Hort Update for the week of 6/19/06
1. Ascochyta leaf blight of turf- Patches or large areas of lawn suddenly turn straw 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. Fungicides generally not recommended. Thiophanate-methyl (Dragon Chemical Systemic; and Fungicide 3336WP) can be used. (NebFact 588).
Online Info at: Ascochyta Leaf Blight On Turfgrass or Ascochyta Leaf Blight of Turf
2. Dollar spot of turf - Small (a few inches up to six inches in diameter), roughly circular patches Spots may coalesce into a large patch. Grass blades have tan, band-like lesions with red margins. Damage usually most severe if there is a nitrogen deficiency. Can treat with products containing benomyl, mancozeb, propiconazole, thiophanate-methyl. (NebFact 462 Management Program for Dollar Spot).
Online info: Dollar Spot on Turfgrass
3. Brown patch disease of turf- patches of turf with dead, brown leaves intermingled with living leaves, in a roughly circular pattern. Patches may coalesce to blight large areas of turf. Normally occurs in mid-summer. A close inspection of the leaf blades shows tan, circular dead lesions with a dark brown or margin. Most serious on tall fescue, but affects all turfgrasses. Do not irrigate lawns in late afternoon or evenings if possible. Brown patch can be suppressed by fungicide applications. Preventive applications of Prostar (commercial use), Bayleton, and to some extent chlorothalonil (Daconil), does 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 (late July and August) also may do an adequate job of suppressing further injury. (NebFact 463 Management Program for Brown Patch.)
Online info: Brown patch
4. Summer patch disease of turf- caused by a soil-borne fungus that infects and kills grass roots. Grass blades in affected areas initially change to a dull reddish-brown, then tan, and finally a light straw color. In the final stages of the disease, doughnut shaped patches of dead grass form throughout the lawn. All leaf blades in the affected areas are dead, giving the patch a flat, sunken appearance. Healthy grass may occur within patch centers resulting in a characteristic "frogeye" pattern. When weather conditions are ideal for disease development, affected areas may overlap and blight large areas of the lawn. (NebFact 461 Management Program for Necrotic Ring Spot and Summer Patch.)
Online Info: Summer Patch
5. Thatch problems- lawns with more than 1/2 inch of thatch may show localized areas of drought stress symptoms as the grass plants root into the thatch. Thatch does not hold water well, so the grass in these areas is more easily drought stressed. Check for thatch levels by cutting a triangular section out of the turf and examining the layer of material between the surface of the soil and the crowns of the grass plants.
Online info: Thatch Prevention and Control
6. Watering problems- many areas of Nebraska, both east and west, are experiencing unusually dry conditions for early summer. This is resulting in lawns that are drought stressed. Bluegrass lawns are already becoming brown and going dormant. Lawns with irrigation systems may have grass browning in areas where the sprinkler system does not provide an adequate amount of water. Most lawns will require 1 inch of water per week, applied in two 1/2 inch applications.
Areas of compacted soil, which often occur along driveways or sidewalks, allow very little water penetration and are susceptible to drought stress even more quickly than uncompacted areas of the lawn.
Refer to the publications below for more information about the watering needs of Kentucky bluegrass and tall fescue lawns.
Kentucky Bluegrass Lawn Calendar
Tall Fescue Lawn Calendar
7. Frog-eye leaf spot of crabapple- round, usually brown spots on leaves. May have a purplish margin and many per leaf. Fungus can cause cankering, and rotting of fruit on the tree. No treatment is recommended. However, the cankers and fruit can harbor the fungal spores and re-infect the tree next year. Remove any cankered branches and rotting fruit.
More info and pictures can be found at: Scaffolds Fruit Journal
8. Fireblight- a common and very destructive bacterial disease of apples and pears. The disease is so named because infected leaves on very susceptible trees will suddenly turn brown, appearing as though they had been scorched by fire. Twigs are often first infected through the flowers and then dieback very quickly, resulting in a dark brown to black section of dead stem with a characteristic "shepherd's crook" shape at the tip. May be more severe in trees that experience hail damage the previous year.
