Hort Update for the week of 6/16/2009
1. Bluegrass Billbug are one-fourth inch long black weevils with a distinct snout. During April, May and June they can be observed walking on sidewalks and driveways. On lawns with a history of billbug damage, an application of Merit (imidacloprid) applied during the second week of May provides effective control of larvae. Adult weevils do not damage turfgrass. They deposit eggs in bluegrass stems near plant crowns. Newly-hatched larvae tunnel in grass stems causing discoloration and dieback. Root feeding by older larvae through July may damage roots, causing turf to appear drought stressed. Under heavy billbug pressure, areas of lawn may turn brown and patches of turfgrass may die during summer.
Bluegrass Billbug: http://entomology.unl.edu/turfent/documnts/billbugs.shtml
How to Sample for Insects in Turfgrass: http://extensionhorticulture.unl.edu/Articles/SJB/Sampling.shtml
Denver Billbug- damage from Denver billbug has been reported in western Nebraska. Damage is caused by larvae feeding within stems, plant crowns and eventually on roots. The greatest injury usually occurs from mid-June through late July. In areas where Denver billbug is present, damage also occurs in fall and early spring. Denver billbug adults are larger than bluegrass billbugs, reaching 1/3 to 1/2 inch in length. Denver billbugs are active from early May to June. Because billbug injury is easily mistaken for white grub or sod webworm damage, disease, or even plant stress, examine damaged turf carefully to confirm the presence of billbugs. Newly-hatched billbug larvae tunnel in grass stems, hollowing out the stem and leaving fine sawdust-like plant debris and excrement. Infested stems discolor and when pulled, readily break away at or near the crown. Subsurface feeding by older larvae can completely destroy the plant's root system, causing turf to appear drought stressed. Under heavy billbug pressure turfgrass can turn brown and die. Control is best aimed at the adult weevil prior to egg laying in spring.
2. Chinch Bugs in Buffalograss and Zoysiagrass feed by sucking juices from leaves and stems. They 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 1/10th of an inch long and black and white. Control thatch to reduce chinch bugs. If bugs exceed 20 per square foot, an insecticide treatment is justified. Bifenthrin still best for chinch bug control.
Chinch Bugs in Turfgrass: http://ohioline.osu.edu/hyg-fact/2000/2503.html
3. Helminthosporium leaf spot- Bipolaris (Helminthosporium) leaf spot and melting-out develop during cooler, wet weather in fall and early spring. The fungi causing these diseases survive the winter in the thatch layer and in infected crowns and roots, and occur most often in rainy weather. Common leaf spot diseases include Helminthosporium, Brown Patch, and Septoria leaf spot. All cause lesions or spots on grass blades and dieback of turfgrass resulting in yellowing, a general browning, or brown patches in the lawn. General lawn fungicides applied now can reduce further spread of these diseases in turfgrass.
The best preventive measure is to use leaf spot-resistant cultivars when establishing a new lawn or renovating an old one. A blend of three or more improved Kentucky bluegrass cultivars resistant to leaf spot provides optimum protection against this disease and reduces the possibility of costly fungicide spray programs.
Helminthosporium: http://archive.lib.msu.edu/DMC/Ag.%20Ext.%202007-Chelsie/PDF/e1539-1981.pdf
Diagnostic Key for Lawn Diseases: http://lawnandgarden.unl.edu/html/toolbar/diagtip/lawnkey.htm
4. White Grub Control Timing- In lawns with a history of white grub damage, and when preventive type insecticides are used, the best time to apply these products for control of white grubs is from 3rd week of June to mid-July.
