Eco-friendly Options for Plant Disease Management. Mahfuz Rahman, PhD Extension Plant Pathologist

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1 Eco-friendly Options for Plant Disease Management Mahfuz Rahman, PhD Extension Plant Pathologist

2 What is plant disease & why plants get diseases? Any condition in a plant that interferes with normal growth and development Healthy seeds + Balanced nutrition + Ideal growing environment = Good crop/plant Plant disease is an exception not a rule 1) Chronic exposure to a sub optimal plant growing condition 2) Continuous association of irritant such as pathogen

3 Plant Disease/Disorder Impact of plant disease/disorder: 1) Yield loss; 2) Quality loss and 3) Reduction in aesthetic value Unregulated growth Blossom end rot Bacterial wilt (herbicide injury) (Ca deficiency) (Ralstonia solanacearum) **Abiotic ** Biotic

4 Biotic causes of plant disease Fungus: A eukaryotic organism that is usually filamentous (forming a mycelium) and heterotrophic, has cell walls composed of chitin, and reproduces by sexual and/or asexual spores. **Most diseases on plants are caused by fungi & FLO** Fungal spores (400X) Fungal mycelium

5 Biotic Disease (Fungal-foliar) Continuous association Dynamic Interferes plant s physiology and cell function Infection Process and Establishment Spore can t germinate without a film of water on tissue surface It is a high ATP demanding process Any disruption of ATP production will inhibit spore germination Turgor pressure 8 MPa=1160 psi Intracellular hyphal invasion

6 Biotic diseases Important Env. Factors: RH (leaf wetness) and Temperature Plant diseases result when a susceptible host and a disease causing pathogen meet in a favorable environment Total amount of biotic disease is the function of three interacting factors: Host, Pathogen and environment

7 Septoria leaf spot and Early Blight Septoria leaf spot Early blight 7

8 (In the presence of water droplets) What clues we get here for managing the disease? 8

9 Solanaceous weed hosts of S. lycopersici Night shade Horse Nettle Jimson weed

10 Overview Healthy seeds and transplants Rotation and resistant cultivars (Grafted) Balanced and supplemental nutrition Sanitation & good agri/cultural practices Scouting and monitoring Quick diagnosis and removal of diseased plants (viral diseases and alternative hosts) Applications of biological disease control products Application of resistance inducers

11 Seedborne Diseases Bacterial leaf spot of pepper, and bacterial canker of tomato Early blight, Bacterial spot and speck of tomato Infected seed = primary inoculum. If seed infection is controlled, the disease is controlled Many bacteria, viruses and some fungi

12 Seedborne Bacterial Diseases Clavibacter michiganensis sub sp michiganensis- Tomato canker Xanthomonas campestris pv vesicatoria-tomato spot also on pepper leaf and fruit Bacterial canker Pseudomonas syringae pv tomato -Tomato speck Bacterial spot Treatment: Hot water treated seeds Bacterial speck

13 Bacterial leaf spot on pepper Xanthomonas vesicatoria 1. Survives in seed or crop debris 2. Starts as water soaked lesions 3. Spread by rain splash Control: 1. Certified or treated seed 2. Sonata (Bacillus pumilus) 13

14 tomatoes, peppers, spinach, onions, carrots, and all the brassicas

15 Fiberglass screen; #4 cone style coffee filter; Tea infusers

16 Hot-Water Seed Treatment (tomato) Preheat seed for 10 min. at 100 F (37 C). Transfer to 122 F (50 C) for 25 min. Cool seed immediately and dry completely prior to sowing or re-packaging. Seed may be treated with Biocontrol agents when dry. Stove top hot water seed treatment, precision thermometer

17 Seed Treatment with Bleach Chlorox 25 oz, water 100 oz + 1 table spoon surfactant (Tween 20) Agitate 1 lb seed in 1 gal. water for 1 minute Rinse seeds thoroughly in running tap water for 5 minute Then dry seeds in a single layer Plant within 2 weeks

