Managing Greenhouse Environments
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Questions and Answers

What is a consequence of high humidity in greenhouses?

  • Increase in crop yield
  • Reduction of pests
  • Improvement of plant growth
  • Encouragement of disease development (correct)

Plants should be planted closely together to enhance air circulation.

False (B)

What is one method to reduce condensation in heated greenhouses?

Late afternoon ventilations

_________ fans are used in greenhouses to circulate air and reduce humidity.

<p>Exhaust</p> Signup and view all the answers

Match each air circulation technique to its purpose:

<p>Fans = Circulate air and reduce humidity Ventilation = Exchange warm air with cooler air Plant spacing = Facilitate air movement Overhead baskets = Reduce water evaporation</p> Signup and view all the answers

Which of the following factors influences the orientation of a ridge vent in a greenhouse?

<p>Prevailing winds (B)</p> Signup and view all the answers

Hanging baskets can improve humidity levels in crop canopies.

<p>True (A)</p> Signup and view all the answers

Which of the following is a method to manipulate ventilation in high tunnels?

<p>Opening sidewalls and ridge vents (A)</p> Signup and view all the answers

Temperatures outside the normal range of growth do not affect plant stress levels.

<p>False (B)</p> Signup and view all the answers

What is a recommended solution for surface sterilizing tools and benches?

<p>A dilute solution of household bleach (9 parts water to 1 part bleach)</p> Signup and view all the answers

Good air drainage and gentle __________ are important for selecting a site for new construction.

<p>slopes</p> Signup and view all the answers

Match each practice with its purpose in high tunnel management:

<p>Surface sterilization = Prevent spread of pathogens Regular cleaning of landscape cloth = Maintain cleanliness between cropping seasons Replacing plastic liners = Prevent contamination Monitoring temperatures = Control plant stress levels</p> Signup and view all the answers

What can puddling water on greenhouse floors lead to?

<p>Weedy growth and pathogen sources (D)</p> Signup and view all the answers

What is one of the main factors contributing to increased disease incidence in greenhouses and high tunnels?

<p>High relative humidity (D)</p> Signup and view all the answers

Daytime relative humidity levels between 25% to 70% are usually supportive of pathogen growth.

<p>False (B)</p> Signup and view all the answers

Sweeping landscape cloth between cropping seasons is unnecessary and can be skipped.

<p>False (B)</p> Signup and view all the answers

Name one environmental factor that can stress plants in high tunnels.

<p>Temperature</p> Signup and view all the answers

What temperature and humidity conditions favor the development of plant pathogens?

<p>High humidity above 90% and warm temperatures.</p> Signup and view all the answers

To manage plant diseases, it is important to control __________ and __________ in greenhouse environments.

<p>humidity</p> Signup and view all the answers

Hoses left on the ground may become contaminated with __________.

<p>plant pathogens</p> Signup and view all the answers

Match the following terms with their correct descriptions related to greenhouse management:

<p>High humidity = Promotes disease incidence when above 90% Temperature control = Essential for pathogen management Ventilation = Helps to reduce humidity levels Air circulation = Prevents localized dampness</p> Signup and view all the answers

Which ventilation strategy is most effective in managing high humidity levels in greenhouses?

<p>Opening vents (A)</p> Signup and view all the answers

Why is maintaining air circulation critical in a greenhouse?

<p>To prevent localized dampness and reduce disease spread.</p> Signup and view all the answers

High levels of leaf wetness contribute positively to plant growth in greenhouse settings.

<p>False (B)</p> Signup and view all the answers

Effective __________ strategies can help manage temperature and humidity, minimizing disease risk.

<p>ventilation</p> Signup and view all the answers

Flashcards

Greenhouse ventilation

The act of exchanging air inside a greenhouse with fresh outdoor air to lower relative humidity and reduce disease development.

High humidity effect

High humidity promotes disease development in plants, such as powdery mildew and Botrytis gray mold.

Plant spacing

Adequate plant spacing allows for proper air movement, drying of foliage, and easier application of treatments (like fungicides).

Microclimates

Small, localized areas within a greenhouse or high tunnel that have slightly different conditions from the surrounding areas, particularly high humidity.

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Exhaust fans

Exhaust fans remove warm, moist air from enclosed structures (like greenhouses), replacing it with cooler air.

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Condensation prevention

Ventilation in greenhouses, especially during late afternoon, helps to reduce condensation from forming, which is often a challenge during cooler nights.

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Ventilation in high humidity periods

Continuous operation of systems like fan-jets during high humidity, including nighttime or rainy days, is a key technique for keeping greenhouses healthy by lowering humidity and increasing air circulation.

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High tunnel ventilation

Controlling air flow in high tunnels by opening sidewalls, endwalls, and ridge vents to manage temperature and humidity.

