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Questions about information on this page? Contact Tina Smith or Paul Lopes. 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 10/27/04 (Poinsettias- managing height, upcoming program, New England Greenhouse Conference highlights) Poinsettia Production - Growth Regulators There will be a Poinsettia Program for all growers on Thursday, November 4th, 2 PM - 5 PM at King Farm, Townsend, MA. Tour King Farm Greenhouses and see the 2004 poinsettia crop. There will be a hands-on clinic on managing whitefly using biological control and a talk on managing poinsettia diseases. One pesticide credit has been approved for the program. Preregister by contacting Bob Luczai, Mass Flower Growers Association at 781-275-4811. Highlights from the New England Greenhouse Conference 9/30/04 (Poinsettias, New England Greenhouse Conference) Time to register for the New England Greenhouse Conference, Oct 18 - 20!! See all the details at negreenhouse.org. Poinsettias: Roy VanDriesche and Suzanne Lyon, UMass Plant, Soil and Insect Science, are again working with poinsettia growers here in Massachusetts on using biological control this fall. You can check out the latest fact sheet, Cost effective biological control for poinsettia production. If you battle whiteflies on poinsettias each year, and pesticides just aren't working for you, this may be your solution. Whiteflies, scab and growth regulator updates are available from the University of Maryland scouting report. See their latest report with photos at Scouting report. The September issue of Northeast Greenhouse IPM also has some good information on managing whiteflies on poinsettias. Note for growers managing whiteflies, do not rotate the pesticides Marathon, Flagship and TriStar since they are all in the same family chemistry of Neonicotinoids. 7/28/04 (Powdery mildew) There was a lot of interest in powdery mildew at Summer Field Day last week. The following information from Karen Rane, Plant Disease Diagnostician, Department of Botany & Plant Pathology, Purdue University is very timely for cut flower growers here in Massachusetts. Tina Smith Garden phlox (Phlox paniculata) is often severely affected by powdery mildew. White, powdery patches typical of the disease can be seen now on susceptible phlox cultivars. The disease occurs first on the lower leaves, and appears to "move up" the plant as spores from the initial infections cause disease on younger leaves. In severe cases, virtually all of the foliage can be infected. Plant breeders have developed several garden phlox cultivars that have some resistance to powdery mildew. A partial list of resistant cultivars includes 'Starfire', 'David', 'Orange Perfection', 'Prime Minister', 'Bright Eyes' and 'Rosalinde'. Remember that resistance does not mean the plants will not become infected at all, but symptoms will be less severe or the disease will spread more slowly in resistant plants when compared to susceptible ones. When environmental conditions are favorable for disease development (warm temperatures, high humidity, poor air circulation between plants), powdery mildew can spread very quickly. Protectant fungicides may be necessary to keep the disease in check on susceptible plants. (photos & related information) Note: The varieties, 'Katherine' and 'Franz Schubert' can be
added to the list of resistant cultivars. Treatments with fungicides at
this time will not "cure" the plants, but will protect uninfected
plant parts. Next year, plan to treat at first sign of disease, or earlier
for susceptible varieties, rotate fungicides and replace varieties with
resistant cultivars. According to Dr. Leonard Perry, University of Vermont,
the best treatments for powdery mildew (Erysiphe cichoracearum) on phlox
include: Baking soda, 0.5% (1.5 Tbsp/gal water, weekly) Sunspray Horticultural
Oil (3Tbsp/gal water, every 2 weeks) Both combined (every 2 weeks) Powdery Mildew on Verbena: Powdery mildew is also a common
problem on verbena grown in greenhouses and was a problem again this past
spring. According to results from trials conducted at Michigan State University,
the fungicides Compass 50WG, Terraguard 50W, Strike 50WDG, and Systhane
40WP are highly effective in controlling powdery mildew on verbena. (More
information) And...at Penn State, the following varieties of Verbena
were rated as powdery mildew tolerant: 6/15/04 (Daylily rust) Daylily Rust: Watch for daylily rust, especially on plants being shipped in (excellent pictures and other information, Canada). 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 Dr. 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. 5/26/04 (getting ready for garden mums-crown buds on cuttings) Before long, growers will be planting garden mums for fall sales. Sometimes mum cuttings will have buds at the beginning of the growing season which worries growers. A garden mum cutting that has initiated a terminal bud will usually perform satisfactorily. These cuttings should be given a hard pinch 4 to 6 days after planting, when the plants are fully turgid. This will force out lower breaks, which tend to be more vegetative. Plants will typically grow well with proper attention to moisture and fertilizer levels. It is important to keep them well watered and fertilized. Cuttings that have initiated lateral buds down the stem will not always perform well. Anything that checks the growth of the cutting may push the plants into bud. To review other potential mum problems see the fact sheet, Garden Mums - Past Crop Problems and Production Tips. Also review the fact sheet, Growing Garden Mums for Fall Sales. 