§      Why produce flowering Phalaenopsis orchids in Michigan?
§      Correction on availability Of NCR 581
§      Greenhouse insect management
§      Spider mites appear early this year

Why produce flowering Phalaenopsis orchids in Michigan?
Roberto Lopez and
Erik Runkle
Horticulture

Today, Phalaenopsis orchids are replacing the traditional African violet, chrysanthemum, and azalea as the flowering potted plant for the American home and office. This orchid is being seen everywhere: on television shows, in popular magazines, and on the shelves of their local mass retailers. The exotic array of flower colors, its ease in care (growing and reflowering), and its long flower longevity (2 to 3 months) make the Phalaenopsis orchid a very desirable plant to purchase.

In wholesale value, orchids have become the second most valuable flowering potted crop in the United States. In the past six years, production value has increased 147 percent, and in 2002 the estimated wholesale value was $105.6 million. Industry insiders estimate that of all the orchids sold in the U.S. in 2002, Phalaenopsis accounted for at least 85 to 90 percent of sales. The retail price of a 6-inch potted Phalaenopsis can vary between $7 to $29, depending on the number of flower spikes and the container.

Due to the increasing consumer and grower interest and the lack of scientific information regarding orchid production, in 2000 we initiated a research program at Michigan State University to determine the cultural and flowering requirements of orchids, including Phalaenopsis.

Why orchids in Michigan?
Michigan growers actually have an advantage over growers in warm climates (such as Florida and California) when growing potted orchids that have a cooling requirement. To induce flower spiking, plants need to be exposed to "cool" temperatures. To achieve these cool temperatures, some growers in warmer climates go to extremes to cool the greenhouse, including use of air conditioning, which can be expensive.

Specifically, Phalaenopsis orchids require cool temperatures (less than 79°F, or 26°C) for flowering. Traditionally, growers use a 77/68°F day/night (25/20°C) temperature regimen for spike initiation. After four to five weeks at these temperatures, plants can be grown at a wider range of temperatures to time flowering with their specific marketing date(s). Phalaenopsis grows best under relatively low light levels (1200 to 2000 footcandles, or 240 to 400 µmol×m^-2×s^-1), which makes it ideal for the low light conditions that we receive during the winter in Michigan.

Seedlings or tissue-cultured plants require at least 18 months to reach a mature flowering stage. Since the optimal temperatures for vegetative growth are approximately 81 to 86°F (27 to 30°C), we suggest that growers in northern climates (such as Michigan) purchase mature, nonflowering, bare-root or potted plants. Upon arrival, plants can be cooled and scheduled to flower for holidays such as Christmas, Valentine's Day, Easter, and Mother's Day, or throughout the year.

For more information on the ongoing orchid research program at Michigan State University, please visit: http://www.hrt.msu.edu/faculty/runkle.htm

Correction on availability Of NCR 581
Tom Dudek
Regional Extension Agent

After indicating that NCR 581 Biological Control of Insects and Other Pests of Greenhouse Crops was available from the MSU Extension bulletin system, I learned that it is not in stock. If you would like to obtain a copy of this publication contact the University of Wisconsin Publications web site at: http://cecommerce.uwex.edu/

Or if you would like to view a pdf of the publication:
http://cecommerce.uwex.edu/pdfs/NCR581.PDF
I am sorry for the confusion that was created in the last newsletter.

Greenhouse insect management
David Smitley
Entomology

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 1 gallon zip-lock 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 for insects.

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 sq ft. Check the first plants to flower for thrips. For spider mites and aphids, check susceptible plants like marigold (mites) and pepper (aphids), weekly. Potato wedges can be stuck in soil and checked 24 hours later for fungus gnat larvae.

Systemic insecticides
Use Marathon, Tristar, Flagship or Aria in poinsettia pots, lily pots, or in hanging baskets prone to problems with whiteflies or aphids. Note: Aria does not work on silverleaf whitefly.

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.

Spider mites appear early this year
David Smitley
Entomology

Table 1.  New miticides for the floriculture industry (March 12, 2004)