Management of tomato diseases in high tunnels

Daniel S. Egel, extension plant pathologist

SW Purdue Ag Center, Vincennes

812-886-0198 egel@purdue.edu

Botrytis gray mold

Botrytis gray mold

Botrytis gray mold

white mold/timber rot

white mold/timber rot S. Koike

June 3

white mold/timber rot

July 1

white mold/timber rot

white mold

leaf mold

leaf mold

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Dithane F45

Use and Calibration of a Backpack Sprayer

Dan Egel

SW Purdue Ag Center

812-886-0198

egel@purdue.edu

Label information is well adapted to tractor pulled sprayers

Dithane M-45 tomato rate

3 lbs/A

20 acre field

20 acres X 3 lbs/A = 60 lbs Dithane M45

How much water?

20 gallons per acre

20 acre field

20 gallons/A X 20 acre field = 400 gallons of water

Add 60 lbs of Dithane M45 in 40 gallons of water

What about small acreages?

• What type of equipment to use?

• Calibration

Equipment

“Garden” sprayers-advantages:

• Cheap

• Easy to find

• Easy to use

Disadvantages

• Nozzle volume output is variable-spray or stream

• Spray volume varies with pressure/time

• Wand arrangement makes calibration difficult

.cdn.cnn.com

Backpack sprayer-$80

4-gallon tank

3-nozzle boom-$25

PumpGauge

Flat fan nozzle-

• Designed for pesticides

• Constant output

Pressure gauge

allows one to keep

pressure the

constant.

Calibration

3 foot

100

foot5 rows

Example area calibration

5 rows x 100 ft. = 500 linear ft. x 3 feet wide = 1500 sq. ft.

1500 sq. ft./43560 sq. ft./acre = 0.03 acres treated.

How much product is needed

Dithane F45 is labeled for tomatoes-silent on greenhouses

2.4 quarts (32 fl. oz/qt.) per acre x 0.03 acres treated =

0.07 quarts or 2.24 fl. oz.

2.24 fl. oz. in how much water?

Estimate water needed

Total area to be treated =1500 sq. ft.

To estimate how much water we need, we measure-

• 50 ft (150 sq. ft.) = 1/10 area to be treated.

Measure the area to be calibrated.

Fill sprayer with known amount of water-128 fl. oz.

Spray water on calibration area.

Pump regularly

Pressure

gauge

Good volume

Constant pace

Spray both

sides

Measure water left over from calibration spray.

1-Measure area for calibration 2-Add known amount

of water to sprayer

3-Spray out water. 4-Determine how

much water sprayed

In our example, we had 96 fl. oz. left.

128 fl. oz. – 96 fl oz. = 32 fl. oz.

32 fl. oz. x 10 (to equal total area

to be treated= 320 fl. oz.

We mix 2.24 fl. oz. of Dithane F45

in 320 fl. oz. water

Application/calibration tips

1.The person doing the spraying does the calibration

2. If the person or equipment changes, new calibration

3.Foliage should be thoroughly wet, not dripping.

4.Keep speed constant

a. Metronome

b. Music

Penncozeb tomato rate

2 lbs/A X 0.03 acres treated = 0.06 lbs

How to calculate rate for dry

flowable?

How to measure 0.06 lbs?

1 lb = 16 oz

0.06 lb X 16 oz = 0.96 oz

1 liquid oz.

22 grams

Weight of dry oz.=28.3 grams

Use of liquid measurement for dry oz. underestimates Penncozeb by 20%

$14 kitchen scale

allows

measurements

of small weights

Getty images

Botrytis gray mold

Name these tomato problems!

•Late blight

•Blossom end rot

•Anthracnose

Blossom end rot Late blight Anthracnose

Blossom end rot

•Calcium deficiency

Late blight

•Doesn’t overwinter

in the Midwest

Anthracnose

•Survives on

crop residue

Proper diagnosis is critical.

Botrytis gray mold