White Grubs in Turf NebGuide: http://www.ianrpubs.unl.edu/sendIt/g1619.pdf
5. Yellow Nutsedge is or will soon begin to grow. Yellow nutsedge is a 3-ranked, yellow-green, waxy, grass-like weed. Handpulling and herbicide applications are most effective in controlling yellow nutsedge when done prior to June 21st. Prior to this date, the tubers (nutlets) attached to the visible plant (mother plant) are in the maturation process but will normally not break dormancy and grow if the mother plant is damaged from pulling, spraying or other injury. After June 21st, any activity which removes the mother plant results in the now mature tubers breaking dormancy and sprouting. If a plant has multiple tubers attached to it, it is not uncommon for 3-5 sprouts to emerge resulting in an increase in nutsedge plants. Ideally, spray before June 21st to control the mother plant before it can make daughter tubers. This is not always possible so go ahead and spray after June 21st realizing it is not the optimal time for maximum efficacy. Use Sedgehammer (replaced Manage) or Certainty (Sulfosulfuron) which can be applied by commercial applicators. Certainty should only be applied to pure stands of Kentucky bluegrass. It will injure ryegrass and fescue.
7. Powdery Mildew appears as a light layer of flour on grass blades. It is found in shaded turf areas with reduced air movement and high moisture or humidity levels. The fungus grows on leaf surfaces, shading the underlying leaf blade and reducing photosynthesis. Some yellowing and thinning of turf may be seen in heavily infected areas. Reduce shade and improve air movement through pruning where possible. Preventative fungicide applications may be needed in areas with a history of mildew.
Powdery Mildew Disease in Turfgrass NebGuide: http://www.ianrpubs.unl.edu/sendIt/g1911.pdf
8. EAB larvae has been found in eastern Iowa. It may be isolated in one tree; confirmation is yet to be made. While insecticide treatments for Emerald Ash Borer are available, they are not yet recommended in Nebraska.
Emerald Ash Borer Information: http://www.emeraldashborer.info/
9. Elm Flea Weevil first appeared in the midwest in 2003 and may now be throughout Nebraska. The adult weevil is very tiny (1.6 mm long), dark brown to black, with a prominent “snout”. They can jump when disturbed. Adult feeding results in tiny shot holes in the leaves. At this time, it appears to feed mainly on Siberian elm (Ulmus pumila) which is commonly called Chinese elm in Nebraska. Morton Arboretum is reporting feeding on hybrids containing U. pumila, particularly “Homestead”. Most trees will recover with good plant health care practices. On high value trees or trees under stress, insecticides may be applied as soon adults appear and feeding is noticed. It is late now to apply insecticides.
10. Oak/Hackberry Tree Defoliation- Spring cankerworm or looper caterpillars are suspected of causing the damage. Minor defoliation is a minor concern for otherwise healthy trees and control is likely not necessary. If seeing fairly large numbers of caterpillars treatment with Sevin, Eight, or Spinosad can be used. Do not treat unless insect is present.
11. Ash Rust Yellow/orange, raised spots (pustules) 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
12. Maple bladder galls are bright red galls that later turn black, usually on the upper leaf surface of maple leaves. When galls turn black, they may fall out of leaves, resulting in small holes. A few leaves may be so infested they drop from the tree, but leaf drop is uncommon. 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
13. Anthracnose is a common fungal disease on ash, maple, sycamore and oak. It causes irregular brown areas on leaves. Leaves may become distorted and minor to severe defoliation of a tree can occur. 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 lost leaves.
Anthracnose Diseases of Shade Trees: http://www.oznet.ksu.edu/path-ext/factSheets/Trees/Anthracnose%20Diseases%20of%20Shade%20Trees.asp
14. Slugs are soft, slimy, slender mollusks; not insects. During the evening, slugs feed on leaves and flowers causing various sized holes. During the day, slugs hide beneath plants, pots, weed mats, boards, or in soil. To reduce slugs, traps are helpful. Beer traps, shallow containers of beer sunk in the ground so the top edge is level with the soil, are only moderately successful. A better method is laying wet newspapers, shingles, or boards on the ground overnight. Check beneath these the next day and kill the slugs. Gritty materials, such as diatomaceous earth, can be scattered on the soil surface to reduce slugs. For chemical control, baits containing metaldehyde (Deadline, Defender) or iron phosphate (Escar-Go, Sluggo) are available. As with all pesticides, label directions must be followed carefully. For best control, apply these products on a warm, clear night during dry weather. Place them under boards or traps to help protect birds and pets. Two or more treatments at 5 to 7 day intervals may be needed for adequate control.
