Greenhouse TPM/IPM Bi-Weekly ReportCentral Maryland Research and Education CenterEllicott City, Maryland

August 24, 2012From: Stanton Gill, Extension Specialist – IPM for Greenhouse and Nurseries, Central Maryland Research and Education Center, University of Maryland ExtensionKaren Rane, Extension Specialist, Director of the Plant Diagnostic Clinic, University of Maryland ExtensionAndrew Ristvey, Extension Specialist, Wye Research and Education Center, University of Maryland ExtensionSuzanne Klick, Technician, CMREC, University of Maryland Extension

Aphids on MumsJohn Speaker reported that through the summer, he has not been seeing aphid populations at high levels outdoors. This week, he is seeing increasing aphid population on mums with a coinciding increase in lady bird beetles at an operation on the Eastern Shore. Green peach aphids (peach and green forms), melon aphids (color varies from yellow to green to mottled to black), and chrysanthemum aphids (dark, shiny and amber in color) all feed on mums. Look for the cast skins of aphids, honeydew and sooty mold. Ants are also a good indication that aphids are present since they protect the aphids in order to feed on the honeydew the aphids produce. If you see what looks to be dried up, papery aphids on plants, that’s a good find. They are the mummies which are the remains of the aphid after being parasitized by a tiny predaceous wasp (Aphidius spp.).Control: Monitor for beneficial insects and determine if they are providing enough control to avoid applying an insecticide. If predators are present and control is needed, horticultural oil and insecticidal soaps will have a limited impact on these beneficials. Other insecticides for control include Aria, imidacloprid (Marathon), pymetrozine (Endeavour), azadirachtin (Aza-Direct, Azatin), and abamectin (Avid).

Melon aphids and cast skins

Green peach aphids heavily infesting a chyrsanthemum bud

Look for lady bird beetle larvae on plants (left) which feed on aphids and aphid mummies (right) which indicate the aphids have been parasitized by a predaceous wasp.

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Maryland Greenhouse Growers’ Association (MGGA) Bus Tour September 18, 2012

MGGA will visit Longwood Gardens in Kennett Square, PA, and Lucas Greenhouses in Monroeville, NJ.

Information is available at http://ipmnet.umd.edu/conferences/index.htm

pH Meters: Not just for monitoring nutrient levels

Crop Monitoring:Monitoring pH and EC levels in crops is a very useful way to maintain appropriate nutrient levels for each crop. Although EC readings do not identify specific nutrients that are present, they do indicate whether fertility is too low, high or adequate for the crop and time in the cropping cycle. Measuring pH levels can help indicate if specific nutrients are at levels that can cause nutrient deficiencies or toxicities. For example, high pH levels (above 5.8 to 6.0) can make iron that may be present in the substrate unavailable to pansy plants. Iron deficiency causes interveinal chlorosis of new growth. Sending tissue and substrate samples to a lab for a complete nutrient analysis can identify what nutrients are present in the substrate and whether or not they are present in plant tissue.

Thielaviopsis: At higher pH levels, plants are also susceptible to the root rot pathogen, Thielaviopsis (black root rot), which also causes yellowing of the foliage so checking the roots to see if they are healthy or not is necessary in addition to measuring pH levels. Infected roots will have black lesions, due to the dark, thick-walled spores of the fungus. If you find damaged roots, get a plant sample to a University plant diagnostic lab to confirm if a root disease is the problem.Management: Be sure to check plugs when they arrive for any disease symptoms such as chlorosis and uneven plant growth. Black root rot spores can survive for up to several months on benches and plug trays and even longer on plant debris under benches. Maintain good sanitation in the greenhouse and do not reuse substrate or pots to prevent or reduce the spread of this disease. The incidence of this disease can be reduced by keeping the substrate below 5.8. Fungicides for control include Banrot, Medallion, Hurricane, thiophanate methyl products, and Terraguard.

pH Levels and Pesticides:At the Maryland Plants and Supplies Customer Appreciation Day on August 22, 2012, Suzanne Wainwright-Evans spoke on insect control in greenhouses with a focus on biological control agents. At the start of her talk, she noted how important it is to have the spray solution at the correct pH for good pest control. She mentioned a grower who had a pH level that was out of range when using Avid (optimal range is 6.0 to 7.0). Once the pH level was corrected, the grower was able to get good control of the target insect. Ohio State University has charts supplied by Rick Yates, Griffin Greenhouse Supplies, on various pH ranges for selected fungicides, insecticides, insect growth regulators, and herbicides posted at http://ohiofloriculture.osu.edu/sites/drupal-ohioflori.web/files/file/spray-solution-ph.pdf.

