FarmCareGB

Horticultural Biosecurity

Greenhouse InteriorIt has been estimated that plant diseases are responsible for up to a 15% loss in potential farm income. As with livestock, lowering the challenge of pathogenic organisms will reduce the incidence of disease, increasing both output and quality.

This is most important in the greenhouse environment where there is no natural weathering process to reduce the challenge carried over in debris and dust from previous crops. This together with the high intensity of plants greatly increases the risk of disease. Many plant disease organisms survive in plant debris or dust for months or years in a dry state on the floor, the structural framework, tools, implements, grading and packing lines and clothing. Just as it is in intensive livestock housing, greenhouse hygiene is a fundamental requirement for disease control.

Thus the state of hygiene of the greenhouse and its surroundings, weeds, algae, dirty machinery, rubbish piles of prunings and un-saleable produce all have an impact on plant health. Also adjacent field crops of the same plants can present hazards to the greenhouse crops.

Most disease causing organisms are transmitted by vectors. Controlling contamination on these vectors is the key to successful disease control. Some of the potential sources of disease organisms are listed below:

Boots

Trolley tyres

Overhead ornamentals

Commercial peat

Seed

Transplants

Debris on wires

Insects

Trash piles

Dirty seed trays

Tools

Overalls

Dust on structure

Fruit crates

Grading & packing lines

Outside trash piles

Weeds

Well and creek water

Soil

Visitors

 

One specific chemical formulation with proven efficiency in destroying infective organisms is a powdered stabilized blend of peroxygen compounds, surfactant, organic acid and an inorganic buffer system. FarmCare GB markets this formulation as Viru-Gard. The combination of efficiency, safety and lack of residue concerns makes the use of Viru-Gard an attractive alternative to many of the plant hygiene and disease control chemicals in use today.

Terminal Biosecurity Programme for Greenhouses

Greenhouse BiosecurityThe following procedures should be followed for each greenhouse to be disinfected.

 

 

 

 

 

 

 

 

Stage 1: Removal of Equipment and Dry Cleaning

The removal of all gross organic matter is essential as it contains high levels of contamination and is a major source of infection. High levels of soiling will also reduce the efficiency of the cleaning and disinfection process.

  • Remove trays, pots, containers and equipment from the area to be disinfected and put to one side for cleaning and sanitising.
  • Remove all crop debris, strings etc.
  • Do not leave trash piles near the greenhouse as they may contain spores which are carried back into houses on feet and tyres or are blown in by the wind.

Stage 2:Pre-cleaning and Sanitizing

Following any dry cleaning process high levels of infective material will still remain. Cleaning and sanitizing using products with detergent capacity and biocidal activity to remove soiling from the surfaces ensures greasy deposits do not remain on rough surfaces e.g. concrete and wood. Detergent-sanitizers also reduce the time taken to clean by up to 60%, and reduce the spread of disease in washing water. Fluorine should not be used on glass as it etches the surface providing a surface for increased growth of algae and other infectious organisms.

  • Use FarmCare Quat-Gard at a dilution of 1:1000.
  • Apply with a knapsack sprayer or pressure washer. The pressure washer should be set on a low pressure setting 500psi (35 bars) using a 45° angle jet. The application rate should be 1 litre of solution per square metre of surface area.
  • Start at the apex of the roof and work down the walls to the floor paying particular attention to corners and other areas where dirt accumulates. Caked soiling should be brushed if necessary to aid removal.
  • Allow surfaces to dry where possible before disinfection.

Stage 3: Water System & Equipment Sanitising

Irrigation water and irrigation lines

All water systems contain some contamination, especially the header tanks where dust and dirt can accumulate. This may allow disease such as Pythium, Fusarium and Phytophthora to pass on from one crop to the next. Viru-Gard will also breakdown bio-films and algae.

Run 1% (1:100) Viru-Gard solution through the pipes or soak them in a bath. Flush irrigation lines with clean water after treatment.

