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Hort Update for the week of 8/11/08
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1. Brown Patch causes roughly circular patches of dead and dying grass. Patch centers may be less affected and remain green. 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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2. Annual Weedy Grasses like crabgrass, goosegrass, foxtail and grassy sandbur are all relatively easy to control with properly timed pre-emergence applications early in the season. The abundant rainfall this year and the delay in germination and growth has resulted in significant late-season infestations. Products containing MSMA or quinclorac (check labels) and applied post emergence will work fair to good depending on species.
If possible avoid products that mix either of these chemicals with 2,4-D or dicamba. The potential for injury to non-target plants like trees and shrubs when temperatures are elevated and/or windy is a potential problem.
Control will not be effective as the grassy weeds continue to mature and spraying should be avoided on tillering (actively spreading) annual grasses. If the grassy weeds at your location are large, don’t waste time trying to eradicate them chemically. Keep mowing to limit seedheads and seed production and use a preemergence next year in late April to early May and mid to late June.
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3. Yellow Nutsedge is more abundant this year. Unfortunately, spraying at this time is marginally effective and often results in stimulation of the “daughter” tubers attached to the mother plant resulting in a greater infestation of nutsedge. Remember these nutsedge hot spots for an application of a product containing halosulfuron next year prior to June 21 st but after nutsedge emergence to maximize effective control.
Yellow Nutsedge Control In Home Lawns, http://ohioline.osu.edu/hyg-fact/4000/4010.html
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4. Emerald Ash Borer has been confirmed in southeast Missouri and southeast Wisconsin. It has not yet been found in Nebraska and ash trees should not be treated for EAB at this time. People do need to remain alert for dying ash trees and report these to your local Extension office. Transportation of firewood from other states is a main means of travel for this insect. It is important to buy firewood locally and not transport it across state lines. While this may not prevent EAB from eventually being found in Nebraska, it can buy time in preparing for this pest. It is also important to promote diversity in our tree plantings and to discourage planting of green and white ash in Nebraska.
Emerald Ash Borer, http://www.emeraldashborer.info
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5. Bagworms are most common on evergreens (conifers). These are not the large ugly webs forming in deciduous trees. At this time of year, bagworms are 1 inch or more in length and there is only one larva per “bag”. At this size, Bacillus thuringiensis (B.t.) will not work. Bifenthrin will work in early August. Use the higher dosage rate. Bifenthrin is also an irritant. It causes bagworms to move around, exposing them further to the insecticide. The larvae begin to pupate in mid-August and insecticides are not effective after this occurs.
Bagworm and Its Control, http://ohioline.osu.edu/hyg-fact/2000/2149.html
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6. Fall Webworms are appearing as webbed nests on the ends of branches in cottonwood, crabapple, walnut and other trees. Caterpillars hide in the webbed nests during the day and feed at night. The nests are unsightly, but caterpillars cause little harm to otherwise healthy trees. Tree health is usually not affected until more than 50 percent of the foliage is eaten. If there are enough nests, almost one on every branch, a tree could be completely defoliated. If you can safely reach the nest, use a broom to break up the bag of webworms. Follow up by spraying with a strong stream of water or an insecticide such as permethrin or Spinosad. Prune out the webbed nests when feasible. There are natural parasites and pathogens of fall webworm that often bring these infestations under control. Trees with lots of fall webworm this year may not have many next year. Outbreaks usually last two or three years.
Fall Webworm Management, http://ohioline.osu.edu/hyg-Fact/2000/2026.html
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7. Yellow necked caterpillars and walnut caterpillars are closely related late season caterpillars that feed on tree leaves. Yellow-necked caterpillars feed on a wide range of trees while walnut caterpillars feed primarily on walnut, pecans and some hickories. Walnut caterpillars gather in clumps on tree trunks to molt. Young caterpillars skeletonize leaves, then strip off foliage as caterpillars mature. Large caterpillars pupate in soil where they over winter. Control of these caterpillars is usually not needed on established trees unless defoliation is occurring during the middle of season. Defoliation in late August and early September has minimal impact on tree health because leaves being eaten are close to the time of normal leaf drop.
