Effects of reduced fertilizer rates on pests and integration of biostimulants into

production

Michael Brownbridge, Ph.D.

Effects of (over) fertilization

• Most greenhouse ornamental crops over-fertilized‒ 50 to 75% reductions possible (Zheng et al, 2011; Shelp et al, 2017)

• High N-levels in plant tissue can decrease resistance, increase susceptibility to pests

Insect pests affected by high-N

“…most studies assessing the response of aphids and mites to nitrogen fertilizer have documented dramatic expansion in pest numbers with increases in fertilizer rates.”

Altieri et al. 2014. Manage insects on your farm: a guide to ecological strategiesSARE Handbook Series, Book 7

Ralph E. Berry, Dept. Entomology, Oregon State Univ.

John Palumbo, Univ. Arizona

Nigel Cattlin/Science Source

• All of these pests respond positively to high N levels in plants

• Can we lower fertilizer (esp. N) to • slow population growth• improve biocontrol outcomes?

Pests like thrips, mites can multiply very quickly

Approximately 64 d @ 75° F/25° C

3600 after 21d >12 million after 64d

How you feed a plant makes a difference

33% lower• Chau & Heinz 2006; Chow et al, 2012

• Nutrient concentrations reduced by 50%

– did not affect quality, time of production

– did affect pests

Reducing fertilizer in chrysanthemums

• Organic N levels in leaves affected by fertilizer rates

• Thrips numbers increased with increasing fertilizer (N) levels

• Approx 50% fewer thrips at 50 ppm vs 100 to 300 ppm

• Industry standard 250 to 300 ppm N in the vegetative phase

Vineland data 2019. Do not reproduce.

Lowering fertilizer can improve biocontrol outcomes

• Reproductive rate slowed

• Development rate slowed

Result

• Fewer thrips

• Suppress population growth

• Greater impact from BCAs

21d @ 75° F

<1600 after 21d

Other benefits?• Reduced fertilizer input costs

• Reduced environmental impact, compliance

• Increase susceptibility of pests to diseases?‒ Diet (esp. protein, N) directly affect insect’s ability to mount a successful

functional (physiological) immune response to disease challenges

0 ppm 25 ppm 50 ppm 100 ppm 300 ppm

Effects on plant quality?

What do we know?

• Organic amendments usually result in lower concentrations of soluble nitrogen in plant tissue

• Reductions in pest infestations attributed (in part) to lower nitrogen content in the crop tissues

• Whereas synthetic N leads to higher levels of amino acids in plant leaves…

• Could we grow crops that are less prone to insect pests and diseases by using organic soil amendments?

• What role might biostimulants/biopesticides play in improving nutrient access and uptake, N-content in leaves?

Agricultural biostimulantsAny microorganism or substance based on natural resources, applied to plants, seeds or roots to stimulate natural processes that enhance/benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stress, crop quality and productivity.

Images: CROP SCIENCE

Plant effects of biostimulants

Information source:

Microbial biostimulants

Mycorrhizae• Enhance root development

• Increase access to water/nutrients

• Improve survival, tolerance

Yield benefits in field cropsBacillus firmus

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5.8 bu/A yield benefit

Combined biological (B. firmus I-1582) + chemical seed treatment increases yield over chemical alone

Data from 155 trials (Corn – Illinois, USA) Information courtesy of Nate Royalty, Bayer Crop Science

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Protection from environmental stress through root colonisation & biofilm production

Improves plant phosphorus and iron nutrition

Produces phytohormones that stimulate root development

Probiotic effect through space and food resource competition

Induces plant defenses

Bacillus amyloliquefaciens IT45 (LALRISE®): Benefits to the plant

Data provided by Lallemand

Plant Care STRICTLY CON

FIDENTIAL.

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Selected field trial results with Bacillus IT45

Data provided by Lallemand Plant Care STRICTLY CONFIDENTIAL.

Biopesticides with ‘biostimulant’ properties• Trichoderma harzianum T-22

‒ RootShield® (BioWorks)

• Bacillus subtilis‒ Cease®, Serenade®, Rhapsody® (BioWorks, Bayer)

• Bacillus pumilus‒ PTB180 (PremierTech)

• Clonostachys rosae‒ BVT-CR-7 (Bee Vectoring Technologies)

• Metarhizium brunneum‒ Met52 (Novozymes)

• Beauveria bassiana‒ BotaniGard (BioWorks)

Biopesticides with ‘biostimulant’ propertiesTrichoderma harzianum T22

• Root growth, yield enhancement

….and moreTrichoderma harzianum T22

• Induced responses protect against foliar (fungal) diseases and some viruses

Vitti et al. 2016. Trichoderma harzianumT-22 induces systemic resistance in tomato infected by cucumber mosaic virus. Plant Sci. 7, 1520.