Online info: Fireblight of Apples, Crabapples & Pears
9. Sycamore anthracose- is a fungal disease that infects leaves and twigs. It can cause severe defoliation but this is not a problem on mature trees- they will releaf. There is no treatment once the disease appears. Trees must be treated with a fungicide just as the leaves unfurl in spring to provide control. Unless it is a highly valuable tree, there is no need to treat.
Online info: Sycamore Anthracnose
10. Maple anthracnose- a leaf disease of maple that follows the veins. Leaves may become distorted. It is too late to treat. There may be some defoliation. Rarely causes a problem for the tree.
Online info: Maple Anthracnose or Maple Anthracnose
11. Oak leaf blister - bubble-like blister on leaves caused by a fungus. It does not cause serious damage to trees; they can photosynthesize fine with the disease. Control not needed and it’s too late for control.
Online info: Oak Leaf Blister
12. Herbicide damage - leaves curled, and tissue thickened. Online info: http://extension.usu.edu/plantpath/non-pathogenic-disorders/npd_herbicide_injury.htm
Pictures: Herbicide Injury on Oak- Picture 1 or Picture 2
13. Bagworms -defoliation. Small, brown bags on leaves. Mostly on juniper and spruce. Larvae of a wingless moth so clients can use Bacillus thuriengiensis. Most general insecticides with carbaryl or permethrins work if applied at hatching (late May into June). Pick off and destroy bags.
Online info: Bagworm And Its Control
14. Thrips- buds do not open or open partially and petals are damaged. Thrips are very tiny, sap-sucking insects that get into buds of many flowers and cause serious damage. Difficult to control inside unopened buds where they do the most damage. Malathion can control thrips on leaves and opened flowers. Next year, use an insecticide before the buds form. Commonly susceptible flowers include gladiolus, rose, coral bells, iris, and many more.
Thrips are difficult to control because they can get into an unopened bud where insecticides can't reach. Insecticidal sprays can control thrips on the leaves and opened flowers. A systemic insecticide may help. Next year, use an insecticide before the flower buds form.
Online info: Thrips in Landscapes and Gardens
On Fruits: Western Flower Thrips
15. Ash leaf curling aphid- curled, distorted, sticky leaves. Generally no treatment needed. If choose to control, begin just as leaves begin to curl and use Orthene or Merit (Imidacloprid). Next year, a soil treatment of Imidacloprid (Merit or Bayer Advanced Garden Tree and Shrub Insect Control) can be made in March to be effective in May (needs 60 days to translocate up into tree).
16. Ash sawfly- Light green worms feeding on leaves. Large trees - not practical to control, tree will continue to leaf out. Small trees - control with insecticidal soap, Sevin, Orthene, or Eight.
17. Pine sawfly- Green worms feeding on pine needles Control with Sevin, Malathion, Orthene, or Eight
18. Radishes- many root crops including radishes, carrots and beets will have beautiful foliage, but will not develop roots properly if they are too crowded in the garden or too much fertilizer is applied to the growing area.
Online Info: Growing Carrots And Other Root Vegetables In The Garden
19. Cabbageworm- Found on all cole crops, mainly broccoli and cabbage. Larvae chew holes in leaves. Adult is a white butterfly. Larvae are velvety appearing green worms with yellow stripe, often found on leaf underside. Treat with Bacillus thuringiensis.
Online Info: Imported Cabbageworm
20. Cabbage looper- Found on all cole crops, mainly broccoli and cabbage. Larvae chew holes in leaves, often along veins. Adult is a brown, night flying moth. Larvae are light green, looping worms with white stripes. Treat with Bacillus thuringiensis.
Online Info: Cabbage looper
21. Ash rust - yellow/orange, raised spots on leaves. Maybe some twisting of foliage. Not a problem for trees. No fungicide control needed and it’s too late to treat anyway.
