Sensor system warns of gray mold in greenhouses

Danish Technological Institute is developing an early warning system that can detect the harmful gray mold spores early, before they damage the plants.

Invisible threats cost millions

The horticultural industry faces significant challenges in combating harmful fungal spores such as gray mold. The fungal spores are invisible to the naked eye and attacks are often detected too late when the damage is already extensive. This results in reported yield losses of up to 25-50% for Danish nurseries.

In the project "Sensor-based early warning system for early detection of airborne gray mold spores in greenhouses", the Danish Technological Institute has teamed up with Senmatic, AmiNIC, Aarhus University and three nurseries to develop an advanced warning system that can detect these microscopic threats early and reduce the need for pesticides.

Smart sensors can lighten the air for horticulture

The innovative sensor system that the project set out to develop consists of two main parts - a particle counter and a biosensor. The particle counter continuously measures the number and size of particles in the air and can indicate whether gray mold spores are likely to be present. If this is the case, the biosensor is activated.

The biosensor is equipped with microscopic "tentacles" called peptides that are designed to bind specifically to gray mold spores. By combining the particle counter and the biosensor, growers get a reliable and early warning of the harmful fungus. They can take action before the spores infect the plants and cause devastating damage. The early warning system will not only save yields, but also significantly reduce the horticultural companies' pesticide consumption and overall environmental impact.

"During our trials on Funen, we mapped the ventilation rate in a greenhouse. Based on this, we created a mathematical model for how to ventilate the greenhouse. We could see that proper ventilation can both reduce the infection pressure from harmful fungal spores and lower energy consumption for heating. So it can be a good investment for a nursery to make a data-based calculation of how to ventilate rather than going with a gut feeling," says Thor- Bjørn Ottosen, specialist in air quality at the Danish Technological Institute.

The innovative warning system will be the first of its kind in the world and could potentially open the door for similar detection systems targeting airborne pests.

Equipment for measuring ventilation rates in a nursery using the trace gas method

Progress in the project

New knowledge about variations in spore counts
 

Using the Hirst spore trap, a method recognized for its accuracy and reliability, researchers in the project have documented significant variations in the number of grey mould spores in the air throughout the day, contradicting the previous belief that spore concentrations were constant. This new insight is of great importance for horticulturalists as it highlights the need for monitoring. Previously, spore concentrations were thought to be relatively stable, but the new data shows that the number of spores can fluctuate dramatically, from as little as 26 to over 2,800 spores per cubic meter of air. This indicates that the risk of plant infections can change from day to day and highlights the importance of a real-time monitoring system to effectively manage and prevent gray mold infestations.

Gray mold fungi grown on agar plates

OPC technology could be a promising tool for environmental monitoring of biological aerosols in horticulture

The project investigated whether affordable optical particle counters (OPCs) can be used for real-time monitoring of biological aerosols such as fungal spores.

Main results:

• OPCs were tested in the laboratory with aerosolized spores of the fungus Botrytis cinerea and compared to a reference instrument.
• The low-cost sensors could almost correctly detect the size distribution of the spores compared to the reference instrument.
• All particle counters recorded an increase in concentration during aerosolization, demonstrating their ability to detect changes in real time.

Potential benefits:

• Real-time detection: Rapid identification and response to pathogenic outbreaks.
• Cost reduction: Low-cost OPCs can reduce the cost of traditional monitoring methods.
• Improved accuracy: The ability to distinguish between particle sizes can improve accuracy in detecting specific pathogens.

The study emphasizes the potential of using OPCs to improve the monitoring of biological aerosols in horticulture. Further research and development is needed to assess the full potential of the technology in practical horticultural environments.

Efficient analysis of sensor data in greenhouses
 

For low-cost sensors to be used in greenhouses, it is important that all data used for analysis is accurate and reliable.

At the Danish Technological Institute, two models were trained to predict fungal spore concentrations based on sensor data. The best model reached an accuracy of 81.4% and only 4.9% of high fungal spore events were missed.

This technology allows growers to monitor fungal spore concentrations in their greenhouses very accurately. By knowing when and how many fungal spores are in the air, growers can make quick and effective decisions to protect their plants. For example, if there is a high concentration of fungal spores, growers can quickly respond by adjusting ventilation, applying appropriate fungicides, or changing other environmental conditions to reduce the risk of plant disease.

Horticultural technology providers can integrate the advanced data analytics and cleaning technology into their monitoring systems. This will help them deliver better products to customers who want more accurate and reliable data on fungal spore concentrations in their greenhouses, keeping crops healthy and productive.
 

Peptides can distinguish between gray mold and other fungal spores

In an article under review in the Archives of Phytopathology and Plant Protection, Danish Technological Institute researchers describe how they have developed an innovative method to detect gray mold caused by the fungus Botrytis cinerea, which can be devastating to crops in greenhouses. The method uses an advanced technique called phage display technology to find small proteins known as peptides that can bind specifically to Botrytis cinerea spores. The great advantage of this technology is that these peptides can be integrated into different types of test equipment or sensors. These devices can be installed directly in the greenhouse and provide quick and accurate results on the presence of gray mold. This allows growers to detect the disease very early before it has time to spread and cause major damage.

Experimental setup in one of the nurseries

Bachelor project investigates ventilation in greenhouses
 

In a bachelor project carried out in the fall of 2022 at the Danish Technological Institute and Aarhus University, student Benjamin Clement Johannsen followed the above project and focused on investigating how to improve the understanding and control of ventilation in greenhouses.

Using nitrous oxide (N2O) as a tracer gas, mathematical models were developed and tested to predict how efficiently two greenhouses near Odense could exchange air under different weather conditions. The project showed that greenhouse ventilation is significantly affected by wind direction, wind speed and the physical design of the greenhouse. This emphasizes the importance of knowing ventilation rates accurately, especially in relation to airborne plant disease control, temperature and humidity management. The mathematical models developed can help gardeners better manage the indoor climate, potentially reducing the need for chemical pesticides and increasing productivity. For ventilation system suppliers, the results provide insight into how different design parameters such as window placement and size affect air exchange. This can be used to design more efficient ventilation systems adapted to specific operating conditions.

ABOUT THE PROJECT

Project duration

2021-2025

Type of project

Green Development and Demonstration Program under the Damish Ministry of Agriculture and Food

Project total

8.3 million DKKR.

Partners

Senmatic, AmiNIC, Aarhus University, Danish Technological Institute, PKM, Lundegaard and Hjortebjerg.