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Hort Update for the week of 7/28/08
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1. Annual White Grub eggs typically begin to hatch in early August. Imidacloprid can be used until early August and still provide 80-85% control. Dylox is recommended for rescue treatments after early August and when eight (8) white grubs can be found per square foot. Sevin is labeled for white grubs, but does not work well. Dylox is short lived and white grubs need to be present for it to be effective. Correct irrigation through the summer is important for control and turf recovery from white grub feeding. Watch for the new product called Acelepryn, due out next year. This insecticide will provide 90-95% control of grubs.
White Grub Images, http://entomology.unl.edu/images/seedpest/whtgrubs.htm
White Grubs in Turf Nebguide, http://www.ianrpubs.unl.edu/sendIt/g1619.pdf
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2. Chinch Bugs in Buffalograss 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 cinch 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
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3. Brown Patch causes 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, http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/brnptch.htm
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4. Melting Out- Leaf spot and melting out are two fungal diseaes of turfgrass within the "Helminthosporium" leaf, crown, and root disease complex. The leaf spot pathogen, Bipolaris sorokiniana, and the melting out pathogen, Drechslera poae, both affect bluegrass, ryegrass and fescue. Both diseases are favored by dry periods alternating with prolonged cloudy, wet weather. Fungal spores germinate with contact to water droplets on the turf leaf surface.
Symptoms begin as black to purple leaf spots on the leaf blades, and progress to round or oval spots with buff-colored centers surrounded by a dark-brown to dark-purple margin. Infected leaf sheaths turn a uniform dark chocolate brown, causing leaves to yellow and then drop from the plant. Infected roots and crowns become dark brown and rot. 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 should begin in spring at the first sign of disease.
Leaf Spot/Melting Out, http://www.ces.purdue.edu/extmedia/bp/bp-103-w.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
5. Bagworms are most common on evergreens. These are not the large ugly webs that form in deciduous trees. At this time of year, bagworms are reaching ¾ to 1 inch in size and there is only one larva per “bag”. At this size, Bacillus thuringiensis (B.t.), sold as Dipel or Thuricide, is not the most effective product. Bifenthrin is a better choice and should be used at the higher dosage rate. Bifenthrin is also an irritant, causing bagworms to move around and further expose themselves to the insecticide.
Bagworm and It's Control, http://ohioline.osu.edu/hyg-fact/2000/2149.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
6. Fall Webworms are beginning to appear in trees such as cottonwood and crabapple. At this time of year, the webbed nests are small, but with time will enlarge and become unsightly webbed nests filled with caterpillars, dead leaves, frass and worm excrement. While nests are unsightly, the caterpillars are fairly harmless to most established trees. A broom can be used to break up the bag of fall webworms. Then follow through with strong stream of water or an insecticide. Mechanically remove nests when feasible. Application of insecticides such at Bt (Bacillus thuringiensis), permenthrin, or Spinosad when caterpillars first appear in July can reduce their numbers and web nest sizes.
Fall Webworm Management, http://ohioline.osu.edu/hyg-Fact/2000/2026.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
7. Elm Flea Weevil (EFW) 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.
Elm Flea Weevil, http://www.ipm.msu.edu/cat08land/l06-27-08.htm#9
The Elm Flea Weevil: Not To Be Confused with Flea Beetles, http://extensionhorticulture.unl.edu/Weekly/EFW.4.05.pdf
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8. 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. Infection rates have been extremely high this year in eastern Nebraska due to the extended wet conditions from spring into mid-summer. Spray affected trees with chlorothalonil next spring, to protect the new growth, 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
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9. Sphaeropsis Tip Blight infects pine trees. 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 ineffective. Homewoners should positively identify the cause of problems with pine trees before attempting treatment or removal of the tree.
Diseases of Evergreen Trees, http://www.nfs.unl.edu/documents/foresthealth/diseasesevergreen.pdf
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10. Japanese Beetle adults are showing up on many ornamentals in extreme eastern Nebraska. Japanese beetles are aggressive feeders on the foliage and fruit of nearly 300 species of landscape plants. Japanese beetles feed on the upper leaf surface, removing the soft leaf tissue and leaving the veins in a lacelike or skeletonized pattern. Japanese beetles release a strong aggregation pheromone that attracts additional beetles to a potential food source. The larva (grub) of Japanese Beetles feed on the roots of plants from late summer into early fall.
Management of Japanese Beetles, http://www.ianrpubs.unl.edu/sendIt/g1623.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
11. Aster Yellows is a common disease that affects many ornamental flowers. Susceptible plants include asters, chrysanthemum, coreopsis, cosmos, echinacea (coneflowers), dianthus, gladiola, marigold and petunias. Vein clearing, or loss of green pigment within the veins, is often the first symptom. Stunting, stiff extra bushy yellow growth, deformed or poorly developed flowers which remain green are all common symptoms. There is no cure for infected plants. Remove and discard them to reduce further spread.
