This Month in Mid-Atlantic Horticultural News
Mid-Atlantic Horticultural Rolodex
New fertilizer law hot topic at Md. conference
By DEBORAH SMITH FIOLA
Landscapers, nursery and garden center managers were treated to a day of instruction, tips and practical information Dec. 1 at the University of Maryland Extension Pest Management Conference. Held at Carroll County Community College, the forum included expert speakers, pest management hints, business skills, spraying guidelines, environmental advice, plus a strong dose of enthusiasm.
Pest control was a big topic, from the status of new pests to the progress in managing established pests. The pest on everyone’s mind was the Brown Marmorated Stink Bug (BMSB), addressed by Starker Wright, a specialist from the USDA research station in Kearneysville, W.Va. Notwithstanding the nuisance of this pest, “All farm market crops are still at risk,” he said, “even cut sunflowers.”
Using data from the tree fruit industry, he showed the population level changes over the past few years and discussed the potential reasons why 2011 did not become the huge BMSB disaster of 2010. “There were plenty of stinkbugs out there,” he said, many “constantly reinfesting” plants, for example, moving from wild plant hosts (such as soybean fields, tree of heaven and so forth) to cultivated hosts. The weather may have had an impact in reducing the nuisance population, he said, “particularly the timing of the Hurricane in late August,” when both nymphs and adults are active.
Wright showed research results from pheromone-baited teddar trap studies this summer. The traps that were used (and those on the market) use a pheromone lure of a different species of stinkbug than the BMSB responds to. However, his lab has also performed tests to pinpoint specific ways to improve traps, including visual (light) cues and olfactory stimuli (for example, scent lures). These new trap lures will be formulated and field tested next year. For now (specifically for indoor use over the winter), he verified that light traps will work, including soda bottle traps, Rescue traps and the Strube trap (a fluorescent light/sticky trap — “It’s just messy,” he said.)
Stanton Gill, University of Maryland Extension specialist and program coordinator, updated the audience on the new/recent pests to be found in the area. One new pest is called the Kudzu Bug, an introduced pest from India/China and member of the stink bug family. It “looks more like a beetle than a bug,” he said, since its size and shape is “similar to that of a Colorado potato beetle.” A pest of soybeans, it aggregates in the fall and is already a major nuisance in Georgia and North Carolina, congregating on doors and windows of homes similar to the BMSB. It has been reported at the U.S. National Arboretum in our area.
Gill also provided an update of the Emerald Ash Borer (EAB), citing research from multiple states. “If you want to save an infested tree, you need to start using insecticides while the tree is still relatively healthy,” he said. Safari (Dinotefuran) and imidichloprid (Merit, Imicide, XyTect, IMA-jet) remain the most widely used products against the EAB. Safari is labeled as a bark/trunk spray, while Imidichloprid can be applied as either a soil drench, soil injection or trunk injection. These insecticides are systemic and must be transported through the tree's vascular system to the branches. Results from studies in Ohio showed that Safari “effectively moved into the trees and was translocated to the canopy at rates faster than other soil-applied neonicotinoid products,” said Gill. However, research also has shown that a single injection of TREE-äge (emamectin benzoate) in mid-May/early June provided excellent control of EAB for at least two years.
Foliar pesticides (formulations of permethrin, bifenthrin, cyfluthrin and Carbaryl, and “particularly Onyx, Tempo and Sevin SL”) are designed as protective sprays against feeding by adults only, and “do zip for the larvae feeding under the bark.” In addition, spring (March to early April) applications of imidacloprid gave better control than fall applications.
The Ambrosia beetle continues to spread across the state as well. Traps monitored this summer found high levels of beetles appearing as early as April 11, from Keedysville to Damascus to Waldolf. This tiny beetle is just 2 to 3 millimeters long but it attacks a wide range of plants and can easily kill large shrubs and trees, including honey locust, London plane tree, Zelkova, river birch, American holly, American beech, crepe myrtle, sweet bay magnolia, Kousa dogwood, Hybrid dogwoods (especially the Stellar series), sugar maple, hybrid chestnuts, flowering plum, deciduous azalea, red maple, Styrax and yellow wood. Drought and other conditions that weaken trees seem to promote ambrosia beetle attack. The trees exhibiting serious damage should be removed and destroyed (burned) before the eggs hatch, which occurs 55 days after they are laid. There are no known systemic or other chemicals that can kill the insects once inside the plant. Preventive trunk sprays of Onyx (bifenthrin) or Astro or Peremethrin E.C can prevent females from laying eggs.
University of Maryland Plant Diagnostic Lab Director Karen Rane spoke on the 2011 weather effects upon landscape plants, with a focus on disease. “Fall 2010 was relatively warm,” she said, “but a sudden freeze in December 2010 followed by a cold and windy January and February 2011 was a recipe for winter injury.” Many conifers did not go dormant before the cold temperatures, causing winter injury symptoms to be plentiful this past spring. “There were tons of brown foliage on Leylands and cryptomerias,” she said. Spring 2011 was also wet, setting the stage for foliar diseases. Indeed, anthracnose was rampant, including a new anthracnose found on beech. Rane predicted the potential for a great deal of prospective anthracnose this coming spring, depending on temperatures and wetness, would be high due to plentiful innoculum present from last year.
Other prevalent diseases last spring due to wet weather included brown rot in cherry, fireblight and cedar-rust diseases (notably Cedar-Quince rust on juniper). A record hot July scorched shallow rooted trees like dogwood, followed by Hurricane Irene in late August. “There was 300 times the normal level of precipitation in September,” declared Rane. Bleeding canker (Phytophthora), became problematic on poorly drained sites, as well as wood rot (on cherry).
