cassandra swett ce specialist —vegetable and field crop

Fusarium diseases of tomato: updates on field diagnosis and management

Cassandra SwettCE Specialist—Vegetable and Field Crop Pathology

Plant Pathology Dept., UC Davis

[email protected]

Fusarium wilt Fusarium crown and root rot

Fusarium falciforme stem rot and vine

decline

Fusarium wiltCaused by Fusarium oxysporum f. splycopersici (Fol), race 3• Timing: symptoms begin to appear

NO EARLIER than 45 days after planting

• Late season disease; favored by heat, drought stress, heavy fruit load

• Chlorosis of leaves• Stem is green on the outside but with

brown vascular discoloration• If you cut green branches at 6” and

12” there is often still vascular discoloration

Methods for Fusarium wilt control• Resistant cultivars: F3 cultivars• Crop rotation

• Fol race 3 can survive at least seven months in soil (ongoing)• Rotation crops are not all created equal (ongoing)

• Chemical management?—Brenna’s talk

0

100

200

300

400

0 2 4 6 8

Colo

ny fo

rmin

g un

its /

g so

il

Month

Fol R3 survival over time

0

5

10

15

20

25

70 90 110 130

No.

of p

lant

s with

FW

sy

mpt

oms

Days after planting

CottonWeedsMelonPepperSunflowerTomato

Fusarium crown and root rotCaused by Fusarium oxysporum f. spradicis lycopersici (Forl)

• Plant slowly declines over many weeks

• Crown rot is a LOCALIZED lesion• Stem is brown on the outside and

rotten on the inside• IF you cut at 6” and 12” the stem

will be healthy looking• Roots will also often be decaying

Methods for managing Forl• Some commercial cultivars with resistance (FR) (few)• Several cultivars appear tolerant to Forl

0 5 10 15 20 25 30 35 40

H1776HM4909

N6416H8504N6428H5608H1310

HM3887H1428

HM58801HM5235

% yield difference in FF vs non infested field

Forl resistant check

Fusarium falciformeA poorly understood stem rot and vine decline pathogen with emerging significant impacts on

tomato

Understanding disease(s) caused by fungi in the Fusarium solani species complex in tomato

• First described in as a pathogen of fresh market tomatoes in Australia in 1975

• Symptoms: girdled tap root, rotten crown, plants rarely killed, yield reduced

• Observed in California on processing tomato in 1991• Disease name: Fusarium foot rot• Pathogen name:

• 1975: Fusarium solani • 2007: F. solani f. sp. eumartii • 2019: F. noneumartii

Images: Mike Davis

Stem rot and severe premature vine decline are not part of Fusarium foot rot

symptomology

Fast forward: Plants with severe stem rot samples identified by Gene Miyao in 2017

0

10

20

30

40

50

60

Wound FOL R3(CS3)

F. solani f.sp.

cucurbitae(CS179)

F.falciformeIsolate 1(CS91)



Lesio

n Le

ngth

(mm

)

Confirmed F. falciforme can cause stem rot

Identified as Fusarium falciforme-closely related to F. noneumartii but able to cause stem rot

In 2019: Concern was elevated with multiple F. falciforme fields exhibiting severe losses

High incidence of plants dying early

in the season

Can find F. falciforme in most tomato-producing counties in California

0

5

10

15

20

25

Num

ber o

f sam

ples

Counties

2018

2019

Over 75% of plants can be infected in a field

020406080

100

% with nopathogen

% with F.falciforme

% stem rot, nodecline

% Stem rot +premature vine

decline

Perc

ent o

f pla

nts

75% of plants in the field with F. falciforme rot

With 20-60% of plants developing premature decline in commercial fields

01020304050607080

Yolo farm 1 Yolo farm 2

Perc

ent w

ith P

VD

Premature vine decline causes sunburn and fruit rot

…significantly reducing yields and increasing unmarketable fruit in some cultivars