Pictures at: Ash Rust
22. Cedar-hawthorn rust - yellow-orange spots on leaves. Similar to cedar apple rust. Treat with a fungicide in spring as new growth appears and repeat 3 to 4 times until flower buds open. Nebguide 1327 Cedar apple and related Rusts of Apple and Ornamentals (not online).
Online info and picture at: Hawthorn Rust
23. Rose rust- yellow-orange spots on leaves. No alternate host needed so fungus can keep reinfecting the rose. Sanitation important -remove infected stems and leaves at first appearance. Preventative fungicides include chlorothalonil (Daconil 2787) or systemic fungicides such as triadimefon or triforine (Funginex)
Online info: Growing Roses in Iowa- Rust
24. Maple bladder gall- tiny mites are the cause of these right red galls that start out green, turn red and finally become black. Some leaf drop may be seen with heavily infected leaves. Galls do not affect the health of the tree. If sedired, the time to treat is with a dormant oil just as the buds well in spring. No treatments are effectively one the galls are visible.
Online Info: Mapple Bladder Galls
25. Hawthorn leafminer (also seen on Elm): Squiggly, tunnels created by larvae feeding within the leaves. Leaf browning. By the end of May, larvae leave their mines and pupate within the soil. One generation per year. No control once in leaves. Control usually not needed.
Online Info: Hawthorn Leafminer
26. Phlox Plant bug - appear as small red bugs. They appear as little red bugs and have piercing and sucking mouth parts. Their feeding causes yellow stippling in the leaves and can result in deformed flowers and stunting or death of heavily infested plants. They are primarily a pest of perennial phlox and can cause a lot of damage on a plant if their population is high. Insecticidal soaps are effective. General purpose and systemic insecticides will works. Cut plant down in fall to remove overwintering eggs.
Online info: Plant Bugs On Perennials And Landscape Shrubs
27. Bud worm- being found on petunia and geraniums. Also known as tobacco bud worm. They chew a hole in the bud and feed on the inside. Treat when caterpillars are small with Bacillus thuringiensis, sevin, or a permethrin.
Can find pictures at: Tobacco (Geranium) Budworm
28. Yellow nutsedge- a light green, grass-like weed often found in home laws & ornamental beds. Hand-pull weeds until mid-June to avoid tuber (nutlet) production. Improve soil drainage with core aeration and avoid overwatering. The herbicide Manage (halosulfuron) is no longer being produced to control this weed, but may still be available at retail outlets for homeowners to purchase and apply. Certainty (sulfosulfuron) is a new product that can only be applied by commercial applicators.
Online Info: Yellow Nutsedge Control In Home Lawns
| Current Problems: | Major Symptom: |
Turf |
|
| 1. Ascochyta leaf blight | Sudden browning, sometimes overnight. Resembles drought. |
| 2. Dollar spot | Small, tan patches in lawns. Tan lesions with red margins. |
| 3. Brown patch | Dead, brown leaf blades intermingled with living leaves, in a roughly circular pattern |
| 4. Summer patch | Sunken, dead patches of grass that may have a "frog-eye" pattern of living grass in the center |
| 5. Thatch problems | Dry, brown patches in lawn |
| 6. Watering problems | Dry, brown dormant patches in lawn |
| Trees & Shrubs | |
| 7. Frog-eye leaf spot | Many round, small brown leaf spots on apple & crabapple. May have a purple margin. |
| 8. Fireblight | Dark brown to black sections of dead stems |
| 9. Sycamore anthracnose | Leaf drop and crown thinning of sycamore |
| 10. Maple anthracnose | Brown, blighted areas on leaves; some curling & defoliation |
| 11. Oak leaf blister | Light green, "bubble" lesions on leaves |
| 12. Herbicide damage | Misshapen, curled or cupped leaves on trees, shrubs, vegetables & ornamentals |
| 13. Bagworms | Defoliation of evergreens, and cocoon-like bags of silk and leaf debris attached to branches |
