Chapter 1 Self-test questions

. Which statement below is not related to the increase in the number of plant disease findings over recent decades?

Changes in farming practices.

Pollution.

Climate change.

Increased global trade in plants and trees.

. Which combination of factors are required for a plant disease epidemic?

Suitable host, time, and pathogen.

Suitable pathogen, optimal growth, suitable environment.

Suitable disorder, host, and environment.

Suitable host, pathogen, and environment.

. Why plant scientists consider if plants are growing in a dip or low-lying area when they are investigating the factors linked to an outbreak of disease?

Low-lying areas collect diseases.

Low-lying areas are often water-logged increasing the risk of mould infections such as Phytophthera and Pythium.

Infected plants are often grown in low-lying areas.

It can be harder to clear infected plants from low-lying areas, so infected material gets left behind.

. Which of the following is not classified as plant disease?

Leaf scorch by the sun.

Lichen growing on a tree trunk.

Bacterial root rot.

Powdery mildew growing on leaves.

. What is a biotrophic pathogen?

An organism that feeds on dead cells.

Pectobacterium.

An organism that produces enzymes that break down living host cells enabling the pathogen to stay alive.

An organism that establishes a long term one way feeding relationship with its living host-it does not kill the host organism.

. A suspected pathogen is investigated. Which of the following findings would fully satisfy Koch's postulates?

Causal organism occasionally associated with host, can be isolated pure in culture, re-infects host satisfactorily, re-isolation is a mixed culture.

Causal organism consistently associated with host, can be isolated and grown pure in culture.

Causal organism consistently associated with host, can be isolated as a pure culture, re-infects host satisfactorily, re-isolation identical to original culture.

Disease symptoms consistently reveal a pathogenic organism when molecular tests are performed.

. Which of the following does not adversely impact the economy?

Plants affected by a particular disease/pathogen being eaten as a specialised food product.

Yield reduction as a result of an infection.

Disease outbreak management.

Aesthetic effects of plant disease.

. Which of the following is not a common symptom of plant disease?

Stem or root dieback.

Leaf necrosis.

Stem canker.

Fungal growth on flowers.

. Which one of these factors does not play a major part in the spread of some plant diseases?

Insect vectors.

Contaminated tools and machinery.

Ocean drift.

Plant to plant contact.

. Which of the following is the most important factor required before you apply treatment for a particular plant disease?

Knowledge of the surrounding environment.

Availability of additional healthy plants to replant.

Your boots are clean.

The causal agent has been identified.

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