The biggest problem of 2011 was herbicide damage, specifically damage with Imprelis. As a synthetic auxin, Imprelis was taken up by roots of trees and shrubs adjacent to turfgrass, causing distortion damage similar to 2,4-D injury. “The label says ‘Take Care when applying under the drip line of trees,'” Rane read, “but what exactly does that mean? It does not say ‘Do not apply here.’” Imprelis damage was noticed primarily in spruce, arborvitae and white pine. The damage was first seen in conifers about two to four weeks after application, on new season’s growth. “The most vigorously growing trees were the worst,” said Rane. Even trees like ginkgo were affected, appearing “like variegated edges.”
Unfortunately, even though Imprelis will no longer be sold (it was voluntarily suspended by Dupont), “no one knows for sure how long it will persist in the soil,” she said. Until more is known, she warned not to use treated grass clippings as mulch or in compost (“It will leach out”), not to transplant into treated soil, and not to use wood chips of affected trees as mulch.
Lane Heimer, Maryland Department of Agriculture weed specialist, spoke on invasive weeds, focusing on how they outcompete native plants and have the potential to change soil chemistry. “I’ve seen their root systems penetrate the clay layer of storm water basins,” he said, adding they cause significant economic damage. He stressed that the No. 1 method of control of invasives is to prevent seed formation. “Mulch piles are often covered with weeds – that’s how they move in.”
Ginny Rosenkranz, an Extension educator with Wicomico County Extension, also spoke on weed management, with an emphasis on conditions promoting them. “Spurges like it dry,” she said, “Black medic moves in on compact soil, low fertility and low mowing heights.” Rosenkranz noted that pre-emergent herbicides will not work on gravel driveways or walkways. “Every time you drive or walk on the gravel, you break the chemical barrier,” she said. New herbicides such as Squareone are labeled for hard-to-control weeds like nutsedge and winter annuals, with both pre- and post-emergent capabilities. “Squareone can be applied seven days after seeding a new lawn,” she said. Solitaire is another new herbicide that is absorbed by roots and works like an auxin. It is labeled for both crabgrass and sedges. Tenacity is labeled for athletic fields, with post-emergent activity.
Rosenkranz also warned the crowd to be on the lookout for a new weed in our area called Eclipta. Found in moist disturbed sites, Eclipta is more of a problem in the landscape than in lawns, and its proficiency in setting seed. This dock-like weed is an annual, and a growing problem in the South.
Unconventional pests (“Small Critters”) were also highlighted by Jay Nixon of American Pest Co. Nixon relayed his vast experience in managing groundhogs, opossum, voles, and other pests frequently found in the landscape. He recommended using a piece of a down spout to trap voles, with a mouse trap within, placed perpendicular to a vole run. For groundhogs, the favored trap is the Conibear trap, which is lethal, “but I won’t use them if the customer has a cat or dog,” he warned. What about getting a skunk out of a trap? “Proceed very carefully,” Nixon quipped, suggesting that a blanket covering the trapped skunk will reduce its squirt potential.
Environmental concerns prompted three presentations at the seminar, with a spotlight on water quality, cultural problems and interpreting soil test results. John Lea-Cox, University of Maryland Extension specialist, discussed his recent research on irrigation timers for container nurseries. “How do you really know how much time to schedule between irrigations?” he challenged the audience. He demonstrated how the new DataTrac Irrigation Soil Moisture Sensor software calculates exactly how much water is taken up by plants – on an hourly basis. “I can tell you with utmost confidence that a 2-year-old, 2.5-inch caliper red maple in a gallon pot in 90 degree F. temps on average uses two gallons of water a day,” Lea-Cox said. “So there is no need to apply more water than that.”
His research showed that different tree species require different amounts of water. “Dogwood doesn’t use as much water as maple,” he said. Most tree roots were in the top 6 inches of soil, so probes did not need to go deeper. He also confirmed that “a tree that has a dripper will have 60 percent of its roots within 12 inches of that dripper.” The software requires 3G Internet connectivity and can be built into existing weather stations. Smart-Farms.net has more information available to interested nurserymen.
Andrew Ristvey, an Extension specialist at the Wye Research and Education Center, discussed the buffering ability of soils and its relationship to pH and liming needs. “Do we need to decide to lime according to pH?” he asked. “No!” Ristvey demonstrated a color change test (using audience participation) to prove his point. He also suggested doing a compost test before using compost on plants or adding extra nutrients.
The big topic of the day was the new Maryland Fertilizer Use Act of 2011, a new law designed to reduce the amount of nutrients washing into the Chesapeake Bay from lawns, golf courses and other non-agricultural sources. The law springs from the findings of the Chesapeake Bay Commission, which traced about 14 percent of the nitrogen and 8 percent of the phosphorus entering the bay from primarily residential lawns.
The law limits the amount of phosphorus contained in lawn fertilizer products sold. It also establishes a training, certification and licensing program for anyone hired to apply fertilizer to non-agricultural landscapes, including golf courses, public parks, airports, athletic fields, businesses, cemeteries, etc. Certification classes are being scheduled to instruct turfgrass managers to meet new standards in proper application techniques, uniform standards for applying fertilizers and knowledge of fertilizer products.
In addition, the law will limit fertilizer amounts applied to turf to less than 1 pound nitrogen per 1,000 square feet per application. It also requires that at least 20 percent of the nitrogen component of the fertilizer used be slow release.
The Fertilizer Use Act of 2011 will be implemented in phases over the next two years by the MDA and the University of Maryland. The law will be fully implemented by Oct. 1, 2013. A homeowner education program will also be implemented, according to Rosenkrantz.