Enter to win a copy of "The Well-Tended Perennial Garden" by Tracy DiSabato-Aust
Hort Update for the week of 6/27/08
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1. Denver Billbug (Western Nebraska)- 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.
UNL Billbug Grubs, http://entomology.unl.edu/turfent/documnts/billbugs.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
2. Fungal Leaf Spot Diseasesoccur most often in rainy weather. Common leaf spot diseases include Brown Patch, Helminthosporium and Septoria leaf spot. All of these 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.
Diagnostic Key – Lawns, http://lawnandgarden.unl.edu/html/toolbar/diagtip/lawnkey.htm
Brown Patch, http://extensionhorticulture.unl.edu/Current/BrownPatch.shtml
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3. Yellow Nutsedge growth appears to be delayed by about two weeks. Yellow nutsedge is a 3-ranked, yellow-green, waxy grass-like weed. At this time of year it can be controlled by pulling. Nutlets (tubers) will not start to form until after the longest day of the year, June 21 st. This year, tuber formation may occur later. Pulling before this stage is worthwhile. Chemical treatment is most effective when applied before June 21 in most years. Use Sedgehammer (replaced Manage) or Certainty (Sulfosulfuron) which can be applied by commercial applicators.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
4. Yellow Lawns- due to rainy weather delaying mowing schedules, some homeowners are seeing yellowing symptoms on tall lawns after mowing. Roch Gaussoin, Extension Turfgrass Specialist, recommends raising the mowing height and going ahead with mowing between rainy periods. This is one of the few times where it would be recommended to pick up grass clippings. Some yellowing may be due to scalping (removing more than 1/3 of the grass blade during any one mowing); hence the raised mowing height recommendation. Some yellowing may be due to poor root function in saturated soils.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
5. Ash Rust- yellow/orange, raised spots (postules) on leaves. This fungal disease may cause some twisting of foliage and leaf drop. Ash rust is not a serious disease of trees. Fungicide control is not recommended or needed.
Ash Rust, http://extensionhorticulture.unl.edu/Current/AshRust.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
6. Anthracnose fungal disease found on ash, maple, sycamore and oak. It causes irregular brown areas on leaves. Leaves may become distorted and some defoliation can occur. It is too late to treat trees effectively. Anthracnose is rarely a serious problem for otherwise healthy trees. Most trees produce new leaves to replace diseased leaves.
Diseases of Broadleaf Trees in Nebraska, http://www.nfs.unl.edu/ForestHealth/fh-disease-broadleaf.asp
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
7. Failure to leaf out- there have been a number of reports across the state of shade trees and shrubs failing to leaf or beginning to leaf then dieing back. This may be the result of last years April freeze on trees that have experienced cumulative stresses over the years such as drought, disease, insect damage, poor planting practices, herbicide exposure, etc. The trees/shrubs may have had enough stored food to re-leaf after the April, 2007 freeze and to have appeared healthy through last summer and even produce leaf buds for this year, but then stored food (carbohydrates and sugars) reserves were depleted for this year’s growth; or trees were negatively affected by this years “true winter” due to the cumulative stresses.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
8. Summer pruning- with wind damage to trees, and spring work being delayed due to weather; there has been an increase in questions about summer pruning. Trees and shrubs can be pruned during summer. Make correct pruning cuts. Do not use any wound dressing, tree paint, etc. of any kind. Stop pruning by the middle of August to allow trees to begin their dormancy process. Mid-April through May (a trees active growth period) and mid-August to the first hard freeze are the two times of the year that tree pruning is discouraged.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
9. Wind damage to trees can lead to structural problems and potential hazardous conditions and future problems for a tree if correct pruning is not done. Some key points when wind damage occurs are:
For information on identifying hazards in trees, see http://www.na.fs.fed.us/spfo/pubs/howtos/ht_haz/ht_haz.htm
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
10. Autumn Blaze® maple issues- Reports of dieback in Autumn Blaze®, maple are being checked into by the Nebraska Forest Service and UNL Horticulturists. Autumn Blaze® is a cross between Acer rubrum x A saccharinum (Red maple and silver maple). Problems could be related graft failure, root girdling, or possibly be genetic with lower adaptability to environmental stresses. As fast growing trees with weaker (less dense) wood, these trees are more susceptible to wind damage. Chlorosis (leaf yellowing) is also common due to high pH soils creating an environment where iron and/or manganese is less available to these trees.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
11. Hawthorne leaf miner- Squiggly tunnels created by larvae feeding within leaves. By the end of May, larvae leave their mines and pupate within the soil. One generation per year. No control is effective once leaf minors are inside leaves. Control is usually not needed.
