Indoor farms offer the advantage of higher control over the ability of pests to enter farms and overall lead to a reduction in pest load. Although, it is impossible to close a farm to 100% of pests. They can make their way into the system on people, infected materials, such as seeds, or leaks in the farm envelope. Pests, diseases, hydroponic nutrient imbalance or unexpected changes in environment all have influence over crop health. The relationship between these factors are known as the plant disease triangle (see image below). If one aspect of the triangle is unbalanced the door to disease is opened.
Environment: In closed plant production, the environment refers to the aerial and root zone. The aerial environment is impacted by temperature, humidity, air movement, CO2 and light levels while the root zone is impacted by the temperature of the nutrient solution, oxygen levels, pH, EC and available nutrients. Although highly controlled, it is possible for these environmental parameters to shift, which underscores the importance of continually monitoring the farm’s environments, both with sensors and manually.
Pathogen: Regardless of biosecurity practices, it is extremely difficult to completely prevent the infiltration of pests or disease at some point. Whether it be on humans, infected materials, air leaks in building envelopes, or ventilation, it is likely that eventually we will see an outbreak. Pathogens include small insects, bacteria, viruses, and fungi (including spores). These are in our environments all of the time and without care will make their way into closed farms.
Knowing that it is possible for pests to move into a farm at any time, it is important to continually monitor crop health. Thorough and more formal crop screenings should be included in weekly procedures, but the whole team should be trained to keep their eyes open for changes in crop health on incidence of pests during day to day operations. A clear chain of communication should be outlined to ensure the presence of an anomaly can be communicated quickly and efficiently to Integrated Pest Management (IPM) managers or head growers.
Day to day, growers should be aware of:
- Shifts in any crop coloration. On leaves, this can be global or concentrated, also symptoms may present only on young or old foliage rather than both.
- The presence of any dew or similar materials on leaves. Many pests leave residues on top or the underside of leaves and some diseases present as mold like films.
- Changes in the turgor of the leaves or stems of plants.
- Close investigation should include:
- Checking the underside of leaves for the presence of pests, eggs or residue left by pests.
- Inspect stems, especially at branching points and the base of the plant.
- Closely inspect any flowers, as some pests will find refuge inside.
Traditional tools at growers disposal:
- Sticky traps give an advantage to growers by attracting pests (due to their yellow color) and giving a snapshot of both the type of pests and potential population size in the area. They should be monitored regularly and changed out at a regular interval.
- Portable microscopes or magnifying glasses give a huge advantage to growers. These tools allow growers to have more confidence during inspection, as pests and their eggs can be extremely small.
- Documentation is a great tool to observe trends. If a certain area within a farm is consistently the source of outbreaks it is likely worth further investigation. It could be attributed to: a pocket of stagnant air, location. Documentations allows those trends to be observed over time and the causes addressed if possible.
The Role of Technology in Pest and Disease Detection
The next frontier of pest, disease and overall crop management in indoor farms is machine vision. These systems integrate image capture and processing to autonomously identify a variety of issues with crops. These systems rely on a variety of cameras (including RGB, NIR and thermal) installed permanently within the farm.
Disease detection procedure processes images and detects any lesions on plant foliage. These areas are segmented and processed by their color, shape and texture. When a model has adequate training it can use this information to diagnose diseases. Early pest detection is difficult as their density in the crop canopy begins very low. Pest detection is best achieved with machine vision by using sticky cards, although detection can be done directly from plant leaves. Early detection of both pests and disease is incredibly important in closed plant production as it allows for proactive responses from growers. Removing diseased plants or implementing IPM strategies for pests allow for pesticide free solutions in preventing extensive crop loss.
Regardless of grower experience, the first signs of crop issues are very subtle and may not be visible to the human eye. Research studies have reported machine vision systems detecting plant calcium deficiency one day before humans and plant water stress two hours before humans could detect it. Whether these tools are being used to diagnose issues or simply provide early detection for growers, as this technology continues to develop it will become increasingly indispensable in indoor farms.
Cultivatd’s team of experienced indoor farmers has a range of advanced tools and services available to mitigate risks, and diagnose problems at any scale. Contact us to learn how we can help.