Wednesday, February 11, 2009

Greenhouse - Check Your Incoming Plants for Insects and Mites

Greenhouse growers should check all incoming plugs, cuttings, and prefinished plants for insects and mites. The following is an article on the subject from Michigan State University.

Greenhouse growers are already reporting insect activity. We have already seen warm weather insects like two-spotted spider mites on ivy geranium and Lamium cuttings. Inspect all incoming plant products for hitchhikers that you did not pay for but may be getting when your cuttings come in. Look on the underside of leaves with a 16-20x hand lens for mites, or tap cuttings as you open the box over a white sheet of paper and look for the tiny, yellowish-red specks moving on the paper. Check incoming ivy geraniums and spikes also for thrips as low numbers have been seen both on leaves and on sticky cards. Are cards up in your houses that have product in them? Do not ignore the spikes as they are a magnet for thrips and even spider mites this time of the year.

If you have any tropicals or herbs that you are bringing in like Lantana, lavender and rosemary, pay attention for white flies as we have seen some come along with cuttings from southern growing areas. There is a good chance that they are Q-biotype silver leaf whiteflies which are resistant to some insecticides. Click here for management strategies for Q-biotype if it has been confirmed in your greenhouse. Be sure to isolate your pest problems now and control them before moving them to other houses as the season goes on.If you’re not sure of the insect or plant problem, be sure to get it identified correctly before applying a pesticide. I still see growers putting on products that do not work for the pest they are dealing with. Especially in today’s economic times, indentify first then treat. If you’re not sure of the problem, contact your local Extension educator and we will be happy to come out and help you.

Adapted from "Check incoming cuttings for bugs" in the most recent issue of the Michigan State Greenhouse Alert Newsletter by Thomas Dudek, District Extension Horticulture and Marketing Educator, Michigan State University

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