Lecture 8: Introduction to Fungicides

Approximately how many fungicidal materials are there?

~150

Most fungicidal protectants are used as “_____________”

protectants

A fungicide is something that controls fungal disease by _________/_______ the causal organism.

inhibiting/killing

First fungicides were _______ & ________ based

sulfur & copper

________ fungicides work if applied prior to infection

Contact

In the 1940s and 50s, ________ and _______ were introduced

Captan® and Maneb®

What kind of fungicides are Captan® and Maneb®? Contact or systemic?

Contact

____ fungicides have improved performance (systemic and therapeutic properties), prone to resistance.

QoI

3 reasons fungicides are used

1. To control a disease during the establishment and development of a crop

2. To increase productivity of a crop and to reduce blemishes

3. To improve the storage life and quality of harvested plants and produce

Some of crops’ greatest losses occur ____-_______

post-harvest

For IPM, fungicides can be a vital part of disease management if: they ________ diseases satisfactorily,

control

For IPM, fungicides can be a vital part of disease management if: _______ practices do not provide adequate disease control

cultural

For IPM, fungicides can be a vital part of disease management if: _______ cultivars are not available or not accepted in the marketplace

resistant

For IPM, fungicides can be a vital part of disease management if: certain high value crops have an extremely low _______ for disease symptoms

tolerance

Fungicides are categorized in several ways based on 5 different characteristics. What are they?

1. Mobility in a plant

2. Role in protection

3. Breadth of activity

4. Mode of action

5. Type of chemical: organic or inorganic

2 types of mobility in a plant

1. Contact

2. Systemic

Contact fungicides are also called “___________”

protectants

What are contact fungicides?

They are protectants that remain on the surface of plants (are a residue)

Many contact fungicides are potentially ________ if absorbed

phytotoxic

Identify the type of fungicide based on mobility in a plant: contact or systemic

Contact

True or false. Contact fungicides have after-infection activity.

False. Contact fungicides have no after-infection activity.

Repeated applications of contact fungicides are needed for what 2 things?

1. New growth

2. Replace material

Systemic fungicides are also called “___________”

penetrants

Describe systemic fungicides

They are penetrants that are arbosrbed into plants

Identify the type of fungicide based on mobility in a plant: contact or systemic

Systemic (local)

Identify the type of fungicide: Some move very short distances from application site such as across a leaf blade from one surface to the other

Systemic

Some systemic fungicides move very _____ distances from application site, such as across a leaf blade from one surface to the other (local systemic).

short

Some systemic fungicides are _______ systemic and can move further than local systemics

weakly

Identify the type of fungicide based on mobility in a plant: contact or systemic

Systemic (weakly)

Most systemics move extensively because they are mobile in _____ tissue.

xylem

Most systemics move extensively because they are mobile in xylem tissue. These are applied to the root zone, absorbed and then move upward through the plant with ________ stream.

transpiration