| 14. Thrips | Flower buds not opening or opening partially, petals brown |
| 15. Ash leaf curling aphid | Tightly curled, sticky leaves. Insect found on underside of leaf. |
| 16. Ash sawfly | Light green worms feeding on leaves |
| 17. Pine sawfly | Green worms feeding on leaves |
| Vegetables | |
| 18. Radishes | Roots do not develop, foliage looks good |
| 19. Cabbageworm | White butterfly, green velvety worm. Holes in leaves. |
| 20. Cabbage looper | Light green worms with white stripes. Holes in leaves. |
| Continuing Problems | |
| 21. Ash rust | Yellow-orange raised spots on leaves and petioles. Some twisting of leaves. |
| 22. Cedar-hawthorn rust | Yellow-orange spots on leaves |
| 23. Rose rust | Orange-brown spots on leaf surface |
| 24. Maple bladder gall | Bright red bladder-shaped galls on leaves that turn black. |
| 25. Hawthorn leafminer | Light colored, squiggly lines on leaves. Leaf browning. |
| 26. Phlox plant bug | Yellow stippling in leaves, deformed flowers, plant stunting. |
| 27. Budworm | Failure to flower in petunia and geranium. Holes in flower buds or buds chewed. |
| 28. Yellow nutsedge | 3-ranked, yellow-green, waxy grass-like leaved weed. |
1. Ascochyta leaf blight of turf- Patches or large areas of lawn suddenly turn straw 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. Fungicides generally not recommended. Thiophanate-methyl (Dragon Chemical Systemic; and Fungicide 3336WP) can be used. (NebFact 588).
Online Info at: Ascochyta Leaf Blight On Turfgrass or Ascochyta Leaf Blight of Turf
2. Dollar spot of turf - Small (a few inches up to six inches in diameter), roughly circular patches Spots may coalesce into a large patch. Grass blades have tan, band-like lesions with red margins. Damage usually most severe if there is a nitrogen deficiency. Can treat with products containing benomyl, mancozeb, propiconazole, thiophanate-methyl. (NebFact 462 Management Program for Dollar Spot).
Online info: Dollar Spot on Turfgrass
3. Brown patch disease of turf- patches of turf with dead, brown leaves intermingled with living leaves, in a roughly circular pattern. Patches may coalesce to blight large areas of turf. Normally occurs in mid-summer. A close inspection of the leaf blades shows tan, circular dead lesions with a dark brown or margin. Most serious on tall fescue, but affects all turfgrasses. Do not irrigate lawns in late afternoon or evenings if possible. Brown patch can be suppressed by fungicide applications. Preventive applications of Prostar (commercial use), Bayleton, and to some extent chlorothalonil (Daconil), does 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 (late July and August) also may do an adequate job of suppressing further injury. (NebFact 463 Management Program for Brown Patch.)
Online info: Brown patch
4. Summer patch disease of turf- caused by a soil-borne fungus that infects and kills grass roots. Grass blades in affected areas initially change to a dull reddish-brown, then tan, and finally a light straw color. In the final stages of the disease, doughnut shaped patches of dead grass form throughout the lawn. All leaf blades in the affected areas are dead, giving the patch a flat, sunken appearance. Healthy grass may occur within patch centers resulting in a characteristic "frogeye" pattern. When weather conditions are ideal for disease development, affected areas may overlap and blight large areas of the lawn. (NebFact 461 Management Program for Necrotic Ring Spot and Summer Patch.)
Online Info: Summer Patch
5. Thatch problems- lawns with more than 1/2 inch of thatch may show localized areas of drought stress symptoms as the grass plants root into the thatch. Thatch does not hold water well, so the grass in these areas is more easily drought stressed. Check for thatch levels by cutting a triangular section out of the turf and examining the layer of material between the surface of the soil and the crowns of the grass plants.
