Plant & Pest Advisory

Transcription

1 Landscape, Nursery & Turf Edition May 5, 2011 Plant & Pest Advisory A Rutgers Cooperative Extension Publication Botryosphaeria canker on European hornbeam. Photo by Sabrina Tirpak, Rutgers Plant Diagnostic Lab. INSIDE Canker Diseases in Landscape Plantings: Cytospora and Botryosphaeria Cankers...1 Plant Diagnostic Lab Update...2 Diseases of Turfgrass...3 Edible Landscaping for Food and Beauty Introduction to the American Persimmon...4 Flood Tolerant trees...5 Weekly Weather Summary...5 Canker Diseases in Landscape Plantings: Cytospora and Botryosphaeria Cankers Ann B. Gould, Ph.D., Specialist in Plant Pathology Landscape trees throughout New Jersey have been stressed in previous years by winter damage, poor growing environment, or prolonged moisture extremes (drought or excessive moisture), and it often takes trees five or more years to recover. Not only do these stresses directly impact plant health, they also predispose affected trees to insect pests (such as borers) and diseases, especially cankers. A canker is a localized necrosis of the cambium and bark on trunks, stems, or twigs of woody and non-woody plants. These elliptical lesions girdle the stem, and as they enlarge, tissue distal to the canker dies. Cankers may appear roughened or smooth, sunken or slightly raised, and callous tissue may form at the periphery of the lesion. Fungi that cause cankers are opportunistic organisms that infect plants through wounds, other openings, and at the base of dead branches. The pathogen may spread through the cambium when the host is dormant or actively growing. Fungal pathogens produce fruiting bodies in dead tissue that release spores during favorable weather. A cut made into the wood with a pocketknife at the edge of a canker reveals a sharp transition between wood that appears white and healthy and wood that is brown and infected. Cytospora canker Many canker diseases are caused by fungi that are normally weak pathogens. If host defenses are sufficiently compromised, these cankers may kill weakened trees. A common canker disease of conifer and Prunus species is caused by species of Cytospora (syn. Leucostoma). Coniferous hosts of Cytospora kunzei include spruce (black, Colorado blue, Engelmann, Norway, red, and white), Douglas fir, balsam fir, eastern hemlock, eastern, European, and Japanese larch, and red, eastern white, and Himalayan white pine. Prunus affected by Cytospora leucostoma include apple, crabapple, apricot, ash, blackthorn, cherry, chokecherry, Russian olive, peach, pear, plum, prune, serviceberry, and golden willow. See Cankers on page 2 Page 1 Vol. 17 No. 4

2 Plant Diagnostic Laboratory Update Richard J Buckley, Laboratory Coordinator Turfgrass The long slow slug toward spring is finally starting to pay off. In most locations the turf has greened up nicely. None-theless, warmer soil temperatures and adequate canopy moisture are turning on the springtime disease agents. In my travels, I have seen dollar spot and red thread in landscape turf. Neither disease is widespread by any means, but just starting to get going in the field. In the laboratory, however, the disease of note is brown ring patch. Brown ring patch is also known as Waitea patch and is caused by the fungus Rhizoctonia circinata. The disease causes diffuse yellow rings with scalloped edges on putting greens and tees. Brown ring patch was diagnosed on samples from northern New Jersey and southeastern New York. Yellow patch, which has its own alias, cool season brown patch, is caused by Rhizoctonia cerealis. Yellow patch is more of a late-winter disease than a spring disease. It was diagnosed on a pair of samples from the Philadelphia area during one of the recent cold, rainy periods. Brown ring patch is very similar to yellow patch in initial appearance, but has a higher temperature threshold and does a little bit more damage. It will persist into early summer, and if left untreated, may cause some death of the turf. Brown ring patch will also degrade thatch, which might interfere with the ball roll on a putting green. Interestingly enough, the yellow rings caused by brown ring patch are dynamic and over time appear to float around the turf in a kaleidoscopic dance more attuned to Jerry Garcia than Tiger Woods. Although we are almost out of the woods for yellow patch, be aware that both