Even Dracaena trifasciata, which is known for being beginner-friendly and difficult to kill, can be vulnerable to diseases and pests. As this species tends to be hardy, most gardeners are able to cultivate healthy populations by providing minimal care.
Snake plants typically thrive under neglect, but extended periods of undesirable conditions can compromise their immunity too.
Problems are often caused by extreme conditions or exposure to other infected plants. A common culprit for initial diseases, which can be complicated by secondary infections, is excess moisture. Overwatering is known for weakening snake plants considerably because their root systems are not adapted to waterlogged soil.
When combined with a lack of sun exposure, excessive nutrient levels, and high humidity, too much water can drown the snake plant. It eventually loses its strength to make use of other defenses as a means of survival
A domino effect can occur, leaving your plant at the mercy of multiple diseases. Once you spot any of the symptoms indicated below, you must act quickly.
When it comes to caring for snake plants, the common issues such as yellow leaves, root rot and brown spots need to be addressed.
Root Rot
Rotten roots are perhaps the most common of all snake plant problems. When soil is kept wet or moist for extended periods of time, a variety of potentially harmful soil fungi begins to multiply.
These are normally associated with bacteria and viruses. All of these work in sync to permeate into the root tissues and cause irreversible damage.
Over time, the fungal colonies can work their way into the fleshy upper parts of Sansevieria, causing the foliage to become yellow and to stop growing. Rotten roots can even develop a foul odor. The weakened leaves eventually attract more pests.
If the Sansevieria trifasciata plant is suffering from root rot, uproot the entire plant and remove all infected tissues with gardening shears or a sharp blade. To prevent fungal spread, make sure to disinfect the blade every time you make a cut. If some roots are salvageable, you can repot the plant. If they are fully compromised, you can propagate the remaining healthy leaves via cuttings.
Avoid this problem by ensuring that your Sansevieria trifasciata plant is potted in a porous container with drain holes. Withhold watering through winter and during rainy periods. Water the Sansevieria plant thoroughly only when the soil is fully dry, and place the pot in a well-ventilated area.
Mealybug & Spider Mite Infestations
Mealybugs are small, fleshy insects that appear to have cottony filaments all over their bodies. Their eggs are likewise covered in the same downy material. Spider mites, on the other hand, are much smaller and are more closely related to spiders than insects. Snake plants that are heavily infested with spider mites are covered in delicate silky webs.
Both mealybugs and spider mites feed on the sap of snake plants. Infestations can leave the plant stunted and completely stop leaf growth. The foliage eventually loses its shine and becomes a dull shade of yellow before it is completely sucked dry.
Make sure to separate infected plants to prevent the spread of these pests. Once you spot a few bugs, try to manually remove them. Delaying removal can result in the growth of pest colonies, which may have to be treated with soap solutions, neem oil, or organic pesticide. A forceful spray of water can help dislodge the pests beforehand.
Southern Blight
A snake plant can quickly be killed by southern blight. This fungal disease is caused by Sclerotium rolfsii, a nasty fungus that enters your plant’s tissues and consumes them from within. Over time, infected tissues begin to look blanched and eventually turn brown once they grow soft and soggy. This disease can decimate most plant tissues in as little as 10 days.
Once you begin to perceive signs of southern blight, you must take action. Unlike other pests that can be eliminated with organic treatments, this one will likely require a chemical-based fungicide. One that contains methyl bromide should effectively prevent colonies from spreading further.
When applying fungicide, make sure to follow the instructions on the label and protect your face and hands from exposure. Isolate any snake plants that have been infected by the fungus and dispose of or completely sterilize soil and pots that have come in contact with it. If you must use tools to cut away some of the infected parts, these must be sterilized as well.
Anthracnose Disease
Anthracnose disease is another fungal disorder that can quickly necrotize snake plant tissues. Also referred to as Colletotrichum leaf spot, this disease often appears in the form of brown-red lesions along the length of leaves. Once the disease has progressed, the leaves become distorted and waste away.
This fungus tends to attack the snake plant when ambient conditions are warm and wet. Make sure to isolate any affected snake plants as those in proximity to affected tissues can catch the disease. Rainy weather can stimulate the spread of fungal spores. Fungicides may need to be intermittently applied to the infected tissues to thoroughly eliminate the fungus.
Red Leaf Spot
At the early stages, this complex fungal disorder causes small red spots to appear on the mother-in-law’s tongue plant foliage. Eventually, this disease can often look like burns from a cigar as Helminthosporium pathogens increase in number and affect a larger area.
A fungicide that contains copper or sulfur should help prevent the spread of the disease, though it won’t aid in the recovery of affected tissues. To maintain the appearance of the snake plant, leaves that are covered in lesions should be removed and disposed of properly.
Burned Roots
Highly chlorinated tap water can scorch the roots of mother-in-law’s tongue. This phenomenon is difficult to detect without uprooting the plant. As healthy roots are vital for the production and survival of foliage, the leaves of an affected snake plant can turn yellow or begin to turn brown at their edges.
Prevent this from occurring by using distilled water or filtering out chlorine from tap water. If you are unable to acquire a filter (reverse osmosis), you can also fill a bucket with tap water and let it stand overnight. Known as the evaporation method, this should reduce the chlorine concentration as chlorine can escape as a gas. Another great way to avoid this issue is by using collected rainwater!
References
Stephen Brown, Fact Sheet: Anthracnose Disease of Ornamental Plants: A Pictorial,
http://blogs.ifas.ufl.edu/leeco/2018/02/03/factsheet-anthracnose/