Aster Yellows, http://www.oznet.ksu.edu/library/hort2/MF1086.pdf
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12. 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
Hort Update for the week of 7/28/08
| Current Problems: | Major Symptom: |
| Lawns | |
| 1. Annual White Grubs | Insecticides, application timing, and a new product |
| 2. Chinch Bugs- Buffalograss | Patchy areas which turn yellow, then dry out and turn brown |
| 3. Brown Patch | Roughly circular patches of dead and dying grass |
| 4. Melting Out | Yellowing, thinning & irregular brown patches in lawns |
| Trees/Shrubs | |
| 5. Bagworm | Browning in evergreens & 3/4” tan, spindle-shaped bagworms found |
| 6. Fall Webworms | Webbed nests in deciduous trees containing caterpillars & frass |
| 7. Elm Flea Weevil | Tiny holes chewed into leaves; tiny weevils with long snout |
| 8. Siroccocus Shoot Blight- Spruce | Needles on twig tips die; some droop & curl; needles drop |
| 9. Sphaeropsis Tip Blight- Pine | Current year’s growth is brown and stunted. Entire branches may die. |
| Landscape Plants | |
| 10. Japanese Beetles | Skeletonized leaves, particularly roses. Coppery-brown, oval beetles, 1/3 to ½” length, with metallic green head. |
| 11. Aster Yellows | Poorly developed flowers that remain green when blossom opens |
| Miscellaneous | |
| 12. Cicada Killer Wasps | Large black and yellow wasps creating small soil mounds |
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1. Annual White Grub eggs typically begin to hatch in early August. Imidacloprid can be used until early August and still provide 80-85% control. Dylox is recommended for rescue treatments after early August and when eight (8) white grubs can be found per square foot. Sevin is labeled for white grubs, but does not work well. Dylox is short lived and white grubs need to be present for it to be effective. Correct irrigation through the summer is important for control and turf recovery from white grub feeding. Watch for the new product called Acelepryn, due out next year. This insecticide will provide 90-95% control of grubs.
White Grub Images, http://entomology.unl.edu/images/seedpest/whtgrubs.htm
White Grubs in Turf Nebguide, http://www.ianrpubs.unl.edu/sendIt/g1619.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
2. Chinch Bugs in Buffalograss 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 cinch 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. Brown Patch causes 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, http://www.oznet.ksu.edu/dp_hfrr/extensn/problems/brnptch.htm
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
4. Melting Out- Leaf spot and melting out are two fungal diseaes of turfgrass within the "Helminthosporium" leaf, crown, and root disease complex. The leaf spot pathogen, Bipolaris sorokiniana, and the melting out pathogen, Drechslera poae, both affect bluegrass, ryegrass and fescue. Both diseases are favored by dry periods alternating with prolonged cloudy, wet weather. Fungal spores germinate with contact to water droplets on the turf leaf surface.
Symptoms begin as black to purple leaf spots on the leaf blades, and progress to round or oval spots with buff-colored centers surrounded by a dark-brown to dark-purple margin. Infected leaf sheaths turn a uniform dark chocolate brown, causing leaves to yellow and then drop from the plant. Infected roots and crowns become dark brown and rot. 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 should begin in spring at the first sign of disease.
Leaf Spot/Melting Out, http://www.ces.purdue.edu/extmedia/bp/bp-103-w.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
5. Bagworms are most common on evergreens. These are not the large ugly webs that form in deciduous trees. At this time of year, bagworms are reaching ¾ to 1 inch in size and there is only one larva per “bag”. At this size, Bacillus thuringiensis (B.t.), sold as Dipel or Thuricide, is not the most effective product. Bifenthrin is a better choice and should be used at the higher dosage rate. Bifenthrin is also an irritant, causing bagworms to move around and further expose themselves to the insecticide.
Bagworm and It's Control, http://ohioline.osu.edu/hyg-fact/2000/2149.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
6. Fall Webworms are beginning to appear in trees such as cottonwood and crabapple. At this time of year, the webbed nests are small, but with time will enlarge and become unsightly webbed nests filled with caterpillars, dead leaves, frass and worm excrement. While nests are unsightly, the caterpillars are fairly harmless to most established trees. A broom can be used to break up the bag of fall webworms. Then follow through with strong stream of water or an insecticide. Mechanically remove nests when feasible. Application of insecticides such at Bt (Bacillus thuringiensis), permenthrin, or Spinosad when caterpillars first appear in July can reduce their numbers and web nest sizes.
Fall Webworm Management, http://ohioline.osu.edu/hyg-Fact/2000/2026.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
7. Elm Flea Weevil (EFW) 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.
Elm Flea Weevil, http://www.ipm.msu.edu/cat08land/l06-27-08.htm#9
The Elm Flea Weevil: Not To Be Confused with Flea Beetles, http://extensionhorticulture.unl.edu/Weekly/EFW.4.05.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
8. 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. Infection rates have been extremely high this year in eastern Nebraska due to the extended wet conditions from spring into mid-summer. Spray affected trees with chlorothalonil next spring, to protect the new growth, 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
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
9. Sphaeropsis Tip Blight infects pine trees. 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 ineffective. Homewoners should positively identify the cause of problems with pine trees before attempting treatment or removal of the tree.
Diseases of Evergreen Trees, http://www.nfs.unl.edu/documents/foresthealth/diseasesevergreen.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
10. Japanese Beetle adults are showing up on many ornamentals in extreme eastern Nebraska. Japanese beetles are aggressive feeders on the foliage and fruit of nearly 300 species of landscape plants. Japanese beetles feed on the upper leaf surface, removing the soft leaf tissue and leaving the veins in a lacelike or skeletonized pattern. Japanese beetles release a strong aggregation pheromone that attracts additional beetles to a potential food source. The larva (grub) of Japanese Beetles feed on the roots of plants from late summer into early fall.
Management of Japanese Beetles, http://www.ianrpubs.unl.edu/sendIt/g1623.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
11. Aster Yellows is a common disease that affects many ornamental flowers. Susceptible plants include asters, chrysanthemum, coreopsis, cosmos, echinacea (coneflowers), dianthus, gladiola, marigold and petunias. Vein clearing, or loss of green pigment within the veins, is often the first symptom. Stunting, stiff extra bushy yellow growth, deformed or poorly developed flowers which remain green are all common symptoms. There is no cure for infected plants. Remove and discard them to reduce further spread.
Aster Yellows, http://www.oznet.ksu.edu/library/hort2/MF1086.pdf
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
12. 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