15. Rose Rust first appears on the undersides of leaves and other plant parts as orange powdery "pustules". No alternate host is needed for this rust disease and so the fungus can keep re-infecting the rose. Sanitation is important. Remove infected stems and leaves at first appearance. Careful pruning of old canes helps reduce rust carry-over on the canes and promotes air movement and drying of leaves. Plant resistant varieties. Use preventive fungicides [chlorothalonil (Daconil 2787)] or systemic fungicides [triadimefon or triforine (Funginex)].
16. Pesticide Selection Guide is available online as a pdf publication: http://www.ianrpubs.unl.edu/sendIt/ec1566.pdf
17. Bean Leaf Beetles chew small holes in bean leaves. As fruit appears, they will chew small holes into the pods as well. Beetles drop to the ground when disturbed and may be difficult to detect. When damage first appears, control with carbaryl (Sevin) or permethrin (Eight) dust. Neem oil will work well also.
18. Herbicide Injury is most common on tomatoes, but all plants can show symptoms of leaf curling, leaf cupping, distorted veins and sometimes discoloration. If more than one type of plant in the garden or yard is affected, herbicide injury is suspected.
19. Weed Control in vegetable gardens is most often done by mechanical means (hand-pulling and hoeing) or with the use of mulch. Grass clippings can be used as mulch in vegetable gardens. Allow them to dry and turn brown before using as mulch. If herbicides are applied to the lawn, do not use these clippings as mulch or wait until after at least three mowing before using the clippings as mulch. Preen labeled for vegetables gardens can be used as a pre-emergent to control weeds as they are germinating.
20. Peach Leaf Curl is a fungal disease (Taphrina deformans) that causes developing leaves of peach and related species to become thickened and puckered and to have a red 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 springs. 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 spring just prior to leafing.
Peach Leaf Curl: http://plantclinic.cornell.edu/FactSheets/peachleafcurl/peachleafcurl.htm
21. Cedar-Apple Rust or Apple Scab is causing leaves of some apples and crabapples to yellow and drop. Fungal infections occurred early this spring just as leaf buds were beginning to break. While severe defoliation can occur, and this is a stress for the tree, few trees will die unless severe defoliation occurs year after year. Fungicide applications need to be applied just as tree leaves are breaking bud in early spring and repeated as recommended to be effective. In some cases, it is suspected leaves are dropping due to dry soils we experienced.
Cedar-Apple Rust NebGuide: http://www.ianrpubs.unl.edu/sendIt/g1907.pdf
| Current Problems: | Major Symptom: |
| Lawns | |
| 1. Bluegrass billbug injury | Browning of turfgrass. Appears similar to drought stress. |
| 2. Chinch bugs in zoysia & buffalograss | Patchy areas which turn yellow, then dry out and turn brown |
| 3. Helminthosporium leaf spot | Some browning and thinning of lawn. Leaf spots on grass blades. |
| 4. White grub control timing | 3rd week of June through mid - July; around July 4th is good |
| 5. Yellow nutsedge | Now to June 21st most effective time to control. |
| 6. Aschochyta tip blight | Browning of turf. Similar to drought. Grass blade tips are white. |
| 7. Powdery mildew | Grass blades appear to be dusted with flour in shady areas. |
| Trees & Shrubs | |
| 8. EAB larvae found in Eastern Iowa | Treatment not yet recommended for EAB in Nebraska. |
| 9. Elm flea weevil | Tiny holes chewed into leaves; tiny weevils with long snout. |
| 10. Defoliation of oak and hackberry | May be from spring canker worm or looper caterpillars. |
| 11. Ash rust | Raised orange spots on leaves; some leaf curling. |
| 12. Maple bladder gall | Red changing to black bladder-like bumps (galls) on leaves. |
| 13. Maple anthracnose | Irregular brown areas on leaves, often along leaf veins. Leaf drop. |
| Gardens & Ornamentals | |
| 14. Holes chewed in leaves | Slugs a possibility. Slime trails may be present on leaves. |
