Starting with high quality disease and insect free plant material is a critical step in the management of diseases and insect pests in your greenhouse. The first step in ensuring disease and insect free plants in your greenhouse is to purchase high quality pest free plant material from reputable producers. When the new plant materials are brought into the greenhouse they should be inspected thoroughly for any symptoms of disease or insect pests. Inspect incoming plants for key insects, diseases, weeds and cultural problems. Inspect the entire plant - leaves, stems and roots for signs of pest activity and for general health. Train employees to identify diseases and insect pests. If at all possible, do not accept plant shipments with serious insects or diseases with wide host ranges, and are difficult to treat. For example, incoming plants may be infested with resistant insects, mites or Botrytis spores that will be more difficult to treat. Do not accept plant material infected with incurable diseases, such as viruses, bacterial leaf spot diseases, or foliar nematodes. Incoming plant materials should also be quarantined from the rest of the crop until you are sure they are disease and insect pests free. If possible set a small area in the greenhouse aside as a quarantine area and keep plant material from different suppliers separate.
If you find isolated evidence of insect activity, such as aphids, and decide to keep the shipment, place in the quarantine area. Treat immediately and hold the plants in this area until you are sure that they are healthy, salable and free of pest problems. Ask workers to enter this quarantine area at the end of the day to avoid moving pest problems throughout your operation.
See the fact sheets: Ten Basic Steps to Less Disease in your Crop, Ohio State University
IPM Scouting and Decision Making, UMass Extension
Scouting and Decision Making, UConn Extension
Geoffrey Njue, University of Massachusetts Extension
