|
 |
|
June
o3 (IPM for perennials, greenhouse disease management) Posted
11/14/03 Note: Applications of pesticides to poinsettias with bracts is risky since there are so many variables. Differences in cultivars, culture and environmental conditions may increase or decrease bract sensitivity to pesticides. If you are inexperienced with a particular pesticide, always test a small portion of your crop before treating your entire crop. When in doubt, contact the technical representative for the product you plan to use. Botrytis - When cooling your greenhouses as poinsettias mature, avoid night temperatures below 60°F. Ventilate as much as possible during the day and water so that foliage will be dry before night. For details see our new fact sheet, Reducing Humidity in the Greenhouse. Fenhexamid (Decree) plus CapSil are effective and safe when used as directed. It is recommended to use CapSil as a surfactant to minimize visible residue, and that the spray is applied to glisten, (similar to Cycocel application). The re-entry time is 4 hours and EPA considers Decree a reduced risk pesticide. Powdery Mildew - Regular scouting is very important to detect, especially hangers. Potassium bicarbonate (Milstop) works good but leaves a residue, triadimefon (Strike), leaves minimal residue, however Strike should not be applied more than 4 times due to its growth regulator effect. Also, copper sulfate pentahydrate (Phyton 27) can be used, but should be appled at a time of day to allow quick drying to prevent phytotoxicity. Triflumizole (Terraguard 50W) can also be used, but leaves a residue. Pythium - Pythium is the most common late season cause of root rot on poinsettias. Overwatering and high soluble salts increases incidence of Pythium. Registered fungicides include Mefenoxam (Subdue Maxx), propamocarb (Banol), etridiazole (Truban), etridiazole plus thiophanate methyl (Banrot). Banrot is labeled for pythium and rhizoctonia. Note: Almost half the samples brought to the diagnostic lab tested for Pythium are resistant to Subdue. If you have problems with Pythium and are using Subdue, this may be the problem. Note: Be very careful to follow label directions to avoid phytotoxicity. Follow the specific guidelines for the correct volume of the diluted fungicide that should be applied to the media. This will depend on the pot size. Need to look up a pesticide label? Check out our labels links from this page. Click on Greenbook or Crop Data Management Systems in the yellow box to access the data bases. Posted
10/1/03 Pansy Trials Weeds, Weeds, Weeds Instead, This will provide a surface that is easy to keep weed free and help to eliminate whitefly problems. Pesticide Use for Whiteflies on Poinsettias Pesticides that are effective for whitefly early in the season, prior to Marathon include: azadirachtin (Azatin) +abamectin (Avid), acephate (Orthene) + pyrethroid, pyridaben (Sanmite) and pyriproxyfen (Distance). Imidacloprid (Marathon) is best applied after plants are pinched and new shoots are 1-2 inches long, and when the roots have reached the inside of the pot. This is usually about 5 weeks after potting. Water moderately, but throughly after application, allowing no leaching and runout from containers for at least three irrigations or 10 days whichever is longer. Media with 30% or more bark content will result in a shorter period of protection. Applied properly, Marathon drench or granular applications will provide 8 to 10 weeks of whitefly control. If whiteflies are a problem late in the season, pyriproxyfen (Distance) can be used prior to bracts coloring. After bracts color, Sanmite or Azatin + cyfluthrin (Decathlon) or pymetrozine (Endeavor) have reportedly been effective. When using Endeavor on open bracts, residue may be apparent, especially on darker color bracts. Marathon II has also been used, however growers have reported slow results with a late season application. Note: Applications of pesticides to poinsettias with bracts is risky since there are so many variables. Differences in cultivars, culture and environmental conditions may increase or decrease bract sensitivity to pesticides. If you are inexperienced with a particular pesticide, always test a small portion of your crop before treating your entire crop. When in doubt, contact the technical representative for the product you plan to use. Biological control of whiteflies on poinsettias is cost effective and works! See two fact sheet on the subject: Economics at $0.10 per pot and Grower's Guide for Using Biological Control on Poinsettias. Daylily Rust Alert: The first case of Daylily Rust has been confirmed