Online info: Thatch Prevention and Control
6. Watering problems- many areas of Nebraska, both east and west, are experiencing unusually dry conditions for early summer. This is resulting in lawns that are drought stressed. Bluegrass lawns are already becoming brown and going dormant. Lawns with irrigation systems may have grass browning in areas where the sprinkler system does not provide an adequate amount of water. Most lawns will require 1 inch of water per week, applied in two 1/2 inch applications.
Areas of compacted soil, which often occur along driveways or sidewalks, allow very little water penetration and are susceptible to drought stress even more quickly than uncompacted areas of the lawn.
Refer to the publications below for more information about the watering needs of Kentucky bluegrass and tall fescue lawns.
Kentucky Bluegrass Lawn Calendar
Tall Fescue Lawn Calendar
7. Frog-eye leaf spot of crabapple- round, usually brown spots on leaves. May have a purplish margin and many per leaf. Fungus can cause cankering, and rotting of fruit on the tree. No treatment is recommended. However, the cankers and fruit can harbor the fungal spores and re-infect the tree next year. Remove any cankered branches and rotting fruit.
More info and pictures can be found at: Scaffolds Fruit Journal
8. Fireblight- a common and very destructive bacterial disease of apples and pears. The disease is so named because infected leaves on very susceptible trees will suddenly turn brown, appearing as though they had been scorched by fire. Twigs are often first infected through the flowers and then dieback very quickly, resulting in a dark brown to black section of dead stem with a characteristic "shepherd's crook" shape at the tip. May be more severe in trees that experience hail damage the previous year.
Online info: Fireblight of Apples, Crabapples & Pears
9. Sycamore anthracose- is a fungal disease that infects leaves and twigs. It can cause severe defoliation but this is not a problem on mature trees- they will releaf. There is no treatment once the disease appears. Trees must be treated with a fungicide just as the leaves unfurl in spring to provide control. Unless it is a highly valuable tree, there is no need to treat.
Online info: Sycamore Anthracnose
10. Maple anthracnose- a leaf disease of maple that follows the veins. Leaves may become distorted. It is too late to treat. There may be some defoliation. Rarely causes a problem for the tree.
Online info: Maple Anthracnose or Maple Anthracnose
11. Oak leaf blister - bubble-like blister on leaves caused by a fungus. It does not cause serious damage to trees; they can photosynthesize fine with the disease. Control not needed and it’s too late for control.
Online info: Oak Leaf Blister
12. Herbicide damage - leaves curled, and tissue thickened. Online info: http://extension.usu.edu/plantpath/non-pathogenic-disorders/npd_herbicide_injury.htm
Pictures: Herbicide Injury on Oak- Picture 1 or Picture 2
13. Bagworms -defoliation. Small, brown bags on leaves. Mostly on juniper and spruce. Larvae of a wingless moth so clients can use Bacillus thuriengiensis. Most general insecticides with carbaryl or permethrins work if applied at hatching (late May into June). Pick off and destroy bags.
Online info: Bagworm And Its Control
14. Thrips- buds do not open or open partially and petals are damaged. Thrips are very tiny, sap-sucking insects that get into buds of many flowers and cause serious damage. Difficult to control inside unopened buds where they do the most damage. Malathion can control thrips on leaves and opened flowers. Next year, use an insecticide before the buds form. Commonly susceptible flowers include gladiolus, rose, coral bells, iris, and many more.
Thrips are difficult to control because they can get into an unopened bud where insecticides can't reach. Insecticidal sprays can control thrips on the leaves and opened flowers. A systemic insecticide may help. Next year, use an insecticide before the flower buds form.
Online info: Thrips in Landscapes and Gardens
On Fruits: Western Flower Thrips
15. Ash leaf curling aphid- curled, distorted, sticky leaves. Generally no treatment needed. If choose to control, begin just as leaves begin to curl and use Orthene or Merit (Imidacloprid). Next year, a soil treatment of Imidacloprid (Merit or Bayer Advanced Garden Tree and Shrub Insect Control) can be made in March to be effective in May (needs 60 days to translocate up into tree).