of these diseases will continue to pop up during wet periods into June. Ornamentals Ornamental plants are coming in with increasing frequency as well. Of course, we looked at loads of winter damage in the usual suspects. We ve also had more than a couple plants in the last week that represented transplant failures from landscapes See Lab Update on page 3 In Prunus species, a yellow to orange-brown oozing is associated with the cankered regions on the branch. In conifers, cankered regions are resin-soaked, often first affecting the lower branches and progressing up the tree. Botryosphaeria dieback and canker The fungus Botryosphaeria is another weak opportunist that attacks trees and shrubs wounded or weakened by environmental stress, particularly drought. The disease can result in a branch dieback that may kill trees or severely reduce their aesthetic value. Indeed, Botryosphaeria canker is quite evident now on older rhododendrons in landscape plantings affected by recent hot, dry weather. Canker from page 1 Species affected by Botryosphaeria canker include ash, birch, cotoneaster, crabapple, dogwood, elm, firethorn, hop hornbeam, mountain laurel, locust, magnolia, mimosa, photinia, pieris, privet, rhododendron, and wax myrtle. Symptoms of Botryosphaeria canker vary with the species and age of the host and the severity of the predisposing stress. In rhododendron, you might first notice that the leaves are wilted, off-color, and curled downward parallel to the midrib. The affected tissue eventually turns brown, and more branches may be affected as the season progresses. These symptoms are due to the presence of cankers closer to the soil line, which form as the fungus kills infected bark and sapwood tissue. The cankers range from small, elliptical lesions that coalesce into large diffuse areas of blighted tissue, to large, elongate cankers delimited by callus tissue. Affected bark turns dark, rough, and may peel away. Multiple cankers of various sizes often develop on branch tissue, growing slowly until the limb is girdled and killed. The entire plant may be killed once the canker moves from the branch into the main stem. Canker management Environmental stresses can readily predispose plants to attack. When planting new trees and shrubs, choose a site that is suitable to the horticultural requirements of the species. For example, planting sun-loving plants in shady locations or placing plants outside their natural range can predispose these plants to canker disease. In older, established plantings, maintain or improve plant vigor with proper pruning, fertilization, and irrigation. Since drought stress predisposes trees and shrubs to canker development, watering during times of drought is particularly important. Prune moderately affected trees at least 6- to 8- inches below discolored tissue during dry weather. If possible, remove the branch at the branch collar; make a clean cut flush with the collar, not with the trunk. When pruning for disease control, surface sterilize pruning tools between cuts. Remove and discard (compost, chip, bury, burn) infected plant parts, and discard severely affected trees. Fungicides are ineffective against canker diseases and are not recommended. Since trees affected by drought stress, mechanical injury, or winter injury and storms are susceptible to canker development, expect to see more canker problems this growing season. Keep this in mind when monitoring landscape trees and shrubs for plant health. Page 2 Vol. 17 No. 4

3 Lab Update from page 2 installed last season. Despite excellent post-plant care, many new transplants could not keep up with the extreme heat and drought last summer and the snow, ice, and cold last winter. Another aspect of the extreme weather over the last two years is that landscape plants subjected to those stresses are often predisposed to attack by canker causing fungi. We are already starting to see evidence of this in the lab. A sample of European hornbeam (which by the way has few disease problems) was diagnosed with Botryosphaeria canker. Botryosphaeria is a relatively fast growing fungus that had already girdled several branches on the tree. A Japanese red maple was diagnosed with Cytospora canker. Cytospora is another relatively fast growing fungus that exploits plant material that has been damaged or stressed in some manner. Drought stress