recently in Massachusetts on Cape Cod. It has been found on plants in the Twice as Nice Series, Culivars 'Raspberry Candy' and 'All Fired Up'. For information on Daylily Rust see the fact sheet Daylily Rust. Commercial flower growers who have plants suspected of rust infection should send samples to Rob Wick, Plant Disease Diagnostic Lab. Call Rob prior to sending samples at (413)545-1045. Leaf samples should be placed between paper towels and then placed in a plastic bag before packaging for mailing. The standard diagnostic fee will be charged. Poinsettia - Fungus gnat control is important at this time of the growing season. You can drench with Steinernema feltiae or one of the other materials listed in this fact sheet. http://www.umass.edu/umext/floriculture/fact_sheets/pest_management/fungnat.html Advice from Jack Williams of Ecke: On pinching poinsettias Jack has the following comments: Most of the new varieties of poinsettia on the market are the darker leaf types. These darker leaf types will do better with a soft to medium pinch rather than a hard pinch most growers did with old varieties such as 'Annette Hegg'. A soft to medium pinch will give better bud breaks on the new varieties on the market. Also, remove large leaves that cover elongating stems. Otherwise the stems will grow straight out and tend to be more prone to breaking. You want the stems to grow upward to have the least stem breakage. Jack mentioned that Poinsettia root zone temperatures should not go above 85°F or else the root system shuts down. He suggests watering during the heat of the day to help cool down soil temperatures. Use a soil temperature probe to check your substrate temperature. Poinsettia Tips from Stanton Gill, University of Maryland, from The Poinsettia and Alternative Greenhouse Crops conference on July 1st sponsored by The Maryland Greenhouse Growers Association. For Information on Poinsettias: Cut Flowers - Corn Borer Corn borers are being found on mums and perennials. If you see larvae hatching and while larvae are small, you could use a pesticide containing Bacillus thuringiensis (Bt), which is actually a fungus that attacks the insect. When larvae are large and found inside the stems there isn't much you could do since the larva are protected in the stem. Be ready for the next generation as there are two generations per season. For info about the corn borer on ornamentals. For a Photo of the European corn borer larvae. There are two generation of European Corn Borer here in Massachusetts.
The following website (from the UMass Extension Vegetable Program) contains
information on their life cycle. See page 5 on the website below. July Large numbers of thrips create problems for plants and people during these warm summer days. If they land on the bare skin, they may "rasp" the skin, causing a sudden burning sensation at the bite site. They soon find that the human skin is devoid of chlorophyll and fly away or crawl to a new site and rasp the skin again. In some people an itching sensation may persist for several days. Thrips do not seek humans as a food source, their bites being accidental. Best protection from thrips bites is to wear long-sleeved shirt. Peak activity occurs during bright sunlight. Resources: http://muextension.missouri.edu/explore/agguides/pests/g07396.htm. For information on Thrips as plant pests see our Thrips fact sheet. Garden chrysanthemums help fulfill a consumer demand for fall color, and more and more garden mums are being used by landscapers in late fall plantings. June is the time that growers plant rooted cuttings for fall sales. Review the fact sheet, "Growing Garden Mums for Fall Sales" for growing tips. Retail Garden Centers in Massachusetts needing help answering home gardeners questions can refer questions to several volunteer garden hotlines. Retailers are invited to reproduce and distribute this information to their cusomers. Outdoor Cut Flowers - Weeds are
a challenge when growing cut flowers. The fact sheet, Herbs - A common question asked this time of year is, "What pesticides can be used on herbs?. The publication Pest Management for Herb Bedding Plants Grown in the Greenhouse contains information on pests, management strategies and pesticides registered for herbs. This publication was a joint effort of University of Massachusetts Floriculture Program and University of Connecticut. June Botrytis
blight and Powdery
mildew were disease problems this spring. These fact sheets
written by Gary Moorman, Professor of Plant Pathology, Penn State University
provide useful information on these diseases. Also see |
||||
 |
||||
|
