Many growers started later this season, but greenhouses are gradually becoming full of plant material. In my site visits across the state, the primary pest activity I have seen include thrips and scattered aphids and spider mites. Fungus gnats tend to be more of an issue in overly moist green houses.
Use yellow sticky cards to detect thrips before their feeding damage (scarring and distortion of leaves) is observed. To manage thrips, shorten spray intervals to 4-5 days and rotate pesticides with different modes of action. Some options for management (based upon grower feedback) include Avid (abamectin-group 6) tank mixed with azadirachtin- Group 18B), Botanigard or Mycotrol tank mixed with Azatin, Pedestal (novaluron-group 15) tank mixed with Pylon (chlorfenaphyr- group 13), Safari (dinotefuran Group 4A) to help suppress thrips. Overture (pyridalyl) (unknown mode of action) has contact, translaminar and some ingestion activity and can be added into your rotation program. It is labeled for thrips and caterpillars but may take from 7 to 14 days before you see control. Horticultural oil (Pure Spray Green, Saf-T-Side, or Suff Oil X ) may also be an option provided label cautions regarding plant safety are followed. In propagation houses, some growers are using beneficial nematodes for both fungus gnats and adult thrips.
Biological control agents for thrips must be used preventatively and include the predatory mites Neoseilus cucumeris, and Amblyseius swirskii. The soil dwelling predatory mite, Hypoaspis miles may also feed upon thrips pupae in the growing medium. Minute pirate bugs (Orius sp), also feed upon thrips and their establishment in ornamental greenhouses may be encouraged with the use of the pollen producing Ornamental Pepper “Black Pearl”.
Spider Mites – have been noted coming in on incoming plants. such as Ipomoea “. Look on the underside of the leaves, for the spider mites, and their round eggs. On plants with thick leaves, their feeding damage may resemble nutrient deficiency.
Fortunately, there are a number of miticides that work well. If spray coverage will be difficult, use translaminar (moves thru the leaf) miticides such as abamectin (Avid), etoxazole (TetraSan), chlorfenapyr (Pylon) and spiromesifen (Judo). Read the label carefully regarding plant safety precautions before applying.
Contact materials such as insecticidal soaps and horticultural oils may be used provided plant safety precautions are followed. Continue monitoring to see how effective the treatments were and if repeat treatments are needed. For a complete listing of available miticides, see the most recent edition of the New England Greenhouse Floriculture Guide.
Beneficial predatory mites active against spider mites include the fast acting Phytoseiulus persimilis and the slower acting Neoseilus californicus.
If you missed the recent Spring Bedding Plant meetings, held in Feb, the PowerPoint presentations are online at the UCONN IPM web site (www.hort.uconn.edu/ipm) Look under What’s New in the upper right hand corner.
|New England Greenhouse Update now online. University Extension Specialists in New England, in conjunction with USDA's Northeast Sustainable Agriculture Research and Education, contribute information to this new website. Timely updates are provided for commercial growers of greenhouse crops and flowers in Massachusetts, Connecticut and Rhode Island. You can use this additional resource for more information about current observations and recommendations on environmentally safe production practices.|
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