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Ideal temperature for plant growth

Plants grow best within a specific temperature range. Outside this range, they experience stress and become more susceptible to diseases.

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Why sterilize work surfaces?

Cleaning benches, tools, and floors eliminates disease-causing pathogens that can spread from contaminated items.

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Bleach solution for sterilization

A mixture of 9 parts water and 1 part bleach effectively kills most pathogens.

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Landscape cloth cleaning

Sweep and spray landscape cloth with high-pressure water between growing seasons to prevent pathogen buildup.

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Plastic liner replacement

Float bed liners should be replaced annually to prevent pathogen buildup.

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Puddling

Water accumulating on the floor increases humidity, promotes weed growth, and can harbor pathogens.

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Hose contamination

Hoses left on the ground can become contaminated with plant pathogens.

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Plant debris removal

Cleaning up plant debris after harvest helps prevent the spread of pathogens and diseases next season.

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Ideal disease environment

Greenhouse and high tunnel conditions, often warm and humid, create ideal situations for plant diseases to thrive.

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Key disease factors

High relative humidity (above 90%), free moisture on plants, and warm temperatures are crucial for disease development.

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Disease management goal

The primary goal is to produce high quality, marketable products by preventing and controlling plant diseases.

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Humidity management

Controlling relative humidity is essential for disease prevention, particularly keeping it below 90% to inhibit pathogen growth.

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Optimal daytime humidity

Daytime relative humidities of 25% to 70% are generally considered optimal for preventing disease development.

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Ventilation

Exchanging air inside a greenhouse with fresh outdoor air helps lower humidity, preventing disease spread.

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Continuous ventilation

Maintaining ventilation even during high humidity periods, including nighttime or rainy days, is crucial for keeping greenhouses healthy.

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Study Notes

Managing Greenhouse & High Tunnel Environments

  • Greenhouse and high tunnel environments are often warm and humid, which can promote disease development
  • Key factors for disease development include high relative humidity (90% or more), free moisture (leaf wetness, wet soil), and warm temperatures
  • Managing these environments is crucial for high-quality produce
  • Managing relative humidity and temperature are key to minimizing disease spread

Managing Relative Humidity

  • High relative humidity promotes many leaf, flower, and fruit diseases (including powdery mildew and gray mold)
  • Daytime relative humidity between 25% and 70% often inhibits pathogen infection
  • Humidity above 90% for prolonged periods can increase disease incidence
  • Practices that manage humidity and temperature help mitigate this

Air Circulation

  • Continuous air flow systems (fan-jet or horizontal) should operate in greenhouses for high humidity periods, particularly at night and during rainy days
  • Exhaust fans can aid circulation when greenhouse sides are closed
  • Exchange air inside greenhouses and tunnels with fresh outdoor air to reduce internal humidity
  • Opening sidewalls and vents can help ventilate high tunnels.

Ventilation

  • It's important to exchange air in greenhouses and high tunnels with fresh outdoor air to reduce internal humidity
  • Ventilation in high tunnels can be manipulated by opening sidewalls, endwalls, and/or ridge vents.

Plant Spacing

  • Closely-spaced plants and overlapping canopies create microclimates with higher humidity, which can be the first sites of disease development
  • Adequate plant spacing promotes air movement, facilitating drying of foliage and making spray coverage easier

Water Management

  • Water dripping on foliage can contribute to diseases. Drip irrigation is a better choice than overhead irrigation.
  • Water only as needed, monitoring plants closely for variations in light, temperature, and humidity.
  • Consider plant groupings for consistent water needs.

Sanitation

  • Disease-causing pathogens spread via used pots, dirty tools, work surfaces, and contaminated hoses
  • Regularly sterilize benches, tools, and work surfaces with a dilute bleach solution or commercial disinfectant.
  • Remove diseased plant material immediately and bag (don't compost).
  • Clean-up plant debris on benches, ground beds, and walkways, preventing further pathogen spread.

Soil Management

  • Commercial, pathogen-free growing media are ideal for commercial production in flats and pots
  • Ensure soil doesn't become excessively wet and avoid contact with natural soil
  • Rotate crops and soil beds to prevent soilborne pathogen buildup
  • If using natural soil, follow recommendations for crop rotation and soil maintenance to minimize pathogen buildup.

Other Important Considerations

  • Tobacco mosaic virus (TMV) is spread physically through contact; wash hands thoroughly after tobacco product use.
  • Avoid bringing soil from outdoors into greenhouses to prevent soilborne pathogen introduction.
  • Avoid excessively wet conditions as these can increase humidity and pathogen growth.

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Related Documents

Managing Greenhouse & High Tunnel Environments 2016 PDF

Description

This quiz focuses on the management of greenhouse and high tunnel environments, emphasizing the control of humidity and temperature to prevent disease. It covers key factors affecting disease spread and the importance of air circulation in maintaining optimal conditions for high-quality produce.

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