Greenhouse TPM/IPM Report Central Maryland Research and Education Center Ellicott City, Maryland

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1 Greenhouse TPM/IPM Report Central Maryland Research and Education Center Ellicott City, Maryland September 18, 2018 From: Stanton Gill, Extension Specialist IPM for Greenhouse and Nurseries, Central Maryland Research and Education Center, University of Maryland Extension Karen Rane, Extension Specialist, Director of the Plant Diagnostic Clinic, University of Maryland Extension Andrew Ristvey, Extension Specialist, Wye Research and Education Center, University of Maryland Extension Suzanne Klick, Technician, CMREC, University of Maryland Extension Wet Conditions - Perfect for Fungus Gnats By: Stanton Gill, UME Starting on September 9, the rains came in and we had downpour after downpour. September 10 was like a day that the sun never came up with mist and heavy cloud cover all day. On September 17 and 18, we had more rain in the area with periods of heavy rain and steady cloud cover. It is hard in a September like this one to NOT HAVE FUNGUS GNATS active in your crops. Keeping plants on the dry side is really tough when all you have is cloud cover and rain coming at your regularly. The larvae of fungus gnats primarily feed on fungi and organic matter in substrate, but also chew roots and can be a problem in greenhouses, nurseries, and interior plantscapes. Fungus Gnats Versus Shoreflies: Both found in this kind of weather If you are using yellow sticky cards to monitor for insects, grab a X hand lens and look closely at your sticky cards. Fungus gnats (Orfelia and Bradysia species), also called darkwinged fungus gnats (Sciaridae), are dark, delicate-looking flies similar in appearance to mosquitoes. Adult fungus gnats have slender legs with segmented antennae that are longer than their head. Their long antennae distinguish them from the more robust shore flies, which are also found in greenhouses and associated with algae and decomposing organic matter, but have short bristle-like antennae. Although a few species are up to 1 2 inch long, fungus gnat adults commonly are about 1 16 to 1 8 inch long. Wings are light gray to clear, and the common Bradysia species have a Y-shaped wing veins. Fungus gnats, Bradysia spp., have Y-shaped wing veins Photo: Jim Baker, North Carolina State University, Bugwood.org Shore fly adults are more robust than fungus gnats and have white spots on their wings Damage Adult fungus gnats are primarily considered a nuisance. Larvae, however, when present in large numbers, can damage roots and stunt plant growth, particularly in seedlings and young plants. Significant root damage and even plant death have been observed in interior plantscapes.

2 Life Cycle There are four stages of fungus gnat development - egg, larva (with four larval stages or instars), pupa, and adult. Look for all stages in damp organic media where females lay eggs and larvae feed. At 75 ºF, eggs hatch in about 3 days, the larvae take approximately 10 days to develop into pupae, and about 4 days later the adults emerge. A generation of fungus gnats (from female to female) can be produced in about 17 days depending on temperature. The warmer it is, the faster they will develop and the more generations will be produced in a year. Dealing With This Pest Most of the fungus gnat s life is spent as a larva and pupa in organic matter or soil, so the most effective control methods target these immature stages rather than attempting to directly control the mobile, short-lived adults. Physical and cultural management tactics primarily the reductions of excess moisture and organic debris are key to reducing fungus gnat problems. Tough to do when it rains regularly like it has for the last 10 days. Get the HAF going and hold back on the watering. Biological Pesticides and Natural Enemies for Fungus Gnat Larvae Control Bacillus thuringiensissubspecies israelensis (Bti) (Gnatrol): Bti provides temporary control of fly larvae, such as mosquitoes, black flies, and fungus gnats. Repeat applications are often needed. Bti is a different subspecies than the Bt used to control the caterpillars of moths and butterflies. Hypoaspis(=Geolaelaps or Stratiolaelaps) miles: Hypoaspis feeds on the upper layers of moist sol and preys on fungus gnat larvae and pupae, thrips pupae, springtails, and other tiny invertebrates. These mites are available commercially in shaker containers. Apply at recommended rates of 6-24 mites per container or square foot of media. Apply before fungus gnat populations are a problem. Steinernema feltiae - This beneficial nematode is effective when temperatures are between 60 to 90 F and conditions are moist. These nematodes search for prey so moist conditions enable them to continue to be active. Nematodes can be applied as a drench usin conventional spray equipment. Be sure to remove the filter before application. Chemical Controls Be sure to read the label of all chemicals to make sure they do not damage the plants being treated. Some poinsettia cultivars are damaged by some soil treatments. Treating the substrate with one of the following can control the larval stage of fungus gnats: Distance, Azadirachtin, bifenthrin, dinotefuran, and Enstar II. Fungus gnat damage to a poinsettia stem growing in an oasis cube Note the black head capsule of this fungus gnat Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

