Insects and diseases are a major challenge in greenhouse production. Integrated Pest Management (IPM) is an important tool to managing pests by using physical, cultural, biological, and chemical tactics that are, safe, profitable, and environmentally compatible. It is an approach that is adaptable to all greenhouse grown crops, and focuses on pest management rather than pest elimination with harsh chemicals.
Cultural controls aim to make a crop’s environment less suitable for pests. They are mostly preventative measures that can be thought of as best practices in the production of a crop. Sanitation plays are major role in any pest control program, but on its own it may not fully control a pest problem. Simple tasks like removing dead and dying leaves, keeping walkways and surfaces of beds clean, carefully checking for pest infestations when bringing in new plant material in the greenhouse are all simple ways to avoid the spread of pests.
Light, temperature, humidity, water and nutrients can also have an effect on pests and diseases. Management of temperature and humidity are important in the management of plant diseases such as powdery mildew and Botrytis. Spider mites prefer hot, dry conditions, so increasing humidity with overhead misting can help slow down their development. Though adjusting the environmental controls in a greenhouse can have a positive impact on a pest problem the technique can get complex, as the grower needs to take into consideration the environment required by the plants in the greenhouse.
Exclusion (keeping insects away) finds itself as both a cultural and physical control for dealing with pests. In a cultural sense, proper crop spacing can help keep insects from spreading from one plant to another. Another method is exclusion with trap crops, where the grower uses a crop that pests prefer as a deterrent to keep them off of the money crop. Also, proper nutrient levels can aid in exclusion. Nitrates in particular can impact the development and production rates of insects: Aphids love nitrates.
Physical controls are a combination of preventative and monitoring measures, mostly with screens and/or sticky tape. Screening a greenhouse can greatly reduce the entrance of pests like thrips, aphids, whiteflies, and any other airborne pests you can think of. The insects that can be kept out of the greenhouse, as well as airflow restriction all depends on the type and mesh size of the screen used. It is important to know the main pest issue that’s at hand before shopping for screens, as insects come in different shapes and sizes. The smaller the mesh size of the screen the less airflow, and greater chance for the screen to get clogged with debris. Screening can also be used to keep beneficial insects inside of the greenhouse.Technology like positive pressure cooling can also aid in insect exclusion, but that’s for another blog post, see here for more information.
Yellow sticky tape (picture above) helps control insect problems by trapping them as they land or walk onto it. This approach can have the opposite effect if the grower is using a biocontrol program, as the good insects will also get trapped on the tape.
Cultural and physical controls are important aspects in IPM. Over the years they have proved to work well with preventing pests, but what can you do if your greenhouse is already infested? Stay tuned for my next post: IPM Biocontrol, where I will explain biocontrol, the next technique on the IPM list.
Do you have any experience with this topic? How do you manage your greenhouse pests? Please leave your thoughts in the comment section below.