Moveable Equipment

Equipment removed from the house can carry heavy pathogenic contamination and if not thoroughly cleaned can lead to carry over of infection to the new crop.

  • Where there is a high risk of carry-over of infectious organisms on trays, pots, containers wash or dip them in a 1% (1:100) Viru-Gard solution.
  • Where there is a low risk of infective material either soak and scrub equipment in a tank or pressure wash with FarmCare Quat-Gard (at a dilution of 1:250).
  • Store equipment where it will not be re-contaminated.

Stage 4: Disinfection

GreenhouseThe level of disease organisms, particularly viruses, present after cleaning and sanitizing is still high enough to offer a serious challenge to young or recently introduced plants. The use of a broad spectrum disinfectant active against viruses, bacteria, yeasts, moulds and other pathogenic organisms is essential to complete an effective disease control programme. It is of prime importance to ensure all surfaces are thoroughly wet with disinfectant to break the chain of infection. Dirt floors harbour millions of spores. Laying concrete floors improves hygiene and assists the disinfection process.

  • For routine disinfection of glasshouse structures apply 0.5% (1:200) Viru-Gard solution at a rate of 300ml per square metre (1 gallon/150 sq. ft) of surface area. Concrete floors require two passes a 1% solution for routine disinfection.
  • Use a knapsack sprayer or pressure washer at 35 bars (300psi) with a 45o spray head.

Stage 5: Fogging and Aerial Disinfection

When the greenhouse has been thoroughly cleaned and disinfected all moveable equipment should be returned. To disinfect inaccessible areas of the house that might have been overlooked, the house should be fogged. It is particularly important to fog any reception and storage area.

  • Spray Viru-Gard diluted at 1:100. Spray into the eaves using a very fine mist from a pressure washer or using a mechanical fogger.
  • Use at a rate of 1 litre of solution per 100 m³. Fogging with Viru-Gard is safer and more effective than traditional methods of fogging with aldehydes as the greenhouse can be entered soon after fogging limiting downtime to a minimum.

Continuous Protection with Plants in the House

Regular Fogging

TomotoesTo avoid the buildup of pathogens during the growth phase of a crop, routine fogging once a week with Viru-Gard is advised. The Viru-Gard formulation has been proved to be non-phytotoxic.

  • Spray Viru-Gard diluted at 1:200. Spray into the eaves using a very fine mist from a pressure washer or using a mechanical fogger.
  • Use at a rate of 1 litre of solution per 100 m³. Fogging with Viru-Gard is safer and more effective than traditional methods of fogging with aldehydes as the greenhouse can be entered soon after fogging limiting downtime to a minimum.

Site Security

Between applications of the Terminal Disinfection Programme there are many opportunities for introduction of infection to the greenhouse. Measures must be taken to reduce the risk of disease being brought onto the site with visiting vehicles and personnel and minimizing the movement of infective material from house to house.

Visitor Control

The following will help you to avoid pathogens being introduced into your greenhouse or spreading disease from one house to another.

  • Access to your greenhouse should be limited
  • Transport vehicles should be cleaned and disinfected upon arrival and on departure.
  • Require that all visitors wear clean or disposable clothes, overalls, hats, gloves and boots.

Pruning

Prune with a sterilized knife. Use Viru-Gard to sterilize by dipping (not soaking) in a 1.0% solution at the end of each row. Alternatively use a sponge soaked in a Viru-Gard solution.

Foot dips / Disinfectant Soaked Mats

Ensure foot dips or foam Mats are placed at the entrance to each greenhouse.
Fill foot dips with a solution of Viru-Gard diluted 1:100 and replenish twicw weekly or more often if heavily soiled. Ensure that soaked mats remain wet with a 1% Viru-Gard solution.

Hand Hygiene

Dirty or unwashed hands transfer infection. All visitors to the site should be required to wash their hands before entering the site using a germicidal hand soap. All staff should wash their hands before starting work, after breaks and when changing work activities.