| 15. Rose rust | Raised orange spots on rose leaves; some leaf drop. |
| 16. Pesticide Selection Guide for Ornamentals | New UNL Extension publication, EC 1566, is now available through IANR publications |
| Fruits & Vegetables | |
| 17. Bean leaf beetle injury | Small holes chewed in leaves of beans. |
| 18. Herbicide injury to crops | Leaf curling; distorted veins; discoloration. |
| 19. Weed control in gardens | Hand-pull, hoe, mulch, herbicides. |
| 20. Peach leaf curl | Distinct puckering and reddening of leaves in various fruit trees. |
| 21. Cedar-apple rust or apple scab | Leaf yellowing/browning and drop in apples and crabapples. |
| 22. Ticks and Lyme disease in Nebraska | |
1. Bluegrass Billbug are one-fourth inch long black weevils with a distinct snout. During April, May and June they can be observed walking on sidewalks and driveways. On lawns with a history of billbug damage, an application of Merit (imidacloprid) applied during the second week of May provides effective control of larvae. Adult weevils do not damage turfgrass. They deposit eggs in bluegrass stems near plant crowns. Newly-hatched larvae tunnel in grass stems causing discoloration and dieback. Root feeding by older larvae through July may damage roots, causing turf to appear drought stressed. Under heavy billbug pressure, areas of lawn may turn brown and patches of turfgrass may die during summer.
Bluegrass Billbug: http://entomology.unl.edu/turfent/documnts/billbugs.shtml
How to Sample for Insects in Turfgrass: http://extensionhorticulture.unl.edu/Articles/SJB/Sampling.shtml
Denver Billbug- damage from Denver billbug has been reported in western Nebraska. Damage is caused by larvae feeding within stems, plant crowns and eventually on roots. The greatest injury usually occurs from mid-June through late July. In areas where Denver billbug is present, damage also occurs in fall and early spring. Denver billbug adults are larger than bluegrass billbugs, reaching 1/3 to 1/2 inch in length. Denver billbugs are active from early May to June. Because billbug injury is easily mistaken for white grub or sod webworm damage, disease, or even plant stress, examine damaged turf carefully to confirm the presence of billbugs. Newly-hatched billbug larvae tunnel in grass stems, hollowing out the stem and leaving fine sawdust-like plant debris and excrement. Infested stems discolor and when pulled, readily break away at or near the crown. Subsurface feeding by older larvae can completely destroy the plant's root system, causing turf to appear drought stressed. Under heavy billbug pressure turfgrass can turn brown and die. Control is best aimed at the adult weevil prior to egg laying in spring.
2. Chinch Bugs in Buffalograss and Zoysiagrass feed by sucking juices from leaves and stems. They 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 1/10th of an inch long and black and white. Control thatch to reduce chinch bugs. If bugs exceed 20 per square foot, an insecticide treatment is justified. Bifenthrin still best for chinch bug control.
Chinch Bugs in Turfgrass: http://ohioline.osu.edu/hyg-fact/2000/2503.html
3. Helminthosporium leaf spot- Bipolaris (Helminthosporium) leaf spot and melting-out develop during cooler, wet weather in fall and early spring. The fungi causing these diseases survive the winter in the thatch layer and in infected crowns and roots, and occur most often in rainy weather. Common leaf spot diseases include Helminthosporium, Brown Patch, and Septoria leaf spot. All cause lesions or spots on grass blades and dieback of turfgrass resulting in yellowing, a general browning, or brown patches in the lawn. General lawn fungicides applied now can reduce further spread of these diseases in turfgrass.
The best preventive measure is to use leaf spot-resistant cultivars when establishing a new lawn or renovating an old one. A blend of three or more improved Kentucky bluegrass cultivars resistant to leaf spot provides optimum protection against this disease and reduces the possibility of costly fungicide spray programs.