Yellownecked Caterpillar, http://www.oznet.k-state.edu/hfrr/extensn/problems/YellowneckedCaterpillar.htm
Walnut Caterpillar, http://www.na.fs.fed.us/spfo/pubs/fidls/Walnutcat/walnutfidl.htm
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8. Ash Flower Galls appear as clusters of green galls on seedless (male) ash trees. These galls eventually turn black. They are unsightly but not harmful to ash trees. They are caused by the ash flower gall mite that attacks the male flowers, causing them to become deformed. Control is not needed or recommended.
Internet Resource- http://www.oznet.k-state.edu/dp_hfrr/extensn/problems/Ash_Flower_Gall.htm
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9. Phlox Plant Bug are little red bugs with piercing-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
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10. Rose Cane Borers cause tunnels in rose canes or small, sparse, yellow or wilted rose leaves. Insects that bore into roses are not always harmful to the garden. The most common tunnelers are hunting wasps that, for the most part, are beneficial predators. These small, harmless wasps nest in the rose piths but do not injure the plant. They feed on aphids and provide some insect control. Female wasps lay eggs on cut canes. The eggs hatch into caterpillars which tunnel into the cane pith. They feed for about two weeks on aphids brought to the nest by the female wasp. After two weeks, the larva goes into a dormant state before emerging as an adult wasp. If the wasps do significant damage to a plant, prune the rose cane below the wasp nest area where there may be a slight swelling. Seal this cut and routine pruning cuts with water-insoluble glue or nail polish to prevent more nests of eggs.
Rose Cane Borer, http://www.ext.colostate.edu/PTLK/1463.html
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11. Blossom end rot is a common problem of tomatoes, but is also found on peppers, eggplant, squash and watermelon. It occurs as a flat, dry, sunken, brown rot that is seen on the blossom end of the fruit, opposite the stem end. This problem is not an insect or disease. It is a physiological disorder associated with a calcium deficiency in the developing fruit.
Rarely is blossom end rot the result of a lack of calcium in the soil, but rather occurs when plants cannot pull up calcium quickly enough for developing tissues. Calcium is a nutrient that must be dissolved in water to move within a plant, so water deficits are contributing factors. Drought stress, low daytime humidity, high temperatures and rapid, vegetative plant growth caused by excess nitrogen favor blossom end rot development.
To reduce blossom end rot, use these cultural techniques:
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12. Stink Bug are shield-shaped bugs with a triangle on their backs. Most are brown or green with red or yellow markings. They have piercing-sucking mouthparts and damage plants by puncturing tissue and feeding on sap. Stink bugs attack a variety of fruits and vegetables, often leaving blemishes or depressions. Although they can feed on leaves and stems, reproductive structures, such as corn ears, tomato and pepper fruit, seeds, and pods are preferred feeding sites. Handpick bugs or their barrel-shaped eggs found on leaf undersides. Eliminate weedy areas in early spring to reduce population build up. Insecticides are generally not recommended in gardens for stink bugs, but can be used. Keep in mind some stink bugs feed on other insects and are beneficial predators.
Stink Bugs, http://ipm.ncsu.edu/AG271/soybeans/stink_bugs.html
Hort Update for the week of 8/11/08
| Current Problems: | Major Symptom: |
| Lawns | |
| 1. Brown Patch | Roughly circular patches of brown and dying grass |
| 2. Annual Weedy Grasses | Goosegrass, crabgrass, foxtail, sandburs |
| 3. Yellow Nutsedge | Pale green to yellowish, 3-ranked, triangular shaped leaves |
| Trees/Shrubs | |
| 4. Emerald Ash Borer | Just confirmed in southeast Missouri & southeast Wisconsin |
| 5. Bagworm | Browning in evergreens & 1” tan, spindle-shaped bagworms found |
| 6. Fall Webworms | Webbed nests in deciduous trees containing caterpillars & frass |
| 7. Yellow-necked & Walnut caterpillars | Caterpillars feeding in masses on deciduous trees |
| 8. Ash Flower Galls | Green galls found in seedless ash trees. Leaves are unaffected. |
| Landscape Plants | |
| 9. Phlox Plant Bug | Yellow stippling in leaves, deformed flowers, plant stunting. |
| 10. Rose Cane Borer | Tunnels in rose canes. Small, sparse, yellow leaves. |
| Vegetables/Fruits | |
| 11. Blossom End Rot | Leathery to soft brown rot on bottom of tomatoes & other fruit |
| 12. Stink Bugs | Blemishes or depressions on various fruits & vegetables |
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1. Brown Patch causes roughly circular patches of dead and dying grass. Patch centers may be less affected and remain green. 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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2. Annual Weedy Grasses like crabgrass, goosegrass, foxtail and grassy sandbur are all relatively easy to control with properly timed pre-emergence applications early in the season. The abundant rainfall this year and the delay in germination and growth has resulted in significant late-season infestations. Products containing MSMA or quinclorac (check labels) and applied post emergence will work fair to good depending on species.
