Keep your plants from falling ill by recognizing the signs early and taking precautions.
Plant disease will appear in nearly every garden at some point or another. Some are minor and can be avoided or kept at bay by giving your plants proper care and choosing resistant varieties. Some, however, will cause devastation regardless of efforts. That’s why it is important to know the kind of diseases you may encounter in order to decide on how to react. Below is an overview of the most popular plant illnesses you will encounter, accompanied by tips on how to prevent and treat them.
What Triggers Plant Diseases?
Bacteria, viruses, and fungi are responsible for most plant diseases that infect a stressed host, typically a stressed plant. There are some environmental factors such as wet, hot, or cloudy weather that may cause or exacerbate outbreaks.
Bacteria are tiny, single-celled microorganisms that survive on organic matter and typically require a living plant host. They gain access to plants through wounds or are carried by insects, hands, or water. Fungi live on or inside plants and have a propensity to cause visible symptoms. Viruses, the smallest and most difficult to manage, are typically spread by insects but may be carried by infested seeds or infected tools.
1. Leaf Spots
Leaf spots are a global sign of plant disease and can be caused by fungi, bacteria, or viruses. Other symptoms can include wilting, curled or torn leaves, distorted flowers or fruits, yellow or other-colored leaves, and growth inhibition. Black spot, a common fungal variety infecting roses, causes dark spots and premature leaf drop.
These diseases thrive in wet conditions. Improve air circulation to help foliage dry faster and water at the base rather than overhead. Using drip irrigation or a watering wand helps keep leaves dry and disease-free.
2. Mosaic Virus
Mosaic virus-infected plants are mottled green or yellow on leaves, with distortion as cupping or curling. Peonies are particularly vulnerable. Mosaic virus is not curable—destroy plants as quickly as possible to stop further infection, and do not replant in the same spot.
3. Powdery Mildew
This kind of fungal infection appears as a white powdery dust on stems and leaves. It flourishes in hot, dry climates with high humidity and affects plants like lilacs, squash, and zinnias. Prevent it from occurring by planting disease-free plants and keeping your plants well spaced to allow air circulation. Spacing helps to prevent mildew because it reduces moisture buildup.
4. Rose Rosette Disease
Innocently introduced by a small mite, this incurable virus infects rose bushes. Only treatment is to uproot and burn infected plants. Warning signs include thickened, reddish stems, excessive thorn production, and bushy or curled new growth. Destroy infected roses immediately to prevent spread.
5. Rust
Rust is a plant disease caused by fungus, and it looks like orange, golden, or reddish-brown blisters on leaves. There is a specific plant that each rust species infects—cedar-apple rust, for example, needs an apple and a cedar host in which to complete its life cycle. Unpleasant though it may be, rust will not cause much long-term damage if the rest of the plant is healthy. Plants can heal themselves with proper care.
How to Prevent Plant Diseases
The most effective protection of your plants is to prevent diseases from occurring in the first place. Good prevention methods involve:
• Planting disease-resistant varieties.
• Giving plants a good amount of space so air can circulate and dry out leaves quicker.
• Giving correct care (adequate sun light, regular watering, and balanced nourishment).
• Spraying on a preventative on healthy plants at home: 1 tsp of baking soda and 1 tsp of horticultural oil combined in 1 quart of water.
• Killing any infected plant parts or entire plants upon first display of symptoms.
• Not composting ill plant matter, since home compost heaps are rarely hot enough to kill diseases.
Get Rid of Pests from Your Plants
Some plants are very vulnerable to insects. Tomato hornworms, for example, will make short work of stripping a plant bare. Aphids are more likely to be where soil is poor or plants are dense—ladybugs can be controlled naturally to hold them in check. Ants on citrus trees won’t damage anything directly, but they will tend to protect other insects like scale; eliminating them keeps more unwanted pests at bay. Insects are found in every garden—knowing which ones are beneficial and which ones are detrimental is the secret to a healthy landscape.