Helminthosporium: http://archive.lib.msu.edu/DMC/Ag.%20Ext.%202007-Chelsie/PDF/e1539-1981.pdf
Diagnostic Key for Lawn Diseases: http://lawnandgarden.unl.edu/html/toolbar/diagtip/lawnkey.htm
4. White Grub Control Timing- In lawns with a history of white grub damage, and when preventive type insecticides are used, the best time to apply these products for control of white grubs is from 3rd week of June to mid-July.
White Grubs in Turf NebGuide: http://www.ianrpubs.unl.edu/sendIt/g1619.pdf
5. Yellow Nutsedge is or will soon begin to grow. Yellow nutsedge is a 3-ranked, yellow-green, waxy, grass-like weed. Handpulling and herbicide applications are most effective in controlling yellow nutsedge when done prior to June 21st. Prior to this date, the tubers (nutlets) attached to the visible plant (mother plant) are in the maturation process but will normally not break dormancy and grow if the mother plant is damaged from pulling, spraying or other injury. After June 21st, any activity which removes the mother plant results in the now mature tubers breaking dormancy and sprouting. If a plant has multiple tubers attached to it, it is not uncommon for 3-5 sprouts to emerge resulting in an increase in nutsedge plants. Ideally, spray before June 21st to control the mother plant before it can make daughter tubers. This is not always possible so go ahead and spray after June 21st realizing it is not the optimal time for maximum efficacy. Use Sedgehammer (replaced Manage) or Certainty (Sulfosulfuron) which can be applied by commercial applicators. Certainty should only be applied to pure stands of Kentucky bluegrass. It will injure ryegrass and fescue.
6. Aschochyta Leaf Blight- Patches or large areas of lawn suddenly turn straw or tan color. Resembles drought stress. 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 or needed.
Aschocyta Leaf Blight: http://www.ext.colostate.edu/pubs/garden/02901.html
7. Powdery Mildew appears as a light layer of flour on grass blades. It is found in shaded turf areas with reduced air movement and high moisture or humidity levels. The fungus grows on leaf surfaces, shading the underlying leaf blade and reducing photosynthesis. Some yellowing and thinning of turf may be seen in heavily infected areas. Reduce shade and improve air movement through pruning where possible. Preventative fungicide applications may be needed in areas with a history of mildew.
Powdery Mildew Disease in Turfgrass NebGuide: http://www.ianrpubs.unl.edu/sendIt/g1911.pdf
8. EAB larvae has been found in eastern Iowa. It may be isolated in one tree; confirmation is yet to be made. While insecticide treatments for Emerald Ash Borer are available, they are not yet recommended in Nebraska.
Emerald Ash Borer Information: http://www.emeraldashborer.info/
9. Elm Flea Weevil first appeared in the midwest in 2003 and may now be throughout Nebraska. The adult weevil is very tiny (1.6 mm long), dark brown to black, with a prominent “snout”. They can jump when disturbed. Adult feeding results in tiny shot holes in the leaves. At this time, it appears to feed mainly on Siberian elm (Ulmus pumila) which is commonly called Chinese elm in Nebraska. Morton Arboretum is reporting feeding on hybrids containing U. pumila, particularly “Homestead”. Most trees will recover with good plant health care practices. On high value trees or trees under stress, insecticides may be applied as soon adults appear and feeding is noticed. It is late now to apply insecticides.
10. Oak/Hackberry Tree Defoliation- Spring cankerworm or looper caterpillars are suspected of causing the damage. Minor defoliation is a minor concern for otherwise healthy trees and control is likely not necessary. If seeing fairly large numbers of caterpillars treatment with Sevin, Eight, or Spinosad can be used. Do not treat unless insect is present.
11. Ash Rust Yellow/orange, raised spots (pustules) 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
12. Maple bladder galls are bright red galls that later turn black, usually on the upper leaf surface of maple leaves. When galls turn black, they may fall out of leaves, resulting in small holes. A few leaves may be so infested they drop from the tree, but leaf drop is uncommon. 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
13. Anthracnose is a common fungal disease on ash, maple, sycamore and oak. It causes irregular brown areas on leaves. Leaves may become distorted and minor to severe defoliation of a tree can occur. 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 lost leaves.
