Known for their colorful, vibrant foliage, prayer plants (Maranta leuconeura) are popular tropical houseplants that offer a host of uses and benefits. Their famous leaves curl up at night, resembling a pair of praying hands, before unfurling in the morning. Unfortunately, these beautiful houseplants can become afflicted by various pests and diseases. In this article, we’ll explain how to identify and tackle 11 common prayer plant diseases and pests.
Common Prayer Plant Diseases and Pests – The Essentials
Prayer plants are vulnerable to diseases like botrytis blight and powdery mildew, especially when grown outdoors. As houseplants, prayer plants can suffer from root rot or pests like fungus gnats or thrips. Use horticultural oils, insecticidal soap, and fungicides to tackle these diseases and pests.
Common Prayer Plant Diseases and Pests and How to Identify:
1. Botrytis Blight
Botrytis blight is a debilitating fungal disease that can attack prayer plants. It’s caused by the Botrytis cinerea fungus and thrives in wet, humid conditions. Botrytis blight is also known as gray mold after the growths that appear on infected leaves.
If your prayer plant has botrytis blight, you’ll need to dispose of it. Clear any surrounding leaf debris which may still harbor the fungus and treat the soil with organic fungicides.
2. Helminthosporium Leaf Spot
Helminthosporium leaf spot is another fungal disease to be aware of. This leaf spot disease thrives in waterlogged soil and causes yellow or tan spots on infected leaves. It can also cause brown or purple lesions on the stems.
Get rid of the waterlogged soil around the plant and use neem oil or fungicides to destroy the infection. Replant your prayer plant in fresh, well-draining soil and water at the base of the stems.
3. Powdery Mildew
Powdery mildew is no stranger to many gardeners. This fungal disease loves waterlogged soils and hot, dry conditions during the day and cold, wet conditions at night. Symptoms include tell-tale white growths on the leaves and stunted or misshapen growth.
Water your prayer plants at the base during the morning. This prevents your plant from sitting in water when it’s cold at night. Remove affected foliage and apply neem oil or fungicides if necessary.
4. Root Rot
Overwatering is a common problem for prayer plants and often leads to root rot. If your prayer plant sits in waterlogged soil, the roots will start to rot. Other symptoms include drooping leaves and yellowing foliage.
Replace any waterlogged soil around the plant and trim off any brown, mushy, or smelly roots. Repot the prayer plant in fresh, well-draining soil and only water if the top 2 inches of soil are dry.
5. Southern Blight
Southern blight is a fungal disease caused by the Athelia rolfsii fungus, which infects the soil around prayer plants. Symptoms include discolored or wilting leaves and white lines of mycelia on the stems. This fungus thrives in warm, wet environments such as waterlogged soil.
Tackling Southern blight requires drastic measures. Dispose of the infected soil and replant your prayer plant into fresh, well-draining soil.
6. Aphids
Aphids are common garden pests that can suck the sap from prayer plants. They form colonies of small green or black insects that gather along stems or underneath leaves. Symptoms of an aphid infestation include black mold, distorted leaves, and stunted growth.
You can remove aphids by spraying your prayer plant with a hose. Horticultural oils, insecticidal soap, and pesticides can also treat aphid infestations.
7. Fungus Gnats
Fungus gnats are annoying pests that will lay their eggs in saturated soils. One adult female can lay up to 150 eggs in one week before dying. Once the larvae hatch, they will consume the roots of your prayer plant, causing severe damage.
Replace the top 2 or 3 inches of soil to remove eggs and larvae. Use sticky traps or bottle caps filled with almond oil to dispatch the adults.
8. Mealybugs
Mealybugs are scale insects that can infest prayer plants and consume plant cells. You can spot these insects moving on your plant as tiny white blobs. Other symptoms of a mealybug infestation include sticky white deposits of honeydew that can turn into black sooty mold.
Tackle mealybugs using horticultural oils or insecticidal soap. While most infestations can be dealt with, you may have to discard the plant if the infestation gets out of control.
