Hort Update for the week of 7/30/07
| Current Problems: | Major Symptom: |
Lawns |
|
| 1. Summer patch | Circular or S-shaped tan patches; may have a tuft of green in centers |
| 2. Brown patch | Roughly circular patches of dead and dying grass |
| 3. Melting out | Yellowing, thinning & irregular brown patches in lawns |
| 4. Yellow nutsedge | Yellow-green, 3-ranked, grass-like weed with waxy leaves |
| 5. Lawn yellowing | Turf a uniform or patchy pale green to yellow color |
| 6. Chinch bugs | Patchy areas in turf turn yellowish, then dry out and die |
| Trees & Shrubs | |
| 7. Sirococcus shoot blight | Needles on twig tips die; some droop & curl; needles drop |
| 8. Sphaeropsis tip blight | Current year’s growth dies, eventually entire branches may die |
| 9. Cytospora canker | Branches and tops of trees die |
| 10. Bagworms | Defoliation of evergreens and small brown bags on stems |
| 11. Dutch elm disease | Leaves yellow & turn brown, then branches, and finally the entire tree dies |
| 12. Walnut caterpillars | Reddish worms feeding in masses on walnut trees |
| 13. Two-spotted spidermite | Foliage has whitish specks, then turns from green to yellow or bronze color |
| 14. Apple scab | Olive green to brown spots on leaves; leaves drop |
| 15. Cedar-apple rust | Yellow to orangish spots on leaves, raised pustules; leaves drop |
| 16. Cottonwood borers | Large black and white beetles emerge from Poplar trees |
| 17. Oak galls | Various bumps, spots, fuzzy growth, etc. on leaves & petioles |
| Vegetables/Fruits | |
| 18. Bacterial wilt | Vine crops suddenly wilt and do not recover |
| 19. Tomato spotted wilt | Yellow rings on ripening tomatoes |
| 20. Squash vine borer | Vines or entire plants wilt; base of main stem soft with frass evident |
| 21. Sunscald | White papery areas on surface of fruit exposed to sun |
| 22. Blotchy ripening | Areas of tomato fruit remain green or yellow |
| Miscellaneous | |
| 23. Grasshoppers | Chewing damage on fruits, vegetables & ornamentals |
| 24. Cicada killer wasps | Large black and yellow wasps creating small soil mounds |
""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 1. Summer patch- One to two foot, tan colored, circular, crescent, or serpentine shaped patches. Tufts of healthy green grass may remain in patch centers and is known as frog-eye. This is a root disease. No leaf lesions or leaf spots will be found. Infected plants have a dark brown to black crown and root rot. Control includes proper lawn care practices to reduce stress, overseeding with resistant cultivars, and fungicide applications made in April and May when the fungus is infecting roots. Summer Patch, http://nu-distance.unl.edu/homer/disease/Hort/Turf/TuSumPtch.html Information on resistant cultivars may be found at: National Turfgrass Evaluation Program, http://www.ntep.org/reports/kb00/kb00_06-10/kb00_06-10.htm """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 2. Brown patch- Roughly circular patches of dead and dying grass. Patch centers may be less affected and have a frog-eye-like symptom. Tan colored, irregularly shaped leaf spots with reddish margins are found on leaf blades. Preventive applications of Prostar (commercial use), Bayleton, and chlorothalonil (Daconil) do a fairly good job of suppressing the disease when applied at monthly intervals (June, July, August). Curative applications of chlorothalonil beginning a few days after symptoms of brown patch develop may do an adequate job of suppressing injury. In many cases, lawns damaged by brown patch wll recover in two to three weeks, provided the outbreak is not sustained by continuous hot, humid weather; and treatment may not be necessary. Brown Patch of Tall Fescue, http://www.oznet.ksu.edu/path-ext/factSheets/Turf/RhizoctoniaBrownPatchOfTallFescue2.asp """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 3. Melting out- is a fungal disease of turfgrass that usually follows Bipolaris leaf spot disease. Like leaf spot, melting out begins as black to purple leaf spots; then attacks plant roots and crown causing these to become dark brown and rot. This stage is called melting out because turfgrass gradually thins, appears yellowish, and may have irregular patches of dead grass. The dead grass is easily removed when raked. Leaf spot and melting out are diseases of stressed turf. Control with proper cultural practices that maintain turfgrass vigor. Fungicide sprays are recommended on lawns with a history of melting out disease. Application needs to begin in the spring at the first sign of Bipolaris leaf spot. Leaf Spot and Melting Out Diseases, http://www.ext.colostate.edu/pubs/Garden/02909.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 4. Yellow nutsedge is a 3-ranked, yellow-green, waxy, grass-like weed. At this time of year it cannot be effectively controlled by pulling. Tubers (nutlets) have formed and pulling will prompt regrowth. Herbicide treatment is most effective if applied by June 21 or as soon as Nutsedge first appears. Applications now may provide some control yet. The products Sedgehammer and Certainty (Sulfosulfuron) are recommended. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 5. Lawn yellowing- Yellowing of large sections of lawns or a splotchy appearance to lawns at this time of year is usually due to root issues brought on by lawn watering practices; in many case overwatering. If soils remain consistently wet, roots do not function as well and absorption of nutrients, like iron, is affected. Denitrification, resulting in a loss of nitrogen, can also occur on too wet of soils. When watering lawns, moisten the soil four to six inches deep; then wait until a lawn shows signs of needing water, i.e. darker, blue-green color; footprints remaining after walking across the lawn, before watering again. An application of iron during July or August may promote green up. """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 6. Chinch bugs- feed by sucking juices from leaves and stems, and inject a toxin while feeding which disrupts translocation of water and nutrients. Damage appears as patchy areas which turn yellow, then dry out and turn brown. Damage is usually heaviest in sunny locations during hot, dry periods. Chinch bug nymphs are red with a white band, then orangish, and finally brown to black. Adults are 1/10 th of an inch long and black and white. Control thatch to reduce cinch bugs. If bugs exceed 20 per square foot, an insecticide treatment is justified. Chinch Bugs in Turfgrass, http://ohioline.osu.edu/hyg-fact/2000/2503.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 7. Sircoccus shoot blight causes tip dieback on spruce. Current year’s growth, and sometimes one year old growth, dies and turns reddish brown and needles drop. Infected shoots may curl into a hook shape. Small black fruiting bodies are found on bud scales and other parts of dead shoots. Spray trees with chlorothalonil in spring when needles are one-half to 2 inches long; repeat in 3 to 4 weeks. Diseases of Evergreen Trees, http://www.nfs.unl.edu/documents/foresthealth/diseasesevergreen.pdf """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 8. Sphaeropsis tip blight infects pine, mainly older Austrian pine. New shoots die in spring. Entire branches may die if the tree is otherwise stressed. Small black fruiting bodies appear on the base of cones and the base of infected needles. A fungicide application made during the third week in April and repeated the first week in May provides optimum disease control in most years. Fungicides applied after mid-May usually ineffective. Diseases of Evergreen Trees, http://www.nfs.unl.edu/documents/foresthealth/diseasesevergreen.pdf """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 9. Cytosopora canker- usually affects 10-15 year old spruces trees and causes the top half of trees, and/or entire branches to die. Resin may ooze from branch or trunk cankers. There are no fungicide controls. Prune dead branches and avoid stress. Mulch and water correctly. Avoid overwatering. Diseases of Evergreen Trees, http://www.nfs.unl.edu/documents/foresthealth/diseasesevergreen.pdf """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 10. Bagworms cause browning or defoliation of mainly spruce and juniper. Small bags covered with brown needles found on stems. Bacillus thuriengiensis or insecticides containing carbaryl, permethrin, etc. work best if applied at hatching (late May into June). Effectiveness is minimal at this time of year, but may reduce damage if larvae have not pupated. Larvae usually pupate in August. Cut open bags to see if larvae are still active. If larvae are in pupal stage, it is too late to apply an insecticide. Pick off and destroy bags at this time of year. Insect Pests of Evergreen Trees, http://www.nfs.unl.edu/documents/foresthealth/insectevergreen.pdf """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 11. Dutch elm disease is a wilt disease that causes branches, then entire trees to die. Black or brown streaks may be found in the wood. Remove dead trees and destroy the wood. Do not use it for firewood. A trunk injected fungicide is available. See resource for information. Diseases of Broadleaf Trees, http://www.nfs.unl.edu/documents/foresthealth/diseasesbroadleaf.pdf """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 12. Walnut caterpillars- Large, hairy reddish larvae feed in masses on walnut leaves. When disturbed, larvae arch both ends of their bodies. Larvae mass together on lower parts of trees to molt and leave hairy cast skins. Control on large established trees is usually not needed. All purpose insecticides will work well. Spray the tree or the caterpillars when they are massed together on the trunk; band the trunk with Tanglefoot; or, prune and destroy twigs on which caterpillars are massed. Walnut Caterpillars, http://www.oznet.k-state.edu/dp_hfrr/extensn/problems/walcater.htm """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 13. Two-spotted spidermites – Spider mites affect a wide variety of plants from trees and shrubs to ornamentals and vegetables. Mites and their webs can barely be seen with the naked eye. They feed by sucking plant juices with piercing-sucking mouth parts, causing white or yellowish specks on leaves; then off-green to bronze discoloration. Controls range from hosing down plants with a strong spray of water (syringing) to using insecticidal oils or soaps, or using insecticides such as Kelthane, malathion, Cygon or Orthene when mites are active. Tap a branch over a white sheet of paper to monitor for active mites. They’ll appear as specks moving around on the paper. NOTE: Carbaryl (Sevin) can increase mites by killing their predators. Spider Mites and Their Control, http://ohioline.osu.edu/hyg-fact/2000/2012.html Spider Mites, http://www.ext.colostate.edu/PUBS/INSECT/05507.