and Cytospora perfect together! See canker article on page 1. Close up of Botryosphaeria fruiting bodies. Note the white interiors of fruiting bodies that were sliced in half. Photo by Sabrina Tirpak, Rutgers Plant Diagnostic Lab. Diseases of Turfgrass Bruce B. Clarke, Ph.D., Specialist in Turfgrass Pathology Anthracnose This disease, caused by the fungus Colletotrichum cereale (previously known as C. graminicola), has started to develop on annual bluegrass greens in the region. This fungus typically attacks turf growing under stress (i.e., low nitrogen fertility, soil moisture extremes, etc.). Low cutting height (e.g., below inch) will also enhance disease development. To identify anthracnose in the field, look for small black fruiting bodies (acervuli) with protruding black spines on affected leaves or stems. Anthracnose can be suppressed by increasing turf vigor through the use of light, frequent applications of nitrogen (e.g., 0.1 to 0.2 lb N every 7 to 14 days), and by maintaining adequate soil water content. The application of a seedhead suppressant in April (e.g., Embark or Proxy-Primo) followed by sequential applications of Primo every two weeks from mid- to late-april through September will not increase anthracnose and, in some cases, may further reduce disease severity. Recent research at Rutgers University has also shown that anthracnose can be significantly reduced and acceptable greens speed (i.e., ball roll distance) maintained by raising the cutting-height while increasing mowing frequency and/or rolling every other day. For best results, apply Armada, Banner, chlorothalonil, Compass, ConSyst, Disarm, Eagle, Endorse, Headway, Heritage, Insignia, Spectro, Tartan, Tourney, Trinity, Triton or thiophanate-methyl on a preventive basis and repeat every 14 days through September per manufacturer s recommendations. Signature, the phosphites, Medallion and Chipco 26GT can also be used to effectively suppress this disease, but these products are most efficacious when applied in a tank mixture with one of the previously mentioned fungicides. Tank mix or alternate fungicides with different modes of action every 14 to 21 days when conditions are conducive for disease development to reduce the potential for fungicide resistance. Brown Ring Patch This disease is very active on golf courses in the tri-state region at this time. Brown ring patch (aka Waitea Patch), is a relatively new disease of annual bluegrass putting greens caused by the fungus Rhizoctonia circinata var circinata (= Waitea circinata var circinata). Bentgrass can also be affected; however, annual bluegrass is typically much more susceptible. This disease is similar in appearance to yellow patch, but it can occur at much higher air temperatures (50 to 85 o F for brown ring patch, compared to 50 to 65 o F for yellow patch). Infested patches become chlorotic and range in size from several inches to one to two feet in wide. The centers of patches are frequently green, resulting in a frog-eye or donut-shaped effect. The outer ring (1/4 to ½ inch in diameter) often turns bright yellow and later necrotic during warm, wet weather. The fungus can break down thatch, so the outer rings may become depressed as the thatch is decomposed. Since the leaves, crowns and thatch are affected, brown ring patch can be difficult to control with one fungicide application. Daconil (chlorothalonil), Chipco 26GT (iprodione), Endorse (polyoxin-d), Heritage (azoxystrobin), Insignia (pyraclostrobin), Medallion (fludioxonil), ProStar (flutolanil), and Triton and Trinity (triticonazole) have provided good control when used on a curative basis when applied on a 14 day interval, but this disease is most effectively suppressed when fungicides are applied on a preven- See Turf Diseases on page 4 Page 3 Vol. 17 No. 4

