UKPCS Science Life Sciences-Botany- Plant pathogens #111

Plant pathogens

Plant pathogens

Plant pathogen- Fungi

BROWN PATCH – It is a turfgrass disease caused by different species of the Rhizoctonia fungus. Patches of brown and yellow color appear on the lawn in irregular shapes.

CANKER – There are some fungal infections that affect the roots and barks of the plants. One such fungi is canker fungi. It is found on woody trees and is notorious for causing localized damage to the barks of trees.

CLEMATIS WILT – It is caused by a fungus (Phomaclematidina), which makes an entry into the plant body through cuts and wounds created by insects. G

DOWNY MILDEW – This disease is caused by Peronosporaceae which affects a number of plants.  It affects the growth and strength of the plant.

CLUB ROOT – This infection is found in cabbages, turnips, and radishes which is caused by the Plasmodiophorabrassicae fungus. The color of the leaves changes to bluish-green, and the roots if pulled out appear clubbed and are easily broken.

BLACK SPOT – Diplocarponrosae is the fungus that causes the black spot disease on a rose plant. Blackish spots that appear on the leaves gradually spread upwards and weaken the plant. It is mostly observed in humid climate.

YELLOW SPOTS – These spots are caused by Pyrenophoratritici-repentis fungus. Yellow-colored spots develop on the leaves and the stem, and if not taken care it dries up or infects the whole plant.


  1. It sounds obvious, but always select healthy plants in the first place – fungus preys on the weak! Full sun (or grow lights with a ultraviolet (UV) component) is nature’s natural antifungal agent.
  2. If growing indoors, be sure to allow adequate space between plants and plenty of oscillating fans to provide air movement in your grow space.
  3. Maintain a high level of cleanliness in your garden and never keep trash bags full of dead plant material in or near your garden.
  4. Avoid long periods of high humidity. Also, avoid large temperature swings in the garden.
  5. Remove diseased leaves and throw away in garbage, not the compost. Also remove any yellowing or dead leaves hanging on the bottom of the plan


Plant pathogen Bacteria:

Bacterial Leaf Spot

Bacterial leaf spot is easily identified by the infected plant’s foliage symptoms. Plants that are infected with bacterial leaf spot will develop dark-colored, water-soaked spots that are accompanied by encasing yellowing halos. There is no cure for bacterial leaf spot.


However, the potential for bacterial leaf spot can be reduced by keeping the area free of decomposing debris and watering your plants at soil level. Planet Natural explains that the spread of bacterial leaf spot can be controlled with a copper-based fungicidal spray if applied at first signs of infection.

Crown Gall

Crown gall is a root and stem disease that is most commonly found on woody plants. Roses and flowering fruit trees are common victims of crown gall. Crown gall disease is a soil-borne bacterial disease for which there is no cure and the disease can thrive in the soil for several years without a host.


Planting resistant plants is the best protection against crown gall disease.

Fire Blight

Fire blight is a destructive bacterial disease that is especially threatening to rosebushes and pome fruit trees. This disease lies dormant in the plant and in decomposing matter that lies around the plant. The bacterium begins its growing season as your plant enters its growing season. It enters the natural openings of the plant through its twigs and branches and is often transported by insect and honey bee bites.


Fire blight can be controlled by pruning away the diseased and infected areas of the plant. The potential for fire blight infections and repeat infections can be reduced by applying a copper-based fungicidal spread several times throughout the year.


Plant pathogen Virus

The following main diseases caused by virus in plants. The diseases are:

  1. Tobacco Mosaic
  2. Cucumber Mosaic
  3. Yellow Vein Mosaic of Bhindi

Control Measures:

There are no known chemical treatment used under field conditions that eliminate viral infection from plant tissues once it occurs.

However, some important control measures to check the infection are:

  1. Discarding infected plants.
  2. Growing virus free plants.

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Hemant Bhatt

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