If possible avoid products that mix either of these chemicals with 2,4-D or dicamba. The potential for injury to non-target plants like trees and shrubs when temperatures are elevated and/or windy is a potential problem.
Control will not be effective as the grassy weeds continue to mature and spraying should be avoided on tillering (actively spreading) annual grasses. If the grassy weeds at your location are large, don’t waste time trying to eradicate them chemically. Keep mowing to limit seedheads and seed production and use a preemergence next year in late April to early May and mid to late June.
"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
3. Yellow Nutsedge is more abundant this year. Unfortunately, spraying at this time is marginally effective and often results in stimulation of the “daughter” tubers attached to the mother plant resulting in a greater infestation of nutsedge. Remember these nutsedge hot spots for an application of a product containing halosulfuron next year prior to June 21 st but after nutsedge emergence to maximize effective control.
Yellow Nutsedge Control In Home Lawns, http://ohioline.osu.edu/hyg-fact/4000/4010.html
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4. Emerald Ash Borer has been confirmed in southeast Missouri and southeast Wisconsin. It has not yet been found in Nebraska and ash trees should not be treated for EAB at this time. People do need to remain alert for dying ash trees and report these to your local Extension office. Transportation of firewood from other states is a main means of travel for this insect. It is important to buy firewood locally and not transport it across state lines. While this may not prevent EAB from eventually being found in Nebraska, it can buy time in preparing for this pest. It is also important to promote diversity in our tree plantings and to discourage planting of green and white ash in Nebraska.
Emerald Ash Borer, http://www.emeraldashborer.info
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5. Bagworms are most common on evergreens (conifers). These are not the large ugly webs forming in deciduous trees. At this time of year, bagworms are 1 inch or more in length and there is only one larva per “bag”. At this size, Bacillus thuringiensis (B.t.) will not work. Bifenthrin will work in early August. Use the higher dosage rate. Bifenthrin is also an irritant. It causes bagworms to move around, exposing them further to the insecticide. The larvae begin to pupate in mid-August and insecticides are not effective after this occurs.
Bagworm and Its Control, http://ohioline.osu.edu/hyg-fact/2000/2149.html
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6. Fall Webworms are appearing as webbed nests on the ends of branches in cottonwood, crabapple, walnut and other trees. Caterpillars hide in the webbed nests during the day and feed at night. The nests are unsightly, but caterpillars cause little harm to otherwise healthy trees. Tree health is usually not affected until more than 50 percent of the foliage is eaten. If there are enough nests, almost one on every branch, a tree could be completely defoliated. If you can safely reach the nest, use a broom to break up the bag of webworms. Follow up by spraying with a strong stream of water or an insecticide such as permethrin or Spinosad. Prune out the webbed nests when feasible. There are natural parasites and pathogens of fall webworm that often bring these infestations under control. Trees with lots of fall webworm this year may not have many next year. Outbreaks usually last two or three years.
