Inspecting incoming plant material is key to greenhouse pest control

Don’t propagate pests in your propagation house. Remember to inspect incoming propagules.

Mandevilla cuttings. Instead of rooting these cuttings, the grower was propagating bacterial soft rot. Photo credit: Jan Byrne, MSU Diagnostic Services

Mandevilla cuttings. Instead of rooting these cuttings, the grower was propagating bacterial soft rot. Photo credit: Jan Byrne, MSU Diagnostic Services

Most greenhouse employees know that greenhouse sanitation is critically important to managing pests in the production environment. However, when incoming plant material containing pests is planted in the propagation house, even the cleanest greenhouse can turn into a problem. This is because the propagation environment is ideal for many diseases to develop and you may find yourself propagating the disease rather than the plant (see photo).

Michigan State University Extension recommends that the first step to keep this from happening is to purchase high quality certified pest-free stock whenever possible. You may even want to visit your plant supplier to see their sanitation program before purchasing from them. While the initial investment in purchasing high quality propagules may seem more expensive than other sources, consider the cost of not doing so. Receiving inexpensive and potentially low quality plants in the beginning of the season costs more by the end of the season because of increased management costs, lower crop quality, and lost sales revenue. In addition, your reputation may be tarnished which may influence next year’s sales.

When new plant material is brought into the greenhouses, inspect the plant material thoroughly. It is imperative that employees inspecting the plant material can identify diseases and insects so they can reject the shipment or send the plants to a quarantined area of the greenhouse. Also, look for injury symptoms on arriving plants as injured plant material is much more susceptible to some diseases.

Suspicious plants that are not rejected or discarded should be tested for diseases immediately either with in-house testing or sent to professional labs like Michigan State University Diagnostic Services. For more information on using in-house pathogen testing, see the e-GRO article titled “Questioning a Plant Pathogen in your Greenhouse Crop?” For more information on how to send samples to a professional diagnostic lab, see the lab’s website for instructions.

If possible, keep plants from different sources (suppliers) in separate areas of the greenhouse. This way, pests and problems on plants from one producer don’t spread to clean plants from another producer. Once you are sure the new plants are clean, the plants can then be moved together.

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