Defend Your Plants From Destructive Diseases

Let’s talk prevention. It may not be the most exciting topic. But it’s an important one, especially when it comes to plant diseases—which are notoriously hard to treat post-infection. Plus, plant diseases can quickly decimate crops and are easily spread by wind, water, insects and even you (if you’re not careful).

That said, the risk of plant disease is relatively low. For it to take hold in your garden, there must be a susceptible plant, a pathogen and the right environmental factors. (Your goal should be ensuring those 3 variables don’t align.) Risk is lower still with Tower Garden—compared to traditional soil gardening methods—for 2 primary reasons:

But infection still is possible. Which is why smart gardeners take the following preventative measures.

6 Steps of Preventing Plant Diseases

Follow these steps to minimize the risk of plant diseases in your Tower Garden:

  1. Grow disease-resistant/tolerant plants. Reference plant descriptions on seed packets, in catalogs or on websites to determine resistance.
  2. Match your plants to your growing conditions. Stressed plants are more prone to infection. For example, sun-loving zucchini will be more susceptible for mildew in the shade, and basil may develop leaf spot in cool, damp weather.
  3. Avoid a wet environment and prune often to improve air circulation. Most plant diseases thrive in moist environments with poor air circulation.
  4. Control garden pests. Aphids, cucumber beetles, leafhoppers and other bad bugs are often responsible for transmitting diseases.
  5. Keep a clean growing environment. Remove dead plant debris, and use sanitized tools.
  6. Destroy diseased plant material. To keep diseases from spreading, do this as soon as you see signs of infection! If a plant has become too diseased despite control efforts, replace it with a new plant.

3 Types of Plant Diseases

Many plant diseases exist, but those that you may encounter in your Tower Garden fall into 3 general categories: bacterial, fungal and viral. Here’s a quick look at each type.

Bacterial Diseases

Fast-spreading bacterial diseases are difficult to control. Bacteria are too small to see without a microscope, but symptoms of infection typically include dark streaks on plant foliage. Prevent bacterial diseases from spreading by removing and destroying infected plants upon detection.

Common bacterial plant diseases include

Bacterial Blight
Bacterial blight infections occur in warm weather on plants previously injured through insect feeding or other damage. Symptoms appear as water-soaked lesions on the underside of the leaves, which dry and become brown and brittle. A yellow border usually develops around the dead tissue.

Bacterial Leaf Spot
Best identified by black spots or lesions on the leaves of basil, peppers, tomatoes and other plants, bacterial leaf spots thrive in wet, humid conditions and spread through splashing water such as rainfall.

Bacterial Wilt
A serious disease of young cucumber plants, bacterial wilt is transmitted by one of the crop’s major pests: the cucumber beetle. Symptoms include wilting leaves and eventual plant death.


Fungal Diseases

The most common plant disease type indoor gardeners may encounter, parasitic fungi often presents as discoloration, dots or fuzzy mold-like growth on plants. Prevention is the easiest, most effective solution. So prune your plants frequently to discourage the stuffy, moist conditions under which fungi rapidly grows and spreads.

If you discover a fungal disease, immediately remove any leaves or plants that show symptoms of infection, and consider treating the remaining plants with natural sprays (e.g., neem oil, potassium bicarbonate, liquid copper).

Here are a few fungal diseases to periodically check for:

A major disease of beans, cucumbers, melons and tomatoes, anthracnose results in stunted plant growth, reduced yields and plant death. Symptoms include dark spots on stems, leaves and fruit.

Blight attacks the plant leaves, stems and fruit of eggplant, peppers and tomatoes. Early blight appears as dark brown, leathery lesions with faint, concentric rings, resembling a target. Late blight lesions have a brown, dead center, surrounded by tissue that appears water-soaked, gray-green or yellowed. Symptoms typically show on lower, older plant leaves first.

A gray-brown fuzzy mold, botrytis usually first appears on dead or dying plant debris, often in cooler environments.

Downy Mildew
Attacking a variety of plants, downy mildew looks like fine white cotton or frosting that darkens over time. It tends to infect lower plant leaves first, spreading rapidly and killing plants during cool conditions.

Wilted leaves, stunted growth and vertical brown stripes on plant stems are the signature of fusarium. This fungal wilt often appears late in the growing season, affecting older leaves first before progressing to younger leaves and resulting in plant death. In some cases, only part of infected plants demonstrates symptoms.

Leaf Spot
There are a few common types of leaf spot fungi, including cercospora leaf spot and septoria leaf spot. But symptoms are generally the same. First, small halo-like spots appear on plant leaves (usually starting with the lower, older leaves). Then, as the disease progresses, spots enlarge, ultimately resulting in small holes before leaves turn brown and die. Leaf spot can attack at any stage of plant development.

Powdery Mildew
One of the most widespread and recognizable fungal diseases, powdery mildew forms a white-gray powdery growth, usually on the upper surfaces of leaves. Warm days and cool nights create an ideal climate for powdery mildew.


Viral Diseases

Like bacteria, plant viruses are too small to see with the naked eye. But they often reveal themselves with stunted and deformed plant growth. Insect pests, such as aphids and leafhoppers, commonly spread viruses. So the best way to prevent them is to prevent pests (read my tips on beating bad bugs here).

Viruses may differ by growing region (insect vectors can travel only so far!). To find out what viruses are common in your area—and what plants are resistant—check with your local Cooperative Extension Service.



Are you having trouble identifying a plant disease, or do you have any questions about what I’ve covered here? Let me know if the comments, and I’ll try to help!

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