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Ornamentals and Turf |
Already this spring we have received notices of different species of ground nesting bees in turf or landscapes. These bees nest singly in tubes excavated in the ground. Commonly they nest in close aggregations, but the tunnel nests are not connected. Each female constructs her own nest without help of other bees. There is only one generation per year, so after a few weeks the activity stops until next year.
These bees do not have a nest guarding instinct as do social wasps and social bees. Just walking by the nests will not prompt the bees to attack as they do not have alarm pheromones and the instinctive behavior to attack. It may be possible to step on one while barefooted and be stung on the foot, but that is about the only hazard from these otherwise beneficial insects. These solitary bees are valuable pollinators of spring crops. We suggest that it is better to coexist with the bees because of their value in the pollination of various plants than try to eradicate them with pesticides. Ornamental and Turf Insect Information Note No. 100 contains more information on these and other ground nesting bees.
The wool sower gall is a distinct and unusual plant growth induced by the secretions of the grubs of a tiny gall wasp, Callirhytis seminator. If a fresh wool sower gall is held in a plastic bag out of the sun (so it will not get too hot), within one to three weeks the tiny, harmless gall wasps will emerge. The wool sower gall is specific to white oak and only occurs in the spring. Pulling the gall apart exposes small seed-like structures. The gall wasp grubs develop inside these structures. (This gall is also called the oak seed gall.) Fortunately, wool sower galls are hardly ever abundant enough to cause harm to white oaks. Gall wasps invariably have alternation of generations in which one generation develops in one type of gall (leaf gall) and their offspring develop into another type of gall (stem gall). Wasps of each alternate generation are slightly different in size and the galls of each generation are enormously different from the parents. The wool sower gall may be the leaf gall of this species because of its transient nature. Ornamentals and Turf Insect Note No. 5 provides additional information on galls.
The cool-season mites, such as southern red mites, spruce spider mites and even boxwood mites, are becoming active. You have not seen any damage or had any complaints yet, because the damage will not be noticed for two months. By then it will be too late to treat for these pests. If you had damage last year, begin to check the shrubs now for activity. A good hand lens may be needed or tap the branch onto a white sheet of paper and watch for crawling specks.
Horticultural oils are a good choice for treatment. Horticultural oils may take off some of the blue luster from blue junipers, however. The BugDoc from Ohio State University states that strong spray from a water hose works well to knock down populations of spruce spider mites on evergreens. Commercial operators may use horticultural oils, Floramite, Talstar or any of several other miticides recommended in the "North Carolina Agricultural Chemicals Manual."
In the eastern part of North Carolina, county Extension agents should be prepared for telephone calls about the snow on the lawn. Those agents who have been in the job for a while know what this means. Tramp weed (Facelis retusa) is growing well now and will be flowering and fruiting soon. Some good photos and guidelines on control are to be found at the following link: http://www.ces.ncsu.edu/depts/pp/notes/ProblemHighlights/2052000.htm.
Yellow and purple nutsedge are growing. Horticulture Information Leaflet HIL-647 provides information on identification and control of yellow and purple nutsedge in landscape plantings. So far this spring I have sprayed the yellow nutsedge in my landscape beds twice, hand weeded many times and there are new green shoots coming up every day. I expect to be battling this weed until frost. County agents will have clients that say that Roundup does not work. It does work but it is slow, and while some plants are dying, other are sprouting from tubers. Last year was a particularly good year for nutsedge to grow and make tubers, so we are in for quite a battle with this weed in 2004.
From the central part of the state to the mountains, Japanese stiltgrass is beginning to grow. It is about 3 to 4 inches tall in the Raleigh area and is probably just germinating in the mountains. Wait a few more weeks to treat it. In landscape beds it can be controlled with selective grass herbicides such as Vantage, Fusilade (Ornamec & Grass B Gon), Envoy and Acclaim Extra. In cool-season turf it can be controlled with Acclaim Extra. MSMA and Drive have not been particularly effective. We have a fact sheet on this weed ready to post on the web. Check the following web site within the next week for this fact sheet: http://www.ces.ncsu.edu/depts/hort/weeds/index.html.
The following article is an April 23, 2004 news release from the North Carolina Department of Agriculture and Consumer Services (NCDA&CS). For more information, contact Gene Cross, Plant Pest Administrator, NCDA&CS Plant Industry Division, telephone: (919) 733-6930, ext. 231.
North Carolina is the tenth state to confirm the presence of a plant disease traced to shipments of ornamentals from a large Southern California nursery, the North Carolina Department of Agriculture and Consumer Services announced on April 23, 2004.
