Greenhouse Update -
April 21, 2008
Leanne Pundt, Extension Educator, University of Connecticut
Adult Shore flies are now prevalent at many different operations. The earlier, cool, rainy weather helped promote the growth of algae on the media surface. Shore flies are primarily nuisance pests that feed upon algae. I have noticed higher populations in very humid houses with limited ventilation. Moving the plants outside (depending upon the crop tolerance for cool night temperatures) will increase the air circulation around the plants, drying out the media and helping to discourage shore flies. Mass trapping of the adults with yellow sticky tape or large yellow cards may also help.
Some growers have tried low rates of insecticidal soap (avoiding known sensitive plants and those in bloom) and spraying when adults are settled and you are more likely to contact them. Conserve may also work against shore flies. The long-term solution is to discourage algae on the surface of your growing media.
Adult shore fly
Leanne
Pundt photo
click image to see a larger view
Thrips and Impatiens necrotic
spot virus
Beside direct feeding damage from the
thrips (see message of
April 4th), symptoms of
impatiens necrotic spot virus (INSV) have
been observed. Almost all greenhouse crops with the exception of
roses and poinsettias are susceptible.
Symptoms may resemble those caused by fungi, bacteria, or chemical spray injury. Infected plants may also show a wide range of symptoms depending upon the species or cultivar infected. Some of the more generic symptoms of INSV include leaf spots, necrotic areas, mottling and ring spots. Plants may also be stunted. Young plants may be especially vulnerable to infection. There is no cure for this virus. As soon as INSV is detected, rogueing of infected plant material, strict thrips management and rigorous weed control are all needed to prevent further losses.
INSV symptoms on Lobelia
Leanne
Pundt photo
click image to see a larger view
Spider Mites are occurring on some of their favorite hosts including lemon balm, lemon verbena, and English ivies, Thunbergia, and Ipomoea “Blackie” and “Tricolor”, etc. Look on the underside of the leaves, along the midvein, for the spider mites and their eggs.
If you are using biological control agents, a fast acting predatory mite that is commercially available is Phytoseiulus persimilis. This predatory mite only feeds upon spider mites, and will disperse or starve with no prey. The adult P. persimilis is bright red in color, pear shaped, long-legged and slightly larger and more active than spider mites. It is best released when mite populations are first noticed, in hot spots of mite activity. Relative humidity should be greater than 75% and temperatures above 68F for some hours of the day. (At low relative humidity (less than 60%), eggs shrivel and do not hatch.) Spider mite colonies should be reduced in two to three weeks.
If using chemical controls, many different and highly effective miticides are now available. Rotate among classes to delay the development of resistance. See the latest New England Greenhouse Pest Management Guide for a listing of available miticides.
For a listing of what’s available for edible herbs, see the bulletin, Pest Management for Herb Bedding Plants Grown in the Greenhouse on this website.
Mites on Ipomoea Blackie – note white empty egg cases
Leanne
Pundt photo
click image to see a larger view
| April 4, 2008 |
| March 24, 2008 |
| March 7, 2008 |
| January 8, 2008 |
| 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. |
|
GREENHOUSE IPM COORDINATOR (commercial interests and growers) |
LEANNE PUNDT | 860-626-6240 |
| . | . | . |
|
HOME GREENHOUSE
QUESTIONS |
phone toll free |
Information on our site was developed for conditions in the Northeast. Use in other geographical areas may be inappropriate.
The information in this material is for educational purposes. The recommendations contained are based on the best available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for information only, and no endorsement or approval is intended. The Cooperative Extension system does not guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of others which also may be available.All agrochemicals/pesticides listed are registered for suggested uses in accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information does not agree with current labeling, follow the label instructions. The label is the law.Warning! Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels. Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner and place. Contact the Connecticut Department of Environmental Protection for current regulations.The user of this information assumes all risks for personal injury or property damage.Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or disability and is an equal opportunity employer.