The Plant Disease Triangle
The three sides of the plant disease triangle represent the three components necessary for plant disease to occur. The three components are the host, the pathogen, and the environment. The host is the plant or part of the plant. The pathogen is the biological infectious agent (i.e., virus, fungi, bacteria, plant parasitic nematodes, phytoplasmas). The environment creates a condition conducive to the spread and/or manifestation of the disease.
Heating with a well-designed, installed low-intensity infrared system can, in many cases, help to interrupt disease-conducive environmental conditions, thus breaking the plant disease triangle. Two of the most common conditions that encourage many plant diseases are plant wetness/free moisture on plants and high humidity. These common greenhouse conditions are controlled very effectively with infrared heating.
Since infrared heating keeps surface temperatures above air temperatures, surface moisture is evaporated more rapidly than is possible with conventional heating systems. Low-intensity infrared heating therefore can help the grower to effectively control humidity– one of the key environmental factors leading to many diseases. This natural and beneficial "side effect" of elevated surface temperature happens with even-heating infrared systems and occurs without the grower applying any special techniques.
- THE EASE OF CONTROLLING FREE MOISTURE ON PLANTS IS A TREMENDOUS BENEFIT OF INFRARED HEATING.
- According to plant pathologists, free moisture/plant wetness promotes the following diseases:
- FUNGAL LEAF SPOTS — CERCOSPORA, ALTERNARIA, COLLECTOTRICHUM
- GRAY MOLD (BOTRYTIS BLIGHT)
- DOWNY MILDEW
- LEAF RUSTS
- BACTERIAL LEAF SPOTS — XANTHOMONAS, PSEUDOMONAS
- ROOT ROTS — PYTHIUM (BLACK ROT OR WATER MOLD), PHYTOPHTHORA (CROWN ROTS), RHIZOCTONIA, SCLEROTINIA SCLEROTIORUM (COTTONY ROT).
- PERIODS OF PLANT WETNESS, AS WELL AS WET POTTING MEDIUM ALLOW A SUITABLE ENVIRONMENT FOR ROOT ROTS. INFRARED HEATING KEEPS THE SOIL WARM TO HELP CONTROL PERIODS OF OVERLY WET SOIL MEDIUM.
Disease can also be spread by insects in wet environments. Certain insects thrive on algae growth on pots, soil, floors, or benches in wet environments. These insects can deliver bacteria or fungus-causing diseases like Thielaviopsis root rot (black root rot). Since infrared heating quickly evaporates moisture on all these surfaces, it can interrupt the wet environment and help to prevent the environmental conditions that attract insects. Insects that thrive on wet environments include fungus gnats and shore flies.
GreenHouse Infrared HeaterS - Gentle, Even Heat, Just Like The Sun
Infrared Heating Benefits
Improves Soil Conditions - Provides better germination, rooting and even plant growth.
Provides Dryer Environment - Eliminating effects of humidity, reducing powdery mildew and disease.
Keeps Plants Warmer Than the Air - Virtually eliminating moisture forming on plants and potential for disease.
Energy Efficient – Uses less energy by heating plants, soil, benches, floors, and objects, not the air.
Promotes Natural Processes - evapotranspiration, photosynthesis, and natural ventilation.
Let’s you focus on growing! Dependable operation, less downtime, increased production
Two Major Types of Low-Intensity Infrared Heaters Used in Greenhouse Applications
Unitary greenhouse infrared heaters
These heaters have a single burner located at one end of the heat exchanger tube. The combustion takes place at the burner end, and the products of combustion are exhausted or vented at the opposite end. As a result, one end of the heat exchanger tube is warmer and gives off more heat than the other end. If the heater is mounted high enough, the end-to-end heat difference is minimized. Since most greenhouse buildings are relatively low (less than 20' [6 m] high), the difference in heat can be noticed from end to end. To minimize the uneven heat distribution, the heater can be installed in a U-shape. As a result of making a U-shape, the overall length of the heater is halved, reducing the area of heat coverage at the floor.
Burners-in-series greenhouse infrared heaters
These heaters are most suitable for greenhouse installations requiring even heating. Burners-in-Series heating systems have multiple burners along the length of a heat exchanger tube. The burners are incrementally spaced along the heat exchanger tube to allow the heat exchanger tube to be reheated before surface temperatures cool. This type of infrared heating system offers heat distribution far beyond the capabilities of unitary heaters or high-intensity heaters. Overall heater lengths can be much longer, and system shape is custom engineered to fit the greenhouse type. Multiple burners are vented through a single pump allowing fewer venting penetrations. Heaters with the trade name CORAYVAC® have a Burners-in-Series design.
Resources
Plant Disease Triangle