Enhanced resistance of tomato to Botrytis cinerea, induced through root treatment with Trichoderma. Martinez-Medina et al. 2013.

Trichoderma-induced plant responses Can also affect pests

Fewer spider mites on tomatoes treated with Trichoderma T22

• Slower spider mite development

• Variety-specific response

Plants infested with potato aphids, roots colonized by Trichoderma T22• Increased recruitment of A.ervi

• Enhanced production of VOCs

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Control Cease RootshieldMicroflora extract

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What value in the production of ornamentals?

The value proposition?‒ Root stimulation in young plants‒ Better root development, improved fertilizer use efficiency‒ Improved uniformity in crop development ‒ Promotion of yield, shelf life

Crop resilience‒ Less energy dealing with stress, more on production‒ Improved crop tolerance as weather conditions change (heat stress, etc.)‒ Improved biocontrol success?

• Can we use biostimulants to ‘compensate’ for reduced fertilizer rates?• What effects on pests?

Synergro® Tomato Nitrogen Reduction and Yield, Clemson, SC

IN-M1 is currently labeled as SYNERGRO® in Canada and GARDEN SOLUTION® in the United States.

Synergro® Lettuce Nitrogen Reduction & Yield Trial, Salinas, CA

Synergro at 3 gal/A (1 gal/A at transplant and weekly applications of 0.5 gal/A)

– maintain or increase yield for grower– reduce nitrogen fertilizer– reducing potential nitrate leaching, input costs

15000 17500 20000 22500 25000 27500 30000

Control

Control + IN-M1

10% N Reduction + IN-…

20% N Reduction + IN-…

30% N Reduction

30% N Reduction + IN-…

Total Marketable Weight (lbs)

31% increase over 30% N reduction alone

4.5% increase over highly-managed grower standard

6 replications per treatment yield average

IN-M1 is currently labeled as SYNERGRO® in Canada and GARDEN SOLUTION® in the United States.

Substrate plus beneficial microbes

1. PRO-MIX® BX

2. PRO-MIX BX + Mycorrhizae™ (Glomus intraradices PTB297)

3. PRO-MIX BX + BiofungicideTM (B. pumilus PTB180) + Mycorrhizae

Effect on plant developmentWeight of foliage

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11/07/2019 24/07/2019 14/08/2019 04/09/2019

Vineland data – preliminary data only, do not reproduce

Effect on western flower thrips

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PT T1 LF PT T2 LF PT T3 LF PT T1 HF PT T2 HF PT T3 HF

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11/07/2019 24/07/2019 14/08/2019 04/09/2019

Vineland data – preliminary data only, do not reproduce

Effects of substrate on other pests?

Treatments• PRO-MIX® BX• PRO-MIX® BX + Biofungicide + Mycorrhizae• PRO-MIX® BX + Met 52EC drench

Information courtesy of Rémi Naasz, Ph.D. PREMIER TECH HORTICULTURE

Information courtesy of Rémi Naasz, Ph.D. PREMIER TECH HORTICULTURE

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Count 1 Count 2 Count 3 Count 4 Count 5 Count 6 Count 7 Count 8 Count 9

17 days 24 days 31 days 38 days 45 days 52 days 66 days 73 days 80 days

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PRO-MIX BXPRO MIX BX Biofungicide + MycorrhizaePRO MIX BX + MET 52mc

• Significant effect of media treatment on fungus gnats • Significantly fewer fungus gnats in the B. pumilus medium

Effects on other pests

Integrating biostimulants into production? • The value proposition – use to achieve different goals?▫ Root stimulation in young plants, better root development▫ Improved uniformity in crop development ▫ Growth promotion, shelf life▫ Enhanced crop resilience

• Early research shows▫ Potential to reduce fertilizer inputs without detriment to the plant▫ Added benefits – reduced insect pest pressure

• Success requires ▫ Understanding which biostimulant will provide the benefits▫ Application practices critical to success

michael.brownbridge@gmail.com

Traditionally considered in isolation from one another, aboveground and belowground components of ecosystems are now thought to be closely linked.

The (crop) plant seems to function as an integrator of the above ground and below ground components of agroecosystems.

This holistic approach is enhancing our understanding of the role of biodiversity at a global level.