|
 |
|
4/21/05 Our "Timely Topics" page is changing to "New England Greenhouse Update"...From now on, timely information is available at negreenhouseupdate.info. "New England Greenhouse Update" is a new, simply designed website that contains current observations at greenhouses in MA, CT and RI. To be added to our email list and notified via email when new information is posted on New England Greenhouse Update, please email your request to: Tina Smith, email: tsmith@umext.umass.edu New England Greenhouse Update by date and subject Questions about information on this page? Contact Tina Smith or Paul Lopes. 3/29/05 (Botrytis, Pesticide phytoxicity) Botrytis - During rainy weather, watch for Botrytis on greenhouse crops. A wide variety of plants are susceptible and plants may be attacked at any stage of growth, especially new tender growth, freshly injured tissue, and senescing or dead tissue. Sometimes Botrytis will appear as a stem canker and is also very common on flowers. Photos: Botrytis stem canker on fuchsia and plant with stem canker, Close-up of spores on Geranium flower. Botrytis cannot be effectivly controlled with fungicides alone. Cultural practices to reduce Botrytis include: Spacing plants to allow good air circulation and reducing humidity and leaf wetness to prevent spore germination. At the least, heat and vent greenhouses in the morning and again before closing up for the evening. Remove all dead and dying vegetation which is vulnerable to Botrytis. Fungicides such as Decree (fenhexamid), Medallion (fludioxonil), Sextant (iprodione) and Compass (trifloxystrobin) or Heritage (azoxystrobin) can be used. Note: Compass and Heritage belong to the same group of fungicides and should not be rotated. For more information see the section on Botrytis in the 2005-2006 New England Recommendation Guide. Pesticide Phytotoxicity - When treating plants with pesticides this growing season, be aware of phytoxocity. Read precautions on labels for crops and only use labeled rates. Medallion 50WP has been shown to cause phytotoxicity to geraniums when used as a drench. Geranium was removed from list of safe plants listed on the label. See 3/8/04 issue of Michigan State University Greenhouse Alert for more information. Injury from Milstop (potassium bicarbonate) has been observed on Verbena when used at the high rate. Injury from Cycocel is common. What causes phytotoxicity? Individual plant cultivars may vary in sensitivity, using concentrations over the labeled rate and tank mixing pesticides can all contribute to phytotoxicity. Tank mixing several pesticides can cause phytotoxicity problems because the adjuvant or soaps used to help pesticides dissolve in water may be phytotoxic at high concentrations, such as soap and oil by themselves can be phytotoxic. When three pesticides are mixed into a spray tank, there may be three times as much adjuvant. When phytotoxicity is suspected from foliar applications of pesticides, watch new growth as it emerges. Plants will often grow out of one-time spray damage. As plants grow, the damage will remain on the oldest leaves and the new growth will appear healthy. 2/25/05 (Test Kits, Pansy Production Checklist) Time to order "On-Site Diagnostic Test Kits" - On-site test kits can be used by growers to detect several important diseases caused by virus, fungi and bacteria. Growers should consider stocking up on a few test kits for this spring. Easy to use dip-stick tests are available for Impatiens Necrotic Spot Virus (INSV), Calibrachoa Mottle Virus and Cucumber Mosaic Virus to name a few. Other types of quick test kits are available for Pythium and Rhizoctonia (pathogens that cause root rot) and for Xanthomonas (Bacterial Wilt). Photos Testing for virus: If a plant is suspected of being infected with a tospovirus because the plant is showing symptoms of virus infection, collect samples from those parts of the plant showing symptoms. Even, when plants are systemically infected, tospoviruses do not spread evenly throughout the plant, so careful selection of tissues is crucial to the success of the test. Collect a sample from the part of the plant showing symptoms, including green or chlorotic tissues adjacent to the necrotic area. Thrips can also be collected from sticky traps and tested using the test kits. There are currently three companies that manufacture test kits available for on-site testing. Not every company carries kits for all diseases. Note: Kits need to be refrigerated. ImmunoStrips from Agdia Inc 30380 County Rd. 6 Elkhart, Indiana 46514 1-800-622-4342, http://www.agdia.com AgroCheck kits from Hydros Inc. 230 Jones Road, Falmouth, MA 02540 Phone: 508 540 2229, http://www.hydros.cc/. Alert Kits from Neogen
Company 620 Lesher Place
Lansing, MI 48912 Phone:
800/234-5333 (USA/Canada) For information on diagnostics and sending samples to the UMass Plant Diagnostic Lab see our Diagnostics page. For an in-depth fact sheet see Western Flower Thrips and Tospovirus. Pansy Production Checklist For in-depth fact sheet on pansy production see Commercial Pansy Production, NC State University. Prevent pest problems by cleaning greenhouses now. Weeds and left-over crops in greenhouses carry pests such as mites, whiteflies, thrips and aphids. Pests will overwinter in unheated greenhouses so prevent pests on spring crops by cleaning and sanitizing greenhouses now. See "Disinfecting the Greenhouse" for details. Put out yellow sticky cards under benches to check pest activity prior to introducing new crops to a greenhouse. Check your fertilizer injector ... This is also a good time to check your fertilizer injector to be sure it is working correctly. To do this, take a fertilizer sample from the end of the hose the next time you fertilize and put it in a clean plastic container for testing. Test the sample using a conductivity meter or send a sample to the University of Massachusetts Soil Test Lab. Fertilizer companies and suppliers often can provide a chart relating conductivity to parts per million concentrations of their various fertilizers. Ask your fertilizer company for their electrical conductivity chart and compare your fertilizer reading to the chart. Conductivity Charts Peters Fertilizers (See table 12, scroll down to page 13) 12/1/04 (Overwintering perennials) Overwintering Perennials Last Minute Poinsettia Pointers are available in Northeast Greenhouse IPM Notes. See information on late season whitefly control and more.... 04
Timely Tips |
||||
 |
||||
|