Anthracnose Diseases of Shade Trees: http://www.oznet.ksu.edu/path-ext/factSheets/Trees/Anthracnose%20Diseases%20of%20Shade%20Trees.asp
14. Slugs are soft, slimy, slender mollusks; not insects. During the evening, slugs feed on leaves and flowers causing various sized holes. During the day, slugs hide beneath plants, pots, weed mats, boards, or in soil. To reduce slugs, traps are helpful. Beer traps, shallow containers of beer sunk in the ground so the top edge is level with the soil, are only moderately successful. A better method is laying wet newspapers, shingles, or boards on the ground overnight. Check beneath these the next day and kill the slugs. Gritty materials, such as diatomaceous earth, can be scattered on the soil surface to reduce slugs. For chemical control, baits containing metaldehyde (Deadline, Defender) or iron phosphate (Escar-Go, Sluggo) are available. As with all pesticides, label directions must be followed carefully. For best control, apply these products on a warm, clear night during dry weather. Place them under boards or traps to help protect birds and pets. Two or more treatments at 5 to 7 day intervals may be needed for adequate control.
15. Rose Rust first appears on the undersides of leaves and other plant parts as orange powdery "pustules". No alternate host is needed for this rust disease and so the fungus can keep re-infecting the rose. Sanitation is important. Remove infected stems and leaves at first appearance. Careful pruning of old canes helps reduce rust carry-over on the canes and promotes air movement and drying of leaves. Plant resistant varieties. Use preventive fungicides [chlorothalonil (Daconil 2787)] or systemic fungicides [triadimefon or triforine (Funginex)].
16. Pesticide Selection Guide is available online as a pdf publication: http://www.ianrpubs.unl.edu/sendIt/ec1566.pdf
17. Bean Leaf Beetles chew small holes in bean leaves. As fruit appears, they will chew small holes into the pods as well. Beetles drop to the ground when disturbed and may be difficult to detect. When damage first appears, control with carbaryl (Sevin) or permethrin (Eight) dust. Neem oil will work well also.
18. Herbicide Injury is most common on tomatoes, but all plants can show symptoms of leaf curling, leaf cupping, distorted veins and sometimes discoloration. If more than one type of plant in the garden or yard is affected, herbicide injury is suspected.
19. Weed Control in vegetable gardens is most often done by mechanical means (hand-pulling and hoeing) or with the use of mulch. Grass clippings can be used as mulch in vegetable gardens. Allow them to dry and turn brown before using as mulch. If herbicides are applied to the lawn, do not use these clippings as mulch or wait until after at least three mowing before using the clippings as mulch. Preen labeled for vegetables gardens can be used as a pre-emergent to control weeds as they are germinating.
20. Peach Leaf Curl is a fungal disease (Taphrina deformans) that causes developing leaves of peach and related species to become thickened and puckered and to have a red 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 springs. 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 spring just prior to leafing.
Peach Leaf Curl: http://plantclinic.cornell.edu/FactSheets/peachleafcurl/peachleafcurl.htm
21. Cedar-Apple Rust or Apple Scab is causing leaves of some apples and crabapples to yellow and drop. Fungal infections occurred early this spring just as leaf buds were beginning to break. While severe defoliation can occur, and this is a stress for the tree, few trees will die unless severe defoliation occurs year after year. Fungicide applications need to be applied just as tree leaves are breaking bud in early spring and repeated as recommended to be effective. In some cases, it is suspected leaves are dropping due to dry soils we experienced.
Cedar-Apple Rust NebGuide: http://www.ianrpubs.unl.edu/sendIt/g1907.pdf
22. Ticks and Lyme Disease in Nebraska- Lyme disease is only transmitted by the black legged deer tick, to our knowledge. We do not have this deer tick in NE as of current spring surveys. There are some residents that contract lyme disease outside of NE. There are other tick transmitted diseases that have some of the same symptoms as lyme disease. To prevent ticks from attaching use sprays. If a tick is attached, remove it, but keep the tick. It could be used for identification of the disease.
Controlling Ticks: http://www.ianrpubs.unl.edu/sendIt/g1200.pdf
