Lecture 8: Introduction to Fungicides (Second Half)

What 4 forms can fungicides be applied as?

1. Dust

2. Granules

3. Gas

4. Liquid

Fungicide can be applied to _____ either in-furrow at planting, after planting as a soil drench (including through drip irrigation), or as a directed spray around the base of the plant

soil

Fungicides can be applied to _____, ______, __________ _____ and other propagules to kill pathogens on the material or to protect young plants from pathogens in the soil

1. seeds

2. bulbs

3. transplant roots

Fungicides can be applied to ________ and other aboveground parts of plants by means of a sprayer

foliage

Fungicides can be applied inside of trees via _____ ________

trunk injection

Fungicides are ________ when applied as a vapor-active chemical in the gaseous phase

fumigants

True or false. Some fumigants are also active against nematodes, insects, and weed seeds

True

Fungicides can be applied to harvested produce as a ___ or _____ in the packing house

dip or spray

Fungicides consist of a _________ product having an active ingredient plus inert ingredients that improve performance

formulated

Fungicides consist of a formualted product having an ______ ingredient plus _____ ingredients that improve performance

1. active

2. inert

nFungicides are typically mixed with _____ then applied by spraying

water

Some fungicides are applied as dusts, smoke, mist, fog, or _______

aerosol

Effective control necessitates ________ _____________ of fungicides, sometimes every 5 - 7 days

multiple applications

Repeated applications of fungicides are needed for what 2 reasons

1. new growth

2. if washed away by rain

What does QoI stand for?

Quinone outside Inhibitor

What does DMI stand for?

DeMethylation Inhibitors

When using fungicides for seed treatments, which kind of fungicide moves into the seed? Contact or systemic?

Systemic. Systemics move into seed, root, and shoot tissues. Contact do not move into the seed.

Fungicide seed treatments can protect seed & seedlings from ____-borne and ____-borne diseases

seed-borne and soil-borne

Fungicide seed treatments are typically at an effective concentration for how many days?

10 - 20 days

Name 3 challenges of fungicide seed treatments (there are 5)

1. Fungicide with appropriate activity may not be available

2. The product may have little or no systemic activity (may not move with the expanding root system)

3. Typically at an effective concentration for 10 - 20 days

4. May be beneficial in some fields but don’t expect consistent advantage

5. Does the product have efficacy against all the important pathogens present?

True or false. Contact fungicides (as seed treatments) control internal pathogens.

False. Contact fungicides (as seed treatments) have no control of internal pathogens.

True or false. Contact fungicides (as seed treatments) only provide protection until the seed coat breaks.

True

True or false. Systemic fungicides (as seed treatments) do not control internal or emergence pests.

False. Systemic fungicides (as seed treatments) do have control of internal and emergence pests

How should you dispose of leftover treated seed?

a. Feed it to your livestock

b. Dump it in a pile & let it compost

c. Mix it in with a load from your bin and take it to the elevator

d. Burn it in a wood or corn-burning stove

e. All of the above

f. None of the above

f. None of the above

You should…

1. follow the instructions on the label and

2. possibly could spread on idle land & disk it in

Fungicides are classified based on their chemical composition. What are the 2 classifications?

1. Organic

2. Inorganic

What 2 elements do organic fungicides contain?

Carbon & Hydrogen

What is the main difference between Organic and Inorganic fungicides?

Organic contain Carbon & Hydrogen. Inorganic do not.

Many of the first fungicides were organic or inorganic?

Inorganic, with sulfur or metal ions (copper, tin, cadmium, and mercury)

True or false. Copper and sulfur are still widely used.

True

Most fungicides used today are organic or inorganic?

Organic

Which element is the oldest effective fungicide known and still used extensively today?

a. Copper

b. Mercury

c. Carbon

d. Tin

e. Sulfur

f. Cadmium

g. Hydrogen

e. Sulfur

What are the 3 physical formulations of sulfur fungicides?

