houseplant pests that can cause leaves to turn white, yellow or brown and die. For small infestations, wiping pests off with an alcohol soaked cotton swab can be effective. A spray bottle filled with 1 tsp. of liquid dishwashing soap to 1/2 gallon of water can also be effective, according to the University of Georgia.

Other Problems

• Incorrect cultural practices can also cause brown leaf margins or spotted and curling. Not watering enough can cause leaves to dry and curl. Keep your maranta plant's soil moist but not soaking. If the leaves begin to droop, you'll know you're watering too much. If you've recently moved you plant outdoors, windburn can cause brown and curled leaves. Also, spots with too much hot, bright light can cause brown sunburned spots. Some chemical insecticides can burn leaves as well so use them with caution.