3 Cut Flower Field Day Highlights The commercial cut flower tour was held on Wednesday, September 12 in Southern Maryland with 48 growers attending. We visited two cut flower operations and the Loveville Produce Auction. Local florists and roadside marketers commonly buy cut flowers and produce at this market held on Wednesdays and Fridays of each week. In its 14th season, the Loveville Produce Auction is a full service produce, ornamental plant, and fruit auction representing 100 growers. This auction is in a 14,000 square foot facility that operates from February through December. Sales begin at 9 am with a drive through auction followed by floor and small lot sales. Visitors during September will find a selection of cut flowers, most summer vegetable crops (tomatoes, watermelons, squash, lopes, peppers, sweet corn, etc...) and the start of late summer crops and transplants. Colorful bouquets with sunflowers, salvia, celosia, and other flowers were available at the auction when we visited The first cut flower farm site we visited was the Weaver s farm in Mechanicsville, MD. The Weavers produce cut flowers in roll-up side greenhouses and in the field on approximately 5 acres. They have a large variety of seasonal cut flowers year round, available by the stem or ready-made bouquets. The Weavers sell both wholesale and retail. They have developed a reputation for producing high quality floral arrangements and bouquets for weddings and events. An innovative device that Elvin Weaver uses is a spray boom of 25 ft length that can be adjusted to various heights over different height crops. Originally, Elvin applied his fungicides and insecticides using a 3 gallon back pack sprayer. In a wet season like 2018, this method was taking huge amounts of time with multiple applications needed with the heavy, frequent rains. He had a Pennsylvania company put together an articulated arm sprayer boom that runs off a gasoline engine. The engine provides the pressure for the spray tank and operates the articulation of the spray boom. The really interesting thing is this equipment was hooked to a wagon with steel wheels that is pulled by two draft horses. I spoke with Elvin about the device and he said the company does make versions that hook on tractors or wagons pulled by tractors. So, if you don t have draft horses on your cut flower farm you can still look into one of these boom sprayers. He reports that it saved huge amounts of time when applying foliar applications of fungicides and insecticides. At the Weaver Farm, this spray boom is pulled by two draft horses

4 The Weavers grow cut flowers for the wholesale market in the field and high tunnels. They use fiberglass stakes to support their cut flower netting. The second cut flower farm we toured was the Hertzler Family Farm. Jacob Hertzler and his family focus on the production of field-grown cut flowers for sale to the wholesale market. Jacob specializes in celosia with a smaller variety of other cuts as well. They also produce a specialty variety of eggplant for wholesale markets in Washington DC. The Hertzlers focus on growing celosia for the wholesale cut flower market, but also produce crops such as marigolds and salvia Fall Soil Tests for Next Year s Cut Flower Production By: Andrew Ristvey, UME In preparation for next year s cut flower production, consider a fall soil test which will give you a leg up on setting your soil s nutrient status for the spring. Fall applications of nutrients will give a reactive head-start in your soil for ready-to-go availability for your plants come March. Nutrients like phosphorus, potassium, calcium and magnesium, and even sulfur (while the soil temps are still warm) can be applied before cold weather arrives.