18 Rotation and Resistant cultivars Diseases and pests build up over time Infected plant debris or stubbles help overwintering many pathogens Rotation should be ideally of 4 years Selection should be made from different family Distribution: Tomato and Potato should not be placed side by side Resistant rootstocks can be used to manage soil-borne pathogens

19 bles/tablelist.htm

20 ~500 tomato varieties and hybrids, 41 diseases and Physiological Disorders

21 Scion and Root stock selection Preferable horticultural traits: Heirloom variety Scion Biotic and abiotic stress tolerance Biotic: Resistance against soil-borne pathogens Verticillium wilt; Fusarium wilt; Bacterial wilt and nematodes Abiotic: High salt, drought etc. Better nutrient and water uptake Root Stock

22 Principles of tomato grafting Right age of root stock and scion (3-4 weeks; 2-4 leaf stage) Same stem size ( mm diameter) Cut o angle; consistent between root stock and scion Preferably below the cotyledon of RS to minimize suckering Silicone clips work well Minimize transpiration loss of water Transfer immediately to healing chamber No direct light; 85-95% RH

23 Small scale healing chamber (Biodome) Any structure to hold humidity Temp: o F First 48 h critical No overhead watering Seven days (new growth) to take out Planting: Grafted area/adventitious roots from scion should not touch the soil

24 Balanced and supplemental nutrition

25 N as needed, Ca, Si a little extra As leaves age, the accumulation of silicon (Si) in the cell walls helps form a protective physical barrier to fungal penetration. Excessive N levels lower the Si content and increase susceptibility to fungal diseases. Excessive N can bring about higher amounts of amino acids and other N-containing compounds in plant tissues to create mineral imbalances. Ca in the middle lamella (the "glue" that bonds adjacent cells) strongly inhibits fungal cell wall degrading enzymes.

26 Sanitation & good agri/cultural practices Spring sanitation for strawberry Wooden stakes risky to recycle Bio-fumigation (high value crop): Caliente brand mustard Pruning of affected areas Avoid rainy day or wet foliage Disinfect pruning device Safe disposal of diseased produce Greenhouse/high tunnel floor disinfestation

27 Scouting and removal Bean anthracnose (Coll. lindemuthianum) Seed borne, exudes pink masses of spores under humid condition.

28 Dark brown-balck slender lesions follow the leaf veins

29 Symptom and spread of viral diseases Symptoms: mosaic, mottling, necrosis stunting, leaf curling, vein yellowing, ring spot etc. Prevention of secondary spread 33

30 Organic Materials Review Institute (OMRI) Approved Products Cu-CuO, (Nordox, AgBio, Inc), Cu(OH) 2 S-Sulfur Serenade = Bacillus subtilis strain 713 Actinovate = Streptomyces lydicus strain WYEC 108 Prestop = Gliocladium catenulatum strain J1446 Mycostop = Streptomyces griseoviridis Root Shield/Plant Shield = Trichoderma harzianum strain T22, Rifai strain KRL-AG2 Online Resource:

31 Biological Control Mechanism Competition- I. Sites-prevent colonization of root tissues II. Nutrients-consumed by beneficial microbes a. Nutrient source-root leakage or Exudates Root-Orange color; Trichoderma-Green

32 Biological Control Mechanism Antagonism-Attack and feed on pathogen Antibiosis-Production of toxins, antibiotics Resistance inducer- SAR & ISR (PGPR)-Sea weed extract, Regalia (jiant knotweed extract), chitosan, SA, INA, JA

33 Bacterial and soilborne disease control A combination of copper and resistance inducer may provide acceptable level of control Seaweed extract: Acadian seaplants Limited Regalia: Marrone Bio-innovations Nematodes and soil-borne diseases: Biofumigation with special mustard variety such as Caliente

34 Biofumigation with Mustard family potential MITC producer, same as hydrolyzed product from Vapam (metam sodium)

35 Thank You! Questions?