Michael B. Dimock, Ph.D.Certis USA, L.L.C. Columbia, MD

Biologicals for

Plant Disease Management

Maryland Biological Control ConferenceDecember 17, 2019

BioControls: A small but growing market

Why the rapid growth?2018 Global market data:• Crop protection: $68 billion• Biocontrols: $3.8 billion (5.6%) Public demand

• Sustainability• Reduction in pesticide use

Pressure on conventional pesticides• Decreasing tolerance of residues • Regulatory actions• Supply chain issues• Pest and pathogen resistance

Development costs• Chemical : 11 years, $286 million • Biopesticide: <5 years, $2 - $7 million

Better knowledge & understanding of how to use biologicals in IPM programs.

Microbials

Beneficial insects, mites & nematodes

BiochemicalsLargest &

fastest growing segment

(>17% CAGR).

Global biocontrols

Microbial Control Agents (MCA’s)

vs MICROBE…with apologies to Antonio Prohías (1921 - 1998) and MAD magazine!

Microbial control agents (MCA’s)

Antibiosis (antimicrobial metabolites)

Infection or parasitism

Colonization/competition

Induced resistance (SAR or ISR)

Biostimulant effects

Modes of Action against plant disease:

Target

Number of active ingredients by taxon Total by targetViruses Bacteria Fungi Protozoa

Plant diseases 6 36 26 65

Insects & mites 10 32 12 1 55

Nematodes 5 2 7

Weeds 1 5 6

Total by taxon: 16 74 45 1 136*Total of 366 of July 2018 (not including plant-incorporated protectants).

Types of microbials included in EPA’s list of ~400 biopesticide active ingredients*

www.epa.gov/pesticides/biopesticides

MCA’s as Biopesticides

Types of microbial control agents

Bacteria

B. subtilis attacking fungalspores.

Bacillus biofungicides

Fungus destroyed by B. subtilis.

Spores of fruit rot fungus Dothiorella aromatica on avocado flower.

Demoz & Korsten, 2006. Biol Contr 37: 68-74.

Ba inhibiting growth of Sclerotinia sclerotiorum (Ssc) on agar.

Ssc alone

Ssc

Ba

Z. Landa

Bacillus amyloliquefaciens(Ba) Multiple modes of action:

1. Produce antimicrobial lipopeptides that kill or inhibit pathogenic fungi & bacteria on contact.

Colonization of tomato root hairs by Ba after soil drench.

Nihorimbere et al. FEMS Microbiol. Ecol. 79 (2012): 176-191.

Treated Untreated

Colonization of kiwifruit flower stigma by Ba.

Balestra et al. 2014. L’Informatore Agrario 22: 50-53.

2. Colonize roots, flowers, other plant surfaces, outcompete pathogens.

Multiple modes of action:1. Produce antimicrobial lipopeptides

that kill or inhibit pathogenic fungi & bacteria on contact.

3. Activate plant defenses (SAR/ISR).4. Promote plant growth & yield (PGPR).

Bacillus amyloliquefaciens(Ba)

Castillo et al. 2013. DOI: 10.5772/54229

UntreatedB. subtilis drench

Bacillus biofungicides

Aviv® Cease® Companion®

Double Nickel® Rhapsody® Serenade®

Serifel® Sonata® StargusTM

Taegro® Triathlon BA®

• Other similar Bacillus species:B. subtilis, B. licheniformis, B. pumilus, etc.

• Broad crop & disease labeling• Foliar, soil, and seed applications• Many strains and EPA-registered products:

Bacillus amyloliquefaciens(Ba)

Bacillus biofungicides

Pantoea agglomerans• Colonizes apple & pear flowers.• Competitive inhibition of fire blight.

BloomtimeTM Biological

Streptomyces lydicusS. lydicus attacking Pythium

Actinovate®

• Colonizes plant structures.• Competes with/excludes pathogens.• Secretes antimicrobial metabolites & enzymes.

P. chlororaphis (blue) vs. rust spore (brown).

AgBiome

HowlerTM USDA-ARS

P. fluorescens A506 colonizes flowers, excludes fire blight

BlightBan®

Pseudomonas species

Other bacterial biofungicides

Types of microbial control agents

https://gardenerspath.com/how-to/organic/trichoderma/

Fungi

BAntibiosis (some strains) Mycoparasitism Root colonizationCompetition Induced systemic resistance Biostimulant effects

Bio-Tam®

RootShield®

SoilGard®

Tenet®

Prestop®

Biocontrol fungi vs. plant disease

Trichoderma virens (Tv) and Gliocladium catenulatum (Gc) attacking Rhizoctonia solani (Rs).

Trichoderma & Gliocladium species

RsGc

Tv penetration points

Rs

Tv Rs

USDA-ARS photo

Trichoderma in furrow at planting

Untreated check

Promotion of early growth in the field

J. López-Bucio et al. 2015. Sci. Hort. 196: 109–123

ControlT. virens

Stimulation of root branching Control of Rhizoctonia

Aureobasidium pullulans

• Colonization of apple and pear blossoms• Competitive exclusion of fire blight bacteria

Blossom ProtectTM

Biocontrol fungi vs. plant disease

Lettuce drop (Sclerotinia minor)

Univ. of AZ

White mold in soybean(Sclerotinia sclerotiorum)

Crop Protection Network

Contans®

Coniothyrium minitans

• Mycoparasite of Sclerotinia species

Intact sclerotium of Sclerotinia minor.

