Greenhouse - Insect Control

The following is a review of insect control for greenhouses including insecticide products registered for different insect pests in greenhouses.

Greenhouse Insect Control

Starting clean

Do not carry-over insects from one crop to another. Keep thrips numbers down to less than 10 per card per week in the fall and winter on poinsettias and Dracaena. Avoid keeping houseplants or allowing weeds to grow in the greenhouse. When each batch of media arrives for a new crop, check it for fungus gnats by filling a one-gallon ziplock bag half-full with moist soil. If fungus gnat adults emerge within two weeks, consider applying a fungus gnat treatment at planting time. Check incoming plant material carefully. If insects are found, treat them with an appropriate product (listed below) to start with as clean a crop as possible.

Scouting

Monitor thrips and whiteflies with yellow sticky cards. Change cards once per week. Use at least one card per house or one per 2,000 square feet. Check the first plants to flower for thrips. For spider mites and aphids, check susceptible plants like marigolds (mites) and pepper s(aphids), weekly. Potato wedges can be stuck in soil and checked 24 hours later for fungus gnat larvae.

Systemic insecticides

Use Marathon, Tristar, Flagship, Safari, or Aria in poinsettia pots, lily pots, or in hanging baskets prone to problems with whiteflies, aphids, mealybugs or soft scales. Note: Aria does not work on silverleaf whitefly. Tristar and Safari also suppress thrips.

Preventing outbreaks

If yellow sticky cards or scouting indicates an increase in aphids, mites, thrips, fungus gnats or whiteflies, apply the following materials once per week until populations decrease to acceptable levels.

Control Products:

Thrips: Avid, Mesurol, Orthene 97, Pylon, Safari, Sanmite, Tristar, and Conserve. Note: Some thrips populations may be resistant to Conserve.

Aphids: Aria, Azatin, BotaniGard, Celero, Decathlon, Discus, Distance, Endeavor, Enstar II, Flagship, Marathon, Ornazin, Orthene 97, Precision, Safari, Talstar, Tristar

Whiteflies: Azatin, BotaniGard, Celero, Decathlon, Distance, Endeavor, Enstar, Flagship, Marathon, Ornazin, Orthene 97, Precision, Safari, Sanmite, Talus, Judo, Tame, Tristar (Note: many populations of silverleaf whitefly are resistant to Marathon, and some may also be resistant to Flagship, Tristar, Safari, Distance and Talus)

Mites: Akari, Avid, Floramite, Hexygon, Judo, Ovation, ProMite, Pylon, Sanmite, Shuttle, Tetrasan.

Broad mites: Avid, Akari, Judo, Pylon, SanMite.

Fungus gnats: Azatin XL, Adept (not on poinsettias), Distance, Marathon, and (drenches) (perhaps other nicotinoids; not yet tested), Mesurol.

Mealybugs: Aria, Celero, Flagship, Orthene, Safari, Talus and Tristar.

New products

Sucrashield isfrom Natural Forces for controlling aphids, mites, thrips, whiteflies and caterpillars on vegetables, herbs and spices in the greenhouse and outdoors. It is also for use on ornamentals, flowers and bedding plants.

This new product is based on a tobacco plant extract and is available now. The active ingredients, sucrose octanoate esters , have an LD50 of 750 to 1500 ppm for whiteflies, and the label rate is 104 oz per 100 gallons (compared with 4 to 8 oz per 100 gallons for most products). This product is similar to some soap or oil products because it is classified by EPA as non-toxic to people, but requires an application rate of 0.8 to 1.0 percent every 7 to 10 days. Sucrashield bears a WARNING on the label because of eye sensitivity. There is no information on the label about phytotoxicity, so caution is recommended until you have tested it yourself, or until phytotoxicity test data is available.

This product will give herb growers another tool to add to the short list of products labeled for use on herbs.

Kontos is from OHP for controlling mites, whiteflies, aphids, and mealybugs. Kontos can be used in the greenhouse, nursery, and interiorscapes on ornamentals and vegetables.

The active ingredient in Kontos is spirotetramat, a tetramic acid derivative similar to Judo. This is a relatively safe product for humans and pets with a CAUTION on the label. Kontos has good activity on spider mites and whiteflies, including highly resistant whiteflies, like the “Q” biotype. Kontos is expected to be available in spring 2009.

Reprinted from "Greenhouse insect management" by David Smitley, Michigan State University Entomology in the MSU Greenhouse Alert Newsletter (1/09) http://www.ipm.msu.edu/grnhouse09/G01-01-09.htm#2