Hawthorne leaf miner, http://www.ppdl.purdue.edu/PPDL/weeklypics/Weekly_Picture5-7-01-2.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
12. Ash sawfly-brown-headed ash sawfly worms, or larvae, chew newly emerging ash leaves in May and early June. Sawflies are only out for about one month every year and are relatively easy to control if needed. The adults are small, non-stinging wasps that come out on sunny days shortly after bud break to mate and lay eggs on young leaves. Eggs hatch and larvae feed, producing tiny holes within the leaves. As larvae grow, they chew whole leaf sections leaving only the tough leaf veins. Damage diminishes rapidly within two to three weeks after eggs hatch and larvae become full-grown. Sawflies are easily controlled, even if infestations are severe. It's key to make timely pesticide applications in late-May when sawfly larvae are small. A strong jet of water knocks many off of trees, preventing more damage. Insecticidal soap sprays will kill larvae. Most Garden insecticides are effective, except Bacillus thuringiensis does not work on sawfly.
Brownheaded Ash Sawfly, http://www.ext.colostate.edu/PUBS/INSECT/05586.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
13. Bagworms possibly reduced- our “normal winter” may have been too much for some bagworms. In cutting open the overwintering bags, unviable eggs are being found. This might help reduce bagworm damage to evergreens this year. Evergreens should still be watched for young bagworms. Large bagworm populations can completely defoliate an evergreen in a short period of time.
Bagworms, http://extensionhorticulture.unl.edu/Current/Bagworm.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
14. Apple Scab disease is favored by cool, wet weather. Symptoms first appear on lower leaf surfaces as small, velvety, olive green spots (lesions). On some crabapples, infections may have a reddish color. Older leaf spots become darker and have a more distinct margin. Heavily infected leaves may drop resulting in unsightly trees. Early defoliation may also weaken trees and make them more susceptible to winter injury or other pests. Infected fruits are blemished, often deformed and may drop early. Fruit lesions become ‘scabby’ with age, but are only skin deep. Trees of highly susceptible varieties can be severely defoliated by mid to late summer; and fruit production in apples reduced. Fungicide sprays are most effective when applied just as trees are leafing out in the spring and repeated two to three times.
Diseases of Broadleaf Trees in Nebraska, http://www.nfs.unl.edu/ForestHealth/fh-disease-broadleaf.asp
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
15. Dicamba Herbicide Injury- Many combination herbicides used to control broadleaf weeds in lawns can also cause damage to nearby trees and shrubs. Dicamba, one of the active ingredients in these combination products, persists for long periods in the soil, causing ongoing damage to woody plants. For this reason, caution should be used with products containing dicamba for control of broadleaf weeds in areas near trees and shrubs. These combination products are often marketed as Trimec, Triplet and Three-Way.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
16. Rose Sawflies- brown, skeletonized leaves on roses is often caused by rose sawfly. Sawflies are small, dark, non-stinging wasps. Sawfly larvae are light green with yellowish-orange heads. Larvae damage leaves by feeding on the green tissue and leaving behind the veins. Look closely to find larvae. If they are not present there is no reason to treat. Most garden dusts or sprays will work. Insecticidal soaps must contact sawfly larvae to have an effect.
Defoliaters/leaf feeders of roses, http://www.extension.umn.edu/distribution/horticulture/components/6953_01.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
17. Rose Chafers are scarab beetles approximately 3/8 inch long, slender, and light tan. Adults feed on rose flowers and foliage. Inspect roses for skeletonized leaves and adult beetles. Rose chafers can be hand pick if the infestation is light. The insecticides carbaryl (Sevin) and acephate (Orthene) will control these beetles. However, the beetles are quite mobile and new beetles may replace those killed by insecticides.
Defoliaters/leaf feeders of roses, http://www.extension.umn.edu/distribution/horticulture/components/6953_01.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
18. Leaf Cutter Bees cut out sections of rose and other plant leaves to line their nests. The holes are distinctive being fairly large and round with a smooth edge. Control of leafcutting bees is not recommended as they are beneficial pollinators and the damage they do is rarely harmful to plants.
Defoliaters/leaf feeders of roses, http://www.extension.umn.edu/distribution/horticulture/components/6953_01.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
19. Natural Fruit Thinning (June Drop) appears reduced or delayed- natural fruit thinning usually occurs in June when fruit trees drop a number of fruits, usually due to poor pollination. “June Drop” appears to be delayed this year or may not occur due to a good pollination year. If trees do not experience natural fruit thinning, it will be even more important to manually thin fruit this year. The sooner this can be done, the better. Encourage fruit thinning by July 1 st. See below.
