CPH Plant Diseases and Pathology 3

Question 1

Plant-parasitic nematodes in landscape and nursery settings are best managed by:

Accepted Answer

Using resistant cultivars, soil solarization, and nematicides

Answer

Nematode management relies on an integrated approach combining resistant or tolerant cultivars, soil solarization to kill nematodes with heat, and nematicides where economically justified.

Question 2

Phytoplasmas, which cause diseases like aster yellows in ornamental plants, are transmitted primarily by:

Accepted Answer

Leafhoppers that acquire phytoplasmas from infected hosts and transmit them

Answer

Phytoplasmas are obligate intracellular parasites that reside in phloem tissue and are transmitted in a persistent, propagative manner by phloem-feeding leafhoppers.

Question 3

Mosaic, mottling, and distortion of leaves are most characteristic of which class of plant disease?

Accepted Answer

Viral diseases causing systemic symptom patterns

Answer

Mosaic and mottling patterns result from viruses disrupting chlorophyll production unevenly across leaf tissue, creating a patchwork of green and yellow areas.

Question 4

In plant pathology, the term 'canker' refers to:

Accepted Answer

A localized, dead, sunken or discolored area on a stem, branch, or trunk

Answer

A canker is a defined necrotic lesion on woody tissue — typically sunken, discolored, and sometimes exuding gum or resin — that can girdle and kill affected branches.

Question 5

Botrytis blight (gray mold) caused by Botrytis cinerea is most favored by which environmental conditions?

Accepted Answer

Cool temperatures (60–77°F) and high relative humidity above 90%

Answer

Botrytis cinerea sporulates and infects plant tissue most aggressively at cool to moderate temperatures and very high humidity, which promotes spore germination and mycelial growth.

CPH - Certified Professional Horticulturist Practice Test

CPH - Certified Professional Horticulturist Practice Test

CPH Plant Diseases and Pathology 3