Fall Webworm Management, http://ohioline.osu.edu/hyg-Fact/2000/2026.html
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7. Yellow necked caterpillars and walnut caterpillars are closely related late season caterpillars that feed on tree leaves. Yellow-necked caterpillars feed on a wide range of trees while walnut caterpillars feed primarily on walnut, pecans and some hickories. Walnut caterpillars gather in clumps on tree trunks to molt. Young caterpillars skeletonize leaves, then strip off foliage as caterpillars mature. Large caterpillars pupate in soil where they over winter. Control of these caterpillars is usually not needed on established trees unless defoliation is occurring during the middle of season. Defoliation in late August and early September has minimal impact on tree health because leaves being eaten are close to the time of normal leaf drop.
Yellownecked Caterpillar, http://www.oznet.k-state.edu/hfrr/extensn/problems/YellowneckedCaterpillar.htm
Walnut Caterpillar, http://www.na.fs.fed.us/spfo/pubs/fidls/Walnutcat/walnutfidl.htm
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8. Ash Flower Galls appear as clusters of green galls on seedless (male) ash trees. These galls eventually turn black. They are unsightly but not harmful to ash trees. They are caused by the ash flower gall mite that attacks the male flowers, causing them to become deformed. Control is not needed or recommended.
Internet Resource- http://www.oznet.k-state.edu/dp_hfrr/extensn/problems/Ash_Flower_Gall.htm
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9. Phlox Plant Bug are little red bugs with piercing-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
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10. Rose Cane Borers cause tunnels in rose canes or small, sparse, yellow or wilted rose leaves. Insects that bore into roses are not always harmful to the garden. The most common tunnelers are hunting wasps that, for the most part, are beneficial predators. These small, harmless wasps nest in the rose piths but do not injure the plant. They feed on aphids and provide some insect control. Female wasps lay eggs on cut canes. The eggs hatch into caterpillars which tunnel into the cane pith. They feed for about two weeks on aphids brought to the nest by the female wasp. After two weeks, the larva goes into a dormant state before emerging as an adult wasp. If the wasps do significant damage to a plant, prune the rose cane below the wasp nest area where there may be a slight swelling. Seal this cut and routine pruning cuts with water-insoluble glue or nail polish to prevent more nests of eggs.
Rose Cane Borer, http://www.ext.colostate.edu/PTLK/1463.html
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11. Blossom end rot is a common problem of tomatoes, but is also found on peppers, eggplant, squash and watermelon. It occurs as a flat, dry, sunken, brown rot that is seen on the blossom end of the fruit, opposite the stem end. This problem is not an insect or disease. It is a physiological disorder associated with a calcium deficiency in the developing fruit.
Rarely is blossom end rot the result of a lack of calcium in the soil, but rather occurs when plants cannot pull up calcium quickly enough for developing tissues. Calcium is a nutrient that must be dissolved in water to move within a plant, so water deficits are contributing factors. Drought stress, low daytime humidity, high temperatures and rapid, vegetative plant growth caused by excess nitrogen favor blossom end rot development.
To reduce blossom end rot, use these cultural techniques:
- Prevent drought stress on plants by providing at least 1 inch of water per week, and greater amounts for plants in sandy soils or during very hot, dry conditions.
- Use organic mulch like wood chips, clean straw, pine straw, peat moss, compost, or herbicide-free grass clippings to conserve soil moisture.
- Avoid excess fertilization, especially with ammoniacal nitrogen sources.
- Foliar applications of calcium have little effect on blossom end rot due to poor absorption and movement of calcium from the leaves to fruits.
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12. Stink Bug are shield-shaped bugs with a triangle on their backs. Most are brown or green with red or yellow markings. They have piercing-sucking mouthparts and damage plants by puncturing tissue and feeding on sap. Stink bugs attack a variety of fruits and vegetables, often leaving blemishes or depressions. Although they can feed on leaves and stems, reproductive structures, such as corn ears, tomato and pepper fruit, seeds, and pods are preferred feeding sites. Handpick bugs or their barrel-shaped eggs found on leaf undersides. Eliminate weedy areas in early spring to reduce population build up. Insecticides are generally not recommended in gardens for stink bugs, but can be used. Keep in mind some stink bugs feed on other insects and are beneficial predators.
Stink Bugs, http://ipm.ncsu.edu/AG271/soybeans/stink_bugs.html
