don’t let the root rots beat your beets · roots/100 ft. rcrr (0-7) yield rsa seed treatments 98...

Don’t Let the Root Rots Beat your Beets

Ashok K. ChandaAssistant professor/ Extension Sugarbeet PathologistNorthwest Research and Outreach Center, Crookston

Dept. of Plant Pathology, University of Minnesota

@BeetPath

2019 ASCS Growers’ Seminar

[email protected]

63

45

19

3 2

36

3 2 2 2

44

23

9

1

7

0

10

20

30

40

50

60

70

Rhizoctonia Aphanomyces Rhizoctonia +Aphanomyces

Fusarium Chemical

No. of F

ields

Cause of Problem

2016 2017 2018

Summary of Field Samples 2016 ‐ 2018

July 21, 2015

Rhizoctonia + Aphanomyces

Damping-off Rhizoctonia

Crown and Root Rot

Management of Rhizoctonia• Early planting

Management of Rhizoctonia• Early planting• Crop Rotation

– Length of rotation– Weed control– Crop choice

Soybeans

Navy beans


– Crop choice– Length of rotation– Weed control

• Resistant varieties

Rhizoctonia rating scale

Reynolds et al.

Rhizoctonia & Resistant Variety (~3.4)

40

60

80

100

120

140

160

180

200

220

020406080

100120140160180200220

Soil

tem

p. (°

F)

No.

pla

nts/

100

ft. o

f row

Date

0 20 40 60 4"ST 60°F

020406080100120140160180200220

020406080

1001201401601802002205/26 6/2

6/9

6/16

6/23

6/30 7/7

7/14

7/21

7/28 8/4

8/11

8/18

Soil temp. (°F)

No. plants/10

0 ft. o

f row

Date

0 20

40 60

4"ST 60°F

Rhizoctonia & Moderately Resistant Variety (~4.0)

020406080100120140160180200220

020406080

100120140160180200220

Soil

tem

p. (°

F)

No.

pla

nts/

100

ft. o

f row

Date

0 2040 604"ST 60°F

Rhizoctonia & Susceptible Variety (~5.3)

0.0

8.0

16.0

24.0

32.0

40.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

Yield T/A

Root Rot rating

ResistantSuscetible

Rhizoctonia affects Yield

y = -2.0834x + 32.758R² = 0.6515

y = -3.6922x + 35.206R² = 0.8421



• Resistant varieties• At-planting fungicides

– Seed treatment

Seed treatments

• SDHI class of fungicides• Single site of action (Succinate

DeHydrogenase Inhibitor)• Inhibit fungal respiration

Seed treatments• Kabina 14 g (Penthiopyrad, 2014)• Vibrance 1.5 g (Sedaxane, 2016)• Systiva 5 g (Fluxapyroxad, 2017)• Metlock Suite [Metconazole + Rizolex) +

Kabina 7g (Penthiopyrad), 2014)• Since 2017, 100% seed is treated for

Rhizoctonia and treatment depends on the seed companies’ choice

Seed treatments – 2016

0

50

100

150

200

250

0 7 14 21 28 35 42 49

No. plants p

er 100

ft of row

Days after planting

Kabina 14 g

Metlock Suite + Kabina 7 g

Systiva 5 g

Vibrance 1.5 g

Untreated control

Benefits of seed treatments• Sugarbeet seedlings are very susceptible to

Rhizoctonia early on• Genetic resistance is not expressed until 6-

8 leaf stage• Effective protection of seedling (4-5 weeks)• Ease of use -It comes with seed• Safety• No plugged nozzles




– Seed treatment– In-furrow application

In-furrow fungicides – 2016

• Via Drip Tube• Fungicide in 3 gal Water

and add to 3 gal. 10-34-0

In-furrow fungicides – 2016

0

50

100

150

200

250

0 7 14 21 28 35 42 49

No. plants p

er 100

ft of row

Days after planting

Quadris I‐F 10 fl oz

Satori I‐F 10 fl oz

Xanthion I‐F 9 + 1.8 fl oz

Headline I‐F 9 fl oz

Untreated control

In-furrow fungicides• Benefits

– Sanitizing the furrow (seedling + soil)– More effective than seed treatments – longevity

up to 8-10 weeks (Windels, 2010)• Risks

– Phytotoxicity• cool weather, dry conditions and light soils• Mixing with starter fertilizer and other chemicals

– Plugged nozzles

10-34-0 + azoxystrobin

10-34-0 + Fungicides: 0 minutes (shaken and poured in to a jar after sitting for 6 hours after

mixing and application in the field)

10-34-0 + Fungicides: 10 minutes

Seed vs In-furrow fungicides - 2015

TreatmentNo. harv.

Roots/100 ft.