To date, camellias at seven nurseries and garden centers in the state have tested positive for sudden oak death (SOD), a fungal disease that is fatal to several species of oak trees but is less harmful to certain ornamental plants and shrubs.
Infected plants were confirmed at two locations in Wake County and one location each in Cabarrus, Forsyth, Guilford, Johnston and Mecklenburg counties. These were among 69 locations in the state that received host plants from Monrovia Growers in Azusa, California, during the past year.
Authorities in California detected SOD at the Monrovia site in March. The Azusa facility is not in the area covered by a plant quarantine for SOD, and officials did not expect to find the disease there.
Following notification by the U.S. Department of Agriculture, staff from NCDA&CS began inspecting the North Carolina locations and withheld suspect plants from sale pending test results.
SOD is not harmful to humans or animals, but it has caused the loss of thousands of oak trees in California and Oregon since 1995. Several types of ornamental plants, including camellias, viburnums, rhododendrons and Pieris, may spread the disease. Currently, USDA has identified 60 species of plants as either carriers or potential carriers of the disease, and the list could continue to grow.
"Sudden oak death is of great concern to us because it is new to the East Coast and so little is known about how it will react in North Carolina's climate and environment," Agriculture Commissioner Britt Cobb said. "We know it has caused considerable tree loss in California, but we don't know what the potential impact in North Carolina might be. To minimize the possible spread and impact of this disease, we are working with USDA personnel to destroy the infected plants and others nearby that have the potential to spread the disease."
Cobb said his department would continue to monitor these locations and conduct additional inspections.
Nursery and garden centers throughout North Carolina that received plants from Monrovia have been extremely cooperative in helping our staff trace plants and isolate them for inspection," Cobb said. "Because of their assistance, I am hopeful our efforts will enable us to contain this unwanted plant pest."
USDA has confirmed the presence of SOD in nine other states that received plants from the Monrovia nursery. They are California, Florida, Georgia, Louisiana, New Mexico, Oregon, Tennessee, Virginia and Washington.
A lot of mystery surrounds sudden oak death. The fungus that causes it, Phytophthora ramorum, was identified only a few years ago. The disease spreads naturally through spores moved by wind or water. It spreads more rapidly to new areas when moved inadvertently on plant material or other articles.
The discovery of sudden oak death in plants at the Monrovia nursery raised concerns that the disease could have been introduced to numerous locations across the country. In the past year, the Monrovia site shipped potentially infected plants to more than 1,200 locations in 39 states and Washington, D.C.
In response to detecting SOD at Monrovia, USDA notified NCDA&CS of 69 locations in North Carolina that had received host plants from the Monrovia site during the past year. NCDA&CS and USDA staff contacted each location and determined that 44 sites still had plants from those shipments. The shipments primarily contained camellias, viburnums and lilacs.
Many plants at those locations already had been sold. State and federal authorities placed holds on more than 12,000 plants remaining at the 44 sites. The held plants were inspected for symptoms of the disease, and samples from suspect plants were sent to a laboratory for testing. Plants with negative test results were released for sale.
NCDA&CS personnel are awaiting test results on samples taken at six of the 44 locations. In addition, nine of the locations have plants with newly developing leaves. Inspection of these plants must wait until the disease, if present, has time to develop.
Plants shipped from Monrovia to the other 25 locations in the state had been sold to customers and most could not be traced.
Plant samples collected by the NCDA&CS Plant Industry Division were initially screened for the presence of Phytophthora ramorum at the Plant Disease and Insect Clinic at North Carolina State University's Department of Plant Pathology. Additional testing of cultures by USDA confirmed the presence of the organism in camellias.
NCDA&CS will be responding to SOD in three phases, said Gene Cross, the department's plant pest administrator. Initially, staff will address locations where the disease has been confirmed. In May and June, the second phase will involve taking part in a national survey of high-risk locations to determine the scope of the problem. Once the survey is completed, the NCDA&CS anticipates it will begin assisting homeowners and others who bought plants that may carry the disease. This phase should begin in mid-June, Cross said.
This is an evolving situation, and our primary focus at this time must be on nurseries and garden centers," he said. "The results of these inspections and survey efforts will help us determine what steps we need to take to contain this plant disease."
The USDA Animal and Plant Health Inspection Service has established a sudden oak death hotline for individuals or businesses that may have questions or need additional information. The toll-free number is (888) 703-4457. Additional information may also be found online at http://www.aphis.usda.gov/ppq/ispm/sod/ and http://www.suddenoakdeath.org/.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on May 3, 2004 by Stephen J. Toth, Jr.