5 If you have taken soil tests before and have had a full nutrient profile performed including all your micronutrients, and you have not had symptoms of micronutrient deficiencies, a basic soil analysis can be done which covers nutrients like phosphorus, potassium, calcium, magnesium, ph, cation exchange capacity, base ion saturation and organic matter. Some laboratories give nutrient analyses values in parts per million or milligrams per kilogram (ppm) and others report in lb per acre. The conversion is 1 lb per acre = 0.5 ppm. For example, if your lab reports a sulfur result of 60 lb per acre in your soil, the conversion is 30 ppm. Another reporting method may be the Fertility Index Value (FIV). The FIV a continuous relative scale of nutrient availability, based on laboratory tests. Nutrients typically reported with FIV include phosphorus, potassium, calcium and magnesium. Depending on the laboratory, there are several methods of extracting nutrients from soils when testing for availability and each report could have different results. The FIV is a common, normalized scale developed to compare one soil analysis to another. Some laboratories will give test results in FIV, which is a continuous scale that starts at 0. Low nutrient availability is 0-25; Medium nutrient availability is 26-50; Optimum nutrient availability is ; Excessive is 101 or greater. For a guide to FIV categories see University of Maryland Soil Fetility Management fact sheet SFM-3 for a detailed explanation. High tunnel soils may be of particular concern because of their lack of exposure to rainfall and accumulation of salts from irrigation water and fertilizers. Because of this, soil tests taken every two years or less after initial covering will help gauge the extent of mineral accumulation and possible ph change. A high tunnel owner should know their water quality, chiefly the alkalinity (carbonates) which drives ph higher in soils especially under high-tunnel production. For further information about taking and interpreting soil analyses, feel free to contact Andrew Ristvey at aristvey@umd.edu. Poinsettia Pests By: Stanton Gill Brian Kunkel (University of Delaware), Suzanne Klick, and Rachel Ross, and I are evaluating several new chemistries this fall for whitefly control on poinsettias. We took the first set of data on Monday (Sept. 17) and will take a second set of data in 2 weeks. We will let you know the results this winter. As we examined hundreds of poinsettias on Monday we saw two things. One was some of the poinsettia leaves had thriving populations of two-spotted spider mites. Normally, I would expect to find Lewis mite, which is a type of tetranychid mite. This time we were finding two-spotted spider mite, which is also a tetranychid mite. The bottom line is monitor your poinsettia foliage in September, flipping over the foliage and looking with a hands lens at the undersides of the foliage. If mites are found, then the mite growth regulators Tetrasan or Hexygon can be used. Sanmite and Judo all work on mites. Check the undersides of foliage for two-spotted mites; adults, nymphs, eggs, and cast skins may be present

6 The other interesting pest we found on our plants was citrus mealybug. Citrus mealybug does very nicely on poinsettias. If you had previous crops in the greenhouse such as hibiscus or other tropical type plants that tend to harbor mealybug, then you need to monitor for this pest. In our mealybug trials this summer, Brian and I found Mainspring and Altus both worked very well on mealybug. Also check poinsettia plants for the presence of citrus mealybugs New Plants Conference at Country Springs Nursery on October 25, 2018 Succulents, Temperennials, and Shrubs for Low Maintenance Landscapes: Scott Aker, U.S. National Arboretum Consumers want plants that do provide color and texture all season long and withstand weeks of drought bracketed by weeks of flooding. See some of the newest succulents outdoor containers that extend the range of plants that thrive with little or no watering on sunny decks and patios, learn about tender plants that thrive in heat and humidity and fill space in beds quickly, and find out about the best new shrubs to provide seasonal interest and create a framework for everything else in mixed plantings. Scott Aker will share some of his favorites that could be profitable new plants for you to consider. New Cultivars from the University of Connecticut: Dr. Mark Brand, University of Connecticut The University of Connecticut has a long history of horticultural plant breeding and cultivar introduction. Recent plant improvement efforts have focused on shrubs with an emphasis on development of dwarf and sterile cultivars. Breeding of dwarf buddleia, sterile Japanese barberry, aronia, cold hardy rhododendons, and shrub Prunus will be explored. Interesting Palms, Citrus and Aloes that are Hardy: Dr. Ralph Denton, Pungo Palms Nursery Pungo Palms is a nitch nursery specializing in plants that will give an owner a unique subtropical landscape. We started growing palms as a hobby and decided to open our nursery to the pubic 14 years ago. The nursery plants can be divided into the following categories: Cold hardy citrus, Cold hardy palms, desert plants, and other exotics. You can learn of potential new hardy plants that could expand your market Hot Tropical and Cool Edibles: Heather McDermott, AgriStarts Tropicals are hot in the industry! From making mixed containers pop on a customer's deck or patio, tropicals are always a good bet. Edibles are more prominent than ever with new varieties made available to the public and others being 'discovered' in other countries to bring to the US Market. Learn about a few of the varieties in the trade! Bulbs as Companion Plants: Brent Heath, Brent and Becky s Bulbs Whether you are planning to plant bulbs in a fresh, newly prepared empty garden, or whether you are adding them to an already existing one, this seminar will have the answers for you! With exquisite slides illustrating the seminar, you will be introduced to the best of the best...the right bulbs for the right spots. You'll learn how to combine bulbs, perennials, annuals, ground covers and flowering shrubs that will create just the feeling you want to generate for four seasons in your garden. After seeing and experiencing this seminar, you'll leave with information and inspiration to produce a garden that you, your neighbors and friends will enjoy all year. Brochure and Registration Information 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 and Stanton Gill unless stated otherwise. The University of Maryland Extension programs are open to any person and will not discriminate against anyone because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry, national origin, marital status, genetic information, political affiliation, and gender identity or expression.