Plant Pathology Section 2 PDF

SECTION 2 By/ Hala Ahmed Demonstrator At Plant Pathology Department ◦ Disease symptoms: They are unwanted changes that appear on the plant as a result of infection with a disease. ◦ Examples of these symptoms: 1. Discoloration: It occurs as a result of a change in the natura...

SECTION 2 By/ Hala Ahmed Demonstrator At Plant Pathology Department ◦ Disease symptoms: They are unwanted changes that appear on the plant as a result of infection with a disease. ◦ Examples of these symptoms: 1. Discoloration: It occurs as a result of a change in the natural green color of the plant disappearing part or All chlorophyll in the affected part or in the whole plant. The disappearance of color in specific spots or in widespread spots may be known as mosaic, or the color may disappear from all the affected part and is known as yellowing. 2. Spotting and perforation of leaves: Death of specific spots of the plant. These spots vary in shape, size and color, then The center of the spots dries up and becomes brittle and easy to crumble, leaving a hole in its place. 3. Blight: It is a quick death for a big part of the paper and the injury may lead to the death of a whole branch including It carries leaves, flowers and fruits and may reach the death of the entire plant. EX/ Late blight in tomatoes and potatoes 4. CanKer: It is the death of the surface layer of the affected part and it cracks and results in a wound that does not heal. 5. Rot: It is the death and decomposition of the affected tissues and often occurs to the water-rich parts or parts of plant that store food. EX/ Black rot in onions 6. Wilting: It means that the plant loses more water than it absorbs, resulting in the empty losing its swelling. It has two types: permanent wilting (pathological) and temporary wilting (disappearing when the effect disappears). EX/ Fusarmic wilt in tomatoes 7. Stunting or Atrophy: The size of the plant decreases (stunting) or the size of the affected part decreases (atrophy) due to the lack of food or water reaching the affected part. 8. Tumors: It occurs as a result of a disorder in the growth regulators within the plant tissues that lead to rapid cell division or an increase in cell size, and both may occur together. EX/ Crown gall in trees 9. Rust: They are pockets filled with the parasite below the skin, so these spots rise, and if the pressure increases on them under the skin of the plant, they explode. EX/ Yellow Rust in wheat 10. Scab: The death of superficial spots on the affected plant part are somewhat high and rough and these spots result from the increase in the growth of the affected tissues and their explosion and transformation into cork tissues. EX/ Ordinary scab in potatoes  Pathological signs: ◦ The presence of the pathogen or one of its structures at or near the site of infection, such as mycelium, spores, Sclerotia, bacterial growths. ◦ Ex/ Powdery mildew in grapes