95

5

75

25

020406080

100

Percent market Percent unmarket

% o

f tot

al fr

uit b

iom

ass Healthy

Vine decline

20% decrease 5 fold increase

Field diagnosis of F. falciforme-look alike problems and tips

FF symptoms share similarities to other disorders, leading to misdiagnosis

Foot and crown rot

Looks a lot like

Fusarium crown and root rotSouthern blight

Stem rot

Stem rotLooks a lot like Fusarium wilt or

Verticillium wilt

Foliar yellowing / bleaching symptoms

Looks a lot like? Branch chlorosis Whole plant chlorosis

Fusarium wilt

Looks a lot like Virus

Herbicide damage

Deep leaf curling, deformity, little leaf

Leaf speckles leaflet blight leaf death

Leaf death whole plant deathWhole process ~3-5 weeks

Leaf death whole plant death

Boron toxicitySalt damage

Diagnosing plants with similar symptoms to other wilt and rot pathogens requires LABORATORY diagnosis

In development: easy to use, cost effective, rapid molecular-based tools that rapidly differentiate Fusarium pathogens of tomato

Diagnosing plants with foliar symptoms similar to abiotic disorders and viruses IS POSSIBLE in the field (to an extent)

Look for a discrete rot in the foot, crown and/or stem

+ LikelyF. falciforme

Ongoing: Is F. falciforme a new pathogen causing a new disease or a more severe manifestation of Fusarium foot rot?

Managing Fusarium falciformeNo management options known

Commercial cultivar resistanceChemical management (Brenna-next)

Management methods for Fusarium falciforme will be different than Fusarium wilt and Fusarium crown and root rot

Since this is a completely different species, F3 and Forl resistance do not work to control F. falciforme

020406080

100

% p

lant

s with

FF

Fusarium falciforme managementCultivar resistance screening

16 commercial varieties

-20 -10 0 10 20 30 40 50 60 70

HM58841 (F2)

H8504 (F2)

HM4909 (FR)

H1776 (F2)

HM58801 (F3)

HM5235 (F3)

N6428 (F3)

H5608 (F2)

H1428 (F2)

HM3887 (F2)

N6416 (F2)

H1310 (F3)

H9663 (F2)

% reduction in yield caused by F. falciforme

Alyssa Brackrog

Cultivar performance against Fusarium falciforme: 2019 field trial

Better yield performance associated with lower premature vine decline incidence

05

1015202530

H560

8

H142

8

HM58

841

H850

4

H177

6

HM52

35

N64

28

HM58

801

HM49

09

HM38

87

N64

16

H131

0

H966

3

% p

lant

s dea

d/dy

ing

Alyssa Brackrog

All cultivars: 85-100% of all plants developed rot

020406080

100H8

504

(F2)

HM52

35 (F

3)N

6416

(F1)

HM38

87 (F

2)H1

776

(F2)

HM49

09 (F

R)H9

663

(F2)

HM58

841

(F2)

HM58

801

(F3)

H560

8 (F

2)H1

310

(F3)

N64

28 (F

3)H1

428

(F2)

% p

lant

s with

foot

rot

Alyssa Brackrog

No COMPLETE resistance

Progress on F. falciforme IPM• Developing field diagnosis guide• Cultivars with FR and F3 genes ARE NOT resistant to FF• Commercial cultivars have field tolerance to Fusarium falciforme

• HM58841• H1776, HM 4909, H8504?, HM58801, HM5235, N6428

• Some cultivars are highly susceptible to F. falciforme--avoid if possible in heavily infested fields

• H9663, H1310, N6416 and HM3887

• Fungicide and fumigants may fit into IPM programming for F. falciforme—Brenna’s talk

• Crop rotations / alternate hosts?

To see this in action:Biennial Tomato Disease

Field Day-UC Davis

Next field day: 20211:1 available by

appointment

The amazing Swettonians!

• People who conducted/assisted with these projects: Alyssa Brackrog, Kelley Paugh, Johanna Del Castillo, Erin Helpio, Beth Hellman, Justine Beaulieu, Megan Kozel, Andrea Paulk, Karla Espino, Mirialini Narayan,Harrison Powell, Greg Sugwara, Elver Raymundo, Emma Centeno

• Field support: Bryan Pellissier, Lexi, Armstrong field assistants

• Collaborating farm advisors: Brenna Aegerter, Gene Miyao, Amber Vinchesi, Tom Turini, Joe Nunez, Scott Stoddard, Margaret Lloyd, Joe Nunez

• Research advisors: Zach Bagley, industry breeders and pathologists, many tomato growers

Questions?

[email protected]

Thank you!

Funding for [Project or Publication] was made possible by the U.S. Department of Agriculture’s (USDA) Agricultural Marketing Service through grant 19-0001-037-SF. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the USDA.”

cassandra swett ce specialist —vegetable and field crop

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