4 Turf Diseases from page 3 tive basis in early spring (mid- to late-april in the tri-state area). Multiple applications may be needed once symptoms develop and fungicides must be applied in sufficient water to ensure good penetration into the crown and thatch (e.g., at least 2 gal water / 1,000 sq ft at 30 to 40 psi). Once infections are arrested with fungicides, symptoms may take 14 to 28 days or more to recover. It is important to note that brown ring patch is not controlled with benzimidazole fungicides. Red Thread We are starting to see the development of Red Thread, caused by the fungus Laetisaria fuciformis, on susceptible turf at this time. This disease should become more prevalent in mid-may because of the frequent rainfall events that we have experienced over the last few weeks. Infections are characterized by the appearance of short red threads (1/16-1/4 inch long) emerging from tan-colored leaf blades. Affected patches are typically pink in color and range from 1 to 6 inches in diameter. Although perennial ryegrass and fine fescue are most susceptible, Kentucky bluegrass, velvet bentgrass and tall fescue may also be affected. Red thread is typically found on hungry (low fertility) turf during cool, wet weather. Well-fertilized turf, however, may also be attacked. To obtain optimum disease control, maintain adequate fertility levels, avoid drought stress and excessive thatch, and apply Armada, Banner, Bayleton, Chipco 26GT *, Compass, Curalan *, Eagle, Endorse, Headway, Heritage, Insignia, ProStar, Rubigan, Tartan, Trinity, Triton, Tourney or Touche * per manufacturer s recommendations ( * not for use on residential properties). Stripe Smut This disease, caused by the fungus Ustilago striiformis, is starting to appear in susceptible Kentucky bluegrass plantings. To identify stripe smut in the field, look for thick masses of black spores protruding through shredded leaf blades. Although fungicides are most effective when applied once in mid-october, present infections can such as Armada, Banner, Bayleton, Eagle, Rubigan, Tartan, or thiophanatemethyl. Follow label directions carefully for best results. Turf Field Day Mark your calendars now for this year s Rutgers Turfgrass Research Field Days which will be held on July 26, 2011 (Golf and Fine Turf Research Field Day at Horticultural Farm II, New Brunswick, NJ) and July 27, 2011 (Landscape and Sports Turf Research Field Day and Equipment Demonstrations at Adelphia Research Farm, Freehold, NJ). Additional information and directions to each location will appear in future issues of this newsletter. Edible Landscaping for Food and Beauty Introduction to the American Persimmon Joseph Heckman, Ph.D., Soil Fertility Specialist Pest free is an important attribute for edible landscaping. Pawpaw and Juneberry, as previously described, are practically pest free plants. Another worthy candidate for edible landscaping is the American Persimmon (Diospyros virginiana). This plant grows into a modest size tree from about 20 to 50 feet tall. Persimmon trees are either male or female. Thus, if you want fruit, you will need to grow a female tree. Male trees are useful for pollination but may be unnecessary to plant if there are enough wild trees growing nearby. Persimmon fruit are orange, sweet, and luscious when fully ripe but very astringent while green. A very productive and easy to grow persimmon for New Jersey is the variety Meader. This cultivated variety is available from many nursery companies easily found with a web search. Although persimmon has small flowers that do not put on a big spring show, the tree does have great fall color with a display of orange to scarlet leaves. The summer leaves are dark green and glossy on the upper leaf surface. In my experience American Persimmon is an easy to grow reliable fruit producer at my farm every October. A single tree will likely produce far more fruit than a family can eat. American persimmon. Page 4 Vol. 17 No. 4

5 Flood Tolerant Trees Bert Cregg, Michigan State University, Departments of Horticulture and Forestry Reprinted from Landscape Crop Advisory Alert, March, 2011, Michigan State University Flooding is a fairly common occurrence in the spring. After a flood, we frequently receive phone calls from homeowners wondering how long their trees can survive being underwater. As with most things, the answer is It depends. For the most part, short-term flooding (two or three days) should not cause too many issues with trees. Trees that are flooded when they are still dormant will be less effected by flooding than if the inundation occurred during the middle of the growing season. The type of tree also makes a huge difference in its ability to survive flooding. Many tree species can survive months under water while others may be killed by just a few days of inundation. In general, a species native habitat can give us a pretty good clue as to how well it can recover from