4/28/04 (downy mildew) Downy mildew (not powdery mildew) has recently been diagnosed on argyranthemum in Massachusetts. Close-up photo ..... Plant with Downy Mildew photo . This disease has also been reported on Lamium maculatum, garden impatiens, gazania, dusty miller and gerbera this spring, although we have not seen it on these crops in Massachusetts. Downy mildew (Plasmopara) is a relative of Phytophthora and Pythium.Symptoms appear as a light gray colored, fluffy growth. In the case of argyranthemum, it is showing up on new growth and buds. Downy mildew is host specific in that the downy mildew on impatiens cannot affect snapdragons. Fungicides for treatment include, mancozeb (Dithane, Protect), fosethyl aluminum (Aliette), strobilurins (Compass or Heritage). This disease is known for changing and becoming resistant to systemic fungicides. When you see this disease, it looks as if you could cut back the infected tissue, and have the plant grow out, however, downy mildew is systemic and this will not work. Downy mildew can spread very quicky via air currents and cause a major problem during cool, damp weather. More information on downy mildew can be obtained from Michigan State University. 4/5/04 (media pH and iron, powdery mildew, spider mites) Media pH and iron, powdery mildew and spider mites are all common problems encountered these past couple of weeks by growers in Massachusetts. Iron deficiency is seen regularly on crops such as calibrachoa. Cleome also showed symptoms. Powdery mildew is showing up on begonias and spider mites on sweet potato vine and New Guinea impatiens. For photos and information on these topics, see the latest issue of Northeast IPM Notes. For details on pH and iron, see our fact sheets pH and Fertility Review for Vegetatively-propagated Annuals and How to Prevent Iron Deficiency in spring crops by Dr. Douglas Cox, Dept. Plant & Soil Sciences. Edema continues to be seen on sweet potato vine and cleome. See below for cause and management. 3/2/04 (Uncovering perennials, Edema ) Uncovering overwintered perennials After the plant's chilling requirements has been satisfied, plants can
respond to warm temperatures. In late winter as the temperature increases,
plants can deacclimate to cold temperatures. Plants are capable of reacclimating
if temperatures decrease slowly, however, if the temperature drops too
quickly, plants may be injured. Although difficult, it is important to
inspect plants frequently, especially under structureless systems, to
ensure that shoot growth is not initiated. Etiolated growth is very susceptible
to cold injury. If the inside temperature approaches 45°F or higher,
or if any signs of growth is evident, vent to introduce cool air into
the system to slow plant development. This may be accomplished by simply
opening the end doors, and/or opening vents or rolling up sides, depending
on the structure and weather. Some growers cut holes in the sides of polyhouses
to ensure adequate ventilation while still providing adequate protection
from frosts. Other growers using thermoblankets will roll coverings back
but will keep them handy in case cold weather reoccurs shortly after uncovering.
Edema During periods of cloudy weather, greenhouses are apt to be cool and humid. These environmental conditions favor the development of edema (oedema). When the growing media remains moist and the plant roots absorb water at a faster rate than is transpired through leaf cells, the leaf cells rupture. This rupturing of the leaf epidermis and the inner cells causes the raised, crusty appearance on the underside of the leaf. Edema is commonly found on ivy geraniums and cultivars vary in their susceptibility. Experienced growers will select varieties less susceptible to the problem. Other greenhouse crops susceptible to edema include: sweet potato vine (ipomea), begonias, cacti, ferns, palms, pansy, cleome and cole crop vegetables like broccoli, cabbage and cauliflower. Symptoms of edema appear as bumps or blisters initially on the undersides of lower or older leaves on a plant. They may then turn brownish or tan and become corky. Severely affected leaves will turn yellow and fall off the plant. To reduce the incidence of edema: Use a well drained growing media, avoid over watering, and keep plants on the "dry side" during extended periods of low light and cool temperature. Plants grown in saucerless hangers with reservoirs of water inside the pot are more prone. Ventilate whenever possible to lower humidity and use horizontal air flow (HAF) fans to hasten air movement and maximize plant transpiration. Increase light intensity. Space plants farther apart. Avoid over-fertilizing plants, and avoid cultivars that are highly susceptible to edema in your greenhouse. See the fact sheet "Reducing humidity in the greenhouse" Note: Thrips and mite damage on the undersides of ivy geranium leaves can often appear like edema. Be sure to check for thrips and mites with a hand lens. 2/13/04 1/6/04 12/9/03 Easter is a April 11, 2004. To keep on track growing Easter Lilies, check out the forcing schedule available from http://www.netherlandbulb.com/nbcgrower_easterlily.htm. Perennials are tucked away for winter. To review winter protection information, see our fact sheets on overwintering containerized perennials and preventing rodent damage. How accurate is your fertilizer dosage? This is 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) |
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