Plant Diseases: All You Need to Know

August 11, 2022

While plant diseases are a major problem for gardeners that can cause panic, they are also a natural part of plant life and help to keep plants and animals’ kingdoms in a perfect balance. You would be amazed, but actually, plants can protect themselves from numerous threats, including animals, insects, and even pathogens. They are not completely unarmed. Your job, as the plant owner, is to recognize the disease and help the plant deal with it. This is why you have to learn as much as possible about the aspects of plant disease identification.

What Are Plant Diseases?

The disease of the plant is the change in its normal state that can modify or change the plant’s functions. The disease can spread to any species of plants, no matter whether they are cultivated or wild. There are multiple types of plant diseases, but each species has its own range of possible illnesses. Apart from that, you may find that your plant is sick during a specific period of time; for example, it lacks natural sunlight in winter or there’s a pathogen in the pot nearby. Some plants can be resistant to diseases that others can’t tolerate at all.

plant leaves attack chlorosis

There are common plant diseases and rare ones. The plant gets illness right after it contacts the agent. It changes the usual physiological processes inside the flower and can change its general outlook, function, and growth. Based on the agent that provoked the problem, you can identify the disease. They can be separated into two groups:

  • Infectious. These diseases can be caused by a variety of pathogens, like bacteria, fungus, viruses, mycoplasma, parasites, or nematode. The agent can reproduce and spread inside the host quickly;
  • Noninfectious. These illnesses are usually provoked by poor conditions people create for plants, lack of watering, sunshine, and problems with temperatures and moisture. Even soil can contain toxic ingredients inside. Such illnesses are not transportable, but they are equally dangerous.

If you think that once you found one disease in your plant you may relax, you are wrong. Plants can be damaged by numerous agents at the same time. While your flower may be infected by the nearby plant, it can also lack the water or grow in the soil with toxic elements. Acting together these diseases can kill the flora in no time. The combo of two or more agents is called complex. You have to find out everything about the causes of plant diseases before you start to treat anything.

Types of Widespread Diseases

There are plenty of illnesses that can damage your plant. However, the list of the most widespread of them is limited. You may start your research by checking the most obvious problems and whether your plant can suffer from them. Plant disease management may start with learning the reasons for possible problems. Even if your plants are doing well, it is better to check out the plant disease list in advance:

  • Phytophthora. This disease is caused by fungi. The problem is mainly known in the area of the Pacific Northwest. It is also known as the water mold that is spreading at the overwatered roots and saturated soil.
  • Root rot. It is caused by fungi. Overwatering is the reason of one of the most popular indoor plant diseases. The decaying starts spreading among the roots, killing the plant eventually.
  • Powdery mildew. The disease is provoked by fungus. You can easily identify plant disease because of the white coating on the leaves, flowers, and stems. It is caused by the low moisture level of the soil and high humidity of the air;
  • Canker. It can be caused by bacteria or fungi. It is usually seen as an open wound on the plant. This disease can be even spread by rodents;
  • Black spot. It is a fungal illness that is popular among roses. The disease affects lower leaves in the first place. The wet weather can be the cause of the problem;
  • Yellow leaf disease. It is also known as chlorosis, and it is quite popular among houseplant diseases. Due to the damaged root or poor drainage, the green pigment in the leaf called chlorophyll is missing. The lack of care can also lead to the problem;
  • Rust. This is a fungal illness. The disease forms numerous “rusty” spots on stems and leaves, which can later turn black. There are numerous types of rust that can spread among household and garden plants;
  • Brown spots. The disease is caused by Septoria glycines fungus. It is spread in the mid-Atlantic and north-central states, as well as southeast of the US. It is popular among crops and less popular among household plants;
  • Blight. This is a quite common disease caused by fungi, spread through the spores by the wind. It was the cause of the famous potato famine in the 1840s. It is not usual for household plants;
  • Chlorosis. This disease is mainly caused by virus that does not allow chlorophyll to develop. The green tissue of leaves turns yellow or even bleached. The connection between mineral nutrition and plant disease is tight. Properly picked nutrients may prevent disease;
  • Scale plant disease. You may be familiar with names like scale insects that dwell on household plants. These insects feed on the plants, living on the stems, trunks, and leaves. The plant quickly loses leaves and gets sick;
  • Mosaic plant disease. The mosaic virus causes the major problem here. There are two types of viruses: tomato and tobacco mosaic viruses. It is highly popular in the areas with the hot weather;
  • Scab plant disease. Scab is caused by fungi or bacteria. It affects the stems and leaves of plants. Leaves may fall, as a result, leading to a plant’s slow death.. Usually, the problem spreads in the dry alkaline soil.

