Stanhopea Leaf Spots: Sunburn vs. Fungal Infection

Diagnosing Brown Spots on Stanhopea Orchids in Hot Climates

In New Orleans greenhouse conditions with fans and water systems, Stanhopea brown spots are rarely from excess sun. Here's how to differentiate causes:

Sun Damage (Unlikely for Small Spots)

• Large, irregular bleached/brown areas
• Leaves become yellowish-green overall
• Occurs on highest, most exposed leaves

Fungal/Bacterial Spots (Most Likely)

• Small, discrete brown/black lesions
• Often with yellow halos
• Scattered distribution
• Usually cosmetic unless spreading

Critical Cultural Factors

1. 24/7 fan operation—constant air movement prevents spore germination
2. Basket/mesh pot culture—essential for Stanhopea's pendant spikes and root aeration
3. Morning-only watering—foliage dry by nightfall
4. Humidity 60-80% with excellent circulation

Management

• If spots stable: cosmetic only, no treatment needed
• If spreading: copper fungicide, improve air movement
• Remove severely affected leaves
• Ensure pendant spikes have clearance—no leaf contact

Photo Submission

Upload to photo-sharing site (Flickr, Imgur, Google Photos) and share link for specific diagnosis.