Iron deficiency on pansy

Pansies infected with black root rot

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Brown Marmorated Stink Bugs (BMSB)We received a report on August 14 that BMSB were active on Asian pears in Howard County, but it was noted that the insect activity is very limited there this summer. A cut flower grower reported that amaranth was covered with BMSB. He suggested this plant could be a trap plant for BMSB. They are feeding on the stems, flowers and leaves of the amaranth. Suzanne Wainwright-Evans, Buglady Consulting, visited an interiorscape site in Philadelphia recently and found second instar stink bugs on philodendron and dracena. She noted that it is in a location with high light from a wall of windows and there is moss planted around them to look like water. The manager at the site replaced the plants.

2012 Cut Flower TourOn August 6, 2012, we conducted tours of two cut flower operations in Montgomery County. We started at M and M Plants in Dickerson which is owned by Madgie and Mark McGaughan. They bought their farm several years ago and produce cut flowers, bedding plants, houseplants, herbs, and vegetable starts for sale at farmers’ markets.

While at M and M Plants, Stanton Gill, CMREC, covered some of the insect problems that develop on cut flowers and Dave Clement, HGIC, discussed disease problems. Madgie McGaughan and Leon and Carol Carrier, Plantmasters, Inc., gave a talk on their participation in the Association of Specialty Flower Growers seed trial program. When participating in these trials, they stressed the importance of organizing seed according to time of year for sowing and planting and doing the research to determine the growing requirements of the trial plants. Madgie and Leon noted how important it is to take the data which includes sow date, transplant date, first harvest, number of stems and how the varieties are received by customers. They also make note of insect, disease and any other problems that develop. Madgie said that Sunflower ‘Goldy Double’ is a trial plant that has been well received by customers. Another plant they liked was Celosia ‘Sunday Orange’ which has a rich color. They noted that stems are a bit short so an early pinch would be good.

The tour group checks out what is growing in the high tunnel which is used to extend the cut flower and bedding plant production season.

Purple millet and giant amaranth are two of their field grown crops. Other crops include tuberoses, zinnias, sunflowers, Asclepias, and even cotton.

Asclepias curassavica is one of their annual plants.

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The group moved on to the Montgomery County Extension office for lunch and a talk by Ron Peterman, Long Season Statice, on plants that work well for him. One of the flowers that Ron highlighted is Orlaya grandiflora, white lace, which blooms in May and June, has a wiry stem with blooms that are somewhat like Queen Anne’s lace. White lace does not wilt like Queen Anne’s lace does, and the flowers are small and don’t shed. You need to keep picking it or it goes to seed. He noted that his florists like it better that Queen Anne’s lace.

We finished the day at Farmhouse Flowers and Plants in Brookeville, where the owner, Dave Dowling, gave a tour of his operation which includes greenhouses, high tunnels and field production. He sells at farmers’ markets and to a few florists. Chuck Schuster, UME, gave a talk covering weed control options for cut flower growers.

Lisianthus ‘Mariachi Carmine’ is a cultivar Dave grows that comes into bloom a little later than other lisianthus cultivarsPhoto: Edwin Remsberg

Flowers that Ron highlighted included tuberose, Hypericum HypearlsTM ‘Olivia’,

phlox, sunflowers, and celosia.

Hydrangea ‘Limelight’ growing under shade cloth develops greener blooms that become pink later in season. Plants growing in full sun are more often white and turn brown.

Phlox ‘David’s Lavender’ is a cultivar that is powdery mildew resistant.

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The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by University of Maryland Extension is implied.

Read labels carefully before applying any pesticides.

Photographs are by Suzanne Klick, Shannon Wilhelm and Stanton Gill unless stated otherwise.

University of Maryland Extension programs are open to all citizens without regard to race, color, gender, disability, religion, age, sexual orientation, marital or parental status, or national origin.

OFA Perennial Production ConferenceSeptember 10 - 12, 2012Location: Grand Rapids, Michiganofa.org

ASCFG National ConferenceNovember 12 - 14, 2012Location: Tacoma, Washingtonascfg.org

Upcoming Programs:

Job Announcement:We received a request from Dr. Joyce Latimer, Virginia Tech, to pass along a job announcement:Endless Summer Harvest is in need of a hydroponic grower. Contact Ann Higgins, Director of Public Relations Endless Summer Harvest, LLC, 36474 Osburn Road, Purcellville VA 20132 www.esharvest.com for details.