Inspecting Incoming Plants
Monday, 08 March 2010 13:11
Inspect incoming plants carefully for signs of insects, diseases, weeds and cultural problems. Inspect the entire plant - leaves, stems and roots for signs of pest activity and for general health. Look for any distorted new growth on incoming plugs and transplants that might be caused by thrips. Blackened, firm stems and leaf spots on garden impatiens and New Guinea impatiens are signs of Impatiens necrotic spot virus (INSV). INSV test kits are useful for quick tests of suspicious looking plants.
Look on the undersides of leaves for spider mites. They are often found along the mid-vein of ivy geraniums, ipomea, thunbergia and other susceptible plants. On ivy geraniums, spider mite damage is similar to damage caused by thrips and oedema.
Inspect root health also. Roots should be white with vigorous growth. Roots that are brown or decayed are evidence of root rot disease or may be caused by overwatering or high soluble salts.
When handling and cleaning incoming plants, work in blocks and wash hands thoroughly between blocks of plants. If disposable gloves are worn, change or clean them between blocks. This will prevent spreading infectious diseases that are transmitted mechanically, such Bacterial leaf spot on geraniums and Tobacco Mosaic Virus on petunias and related crops.
If at all possible, do not accept plant shipments with serious insects or diseases with wide host ranges, and are difficult to treat. Do not accept plant material infected with incurable diseases, such as root rots, viruses, bacterial leaf spot diseases, or foliar nematodes. If you need confirmation, isolate a few plants showing symptoms and send them to a diagnostic laboratory. If you find isolated evidence of some insect activity, for example, aphids, and decide to keep the shipment, identify an isolated, quarantine area in which to keep the plants. Treat immediately and hold the plants in this area until you are sure that they are healthy, salable and free of pest problems. Only enter this quarantine area at the end of the day to avoid moving pest problems throughout your operation.
Tina Smith, University of Massachusetts
