How to Treat Plant Disease and Damage

Broken Stem– This is a fairly common result of a plant being banged into, knocked over or having something heavy accidently placed on it. If it wasn’t a clean break and the two parts of the stem are still at all attached, it can often be saved. Carefully put the two broken edges together and tie with raffia or any soft, non binding material, then fasten it to a wooden dowel or other support to keep it upright. Don’t fertilize. In many cases the stem will heal itself. If this doesn’t happen or it was a complete break, root the broken piece and either return to the pot or pot it up by itself for a whole new plant.

Heat/Cold Damage: Most plants are very sensitive to extremes in temperature. Some, like poinsettias, will simply drop all their leaves while others will simply look unhappy. Signs of heat damage are easy to spot: dry, brown, crispy leaves or leaves with pale yellow or brown spots. This most often happens in the summer when a houseplant is left in the hot sun with no protection, and in the winter when it is placed near a heater or radiator. The cure is to move the plant away from the heat source, water well if the soil has dried out, and trim away the damaged leaves. As long as there are still some healthy ones left, the plant will recover.

Cold damage shows itself in a variety of ways. For example Geranium leaves will turn red when exposed to extreme cold. Other plants will usually turn black or brown. The most common cause of this is plants left on a cold windowsill at night with the curtains closed. If the conditions are damp as well as cold, mold often sets in (see below). The treatment is the same as heat damage, unless mold sets in. Remove from the source of the cold and trim away the damage.

Pet Damage: Curious pets can be a plant’s worst enemy. Bite marks and torn leaves can’t be fixed. It’s best to simply remove them. Plants that have been dug up can usually be replanted without any problems. Check for damaged roots first and carefully snip them off. To prevent in the future, move them out of reach.

Disease: There are several diseases that affect houseplants. Here’s a look at the most common and how to treat them.

Botrytis-Also known as Gray Mold, this fungus can be found on all parts of the plant. Begonias, African Violets and Cyclamens are particularly vulnerable to this disorder. Treatment consists of cutting away the affected parts and increasing air circulation. Remove any mold found on the soil, and spray the plant with a fungicide. Commercial versions can be found in any garden center, or make a homemade version by filling a spray bottle with water, a tablespoon of baking soda, and a teaspoon of vegetable oil.

Black Leg–This disorder affects stem cuttings and is caused by a fungus called Botrytis. The fungus invades the cutting and turns the base black. Affected cuttings should be discarded. To prevent, make sure the soil drains well and avoid over watering. Geranium cuttings are particularly prone to getting Black Leg.

Powdery Mildew-This disorder is found on the leaves of affected plants. It appears as a white powder on the leaves. Unlike Gray Mold, Powdery Mildew will not kill affected plants, but it will make them weak. To treat, removed badly mildewed leaves and spray the plant with a fungicide. To prevent, make sure plants have plenty of air circulation.

Leaf Spot– This disease is most often found on Dracaenas and Dieffenbachias. It is characterized by moist brown spots that appear on the leaves. In severe cases, the spots merge and kill the entire leaf. Leaf Spot is caused by a combination of bacteria and fungi. The best treatment is to remove affected leaves, spray with a fungicide, and water sparingly for a few weeks.

Oedema-This disorder is also known as Corky Scab. It isn’t caused by bacteria or fungi, but by the conditions the plant is in. It’s characterized by hard cork-like growths on the underside of leaves. This is a reaction to being kept in low light and overwatered soil. Affected leaves should be removed and the plant should be moved to better light and watered less.

Damping Off-This is a rather common disorder affecting seedlings. A fungus attacks them at the base, causing the stem to rot and the seedling to fall over. To prevent, make sure seedlings are in sterile soil, not over watered, and given good air circulation.

Root Rot-This occurs when plants are overwatered and the roots are deprived of oxygen. The roots literally rot away. The first signs are yellowing leaves and wilting. Eventually, the entire plant collapses. If caught early the plant can be saved. Treatment consists of removing the plant from its pot, removing the soil from the roots, and cutting away any roots that appear mushy and black. The plant can then be replanted in fresh, well-drainied soil. To prevent, don’t overwater.

Viruses- There is no single symptom of viral infection. There may be stunted growth, deformed leaves and flower buds, and white streaks across flowers. Leaves will have pale green or yellow patches. Plant viruses are usually transmitted by insects or were already present when the plant was bought. Unfortunately, there is no cure. If a plant is showing signs of viral infection, throw it out. If the pot is kept be sure to disinfect it thoroughly in a mixture of hot soapy water and bleach.

Fortunately most plant diseases are relatively easy to treat. Better yet, they can be prevented entirely by providing plants with ideal growing conditions. If signs of disease are found, act fast and follow the tips above and there is an excellent chance it can be saved!