Prayer Plant with Pythium Root Rot: Prevention & Cure
Maranta leuconeura
Pythium root rot is a serious fungal disease caused by various Pythium species including P. aphanidermatum, P. ultimum, and P. irregulare. These water molds are present in practically all cultivated soils and attack plant roots under wet conditions, causing rapid wet rot that can extend into the stem. The disease is favored by poor drainage, overwatering, and specific temperatures depending on the species.
ð Symptoms
- âĒ Dark brown to black wet rot of roots
- âĒ Roots soften and disintegrate easily
- âĒ Outer cortical tissue pulls off easily exposing vascular strand
- âĒ Brown and dead root tips
- âĒ Stunted growth and undersized plants
- âĒ Wilting during the day with recovery at night
- âĒ Progressive yellowing of leaves
- âĒ Plant collapse and death in severe cases
- âĒ Crown may turn brown-black with soft rot
â Possible Causes
- â Infection by Pythium species (P. aphanidermatum, P. ultimum, P. irregulare)
- â Soil moisture above 70% of available water capacity
- â Poor drainage and waterlogged substrate
- â Overwatering or too frequent irrigation
- â Favorable temperatures (above 77°F for P. aphanidermatum, lower temperatures for other species)
- â Use of non-pasteurized or contaminated substrate
- â Contaminated pots, tools, and surfaces
- â Spread through contaminated irrigation water
- â Transmission by fungus gnats and shore flies
- â Excessive levels of ammonium or soluble salts in substrate
ð Treatment
Quick Fixes
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Organic Treatment
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ðĄïļ Prevention
- â Use well-drained substrate with adequate air pore space
- â Pasteurize or solarize substrate before use (140°F for 30 min)
- â Avoid overwatering and maintain good water management
- â Ensure proper drainage in pots and beds
- â Inspect roots of new plant material before introducing to collection
- â Keep pots, tools, and growing areas clean and disinfected
- â Keep irrigation hose ends elevated off the ground
- â Avoid excessive levels of ammonium and soluble salts in substrate
- â Use substrate with at least 20% composted pine bark
- â Control fungus gnats that can transmit spores
ðą Care Guide: Prayer Plant
ð§ How to Water
Water when the top inch of soil feels dry. Use filtered water or let tap water sit for 24 hours to dissipate chlorine, which causes rust-like spots on leaves. Keep soil moist but never waterlogged.
âïļ Lighting
Place in bright, filtered or indirect light. Avoid direct sunlight which burns the leaves. East or west-facing windows are ideal locations.
ðŠī Ideal Soil
Use a light, well-draining potting mix rich in organic matter. A combination of peat, perlite, and pine bark works well. Soil should retain moisture without becoming waterlogged.