Hort Update for the week of 6/11/07
| Current Problems: | Major Symptom: |
Lawns |
|
| 1. Flooding | Turfgrass submerged due to high water |
| 2. Dollar spot | Small, tan patches in lawns. Tan lesions with red margins. |
| 3. Aschochyta leaf blight | Sudden browning, sometimes overnight. Resembles drought. |
| 4. Large black beetles | ¾ to 5/8 inch long black beetles attracted to lights in large numbers |
| 5. Mushrooms & slime molds | Appearance of mushrooms in turf or small gray masses on leaf blades |
| 6. Yellow nutsedge | Yellowish-green, grass-like weed in landscapes |
| 7. Powdery mildew | Scattered white patches, resembling powder on leaf blades |
| 8. Moss | Flat patches of bright green plants with fine, thread-like stems. |
| Trees & Shrubs | |
| 9. Ash rust | Raised orange “spots” on ash leaves; some leaf twisting & drop |
| 10. Anthracnose | Irregular brown areas on leaves, often along leaf veins |
| 11. Peach leaf curl | Distinct puckering and reddening of leaves in various fruit trees |
| 12. Plum pockets | Deformed plum fruit appearing as puffed up bladders |
| 13. Maple bladder gall | Bright red or black, bladder-shaped galls on leaves |
| 14. Pine wilt | Browning of entire pine trees in spring |
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 1. Flooding- Heavy rains resulting in some lawns being submerged under water has prompted questions about damage potential. As a rule, Kentucky bluegrass can tolerate submersion for about 3 to 4 days. Older bluegrass cultivars and thatchy bluegrass lawns are less tolerant of submersion. Turf-type tall fescue will tolerate submersion for 5 to 6 days and buffalograss for 2 weeks and up. Submersion for a period of time longer than that listed can result in yellowing and thinning of turf. If as much as 2 to 3 inches of silt is left behind once water recedes or drains away, remove the silt. If the silt fills in a low area, consider leaving the silt and overseeding the area/s. If less than two inches of silt is on the lawn, most turfgrass will grow through. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 2. Dollar spot- small (three to six inches in diameter), roughly circular patches in lawns. Spots may coalesce into a large patch. Grass blades have tan, band-like lesions with red margins. Damage usually most severe where there’s a nitrogen deficiency. With all of the rain this year, much nitrogen may have been leached out of the root zone. The best control may be to fertilize with nitrogen. The turf can be treated with products containing benomyl, mancozeb, propiconazole, thiophanate-methyl. Management Program for Dollar Spot, http://ohioline.osu.edu/hyg-fact/3000/3075.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 3. Ascochyta leaf blight- patches or large areas of lawn suddenly turn straw or tan color. Leaf blades have bleached white tips and blade is constricted where dead tissue merges with green tissue. Considered a minor disease related to weather and management practices. Turfgrass usually recovers in one month or less without treatment. Fungicides are generally not recommended. Thiophanate-methyl (Dragon Chemical Systemic; and Fungicide 3336WP) can be used. Ascochyta Leaf Blight of Turf, http://www.ext.colostate.edu/PUBS/GARDEN/02901.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 4. Large Black Beetles- large numbers of black, shiny beetles, about ¾ of an inch long, accumulating overnight in lighted areas have been reported in Butler, Platte and Merrick counties. These may be the adults of a scarab grub called Dyscinetus picipes. This beetle, and its larvae, appear to be only a nuisance pest; but are brought to homeowner's attention because of their huge numbers. The beetles are attracted to lights at night, especially ultraviolet and mercury vapor lights near natural areas. Once attracted to a light, the beetles stay until dawn; then burrow under any shelter or into the soil. The same process is repeated each night for about one to two weeks. While these are not considered a plant pest, there has been a few cases where vegetation around a light pole was damaged; possibly due to the burrowing of such a large numbers of beetles, maybe root feeding; or maybe toxic body fluids leaching off beetles. While these beetles should only be around for a week or two, their numbers might be reduced by suspending a pan or bucket of soapy water below a light to trap the beetles. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 5. Mushrooms & slime molds -with the warm moist weather this week, we may see development of fungal slime molds & mushrooms in home lawns. There is no treatment for them. Clients should pick and throw away the mushrooms before mowing to reduce the number of spores. But the mushrooms will continue to pop up until the decaying material they feed on is gone, such as buried wood, decaying tree roots, or thatch. Slime molds sometimes look like dog vomit (hence the name dog vomit fungi) and can come in many bright colors, while others appear as grayish mass on turf leaf blades. Symptoms of leaf blade smile molds may be seen as irregular patches of discolored turf ranging in size from several inches to several feet in diameter. Some slime molds feed on decaying material and are often found in mulched ornamental beds, while others use turf leaf blades strictly as a structure to grow on. Slime Molds on Turfgrass, http://ohioline.osu.edu/hyg-fact/3000/3074.html """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 6. Yellow nutsedge- is a 3-ranked, yellow-green, waxy grass-like weed. At this time of year it can be controlled by pulling. Nutlets will not start to form until after the longest day of the year, June 21 st. Pulling before this stage is worthwhile. Chemical treatment is most effective when applied before June 21- Sedgehammer (replaces Manage). Certainty (Sulfosulfuron) is a new product that can only be applied by commercial applicators. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 7. Powdery mildew- often found in shaded turf areas, with reduced air movement and high moisture or humidity levels. This fungus grows on turf leaf surfaces, shading the underlying leaf blade and reducing photosynthesis. Thinning of the turf may be seen in heavily affected areas. Reduce shade and improve air movement through pruning if possible. Preventative fungicide applications may be necessary in areas with a history of infection. Recommended fungicides include Bayleton (triadimefon) or Banner (propiconozole). Powdery Mildew in Turfgrass, http://ohioline.osu.edu/hyg-fact/3000/3081.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 8. Moss- flat patches of bright green plants with fine, thread-like stems. Moss is an opportunistic plant that will grow where turfgrass stands are thin and weak. Most commonly associated with shallow soils; poor soil fertility; low soil pH (acid soils); heavy shade; and excessive moisture. If any of these factors are limiting turf growth, moss can invade the lawn and establish itself. For effective moss control start by modifying the site conditions to favor lawn grasses. Moss Control in Lawns, http://lancaster.unl.edu/hort/articles/2006/Moss.shtml """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 9. Ash rust- yellow/orange, raised spots (postules) on leaves. This fungal disease may cause some twisting of foliage and leaf drop. Ash rust is not a serious disease of trees. Fungicide control is not recommended or needed. Ash Rust, http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/RustAsh.htm """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 10. Anthracnose- common fungal disease on ash, maple, sycamore and oak; causes irregular brown areas on leaves. Leaves may become distorted and some to a lot of defoliation occurs. It is too late to treat trees effectively. Anthracnose is rarely a serious problem for otherwise healthy trees. Most trees will produce new leaves to replace diseased leaves. Anthracnose Leaf Blight of Shade, http://ohioline.osu.edu/hyg-fact/3000/3048.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 11. Peach leaf curl- Fungal disease (Taphrina deformans) causes developing leaves of peach and related species to become severely distorted (thickened and puckered) and have a reddish or purple cast. As spores form on the leaf surface, leaves become powdery gray in color and leaves may turn yellow or brown and drop. This disease is most severe during cool, wet spring. If there is severe defoliation, the tree will be weakened, especially if a heavy fruit crop is allowed to develop. Control is fairly easy if fungicides are applied in very early in spring just prior to leafing. Peach leaf curl, http://ohioline.osu.edu/hyg-fact/3000/3006.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 12. Plum pockets- plum fruit appear distorted, puffy and wrinkle. Same disease as peach leaf curl. See above information. Plum pockets, http://www.ipm.iastate.edu/ipm/hortnews/1997/6-13-1997/peachplum.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 13. Maple bladder galls - bright red galls that later turn black, usually on the upper leaf surface of maple leaves. When the galls turn black, they may fall off the leaves, resulting in small holes. A few leaves may be so infested that they fall off, but this is not common. These galls are caused by the feeding of a tiny mite and do not affect the health of the tree. If desired, the time to treat is at spring bud swell, with horticultural oil. Treatment is not effective once the galls are visible. Maple Bladder Galls, http://www.ipm.iastate.edu/ipm/hortnews/1998/6-5-1998/maplegall.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 14. Pine wilt- is now considered to be present throughout the state. Affected trees go off color, sometimes a few branches at a time but more often the entire tree is affected at the same time, and die within a few weeks. Greyhound by Arbor Systems is available for injection to prevent Pine wilt but the approximate cost is $300.00 per tree with a 10” diameter trunk. Scotch pine trees that die need to be removed and chipped or destroyed ASAP. Pine Wilt: A Fatal Disease of Exotic Pines in the Midwest, http://www.extension.iastate.edu/Publications/SUL9.pdf |
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