Greenhouse Update - July 10, 2006
Leanne Pundt, Extension Educator, University of Connecticut
Bacterial Leaf Spots on various herbaceous perennials including Heuchera, Coreopsis, and others have developed due to the recent warm, humid conditions. Sometimes, infected tissue will have a water soaked appearance and be more angular in outline than fungal leaf spots. A yellow halo may also surround the spots. (See photo). Bacteria are easily splashed from plant to plant as plants are watered by overhead irrigation. Discard infected plants and provide more space for the remaining plants. Keep leaves as dry as possible by watering early in the day. Spray adjacent plants with copper sprays.
Bacterial Leaf Spot on heucherella
Leanne Pundt photo -
click for a larger image
Fungal leaf spots begin as small, reddish brown spots with gray centers. As the disease progresses, the spots enlarge and spread. Stem cankers may also develop. Preventative fungicides containing either chlorothahlonil, iprodione, mancozeb or thiophanate-methyl may be applied according to label directions.
Bacterial leaf spots may begin as small, angular brown spots on the lower leaves. Spots may be surrounded by a yellow halo. Avoid overhead irrigation, and start with clean seed or transplants.
Foliar Nematodes are also spread by splashing water, as they need a film of moisture to move across plant surfaces. Infected leaves are off-color, showing angular spots that turn purple or brown with a distinct margin. (See photo). Examination under microscope is needed to see the small nematodes. Destroy infected plants (do not put in a compost pile) and reduce periods of leaf wetness on remaining plants.
Angular spots due to foliar nematode injury on
Anemone.
Note patch-like appearance
L. Pundt photo -
click for a larger
image
Mites on dahlia, butterfly bush and many other plants are increasing especially in warm greenhouses. Thrips continue to be active. Some feeding damage to the leaves has been observed on garden mums. See Previous Updates for more information.
Here's some information on a new predatory mite for thrips and whitefly from Geri Cashion, EcoSolutions, Inc.
PREDATOR: AMBLYSEIUS SWIRSKII
Swirski-mite is a voracious predatory mite which controls
both thrips and whitefly. It has also demonstrated the ability to
provide added control with spider mite infestations in conjunction
with other predatory mites. It controls both greenhouse and tobacco
whitefly species. It preys on the eggs and 1st larval
stages of whiteflies, and on the 1st larval stages of thrips. It
has a very high rate of reproduction.
Swirskii is not susceptible to diapause, and can be introduced in winter months. It also may be introduced in high temperatures. Without prey it can establish on pollen.
Mode of Action/ Life Cycle:
Predatory mites pierce their prey and suck out the body contents, resulting in immediate control.
Their eggs are deposited on the underside of leaves, often on the leaf hairs near the veins. Total development from egg to adult takes 5 to 6 days dependent on temperature and humidity.
Release technique: Rates vary with plant size and infestation level. From 2 to 5 mites are recommended per square foot.
Two release methods are available. Loose mites are suspended in media that is placed directly on the plant. Sachets with 250 mites are hung on the plant and release mites for about 4-6 weeks.
If you would like to receive an email notice when new greenhouse updates are posted on the website, please email me at: leanne.pundt@uconn.edu . This will be an undisclosed list, and your email address will remain private.
| 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.
