In plants, the main cause of diseases is primarily fungal or fungal-like organisms. However, viruses and bacteria are also reasons for some serious plant diseases in food and feed crops. A few particular nematodes also cause plant disease. Some plant diseases fall into the category of “abiotic” disease. These diseases are non-infectious and get damaged due to air pollution, nutritional deficiencies, or poisonous substances, and grow in undesirable conditions. As of now, we’ll discuss diseases caused by the three main pathogenic organisms: fungus, bacteria, and virus. If you suspect a plant to be a disease, a careful examination of its appearance can give a good idea of the type of pathogen involved.
A symptom of plant disease is physical proof of the pathogen. For instance, fungal fruiting organisms are a sign of disease. When you gaze at a lilac leaf-bearing coarse mildew, you’re actually looking at the fungal organism that’s present (in this case, it’s the Microsphaera alni). Gummosis, which is a bacterial secretion coming out from the cankers, is caused by the bacterial canker of stone fruits. The viscous, liquid secretion is mainly a bacterial composition and is a sign of the disease, although the canker itself is made of plant tissue and is a sign.
A symptom of plant disease is a noticeable result of disease on the plant. Symptoms can range from a prominent alteration in colour, shape, or function of the plant as it reacts to the pathogen. Drooping of the leaf is a usual symptom of verticillium wilt, caused by the fungal plant pathogens Verticillium albo-atrium and V. dahliae. Symptoms of common bacterial diseases include brown, necrotic cuts surrounded by a deep yellow circle at the border or interior of the leaf on bean plants. You are not really looking at the disease pathogen, but rather a symptom that has resulted due to the pathogen.
We list below a few examples of common signs and symptoms of bacterial, fungal, and viral plant diseases:
Fungal disease signs:
Sclerotinia (white mold)
Fungal disease symptoms:
Round dark spots surrounded by lighter tissues on berries (anthracnose)
Death of young seedlings (phytophthora)
Yellowing of leaves
Stripe rust spots on a winter wheat leaf
Bacterial disease signs (difficult to check, but can include):
Bacteria running in water from a cut stem
Bacterial disease symptoms:
Leaf mark with a yellow halo
Sheperd’s crook stem ends on woody plants
Bacterial leaf spot
Deep red kidney bean leaf revealing bacterial leaf spot symptom (brown leaf spot with yellow halo).
Viral disease signs:
None – the viruses themselves are not noticeable
Viral disease symptoms:
Mosaic leaf pattern
Stunted growth in plants
You can see that there are many common symptoms of fungal, bacterial, and viral diseases. Also, when an unknown plant condition is detected, abiotic diseases, herbicide injury, and nematode problems must be considered as possible reasons.
We hope now you have a basic understanding of plant diseases. You will not be apprehensive about starting your own home garden. You can buy cheap plant pots or buy garden pots from numerous online stores.