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20. Fruit thinning- last April's freeze reduced or prevented fruit set in many plants. That, along with good growing conditions this spring, has lead to prolific fruit set in some fruit bearing trees. To prevent fruit trees going into alternate year bearing; having reduced fruit size and flavor; and to avoid branch breakage, it would be wise to thin fruit on fruit trees. Thinning is best accomplished by hand picking fruits after the natural June drop, about July 1. Where fruits are clustered, remove all but one fruit per cluster. Space fruits from 5-8 inches apart, removing the small insect and disease injured fruit first. Fruits may be spaced closer together on the outside and top of the tree than in the center, because these branches receive full sunlight. June drop is referred to as “natural thinning” when trees drop a number of fruit in June. It can occur due to poor pollination and/or heavy of fruit set.
Thinning Fruit Trees, http://hort4.unl.edu/fruit/thin.html
Hort Update for the week of 6/27/08
| Current Problems: | Major Symptom: |
| Lawns | |
| 1. Denver billbug (Western Nebraska) | Browning of turfgrass. |
| 2. Leaf spot diseases | Brown patch, Helminthosporium, Septoria |
| 3. Nutsedge growth delayed | Growth & development delayed by about 2 weeks |
| 4. Yellow lawns | Yellowing symptoms on tall lawns after mowing |
| Trees/Shrubs | |
| 5. Ash rust | Raised orange postules on ash leaves; some leaf twisting & drop |
| 6. Anthracnose | Irregular brown areas on leaves, often along leaf veins |
| 7. Failure to leaf or to leaf & grow | Most likely due to cumulative stresses |
| 8. Summer pruning | Trees and shrubs can be pruned in summer |
| 9. Wind damage | Hire a Certified Arborist; correct pruning cuts are important |
| 10. 'Autumn Blaze' maple issues | Dieback, wind damage, chlorosis |
| 11. Hawthorne leaf miner | Light colored, squiggly lines on leaves. Leaf browning. |
| 12. Ash sawfly | Skeletonized and chewed leaves |
| 13. Bagworms may be reduced | Some bagworm eggs appear not to be viable |
| 14. Crabapple apple scab | Olive colored spots on leaf undersides |
| 15. Dicamba herbicide injury | Dicamba herbicide is especially damaging to trees and shrubs |
| Landscape Plants | |
| 16. Rose slugs | Skeletonized leaves |
| 17. Rose chafer | Skeleonized and chewed leaves |
| 18. Leaf cutter bees | Distinct round holes in leaves. Holes have smooth edges. |
| Fruits | |
| 19. Natural "fruit thinning" delayed | Due to good pollination, June drop may be delayed or not occur |
| 20. Manual fruit thinning | Manual thinning recommended due to heavey fruit crops |
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1. Denver Billbug (Western Nebraska)- 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.
UNL Billbug Grubs, http://entomology.unl.edu/turfent/documnts/billbugs.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
2. Fungal Leaf Spot Diseasesoccur most often in rainy weather. Common leaf spot diseases include Brown Patch, Helminthosporium and Septoria leaf spot. All of these 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.
Diagnostic Key – Lawns, http://lawnandgarden.unl.edu/html/toolbar/diagtip/lawnkey.htm
Brown Patch, http://extensionhorticulture.unl.edu/Current/BrownPatch.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
3. Yellow Nutsedge growth appears to be delayed by about two weeks. Yellow nutsedge is a 3-ranked, yellow-green, waxy grass-like weed. At this time of year it can be controlled by pulling. Nutlets (tubers) will not start to form until after the longest day of the year, June 21 st. This year, tuber formation may occur later. Pulling before this stage is worthwhile. Chemical treatment is most effective when applied before June 21 in most years. Use Sedgehammer (replaced Manage) or Certainty (Sulfosulfuron) which can be applied by commercial applicators.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
4. Yellow Lawns- due to rainy weather delaying mowing schedules, some homeowners are seeing yellowing symptoms on tall lawns after mowing. Roch Gaussoin, Extension Turfgrass Specialist, recommends raising the mowing height and going ahead with mowing between rainy periods. This is one of the few times where it would be recommended to pick up grass clippings. Some yellowing may be due to scalping (removing more than 1/3 of the grass blade during any one mowing); hence the raised mowing height recommendation. Some yellowing may be due to poor root function in saturated soils.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
5. Ash Rust- yellow/orange, raised spots (postules) on leaves. This fungal disease may cause some twisting of foliage and leaf drop. Ash rust is not a serious disease of trees. Fungicide control is not recommended or needed.