RCRR (0-7) Yield RSA

Seed treatments 98 3.9 20.1 6181In-furrow treatments 127 2.7 25.5 7772

Contrast analysis p-value 0.001 0.006 0.0032 0.0148

14 g Kabina ST

Metlock Suite

Met. Suite + 7 g Kabina

7 g Kabina ST

2 g Vibrance

12 fl oz Headline IF

10 fl oz Quadris IF

10 fl oz Equation IF

10 fl oz Satori IF

NS = not significantly different

Seed Treatments In-furrow

Seed vs In-furrow fungicides - 2018

14 g Kabina ST

Met. Suite + 1 g Vibrance

Met. Suite + 7 g Kabina

5 g Systiva

1.5 g Vibrance

9.5 fl oz Quadris

11.9 fl oz AZteroid

Xanthion (Headline + Integral, 9 + 1.8 fl oz/A)

Elatus 9.5 fl oz (* not registered for sugarbeet)

Treatment No. harv. roots/100 ft

RCRR (0-7)

Yield ton A-1 RSA

Seed treatments 151 0.7 32.8 10440In-furrow treatments 141 0.4 32.2 10528

Contrast analysis P-value 0.01 0.01 0.5 0.5

NS NSSeed Treatments In-furrow

NS = not significantly differen




– Seed treatment– In-furrow application

• Postemergence fungicides

4-inch soil temp daily means

40

50

60

70

80

90

100

1‐May

8‐May

15‐M

ay22

‐May

29‐M

ay5‐Jun

12‐Ju

n19

‐Jun

26‐Ju

n3‐Jul

10‐Ju

l17

‐Jul

24‐Ju

l31

‐Jul

7‐Au

g14

‐Aug

21‐Aug

28‐Aug

4‐Sep

11‐Sep

18‐Sep

25‐Sep

Mea

n 4‐inch soil tem

perature

NWROC Wahpeton Renville

65 F 65 F

Postemergence Application - 2017

4-leaf stageJune 12

8-leaf stageJune 20

Cultivar x postemergence interaction on disease incidence - NWROC

0

5

10

15

20

25

30

Untreated 4-leaf 8-leaf

% R

CR

R in

cide

nce

(No.

of r

oots

with

rot r

atin

g >2

)

Postemergence application ( 7 inch band)

Resistant Susceptible

(4.0) (4.8)

Cultivar x at-planting x postemergence (7 inch band) interaction on disease incidence -

SMBSC

0

10

20

30

40

50

60

70

80

Quadris Systiva Untreated

% RCR

R incide

nce

At‐planting treatment

Resistant cultivar

Untreated 4‐leaf 8‐leaf

0

10

20

30

40

50

60

70

80

Quadris Systiva Untreated

% RCR

R incide

nce

At‐planting treatment

Susceptible cultivar

Untreated 4‐leaf 8‐leaf

(4.0) (4.8)

Postemergence fungicides – 2015Quadris vs Generics

RCRR Yield RSATreatment (0-7) T/ANon-inoculatedNo-fungicide control 3.4 24.3 6263

R. solani-inoculated

Equation @ 14 fl oz/A 1.9 d 31.0 a 8066 a

Quadris @ 14 fl oz/A 2.4 d 29.9 a 7908 a

Satori @ 14 fl oz/A 2.4 d 29.6 a 7790 a

No-fungicide control 5.5 a 14.0 c 3411 cANOVA P-value 0.0001 0.004 0.002LSD (P = 0.05)Z 1.4 8.3 2284

Postemergence fungicides• Benefits

– If you are doing a row cultivation--throwing soil onto crowns

– Late season disease control (rain aug-sept)– If sugarbeets are following Rhizoctonia-susceptible

crops in a rotation– Band application (preferred) – severe disease

pressure– Broadcast application – low disease pressure

• Risks– Work better if applied before infection

Rhizoctonia plan for 2019Past

Rhizoctoniapressure

(beets/100 ft. row at

harvest)

Variety (Your Choice)

Seed treatment

In-furrowtreatment

Postemergencetreatment

Low (170-200) ModerateWeak

YesYes

NoNo

NoYes

Specialty < 4.0 Rhizoctonia ratingModerate 4.0 – 4.4Weak > 4.4


Rhizoctoniapressure


harvest)


Seed treatment

In-furrowtreatment



YesYes

NoNo

NoYes

Moderate (130 – 170)

SpecialtyModerate

Weak

YesYesYes

NoNo

Yes/No (History)

Yes/No (History)Yes Yes


Rhizoctoniapressure


harvest)


Seed treatment

In-furrowtreatment



YesYes

NoNo

NoYes

Moderate (130 – 170)

SpecialtyModerate

Weak

YesYesYes

NoNo

Yes/No (History)

Yes/No (History)Yes Yes

Severe (less than 130)

SpecialtyModerateWeak?