C. minitans penetrating sclerotium and consuming contents.

Microbial control of plant disease

Plant defense activators

Plants are endowed with genes for synthesis of antimicrobial compounds conferring resistance against plant pathogens.

Chitinases Peroxidase Proteinases TerpenoidsProteinase inhibitors Defensins Glucanases ThaumatinPhytoalexins Lignin Callose Thionin

Adapted from Reddy P.P. (2012) Plant Defense Activators. In: Recent advances in crop protection. Springer, New Delhi

Plant activators mimic these signals, triggering defenses independent of pathogen infection.

Many of these are “sleeping” genes, quiescent in healthy plants, which require specific signals to activate them.

Plant pathogens provide signals (“elicitors”) which activate these defense genes, a process known as “induced resistance.”

Biopesticides as plant activators

Biochemicals:• Plant extracts (Regalia®, EcoSwing®)

• Algae extracts (Vacciplant®)

• Yeast extracts (KeyPlex® 350, Romeo®)

• Chitin and derivatives (multiple)

Microbials• Bacillus mycoides (LifeGard®)

• B. amyloliquefaciens et al. (previously listed)

• Trichoderma species (previously listed)

• Others?

Bacillus mycoides

Plant activators: Caveat emptor!

Many unregistered biostimulant products are promoted as “plant activators.”

• Fertilizers, micronutrients, and “stress relief” compounds, some containing multiple microbe species at very low concentrations.

• Thinly-veiled claims of disease control with little or no underlying scientific support.

• Currently no EPA regulatory framework or legal definition of plant activator or biostimulant.

Induced resistance

Biofertilizer

BiostimulantMicrobial control

The soil and plant microbiome

Jansson & Hofmockel 2018. Current Opinion in Microbiology 43: 162 – 168.

Types of microbial control agents

Viruses

Bacteriophage

• Highly specific bactericides

• Medical applications since early 1900’s Phage therapyAntibiotic-resistant bacteria

• Food safety applicationsE. coli, Salmonella, Listeria

Viruses that infect & kill only bacteria

Diagram of bacteriophage structure

Bacteriophage attacking E. coli.

Leppänen et al., Adv. Biosys. 2017, 1700070 • Recent products target bacteria

causing plant disease:

AgriPhageTM: Fire blight, Citrus canker, Tomato canker, Bacterial spot/speck

Xyli-Phi PDTM: Pierce’s Disease (grapes)

• Inject their DNA into host cells and hijack metabolism to produce more virus.

Bacteriophage mode of action

• Infected cells disintegrate (lysis), releasing more virus to infect neighboring host bacteria.

Source: National Institute of Allergy and Infectious Disease (NIAID)Screen captures from: www.youtube.com/watch?v=NWo4MwE3zfU&pbjreload=10

Automated Aerial Application

Autonomous Drone Swarms

2018 Winter Olympics (South Korea)

Drone sprayer (UAV)+ Low cost+ Safety– Limited capacity– Daytime only

Photo: BioBest

Flying Doctors®

Using pollinators to deliver biofungicidesVectoriteTM+ CR7

Photo: Verdera

GcRsGliocladium

catenulatum (Gc)vs. Rhizoctonia

solani (Rs).Sutton et al. 1997. Plant Disease 81(4): 316-328.

Cr

Bc

Clonostachys rosea (Cr) vs. Botrytis cinerea (Bc).

A “whipped” rope resists unraveling.

“Nothing is working…

“...might as well try a biological.”

The role of biologicals in IPM

“Last resort”(The wrong way):

“Pulling together”(The right way):

The whipping cord can’t carry the full load alone, but keeps the other strands together, pulling in the same direction.

An analogy

Summer 2019 turf grass trialBrown patch (Rhizoctonia solani) in tall fescue College Park, MD

Untreated checkAUDPC = 244

Microbial plant activatorAUDPC = 63

Chlorothalonil +microbial plant activator

AUDPC = 0

Chlorothalonil +synthetic plant activator

AUDPC = 0

Combining microbials and chemicals

All photos taken from same replicate.

AUDPC = Area under the disease progress curve (mean of 4 reps).

CER-2019-6348

What do biopesticides offer for IPM?

Reduced risk of adverse effects• Workers, bystanders, consumers• Livestock, pets, fish and wildlife• Pollinators, predators, parasitoids

Flexibility in crop/site management & harvest• Standard application technology• Minimal REI and posting requirements• Many exempt from residue tolerance (no PHI/MRLs)

Resistance management• Multiple, unique, non-toxic modes of action• Low risk of cross-resistance to chemicals• Tank mix/rotate for resistance management

www.frac.info

Timing is important!

Relatively short persistence• Degradation by sunlight (UV).• Some sensitive to temperature extremes.• Good and bad - low/no residues, but may need reapplication.

Storage and handling of live microbials• Storage conditions (temperature, moisture, shelf life/expiration).• pH requirements (typically 6 – 8).• Tank mix compatibility & recommended adjuvants.• Check labels and manufacturer’s information.

Considerations for using MCA’s

Preventative/early curative• Rarely effective alone vs. established disease.• Time to colonize plant or infect/parasitize target.• Induced resistance best if triggered pre-infection.

www.epa.gov/pesticides/biopesticides

www.bpia.orgBiological Products Industry Alliance

Biopesticides Program

www.ir4project.org/bpos

www.ibma-global.org/

For more information on biopesticides

MDimock@certisusa.com