Ash Rust, http://extensionhorticulture.unl.edu/Current/AshRust.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
6. Anthracnose fungal disease found on ash, maple, sycamore and oak. It causes irregular brown areas on leaves. Leaves may become distorted and some defoliation can occur. It is too late to treat trees effectively. Anthracnose is rarely a serious problem for otherwise healthy trees. Most trees produce new leaves to replace diseased leaves.
Diseases of Broadleaf Trees in Nebraska, http://www.nfs.unl.edu/ForestHealth/fh-disease-broadleaf.asp
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
7. Failure to leaf out- there have been a number of reports across the state of shade trees and shrubs failing to leaf or beginning to leaf then dieing back. This may be the result of last years April freeze on trees that have experienced cumulative stresses over the years such as drought, disease, insect damage, poor planting practices, herbicide exposure, etc. The trees/shrubs may have had enough stored food to re-leaf after the April, 2007 freeze and to have appeared healthy through last summer and even produce leaf buds for this year, but then stored food (carbohydrates and sugars) reserves were depleted for this year’s growth; or trees were negatively affected by this years “true winter” due to the cumulative stresses.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
8. Summer pruning- with wind damage to trees, and spring work being delayed due to weather; there has been an increase in questions about summer pruning. Trees and shrubs can be pruned during summer. Make correct pruning cuts. Do not use any wound dressing, tree paint, etc. of any kind. Stop pruning by the middle of August to allow trees to begin their dormancy process. Mid-April through May (a trees active growth period) and mid-August to the first hard freeze are the two times of the year that tree pruning is discouraged.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
9. Wind damage to trees can lead to structural problems and potential hazardous conditions and future problems for a tree if correct pruning is not done. Some key points when wind damage occurs are:
- Safety first. Assess the situation and hire a certified arborist to prune/remove damaged branches that are clear hazards using correct pruning practices.
- In many instances time only allows for broken branches and ‘hangers’ to be removed quickly for safety purposes; be sure to have an arborist return to make a correct pruning cut so stubs and/or broken branches are not left in the tree.
- Do not treat the wind damage or wounds with a pruning paint or dressing of any kind as a tree’s best line of defense is a proper pruning cut.
- Do not apply fertilizers or over-irrigate in hopes of helping the tree recover more quickly. These types of activities typically further stress the tree, are unnecessary, and can provide a more favorable growing environment for harmful decay causing organisms. (Source: Eric Berg, Nebraska Forest Service)
For information on identifying hazards in trees, see http://www.na.fs.fed.us/spfo/pubs/howtos/ht_haz/ht_haz.htm
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
10. Autumn Blaze® maple issues- Reports of dieback in Autumn Blaze®, maple are being checked into by the Nebraska Forest Service and UNL Horticulturists. Autumn Blaze® is a cross between Acer rubrum x A saccharinum (Red maple and silver maple). Problems could be related graft failure, root girdling, or possibly be genetic with lower adaptability to environmental stresses. As fast growing trees with weaker (less dense) wood, these trees are more susceptible to wind damage. Chlorosis (leaf yellowing) is also common due to high pH soils creating an environment where iron and/or manganese is less available to these trees.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
11. Hawthorne leaf miner- Squiggly tunnels created by larvae feeding within leaves. By the end of May, larvae leave their mines and pupate within the soil. One generation per year. No control is effective once leaf minors are inside leaves. Control is usually not needed.
Hawthorne leaf miner, http://www.ppdl.purdue.edu/PPDL/weeklypics/Weekly_Picture5-7-01-2.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
12. Ash sawfly-brown-headed ash sawfly worms, or larvae, chew newly emerging ash leaves in May and early June. Sawflies are only out for about one month every year and are relatively easy to control if needed. The adults are small, non-stinging wasps that come out on sunny days shortly after bud break to mate and lay eggs on young leaves. Eggs hatch and larvae feed, producing tiny holes within the leaves. As larvae grow, they chew whole leaf sections leaving only the tough leaf veins. Damage diminishes rapidly within two to three weeks after eggs hatch and larvae become full-grown. Sawflies are easily controlled, even if infestations are severe. It's key to make timely pesticide applications in late-May when sawfly larvae are small. A strong jet of water knocks many off of trees, preventing more damage. Insecticidal soap sprays will kill larvae. Most Garden insecticides are effective, except Bacillus thuringiensis does not work on sawfly.