YesYesYes

NoYesYes

YesYes Yes

Summary- Rhizoctonia Management

• Seed treatments provide excellent early-season protection

• In-furrow applications– Similar to seed treatments under low disease pressure– Better than seed treatments under high disease pressure– May reduce stands under cool and dry soil conditions

• Seed/in-furrow treatments can broaden the window to apply postemergence application (4 to 8 leaf stage)

• Postemergence application is most beneficial under moderate to heavy disease pressure, especially if beets are following soybeans or edible beans

• Generic formulations of azoxystrobin are effective

Aphanomyces

Aphanomyces can be a full-season pathogen

Aphanomyces damping-off Aphanomyces root rot

Life Cycle of Aphanomyces cochlioides

C. Windels, 2012

Zoosporeswim in water

0

1000

2000

3000

4000

5000

6000

7000

0 1 2 3 4 5 6 7

Recove

rable sucrose (lb

/A)

Aphanomyces root rot rating (0‐7)

Correlation of sugar yield with Aphanomyces root rot

r = -0.911 38 dfSignificant at P = 0.01

Integrated Management of Aphanomyces

AphanomycesRoot Rot

Early planting


AphanomycesRoot Rot

Seed Treatment

Early planting

Tachigaren(Hymexazol)


AphanomycesRoot Rot

Seed Treatment

Spent Lime

Varietal Selection

Early planting

Tachigaren(Hymexazol)Resistant variety <

4.4

Breckenridge lime trial: 2014Aphanomyces rating (0-7) Recoverable sucrose (lb/A)

Lime rate Res. + Tach Susc. No Tach Res. + Tach Susc. No Tach0 3.6 5.8 5656 40075 2.6 5.2 7123 603410 2.5 4.6 7211 647315 2.2 3.5 8408 810920 2.2 3.5 8631 8352

Linear ** *** *** ***Quadratic NS NS NS NS

* = significant at P = 0.05** = significant at P = 0.01*** = significant at P = 0.001NS = not significant

Planting: May 22Harvest: September 22

Aphanomyces rating (0-7) Recoverable sucrose (lb/A)Lime rate Res. + Tach Susc. No Tach Res. + Tach Susc. No Tach

0 1.7 4.2 8684 53015 1.4 2.8 8857 880610 1.6 2.4 9395 916415 1.2 1.6 9318 969820 1.3 1.7 9367 10506

Linear ** *** NS ***Quadratic NS * NS **


Planting: April 26Harvest: September 28

Breckenridge lime trial: 2012

Breckenridge lime trial: 2011Original Aphanomyces rating (0-7) Recoverable sucrose (lb/A)

Lime rate (Res. + Susc. varieties) (Res. + Sus. varieties)0 5.6 7385 5.1 196610 4.8 238015 4.2 325820 4.3 3404

Linear *** ***Quadratic NS NS


Planting: May 06Harvest: Sept 26

y = 137.2x + 3135.1R² = 0.9576

0

1000

2000

3000

4000

5000

6000

7000

0 5 10 15 20 25

Recov. Sucrose (lb/

A)

Original lime rate (ton/A)

Significant at P = 0.0001

Breckenridge lime trial: 2016

Benefit of additional 5 T/A lime after 2 years

Supplemental lime

Soil Ca(ppm)

Stand at 7 weeks

(per 100 ft)

Harvested roots

(per 100 ft)Aph RRR

(0-7)Yield

(ton/A)Sucrose

(%)

None 4132 115 101 3.5 20.3 12.6

5 ton/A 4696 133 122 2.6 22.9 12.8

Significance *** ** ** ** ** NS

* = Significant at P = 0.05** = Significant at P = 0.01*** = Significant at P = 0.001

No lime• Add 5-10 ton/A spent lime

5 ton/A• Add 5 ton/A spent lime

10+ ton/A• Apply based on field history

Current lime rate

Aphanomyces Plan for 2019


AphanomycesRoot Rot

Seed Treatment

Spent Lime

Manage Soil

Moisture

Varietal Selection

Weed Management

Early planting

Tachigaren(Hymexazol)Resistant variety <

4.4

Acknowledgements• Sugarbeet Research and Education Board of Minnesota

and North Dakota• Grower cooperators• Scott Pahl, Germains Seed Technology• Seed, chemical, and allied industries• American Crystal Sugar Company quality lab• Minn-Dak Farmers Cooperative• Southern Minnesota Beet Sugar Cooperative

Thank you!

Dr. Ian MacRae Tim

JasonPratibha

KarenAlec Claire

Tim Muira Brandon

Katie

Amanda

Jeff

Hal

@[email protected]

don’t let the root rots beat your beets · roots/100 ft. rcrr (0-7) yield rsa seed treatments 98...

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