Wheel dips

Fill with a solution of Viru-Gard diluted 1:100 and replenish twice weekly or more often if heavily soiled.

Disinfection of Paths, Roadways and Areas around Houses

Keep paths and areas around houses clear of trash piles as these are a potent source of infection. Spores are carried back into houses on feet and tyres or are blown in on the wind. Spray these areas regularly with a 1:100 dilution of Viru-Gard at a rate of 300ml per square metre.

Clothing

Wash clothing weekly and hang out to dry. Mosaic virus can persist for years, in unwashed overalls stored in the dark.

No Smoking

Tobacco products may contain Tobacco Mosaic Virus (TMV)

Ornamentals in Vegetable Greenhouses

Ornamentals such as grapevines, figs, oleanders, and hanging baskets harbour whitefly, thrips, nematodes and disease organisms. Do not grow these plants in a vegetable greenhouse.

Viru-Gard horticultural efficacy

A summary of independent efficacy data for the formulation of Viru-Gard is shown below:

Organism

Disease

Crop

Effective Dilution

Alternaria solani

Early Blight

tomato

1:200

Botrytis cinerea

Grey Mould

several

1:200

Clavibacter michiganensis michiganensis

Bacterial Canker

tomato

1:500

Clavibacter michiganensis sepedonicus

Bacterial Canker

potato

1:100

Collectotrichum coccodes

Black Dot Root Rot

tomato

1:200

Didymella bryoniae

Gummy Stem Blight

cucumber

1:200

Epicoccum nigrum spores

Grass Fungus

grass

1:200

Erwinia amylovora

Fireblight

apple

1:250

Erwinia carotovora atroseptica

Bacterial Stem Rot

tomato

1:100

Fusarium moniliforme

Fusarium Leafspot

 -

1:50

Fusarium oxysporum lycopersici

Fusarium Wilt

tomato

1:200

Fusarium oxysporum radicis-lycopersici

Fusarium Crown & Root Rot

tomato

1:200

Fusarium solani

Pepper Fruit and Stem Rot

pepper

1:500

Geotrichum cutaneum

 -  -

1:25

Penicillium italicum

Root rot

citrus

1:100

Penicillium italicum

 -

citrus

1:100

Penicillium oxalicum

Penicillium Stem Rot

cucumber

1:100

Pepper Mild Mottle Virus

fresh dried leaves and roots

pepper

1:20

Pepper Mild Mottle Virus

glass

pepper

1:50

Pepper Mild Mottle Virus

concrete

pepper

1:20

Pepper Mild Mottle Virus

knives

pepper

1:50

Phomopsis sclerotinoides

Black Root Rot

cucumber

1:200

Phytopthora cactorum

 -

apples

1:100

Pithomyces chartarum

 -

grass

1:100

Pithomyces chartarum spores

 -

grass

1:400

potex virus

Potatox X Disease

potato / tobacco

1:100

Pseudomonas syringae

Bacterial Speck

pepper

1:500

Pseudomonas syringiae syringiae

Bacterial Blast

plums, cherries

1:250

Pseudomonas solanacearum

Brown rot

apples

1:800

Pseudomonas solanacearum

Bacterial wilt

potatoes

1:800

Pseudomonas viridiflava

Bud Rot

kiwi fruit

1:250

Pyrenochaeta lycopersici

Corky Root Rot

tomato

1:200

Pythium aphanidermatum

Pythium Damping-off

several

1:500

Pythium sp

Pythium Damping-off

several

1:50

Rhizoctonia solani

Rhizoctonia damping off

several

1:200

Sclerotinia sclerotiorum

White Mould

several

1:200

Thielaviopsis basicola

Root Rot

tomato

1:500

Verticillium dahliae

Verticilium Wilt

tomato

1:500

Verticillium dahliae

Verticilium Wilt

 

1:50

Xanthomonas campestris

Citrus canker

Various citrus fruits inc. Orange, Lemon, Lime & Grapefruit

1:100

Xanthomonas campestris

Bacterial Spot

cabbage

1:500