flooding. Upland species, such as hickory and many oaks, usually do not survive flooding while bottomland species, like red maple or sweetgum, are more tolerant of flooding. Most evergreen conifers are relatively intolerant of flooding. Exceptions are white spruce and arborvitae, which can tolerate some flooding. Also, deciduous conifers (larch, baldcypress and dawn redwood) are usually very tolerant of flooding. Flood tolerance ratings of trees can sometimes be confusing, and species listed as tolerant on one list may be listed as intolerant on another. The table presented on the next page is excerpted from one of the most comprehensive reviews of flood tolerance in trees and provides a good reference. As you ll note in the table, green and white ash were among the most flood tolerant of our common landscape trees. Understanding the relative flood tolerance of trees will be increasingly important as we think about replacement species for ash. See Table on page 5 Weekly Weather Summary Keith Arnesen, Ph.D., Agricultural Meteorologist Temperatures averaged much above normal, averaging 64 degrees north, 63 degrees central, and 64 degrees south. Extremes were 90 degrees at Canoe Brook on the 27th, and 39 degrees at numerous locations on the 1st. Weekly rainfall averaged 0.70 inches north, 0.54 inches central, and 0.33 inches south. The heaviest 24 hour total reported was 0.75 inches at Long Branch on the 28th to 29th. Estimated soil moisture, in percent of field capacity, this past week averaged 96 percent north, 92 percent central and 80 percent south. Four inch soil temperatures averaged 62 degrees north, 62 degrees central and 64 degrees south. Weather Summary for the Week Ending 8 am Monday 5/ 2/11 R A I N F A L L TEMPERATURE GDD BASE50 MON WEATHER STATIONS WEEK TOTAL DEP MX MN AVG DEP TOT DEP %FC BELVIDERE BRIDGE CANOE BROOK CHARLOTTEBURG FLEMINGTON NEWTON FREEHOLD LONG BRANCH NEW BRUNSWICK TOMS RIVER MISSING TRENTON CAPE MAY COURT HOUSE DOWNSTOWN HAMMONTON POMONA SEABROOK SOUTH HARRISON NA 264 NA NA WES KLINE -- GDD BASE 40 PINEY HOLLOW LAST WEEK 131 (ENDING 4/25/11) THIS WEEK 182 (Ending 5/2/11) Page 5 Vol. 17 No. 4

6 Table from page 4 Relative tolerance of trees and shrubs to flooding during the growing season (Source: Whitlow and Harris 1979) Page 6 Vol. 17 No. 4

7 Plant & Pest Advisory Rutgers School of Environmental and Biological Sciences ASB II, 57 US Hwy. 1 New Brunswick, N.J PLANT & PEST ADVISORY Landscape, Nursery & Turf Edition Contributors Rutgers NJAES-CE Specialists and Staff Bruce B. Clarke, Ph.D., Turf Pathology Ann B. Gould, Ph.D., Ornamentals Plant Pathology Steven Hart, Ph.D., Weed Science Joseph R. Heckman, Ph.D., Soil Fertility Albrecht Koppenhofer, Ph.D., Turfgrass Entomology James A. Murphy, Ph.D., Turf Management Richard J. Buckley, Coordinator, Plant Diagnostic Laboratory RCE County Agricultural Agents and Program Associates Bergen, Joel Flagler ( ) Burlington, Raymond J. Samulis ( ) Camden, Steven Rettke, Program Associate IPM ( ) Cape May, Jenny Carleo ( ) Cumberland, James R. Johnson ( ) Essex, Jan Zienteck, Program Coordinator ( ) Gloucester, Jerome L. Frecon ( , ext. 1) Hunterdon, Winfred P. Cowgill, Jr. ( ) Middlesex, William T. Hlubik ( ) Monmouth, Richard G. Obal ( ) Morris, Peter Nitzsche ( ) Passaic, Elaine Fogerty, Agric. Assistant ( ) Somerset, Nick Polanin ( ) Sussex, Brian Oleksak, Program Associate ( ) Union, Madeline Flahive-DiNardo ( ) Warren, Bruce Barbour ( ) Newsletter Production Jack Rabin, Associate Director for Farm Services, NJAES Cindy Rovins, Agricultural Communications Editor Pesticide User Responsibility: Use pesticides safely and follow instructions on labels. The pesticide user is reponsible for proper use, storage and disposal, residues on crops, and damage caused by drift. For specific labels, special local-needs label 24(c) registration, or section 18 exemption, contact RCE in your County. Use of Trade Names: No discrimination or endorsement is intended in the use of trade names in this publication. In some instances a compound may be sold under different trade names and may vary as to label clearances. Reproduction of Articles: RCE invites reproduction of individual articles, source cited with complete article name, author name, followed by Rutgers Cooperative Extension, Plant & Pest Advisory Newsletter. For back issues, visit our web site at: