LSU AgCenter Ornamental Horticulture E-News & Trial Garden Notes Late May / Early Mid June 2016

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1 LSU AgCenter Ornamental Horticulture E-News & Trial Garden Notes Late May / Early Mid June 2016 Nursery, Landscape & Garden Center Updates Compiled by Allen Owings, Professor (Horticulture), Hammond Research Station, LSU AgCenter Edited by Rick Bogren, Professor (Communications), LSU AgCenter Phone ; aowings@agcenter.lsu.edu; Headline News Buddleia June 14th Colorful Flowers that Take the Heat June 9th Prepare Properly Prior to Planting May 16th Japanese Maples June 9th Plants with Potential Program May 26th Over-Mulching Trees (from Allen Owings) Excessive mulching around trees continues to be a problem in Louisiana. There are many negative results from over-mulching around trees. One of the tendencies in landscapes now is to make piles of mulch (sometimes resembling the shape of a volcano or fire ant mound) around the base of trees, especially small-flowering trees, such as crape myrtles, in residential landscapes. Oaks and other trees are also commonly over-mulched. When mulching, spread out mulch horizontally instead of piling it up vertically. The LSU Ag Center horticulturist says trees normally should be mulched to a depth of 3-4 inches. It is important to keep the root, stem transition area free of mulch. Do not bury the root flare. Problems that result from over-mulching and piling mulch around the base of trees include: -Oxygen starvation of the shallow roots. -Phloem tissue death (caused by reduced oxygen exchange). -Increased fungal and bacterial infections (from increased moisture around trunk).

2 -Heat buildup from mulch decomposition kills stem and trunk tissue. -Mulches can modify soil ph. -Microbes in the mulch compete with tree roots for nutrition. -Accumulated mulch is habitat for rodents that feed on plant tissue. This includes moles, voles and shrews along with mice, rats and more. Recommended mulches for use in Louisiana include pine bark, hardwood, pine straw and similar materials. For more information on caring for your lawn and landscape, contact a county agent in your parish office of the LSU AgCenter. Louisiana Super Plants Announced for 2017 and 2018

3 Thank You Mid South Green Industry Conference Sponsors

4 Under the Sea Coleus from HortCouture (from Allen Owings) The Under the Sea coleus collection from HortCouture includes ten varieties Bone Fish, Copper Coral, Fish Net, Gold Anemone, King Crab, Lime Shrimp, Lion Fish, Red Coral, Sea Weed and Yellowfin Tuna. Plants are currently being trialed at the LSU AgCenter and at Mississippi State University. Initial quality ratings at Hammond, LA favor King Crab and Yellowfin Tuna as the top performing varieties. KING CRAB Coleus Under the Sea Collection YELLOWFIN TUNA Coleus Under the Sea Collection

5 A Heritage Verbena to Consider Appleblossom (from Allen Owings) Appleblossom (aka Texas Appleblossom and Port Gibson Pink ) is one of the better landscape performing of the older Verbena canadensis varieties. Texas selection from Greg Grant. Large cotton candy-pink blooms with a white eye. Flowers fade to blush, white. Hummingbird and butterfly plant. Margie Jenkins Azalea Garden Lecture Series and Spring Field Day Report (from Rick Bogren, AgCenter Communications) A wet fall and warm winter followed by heavy rains this spring provided ideal conditions for pathogens and insects, fueling several problems for gardens and nurseries, said LSU AgCenter plant doctor Raj Singh. His presentation was one of several on May 6 at the annual Margie Jenkins Azalea Garden Horticulture Lecture Series and Industry Open House, an event held at the AgCenter Hammond Research Station in recognition of Jenkins, a longtime Louisiana nursery owner. Singh said leaf gall has been cropping up in azaleas and camellias. The disease won t kill the plants but causes unattractive galls to grow on leaves and turn brown. Removing galls from plants and the ground is essential to manage the disease, he said. Rust disease has also been a problem on flax lilies and roses in Louisiana because of favorable weather conditions this year, he said. Leaf gall and rust are not new problems to Louisiana, Singh said. On the other hand, rose rosette disease is new to the state and has been found in the Shreveport area. Knock Out roses and all other cultivars are susceptible to rose rosette, which can cause thickened canes, excessive thorns and reddish foliage, Singh said. Leaf scorch in sweet olives and oleander is another new disease showing up in Louisiana, Singh said. The leaf scorch bacteria clog channels in plants, restricting the movement of water and causing the plant to wither. There is no cure. Citrus greening and citrus canker continue to have devastating effects on citrus trees in Plaquemines Parish. Disease surveys have almost been completed to determine the spread of these diseases in Louisiana, Singh said.

6 Photo Caption - LSU AgCenter plant doctor Raj Singh, right, talks about plant diseases at the annual Margie Jenkins Azalea Garden Horticulture Lecture Series and Industry Open House at the AgCenter Hammond Research Station on May 6. Photo by Olivia McClure. A Section 18 exemption has been renewed for Louisiana, allowing the use of the Termidor insecticide to control tawny crazy ants, AgCenter entomologist Dennis Ring said. The ants can build up huge populations quickly. It s very important not to move this ant to your area, Ring said. The field day also highlighted plants that perform well in Louisiana landscapes, including both natives and new releases. The Southern Living Plant Collection and Encore azalea lineup both continue to grow, with several new varieties recently or soon to be released to the market, said Buddy Lee, director of plant innovation for Alabama-based Plant Development Services. The Encore Autumn Fire azalea is a recent release with true red flowers on a compact plant that is heat- and cold-tolerant, Lee said. The Sunbow Azalea series offers similar shades the orange-red Solar Glow and yellow Solar Flare along with a honeysuckle fragrance and resistance to powdery mildew. Lee also talked about the Sunshine ligustrum and Lemon-Lime nandina, which both offer bright color and are adaptable to many soil conditions; the Marvel mahonia, which has yellow, fragrant sprays of blooms in late fall and early winter; the Purple Daydream loropetalum, a compact plant and new release; and the Delta Fusion crape myrtle, a new addition to the Delta series with dark pink blooms and burgundy foliage.

7 The White Lightning hydrangea, which has a sturdy stem and large conical blooms, will be released soon, Lee said. He also pointed to cyrilla and cliftonia as examples of plants native to the South that do well in gardens. We re moving to develop native plants that are more adaptable to gardens, he said. Jeff Kuehny, resident director of the AgCenter Botanic Gardens at Burden in Baton Rouge, shared information about some of his favorite annual, perennial and woody ornamentals as well as fruits and vegetables. Some of those plants have been selected for the Louisiana Super Plants program, which promotes plants that are university tested and industry approved as top performers in Louisiana landscapes. More than 30 plants have been named Super Plants in the past six years. Allen Owings, resident director at the Hammond Research Station, gave a tour of the Sun Garden at the station, where attendees saw a number of Super Plants. The 2016 selections include Evolution series salvia, which are available in white and violet and are easy to grow from seed; Serenita Raspberry angelonia, a good choice for a summer bedding plant; and Miss Schiller s Delight viburnum, a native shrub that can be used in place of Indian hawthorn. Also growing in the Sun Garden are 2015 Super Plants, including henna coleus, Fireworks pennisetum, Homestead Purple verbena and Leslie Ann camellia. Attendees also got a preview of 2017 and 2018 Super Plants selections, and saw Plants with Potential, which are less common ornamental plants that perform well in landscapes. Olive and Fig / LFVGA Field Day Report (from Olive McClure, AgCenter Communications) Louisiana fruit and vegetable growers had an opportunity to view two new orchards for olives and figs during an industry field day on May 19 at the LSU AgCenter Hammond Research Station. The demonstration orchards are long-term projects, with 96 young olive trees planted in the spring of 2016 and 88 young fig trees planted so far, said LSU AgCenter horticulturist Jason Stagg. The olive trees will take four to five years before they begin producing fruit, said LSU AgCenter horticulturist Allen Owings. Olives are big in Texas, and we hope to be able to find out if they can be a viable industry in Louisiana, Owings said. Owings reviewed recommended practices for growing olives and noted that the trees aren t insect- or disease-free. The figs are true to type varieties gathered from an orchard at the LSU AgCenter Botanic Gardens at Burden. This permanent collection of LSU-bred figs and other varieties that perform well in the South and have been relocated to Hammond, where they can be propagated for commercial use, Stagg said. The orchard is helping preserve the historic AgCenter fig breeding work done by Ed O Rourke and Charlie Johnson, Stagg said.

8 AgCenter fruit and vegetable specialist Kiki Fontenot reviewed results of recent variety trials for carrots and squash. The first-year carrot trials were conducted at three locations in Tangipahoa, Pointe Coupee and Tensas parishes. We ll do these trials again to get a handle on how well these varieties perform for more than one year, she said. The squash trials haven t been completely harvested yet, Fontenot said, so we re sharing our notes on what we re seeing so far. Fontenot also provided information on herbicide treatments for watermelon production on bare fields without the use of plastic mulch. In addition to suppressing weeds, the chemicals can provide other benefits. If you use herbicides, you get more sunlight and less food-borne pathogens on the melons, she said. With the success of large tea farms in South Carolina and Mississippi, Louisiana growers could benefit from growing tea as an alternative crop to supplement their income, said AgCenter plant researcher Yan Chen. Tea is the second beverage next to water worldwide, Chen said. It had a $10.2 billion sales value in the U.S. in 2014 and a rising market projection for the next 10 years. Growers can harvest high-value tea from the top leaves from the first and second flushes of leaves in the spring, she said. With the release of new blueberry varieties in the past few years, growers should look at how they could perform in their operations, said Eric Stafne, an extension and research professor at Mississippi State University. He reviewed the attributes of new rabbiteye and Southern high bush varieties. Spotted wing drosophila fruit fly can be a problem in blueberry production, Stafne said. Found throughout the United States, the flies begin infesting fruits when they are green and can cause significant damage to fruit. The fruit flies can be controlled by early harvest and by field sanitation. Chemical control, including organic options, is available. Fruit and vegetable growers can qualify for special tax deductions for donating unmarketable or excess produce, said Megan Nuismer Herrington with the Second Harvest Food Bank of Greater New Orleans and Acadiana. Food banks work with donors and supply food pantries throughout the area, she said. The organization can work with growers to pick up and distribute their production. Federal laws provide opportunities for tax deductions for food donations along with Good Samaritan liability protection, she said.

9 Photo Caption - LSU AgCenter horticulturists Jason Stagg, left, and Allen Owings explain during a fruit and vegetable growers field day on May 20 that a new fig orchard is being established at the AgCenter Hammond Research Station to provide true to type fig cuttings for propagation. Photo by Rick Bogren. Hostas Returning at Hammond, Early Season Performance (from Yan Chen) Hostas returned pretty nicely to the shade garden this year, except some loss due to the shrew/mole chowing on the roots and crown. Best ones this year: Cathedral Windows, Guacamole, So Sweet, Patriot, August Moon, Fragrant Bouquet, and Fragrant Blue.

10 LSU AgCenter Soil Testing and Plant Analysis Lab LSU AgCenter Plant Diagnostic Clinic