Plant Diseases and Pathology Flashcards
7 cards from real CPH practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Plant Diseases and Pathology flashcards as text
Powdery mildew on ornamental plants is caused by which type of organism?
Answer: Fungus
Powdery mildew is caused by obligate fungal pathogens in the order Erysiphales, which produce the characteristic white powdery coating on leaf surfaces.
Fire blight, which causes a characteristic 'shepherd's crook' wilting of shoot tips on apple and pear trees, is caused by which pathogen?
Answer: Erwinia amylovora (bacterium)
Fire blight is caused by the bacterium Erwinia amylovora, which infects flowers and young shoots, causing the distinctive scorched, shepherd's-crook symptom.
Dutch elm disease is caused by which type of pathogen, and is primarily spread by which vector?
Answer: Fungus spread by bark beetles
Dutch elm disease is caused by the fungus Ophiostoma ulmi (and O. novo-ulmi) and is spread primarily by native and European elm bark beetles.
Which of the following best describes a 'biotroph' in plant pathology?
Answer: A pathogen that requires living host tissue to complete its life cycle
Biotrophs are pathogens such as powdery mildews and rusts that must obtain nutrients from living host cells and cannot complete their life cycle on dead tissue.
Verticillium wilt causes yellowing and wilting of foliage primarily by:
Answer: Colonizing and blocking the xylem vessels, restricting water flow
Verticillium dahliae colonizes the xylem vessels of host plants, where the fungal mycelium and produced gels physically block water transport, causing wilting.
Which of the following symptoms is most characteristic of iron (Fe) deficiency chlorosis?
Answer: Interveinal yellowing beginning on young upper leaves
Iron deficiency causes interveinal chlorosis on young, upper leaves first because iron is immobile in the plant and cannot be reallocated from older tissue.
The disease triangle concept in plant pathology states that disease development requires:
Answer: A susceptible host, a virulent pathogen, and a favorable environment
The disease triangle model illustrates that plant disease occurs only when a susceptible host, a virulent pathogen, and a favorable environment all overlap simultaneously.