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 14. Apple scab first appears as roughly circular, olive-green spots on upper and lower leaf surfaces which eventually turn dark-green to brown. Leaves often yellow and drop prematurely. Best control is planting resistant cultivars of apple and crabapples. Fungicides need to be applied in early spring and repeated according to label direction to be effective. Scab of Apple and Flowering Crabapple, http://www.oznet.ksu.edu/path-ext/factSheets/Apple/Apple%20Scab.asp """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 15. Cedar-apple rust causes yellow leaf spots which turn orangish, then brown. Leaves often yellow and drop prematurely. Best control is planting resistant cultivars of apple and crabapples. Fungicides need to be applied in early spring and repeated according to label direction to be effective. Cedar Rust Diseases of Ornamental Plants, http://ohioline.osu.edu/hyg-fact/3000/3055.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 16. Cottonwood borers are large black and white beetles that emerge from cottonwoods from late June to mid-August. Damage occurs primarily at the base of infested trees and consists of sawdust-packed tunnels up to ½ inch in diameter bored into the wood, which weakens the trees and interferes with translocation of water and nutrients. Damaged trees may blow over, breaking off at the base. Insecticide treatment is usually not needed due to rarity of attack. Cottonwood Borer, http://entomology.unl.edu/ornamentals/pestprofiles/cotborer.htm """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 17. Oak galls- Oaks are susceptible to a number of galls which range in appearance from pink fuzzy balls or white peach fuzz growing on leaves to green or brown galls growing around leaf petioles. Most galls form in response to insect feeding, often a very small wasp. Oak galls are interesting, but harmless, and control is not needed. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 18. Bacterial wilt is spread on the mouthparts of striped and spotted cucumber beetles. It causes plants in the cucurbit family to wilt and die. Diagnose bacterial wilt by cutting the stem near the soil line and squeezing the cut ends between your fingers. Place the tip of a knife blade on the bead of sap squeezed from the stem and slowly pull the knife blade away. If a slimy string develops between the blade and vine, the plant is likely infected with the bacteria. There is no cure for this wilt disease and most cucumbers and muskmelon are susceptible. Use crop rotation and control cucumber beetles to reduce the disease. Bacterial Wilt of Cucurbits, http://www.oznet.ksu.edu/path-ext/factSheets/Cucumber/Bacterial%20Wilt%20of%20Cucurbit.asp """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 19. Tomato spotted wilt most commonly causes yellow rings on ripening fruit. Early symptoms of spotted wilt can be an inward cupping of leaves and off-color foliage. The top of infected plants occasionally wilt. Spotted wilt virus is transmitted by thrip insects. Virus diseases cannot be controlled once a plant is infected. Sanitation most important in controlling virus diseases. Remove infected plants immediately to prevent spread of pathogens. Control perennial weeds in and adjacent to the garden as these can serve as alternate hosts for viruses. Avoid planting tomatoes next to peppers, or other vegetables and flowers susceptible to these diseases. Control of insects, especially thrips, will help reduce the likelihood of spotted wilt. Tomato Spotted Wilt Virus, http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/tomswv.htm """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 20. Squash vine borers bore into plant stems (mainly squash, pumpkins, and gourds) and their feeding restricts translocation of water and nutrients. The point where a borer enters a stem, usually at the plant base, may have a sawdust-like frass around it and be decayed. Infested plants are weakened or die; depending on the number of borers. Control the borers by practicing good sanitation, physically removing borers by slitting stems when borer activity is noticed, or applying insecticides labeled for vegetables during egg laying, usually from the time vines begin to run and re-applying every 7 to 10 days for 3 to 5 weeks. Squash Vine Borer, http://ohioline.osu.edu/hyg-fact/2000/2153.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 21. Sunscald on tomatoes and peppers causes papery white or tan spots on the surface of fruit exposed to sunlight. Sunburn occurs particularly when plants are defoliated by insects or diseases. Control by maintaining healthy foliage that will shade the plants. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 22. Blotchy tomato ripening is when fruit ripens unevenly and some patches don't ripen. Symptoms often develop in the interior of dense plants with lots of foliage. Cloudy, wet and cool conditions, high nitrogen, low potassium and compacted soils will increase blotchy ripening. This is not a disease or insect problem. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 23. Grasshoppers are being found in large numbers in western Nebraska. They can severely defoliate garden and landscape plants. Effective control includes treating egg hatching areas (roadsides and weedy areas) at egg hatch when the grasshoppers are young. Adult grasshoppers are difficult to control. A Guide to Grasshopper Control in Yards and Gardens, http://www.ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=575 """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 24. Cicada killer wasps are up to 2” long and black and yellow. They dig nests, creating small soil mounds; then sting and drag paralyzed cicadas to the nest and deposit an egg on it. The larval wasp uses the cicada for food. Cicada killer wasps are solitary wasps and do not protect their nest. They are very unlikely to sting humans unless provoked. Cicada Killer Wasp, http://ohioline.osu.edu/hyg-fact/2000/2078A.html |
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