Disease Identification: How to Do It at Home

The classification of plant diseases you’ve seen above is not full. I’ve listed only those types of illnesses you can frequently meet in the country. Yet, there are numerous other options. You can use the plant disease identifier app and learn everything about your particular case. It is highly important to identify the disease as quickly as possible. Don’t forget that the plant can have several illnesses at the same time.

plant leaves with brown spots

Before you get deeper into integrated plant disease management, let’s learn the most common types of pathogens:

  • Fungal-like and fungi organisms. This is the most popular cause of plants’ disease. Fungi are live organisms that can’t provide food by themselves, grow rapidly, and usually need chlorophyll. Some of them can reproduce by spores, others not. They can easily survive winter in the soil, yet they can be killed by cold temperatures. Fungi prefer to overwinter in some southern areas and then can be transported to the north;
  • Bacteria. These single-celled organisms reproduce by splitting into two parts and are also common reasons for plants’ diseases. They are harder to control. Yet the plant has to be wounded or somehow opened to let the bacteria inside. It can stay in the soil for some time. Some of them can live inside insects;
  • Phytoplasmas. They are small organisms, like bacteria. Unlike bacteria, they don’t have the cell walls and can be filamentous;
  • Viruses. Viruses are particles of nucleic acid inside the cell covered in protein that can interfere with other organisms, infecting them. Once the virus infects the host, it quickly replicates there. Viroids are similar to viruses, except for the protein coat which they don’t have. Both can be transmitted to the plant by fungi, nematodes, or even insects. Your plant may be affected via seeds, pruning, or vegetative propagation;
  • Nematodes. They are tiny animals that look like worms. They usually dwell in soil and can be transmitted to your plant via soil. Sometimes other insects can bring them to the plant;
  • Parasitic plants. I’m not sure whether you will meet such plants in your area, but I believe the knowledge still will be useful. These plants can’t produce food for themselves. While they contain enough chlorophyll for their life, they still need other plants to receive water and nutrients. Usually, they can be met in the wild nature.

Signs of disease

I have already mentioned the most common diseases here. Now, let’s find out how to identify them. If you can’t find signs of disease you witness on your plant, you may be dealing with different illnesses and I recommend using specific apps or contacting professionals about it. Learn signs of disease so you could take it under control:

  • Phytophthora. It is known as water mold. You will notice the problem if you pay close attention to the water. If you can check the root, find out whether it is rotten or not. Above the ground you can notice the yellowing of leaves, necrosis, their fall, and the death of plants;
  • Root rot. There are lots of symptoms above the ground if you can’t check out the root itself. The plant stopped its growth, leaves got pale, branches fall down, and the canopy is thinning. Sometimes the fungus starts to grow from the roots;
  • Powdery mildew. The leaves and stems are covered in white. They may curl inside. The water does not soak well into the ground;
  • Canker. You will notice small spots on the leaves that are grey or brown. It looks like there are small wounds on the leaves. Sometimes the stems are affected as well. The leaves got swollen and cracked. After some time, this disease can kill the foliage and girdle the branches;
  • Black spot. If you notice dark stains on the leaves of your roses, the problem is called black spot. These dark spots have a round shape and usually appear on the upper sides of the leaves. The disease spreads from the lower leaves. Once the problem is there, leaves start to yellow and fall off after some time;
  • Yellow leaf disease. You will notice the signs in no time. Leaves began to turn yellow and fall down after some time. The stem is getting fragile as well;
  • Rust. There are rusty circles on the stems and leaves. You will notice the brownish color that after some time will turn into black. Rust spreads quickly around the plant, and the number of rusty circles increases in a few days;
  • Brown spots. The disease is spreading too quickly. You have to act even quicker once you notice dark brown spots on the lower and upper sides of the leaf. These spots have yellow halos around them. Leaves become brown, and stems are getting darker;
  • Blight. Blight may look different on different plants. The most common signs are the sudden browning or yellowing of the leaf. The spots of dark color appear suddenly and quickly spread around on the leaves, stems, and flowers;
  • Chlorosis. Since chlorosis is a lack of chlorophyll, you will be able to notice the disease. The leaves will lose their color completely. At first, they will become yellow and later pale. After some time, it may look as if the plant was breached;
  • Scale plant disease. You will notice small insects on the stem or at the lower part of the leaves. The leaves will turn yellow with time and fall off. The plant will stop growing as well;
  • Mosaic plant disease. The mosaic virus makes the leaves curl inside. They are getting distorted. The plant stops its growth, while the stem and leaves change the color to yellow;
  • Scab plant disease. Scab disease brings crustaceous lesions on stems and leaves. While you will see in no time the illness on peaches and apples, it is hard to recognize the signs of disease on the household plants. Leaves that are affected by the disease easily drop down.

Canker. You will notice small spots on the leaves that are grey or brown. It looks like there are small wounds on the leaves. Sometimes the stems are affected as well. The leaves got swollen and cracked. After some time, this disease can kill the foliage and girdle the branches

Once you notice the first signs of disease on your plants, you have to dig deeper and find the cause. It is better to be able to prevent disease by watering the plant at the right time and providing enough sun and a level of moisture. If you are too late, and the plant is already ill you have to make sure that you have remedies against disease and you can isolate it from the healthy flowers.

Find Out Your Plant’s Disease

The first thing you have to do is to isolate the plant. After that, you can investigate the cause of the problem. If your plant is changing in its color and shape, you may want to find out the reason before it is too late. Here you will find the most popular diseases that your plant may have. If you did not find it in the article, continue to look online. Make sure you find the problem so you can act. Don’t waste your time.

If you have more comments on diseases and their signs, write them down below. Has your plant been sick recently? Did you find the disease? How did you solve the problem?

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