Management of Tobacco Diseases Agent Training Dark Tobacco

Size: px

Start display at page:

Download "Management of Tobacco Diseases Agent Training Dark Tobacco"

Penelope Paul
5 years ago
Views:

1 Management of Tobacco s Agent Training Dark Tobacco April 5, 2007 Princeton, KY Kenny Seebold University of Kentucky Dept. of Plant Pathology

2 What is a Plant? A condition where the normal functions of a plant or its parts are disturbed or harmed Importance of plant diseases: Affect tobacco from seeding through harvest Occurrence & severity depends on: Environment Cropping history Grower practices Affect yield in terms of quantity & quality Cut revenues through direct losses & cost of control

3 Important Considerations identification be aware of the signs and symptoms of tobacco diseases & know all the diseases that can affect tobacco. Understand why, how, and when diseases occur in tobacco. Be familiar with all of the tools at your disposal for disease management.

4 The Plant Triangle Susceptible Host Pathogen Favorable Environment

5 Groups of Plant Pathogens Fungi most diverse and most common group of pathogens Bacteria second only to fungi in abundance Viruses depend on host to replicate require vectors to spread Nematodes microscopic roundworms

6 Chlamydospore (resting spore) Basidiospore Sclerotia & fruiting bodies Bacterial cells Types of inoculum Virus particles

7 Sources of Plant Pathogens Soil & water Seed and transplants Infested crop debris Spores from infected crops or weed hosts Insect vectors aphids thrips

8 Long-Term Survival of Pathogens (Overwintering) Soil and crop debris Resting spores & virus particles (TMV) Living microbial cells Contaminated equipment & tools Spores & cells Alternate hosts Related crops (tomato, pepper) weeds Insect vectors Carried over inside insect (tomato spotted wilt virus)

9 General Pathogen Behavior Most foliar diseases are polycyclic types Multiple disease cycles during the season Most soilborne diseases are monocyclic One disease cycle during the season Strategies for management can be different for each disease type

10 The Plant Triangle Susceptible Host Pathogen Favorable Environment

11 Resistance One of the most effective & inexpensive forms of disease control, depending upon the disease Black root rot Virus complex Angular leaf spot, wildfire Black shank

12 The Plant Triangle Susceptible Host Pathogen Favorable Environment

13 Environment & Planting date Early planting = cool soils in many cases May see problems with root rots & damping-off black root rot

14 Environment & Plant into well-drained soils Increased moisture can promote certain diseases black shank sore shin

15 Environment & Air movement Long periods of leaf wetness = increased risk More airflow = faster leaf drying Avoid shady areas = slow leaf drying Weed control Improves air movement Removes potential sources of inoculum Plant populations High plant populations can equal more disease Poor air movement & increased plant-to-plant spread

16 The Plant Triangle Susceptible Host Pathogen Favorable Environment

17 Cultural Practices that Affect Pathogens Sanitation & Exclusion Pathogen-free transplants Clean equipment, tools, feet when moving from contaminated to clean fields Don t spread infected crop residue on clean fields Turn crop residue under promptly Deep turn to promote breakdown of crop residue

Crop Rotation Rotation with crops that are non-hosts to pathogens is an effective tool to prevent and reduce several tobacco diseases: Deprives pathogen of preferred host(s) Most effective against

18 Crop Rotation Rotation with crops that are non-hosts to pathogens is an effective tool to prevent and reduce several tobacco diseases: Deprives pathogen of preferred host(s) Most effective against pathogens that affect mainly tobacco or those that persist for relatively short times in the environment Black root rot Black shank t effective against pathogens with multiple hosts or those that don t overwinter Blue mold t as effective against extremely persistent pathogens Fusarium wilt

19 Control Other Pests Weeds Refuge for insect vectors May harbor fungal, bacterial, and viral pathogens Buttercup and tomato spotted wilt Insects Effectiveness depends on disease & vector Nematodes Root wounds are points of entry for other pathogens Fusarium wilt of tobacco Black shank

20 Fungicides & Bactericides Can be separated into 2 main groups: Contact materials (protectants) Adhere to surfaces of plants, no penetration or movement in the plant Fungus must come in contact for activity Will not affect established infections hence they protect only and must be applied prior to arrival of fungus. Dithane DF Terramaster 4EC AgriMycin 17

21 Fungicides Systemic fungicides Penetrate plant parts to some degree Move upward or downward within the plant May be taken up by roots Can act as curatives & protectants Ridomil Gold Actigard & Aliette WDG Inducer of plant resistance

22 Fungicides Locally systemic compounds exhibit limited movement in plants. Quadris Acrobat / Forum Quadris active ingredient moves from treated to untreated side of leaves

23 Movement of Fungicides 7 days After Treatment Quadris Ridomil Courtesy Frank Wong Syngenta Crop Protection

24 How Fungi Infect Spore release -> Deposition -> Germination -> Infection -> Symptoms

25 Timing of Application Preventive before infection Curative after infection Systemics only Up to 1-4 days after infection Eradicates new infections (=before symptoms) Cannot kill older infections Cannot eradicate symptoms After that: Protect against new infections Reduce production of spores

26 Anti-Sporulant Activity of Quadris Courtesy Frank Wong Untreated Check Protectant Application Post-infection Application

Using Fungicides Effectively Follow labels carefully Know what you

Rates and safety precautions Must be applied properly for best

rig Sprayer pressure: 60 psi 100 psi range zzles (tips): hollow

27 Using Fungicides Effectively Follow labels carefully Know what you are trying to control! Rates and safety precautions Must be applied properly for best effect: Timely application Properly equipped and calibrated spray rig Sprayer pressure: 60 psi 100 psi range zzles (tips): hollow cones / drop extensions Volume: start low & increase as plants grow 20 gal/a early up to 100 gal/a late in the season

Diseases of Horticultural Crops. Shubin K. Saha D.P.M., Ph.D., Extension Vegetable Specialist Department of Horticulture University of Kentucky

Diseases of Horticultural Crops Shubin K. Saha D.P.M., Ph.D., Extension Vegetable Specialist Department of Horticulture University of Kentucky A disease can be Non-infectious (abiotic) P deficiency Infectious