9. Spider Mites
Spider mites are a group of common houseplant pests closely related to arachnids. These mites often leave webbing around leaves, and you can see them moving across the leaves. Other symptoms include brown or yellow speckles on the foliage.
Use horticultural oils or insecticidal soap to get rid of spider mites. Alternatively, biological control measures such as nematodes or predatory mites can be used.
10. Thrips
Thrips are another type of sap-sucking insect that can prey on prayer plants. These are small, slender black or brown flies. Symptoms include silver stippling on the leaves, stunted growth, and dropping leaves.
Use sticky traps to get rid of adult thrips to stop them from laying fresh eggs. Quarantine infected plants until the infestation is dealt with. Use horticultural oils or insecticidal soap to treat the leaves and destroy any eggs.
11. Whiteflies
Whiteflies are extremely annoying sap-sucking insects that can infest plants in large numbers. When disturbed, a cloud of these tiny white insects may buzz around the plant. Whiteflies leave behind sticky deposits of honeydew that can turn into black, sooty mold.
Get rid of whiteflies by spraying infected plants with a hose. Alternatively, you can use biological controls, horticultural oils, and insecticidal soap to kill them.
Pesticide and Insecticide Options and Solutions
Horticultural Oils
Horticultural oils like canola or neem oil are some of the easiest ways to control prayer plant pests. These should be readily available in grocery stores or garden centers. They work by interrupting the breeding cycles of pests like aphids or whiteflies.
Insecticidal Soap
Insecticidal soaps are an extremely effective way to eliminate pests like aphids, thrips, or whiteflies. When wiped over leaves, insecticidal soap dries out or suffocates active pests. If you can’t find insecticidal soap, make a substitute solution by mixing warm water with some dish soap.
Biological Controls
Biological controls are predatory organisms such as mites or nematodes that prey on specific pests. These controls are extremely effective against pests like fungus gnats or aphids. Always choose the correct biological control measure associated with the pest attacking your prayer plant.
Fungicides and Pesticides
If your prayer plant suffers from a fungal infection, a fungicide is probably the best treatment. Meanwhile, pesticides can be used to destroy large pest infestations. Remember that many synthetic fungicides or pesticides contain chemicals that can kill beneficial bacteria. Use fungicides and pesticides carefully and sparingly.
Sticky Traps
Sticky traps are an easy way to curb populations of pests like fungus gnats or thrips. These traps catch adult pests, which prevents them from laying more eggs. Once the adults have been thinned out, the infestation should stop.
Managing Diseases and Pests
You can protect your prayer plants from diseases and pests by providing the proper care and environmental conditions. You can even grow prayer plants outside in USDA Zones 11 and 12.
Prayer plants need plenty of bright, indirect, or filtered light indoors and partial shade outdoors. East or southeast-facing windows provide the best light conditions. If left in low-light environments, prayer plants may lose their gorgeous colors.
Water prayer plants whenever the top 2 inches of soil feel dry or approximately once per week. Always water at the base of the stems in the morning. This helps you avoid getting water on the foliage, which can lead to fungal diseases.
Position prayer plants in warm, humid areas with temperatures ranging from 60 to 80ºF (15.5 to 26.5ºC). Maintain humidity levels between 50 and 60% using humidifiers or pebble trays.
Prayer plants need well-draining soils that can also hold some moisture. The soil should also be slightly acidic. Fertilize prayer plants once a month during spring and summer. Repot prayer plants every 2 to 3 years with fresh soil.
Wrapping Up
Prayer plants are attractive, active houseplants that can sadly fall victim to various diseases and pests. These include botrytis blight, powdery mildew, root rot, aphids, fungus gnats, or thrips. Use good care practices to prevent pests. If problems do arise, use horticultural oils, insecticidal soap, or fungicides to tackle them.
Andrew is the Editorial Director at Petal Republic. He holds a BSc degree in Plant Sciences and has trained professionally at leading floristry schools in London and Paris. In amongst overseeing a global editorial team, Andrew's a passionate content creator around all things flowers, floral design, gardening, and houseplants.
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