Scouting andFungicides

Jeff Miller

Scouting for Disease

• Can be used to determine when to apply fungicides– When needed instead of “just because”

• Very useful for late blight• Not applicable for some diseases– Rhizoctonia– Pink rot– White mold– Early blight

Principles of ScoutingPages 142-144

1. Examine every field2. Take a directed sample (altered from book)3. Sample across the entire field4. “Take” enough samples5. Keep good records

Fungicides

What is a Fungicide?

Any substance or mixtures of substances intended for preventing, destroying, repelling, or mitigating fungal pests.

Definition adapted from the Environmental Protection Agencywww.epa.gov/pesticides/

Think of Fungicides as Crop Medicines

Fungicides for Use in Potato

• Soil fumigant• Seed treatments• Soil-applied products• Foliar-applied products• Post-harvest applications

Soil Fumigation – Shank Injection

Soil Fumigation – Chemigation

• Chemical injected through water.

• Sensitive to drift by wind.

• Large buffer zones necessary.

Potato Seed Treatment

• Dust, liquid, or both• Dust– Alder, fir bark– 6% MZ– Worker hazard

• Liquid ST– Low volumes (e.g. 4 fl oz/cwt)

Seed Treatment Equipment

Examples from Milestone Equipment catalog.

Dust Liquid

Soil-Applied Fungicides

• Incorporated during row-markout– Broadcast – incorporated– Banded in the row

• In-furrow at planting– Low volume (~5 gpa)– Banded over the seed piece

Foliar Applications

1. Aerial– Airplane– Helicopter

2. Chemigation– Injection in water

3. Ground

Foliar Application Comparisons

Chemigation Aerial

Cost/acre $1.50-2.50 $7.00-9.00

Spray Volume ~ 4500 gallons (0.10-0.15”) 5-10 gallons

Labor (grower) High Very low

Residue in canopy Low* High*

Estimated usage 40-45% 45-50%

Canopy residue is lower with chemigation, but distribution is more uniform.

Post-Harvest Fungicides• After harvest, prior to placement in storage• Few fungicides labeled– Thiabendazole– Phosphorous acid– “Disinfectants”

• During storage• Applied as a volatilized product through plenums– “Disinfectants”– Phosphorous acid

Disinfect vs. Disinfest

Miller Research LLC

Ozone

Pesticide Labels

When used according to the label, pesticides will not cause unreasonable harm to the environment.

The label is the law as to how a product can be used.