Brownheaded Ash Sawfly, http://www.ext.colostate.edu/PUBS/INSECT/05586.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
13. Bagworms possibly reduced- our “normal winter” may have been too much for some bagworms. In cutting open the overwintering bags, unviable eggs are being found. This might help reduce bagworm damage to evergreens this year. Evergreens should still be watched for young bagworms. Large bagworm populations can completely defoliate an evergreen in a short period of time.
Bagworms, http://extensionhorticulture.unl.edu/Current/Bagworm.shtml
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
14. Apple Scab disease is favored by cool, wet weather. Symptoms first appear on lower leaf surfaces as small, velvety, olive green spots (lesions). On some crabapples, infections may have a reddish color. Older leaf spots become darker and have a more distinct margin. Heavily infected leaves may drop resulting in unsightly trees. Early defoliation may also weaken trees and make them more susceptible to winter injury or other pests. Infected fruits are blemished, often deformed and may drop early. Fruit lesions become ‘scabby’ with age, but are only skin deep. Trees of highly susceptible varieties can be severely defoliated by mid to late summer; and fruit production in apples reduced. Fungicide sprays are most effective when applied just as trees are leafing out in the spring and repeated two to three times.
Diseases of Broadleaf Trees in Nebraska, http://www.nfs.unl.edu/ForestHealth/fh-disease-broadleaf.asp
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
15. Dicamba Herbicide Injury- Many combination herbicides used to control broadleaf weeds in lawns can also cause damage to nearby trees and shrubs. Dicamba, one of the active ingredients in these combination products, persists for long periods in the soil, causing ongoing damage to woody plants. For this reason, caution should be used with products containing dicamba for control of broadleaf weeds in areas near trees and shrubs. These combination products are often marketed as Trimec, Triplet and Three-Way.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
16. Rose Sawflies- brown, skeletonized leaves on roses is often caused by rose sawfly. Sawflies are small, dark, non-stinging wasps. Sawfly larvae are light green with yellowish-orange heads. Larvae damage leaves by feeding on the green tissue and leaving behind the veins. Look closely to find larvae. If they are not present there is no reason to treat. Most garden dusts or sprays will work. Insecticidal soaps must contact sawfly larvae to have an effect.
Defoliaters/leaf feeders of roses, http://www.extension.umn.edu/distribution/horticulture/components/6953_01.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
17. Rose Chafers are scarab beetles approximately 3/8 inch long, slender, and light tan. Adults feed on rose flowers and foliage. Inspect roses for skeletonized leaves and adult beetles. Rose chafers can be hand pick if the infestation is light. The insecticides carbaryl (Sevin) and acephate (Orthene) will control these beetles. However, the beetles are quite mobile and new beetles may replace those killed by insecticides.
Defoliaters/leaf feeders of roses, http://www.extension.umn.edu/distribution/horticulture/components/6953_01.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
18. Leaf Cutter Bees cut out sections of rose and other plant leaves to line their nests. The holes are distinctive being fairly large and round with a smooth edge. Control of leafcutting bees is not recommended as they are beneficial pollinators and the damage they do is rarely harmful to plants.
Defoliaters/leaf feeders of roses, http://www.extension.umn.edu/distribution/horticulture/components/6953_01.html
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
19. Natural Fruit Thinning (June Drop) appears reduced or delayed- natural fruit thinning usually occurs in June when fruit trees drop a number of fruits, usually due to poor pollination. “June Drop” appears to be delayed this year or may not occur due to a good pollination year. If trees do not experience natural fruit thinning, it will be even more important to manually thin fruit this year. The sooner this can be done, the better. Encourage fruit thinning by July 1 st. See below.
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20. Fruit thinning- last April's freeze reduced or prevented fruit set in many plants. That, along with good growing conditions this spring, has lead to prolific fruit set in some fruit bearing trees. To prevent fruit trees going into alternate year bearing; having reduced fruit size and flavor; and to avoid branch breakage, it would be wise to thin fruit on fruit trees. Thinning is best accomplished by hand picking fruits after the natural June drop, about July 1. Where fruits are clustered, remove all but one fruit per cluster. Space fruits from 5-8 inches apart, removing the small insect and disease injured fruit first. Fruits may be spaced closer together on the outside and top of the tree than in the center, because these branches receive full sunlight. June drop is referred to as “natural thinning” when trees drop a number of fruit in June. It can occur due to poor pollination and/or heavy of fruit set.
Thinning Fruit Trees, http://hort4.unl.edu/fruit/thin.html