1. Finely ground dust (easiest to apply)

2. Flotation or colloidal (wet paste)

3. Wettable sulfur (dissolve in water and spray)

Which of the 3 physical formulations of sulfur fungicides is easiest to apply?

a. Finely ground dust

b. Flotation or colloidal (wet paste)

c. Wettable sulfur (dissolve in water and spray)

a. Finely ground dust

True or false. A majority of copper fungicides are insoluble in water.

True

What is the most famous copper fungicide?

“Bordeaux Mixture”

The most famouse copper fungicide, “Bordeaux Mixture”, is named after a grape region in which country?

France

The most famouse copper fungicide, “Bordeaux Mixture”, is a mixture of copper ______ & ____

copper sulfate & lime

The most famouse copper fungicide, “Bordeaux Mixture”, was originally used to scare away “freeloader” picking _____ but had fungicidal properties

grapes

nCopper (Cu²⁺) is _______ in high concentrations so limit amount & solubility to prevent damage to host

phytotoxic

True or false. Copper fungicides provide longer protection than organic fungicides.

True. Copper fungicides are not easily washed from plant surfaces which provides longer protection than organics.

What is the mode of action of copper fungicides?

Protein denaturation

True or false. Many copper fungicides also help to supply copper (an essential micronutrient) to plants

True

Which inorganic elemental fungicide is no longer registered?

Mercury

True or false. Mercury was not very effective as seed treatments, dormant fruit sprays, or turfgrass fungicides.

False. Mercury was highly effective as seed treatments, dormant fruit sprays, and turfgrass fungicides.

Why is mercury no longer registered for fungicide use?

It has high environmental toxicity

What was the first organic (sulfur) fungicide?

Thiram

Most new fungicide developments are organic formulations. List 4 reasons why.

1. Higher activity at lower rates

2. Longer activity duration

3. Safer to crops, animals, and the environment

4. Low phytotoxicity & faster soil degredation

Organic fungicides can be separated iinto 2 main groups. What are they?

1. Nonsystemic (contact)

2. Systemic

Which fungicides remain on the surface and are not translocated or absorbed?

1. Contact

2. Systemic

1. Contact

Because contact fungicides remain on the surface and are not translocated or absorbed, _______ is critical

coverage

identify the type of fungicide.

1. Contact

2. Systemic

1. Contact (protectant, nonsystemic)

True or false. Contact fungicides have no after-infection activity.

True. This is why they are referred to as protectants.

Since contact fungicides have no after-infection activity, they are referred to as _________

protectants

True or false. Contact fungicides must be present before the pathogen infects.

True

True or false. Contact fungicides protect new growth, even after the contact fungicide is applied.

False. Contact fungicides do not protect new plant growth.

True or false. Contact fungicides inhibit spore germination and stop infection.

True

True or false. Contact fungicides often target multiple sites of action in fungi.

True

Is the threat of pathogen resistance for contact fungicides high, medium, or low?

Low

Is Captan a contact or systemic fungicide?

Contact

Which chemical family of contact fungicides includes Captan?

Phthalimides

The chemical family Phthalimides (include Captan) includes protective sprays, dusts for fruits, vegetables, ornamentals, & turf, and corn & soybean ____ treatments

seed

Which chemical family of contact fungicides includes Manconzeb (Mazate®, Dithane®)?

Dithiocrabamates

Dithiocrabamates, the contact fungicides includeing Manconzeb (Mazate®, Dithane®), are used as corn and wheat ____ treatments

seed

What is the mode of action of nonsystemic (contact) fungicides?

Multi-site activity

__________ control bacterial diseases in fruits & vegetables

Antibiotics

__________ is an antibiotic that is used for fireblight of apples & pears

Streptomycin

_________ is an antibiotic that is chemotherapeutic against phytoplasma diseases

Tetracycline

What is the mode of action of antibiotics like streptomycin and tetracycline?