16. Ash sawfly- Light green worms feeding on leaves. Large trees - not practical to control, tree will continue to leaf out. Small trees - control with insecticidal soap, Sevin, Orthene, or Eight.
17. Pine sawfly- Green worms feeding on pine needles Control with Sevin, Malathion, Orthene, or Eight
18. Radishes- many root crops including radishes, carrots and beets will have beautiful foliage, but will not develop roots properly if they are too crowded in the garden or too much fertilizer is applied to the growing area.
Online Info: Growing Carrots And Other Root Vegetables In The Garden
19. Cabbageworm- Found on all cole crops, mainly broccoli and cabbage. Larvae chew holes in leaves. Adult is a white butterfly. Larvae are velvety appearing green worms with yellow stripe, often found on leaf underside. Treat with Bacillus thuringiensis.
Online Info: Imported Cabbageworm
20. Cabbage looper- Found on all cole crops, mainly broccoli and cabbage. Larvae chew holes in leaves, often along veins. Adult is a brown, night flying moth. Larvae are light green, looping worms with white stripes. Treat with Bacillus thuringiensis.
Online Info: Cabbage looper
21. Ash rust - yellow/orange, raised spots on leaves. Maybe some twisting of foliage. Not a problem for trees. No fungicide control needed and it’s too late to treat anyway.
Pictures at: Ash Rust
22. Cedar-hawthorn rust - yellow-orange spots on leaves. Similar to cedar apple rust. Treat with a fungicide in spring as new growth appears and repeat 3 to 4 times until flower buds open. Nebguide 1327 Cedar apple and related Rusts of Apple and Ornamentals (not online).
Online info and picture at: Hawthorn Rust
23. Rose rust- yellow-orange spots on leaves. No alternate host needed so fungus can keep reinfecting the rose. Sanitation important -remove infected stems and leaves at first appearance. Preventative fungicides include chlorothalonil (Daconil 2787) or systemic fungicides such as triadimefon or triforine (Funginex)
Online info: Growing Roses in Iowa- Rust
24. Maple bladder gall- tiny mites are the cause of these right red galls that start out green, turn red and finally become black. Some leaf drop may be seen with heavily infected leaves. Galls do not affect the health of the tree. If sedired, the time to treat is with a dormant oil just as the buds well in spring. No treatments are effectively one the galls are visible.
Online Info: Mapple Bladder Galls
25. Hawthorn leafminer (also seen on Elm): Squiggly, tunnels created by larvae feeding within the leaves. Leaf browning. By the end of May, larvae leave their mines and pupate within the soil. One generation per year. No control once in leaves. Control usually not needed.
Online Info: Hawthorn Leafminer
26. Phlox Plant bug - appear as small red bugs. They appear as little red bugs and have piercing and sucking mouth parts. Their feeding causes yellow stippling in the leaves and can result in deformed flowers and stunting or death of heavily infested plants. They are primarily a pest of perennial phlox and can cause a lot of damage on a plant if their population is high. Insecticidal soaps are effective. General purpose and systemic insecticides will works. Cut plant down in fall to remove overwintering eggs.
Online info: Plant Bugs On Perennials And Landscape Shrubs
27. Bud worm- being found on petunia and geraniums. Also known as tobacco bud worm. They chew a hole in the bud and feed on the inside. Treat when caterpillars are small with Bacillus thuringiensis, sevin, or a permethrin.
Can find pictures at: Tobacco (Geranium) Budworm
28. Yellow nutsedge- a light green, grass-like weed often found in home laws & ornamental beds. Hand-pull weeds until mid-June to avoid tuber (nutlet) production. Improve soil drainage with core aeration and avoid overwatering. The herbicide Manage (halosulfuron) is no longer being produced to control this weed, but may still be available at retail outlets for homeowners to purchase and apply. Certainty (sulfosulfuron) is a new product that can only be applied by commercial applicators.
Online Info: Yellow Nutsedge Control In Home Lawns