Inhibits protein synthesis

Which type of fungicides are absorbed into the plant tissue?

1. Contact

2. Systemic

2. Systemic

True or false. There are no fully systemic fungicides for field crops.

True

Systemic fungicides provide protection from the inside, but it is eroded via what 2 things?

1. Dilution

2. Deactivation

True or false. Systemic fungicides may offer some after-infection activity but most new tissue is not protected

True

Reapplication of systemic fungicides may be needed after how many days?

12 - 20 days

Is the threat of pathogen resistance for systemci fungicides high, medium, or low?

medium to high

Which has a higher risk of resistance? Contact or systemic fungicides?

Systemic

2 types of systemic fungicides

1. Local

2. Upward

Which type of systemic fungicide is absrobed into the immediate area of application and not translocated far from the uptake site?

Local

Headline® and Trilex® are examples of which type of systmic fungicde? Local or upward?

Local

Which type of systemic fungicide moves only outward and upward (xylem)?

Upward

Allegiance®, Apron XL®, Bumper®, Dynasty®, Folicur®, Protege®, Quadris®, Tilt®, and Topsin-M® are examples of which type of systmic fungicde? Local or upward?

Upward

Identify the type of systemic. Local or upward.

Local

Identify the type of systemic. Local or upward.

Upward

What are the 2 top inorganic elements that are anti-microbial?

1. Copper

2. Sulfur

What is a chemical that kills fungal pathogens directly?

a. Fungicide

b. Fungistatic

c. Anti-sporulant

a. Fungicide

What is a chemical that slows or stops fungal growth, but doesn’t kill it completely?

a. Fungicide

b. Fungistatic

c. Anti-sporulant

b. Fungistatic

What is a chemical that prevents the fungus from producing spores, so it can’t spread as easily—even if it’s still growing?

a. Fungicide

b. Fungistatic

c. Anti-sporulant

c. Anti-sporulant

What is the difference between a fungicide and a fungistatic?

A fungicide kill fungal pathogens.

A fungistatic slows or stops fungal growth without killing the pathogen.

What is a preventative fungicide?

A fungicide that is used before a plant gets infected. It creates a barrier that stops the fungus from getting into the plant in the first place.

What is a curative fungicide?

A fungicide that is used after infection has started but before symptoms are severe. It works by entering the plant and stopping the fungus while it is still spreading.

What is a therapeutic fungicide?

A fungicide that is similar to curative, but it refers more broadly to treating an infection that is already inside the plant. It helps slow or stop the disease after infection has occurred.

Are contact fungicides preventative, therapeutic, and/or curative?

Contact fungicides are only preventative.

Are systemic fungicides preventative, therapeutic, and/or curative?

Systemic fungicides can be all: preventative, therapeutic, and curative.

List 5 modes of action (there are 10)

1. Nucelic acid synthesis inhibitor

2. Mitosis & cell division inhibitor

3. Respiration inhibitor

4. Amino acid & protein synthesis inhibitor

5. Disrupts signal transduction

6. Lipid & membrane synthesis inhibitor

7. Sterol biosynthesis inhibitor in membranes

8. Cell wall biosynthesis inhibitor

9. Melanin synthesis inhibitor in cell walls

10. Host plant defense induction

What is the most important fungicide group?

Triazoles (these are systemic)

Triazoles are broad-spectrum systemic fungicides with both ________ and _______ activity

preventative and curative

2 examples of Triazoles fungicides

1. Tebuconazole (Folicur®)

2. Propiconazole (Tilt®)

4 things / areas / crops that Trizoles (systemic) are used on

1. Field crops

2. Fruit trees

3. Vegetables

4. Turf

Triazoles mode of action

DMI (Demethylation Inhibitor) which inhibits C14-demethylase needed in sterol production (membrane structure and function, essential for cell wall development)

Methoxy-acrylate is a …

chemical family of systemic fungicides

Carbamate is a…

chemical family of systemic fungicides