Hort Update for the week of 8/14/2009
1. Brown Patch causes roughly circular patches of dead and dying grass. Tan colored, irregularly shaped leaf spots with reddish margins are found on leaf blades. Fungicide applications are often not recommended after August 1. Preventive applications of Prostar (commercial use), Bayleton, and chlorothalonil (Daconil) do a fairly good job of suppressing the disease when applied at monthly intervals in June, July, and August. Curative applications of chlorothalonil beginning a few days after symptoms of brown patch develop may suppress injury. In many cases, lawns damaged by brown patch recover in two to three weeks, provided the outbreak is not sustained by continuous hot, humid weather; and treatment may not be necessary.
2. Dollar Spot Small (three to six inch diameter), roughly circular patches in lawns. Spots may coalesce into a larger patch. Grass blades have tan, band-like lesions with red margins. Damage is usually most severe where nitrogen is deficient. With timely rains this year, nitrogen may have been leached out of the root zone. The best control can be nitrogen fertilization. Turfgrass can be treated with products containing benomyl, mancozeb, propiconazole, thiophanate-methyl.
Dollar Spot Disease in Turfgrass, University of Nebraska-Lincoln Extension
3. Stem Rust symptoms on Kentucky bluegrass include rust colored “powder” (fungal spores) on grass blades, shoes and lawn mowers. Heavily infected turfgrass may have yellowing grass blades. Stem rust typically develops on lawns with slow growth. Fall lawn care, including fertilization and proper irrigation, along with cooler fall weather promotes turfgrass growth and rust disappears. Stem rust is often a problem on compacted soils; hence core aerification is effective in reducing rust disease. Fungicide controls are rarely suggested for home lawns.
Note for Sports Turf- If stem rust occurs on sports fields, the fungal spores can cause problems for allergy/asthma sufferers. Control of stem rust is recommended on sports turfs using a combination of turf management and timely fungicide applications.
Rust Turns Lawns Orange, University of Illinois Extension
Rust on Sports Turf, Ohio State University
4. White Grub damage is showing up in Western Nebraska. Larvae feed on turfgrass roots causing lawn areas to turn brown and sometimes die if grubs damage a large percentage of roots. Most white grub eggs have hatched and their numbers should be similar to past years; however, in eastern Nebraska growing conditions have been conducive to Kentucky bluegrass and is likely preventing or delaying damage. Turfgrass should continue to be inspected for white grubs. If birds are feeding in a lawn, or browning occurs, roll the sod back to look for c-shaped, cream colored, red headed larvae. If eight (8) white grubs are found per square foot, an insecticide application may be justified. At this time of year, Dylox is the insecticide of choice. Do not apply Merit or Meridian at this time of year.
White Grubs in Turf, University of Nebraska-Lincoln Extension
5. Dormant Kentucky bluegrass- As a cool season turfgrass, KBG can go dormant in dryer, heat exposed areas. Homeowners may mistake summer dormancy for disease or death of turf and request treatment or reseeding. Positively confirm cause of browning before treating. Cooler weather and/or irrigation may be all that is needed.
6. Annual weedy grasses such as Canada bluegrass and annual bluegrass are weaker weedy bluegrasses that begin to die out during hot summer weather creating brown or thin patches in lawns. These may be confused for disease/insect injury. Annual weedy grasses are dying later this year due to cooler summer weather. Normally they would have started dying out 3 weeks ago. Overseed bare or thin areas to establish turfgrass that will compete with annual weedy grasses.
Rough Bluegrass (Poa trivialis) is a pale green, stolon-forming perennial grass that forms pale green patches in lawns, especially in shady, moist or overwatered areas. It is not heat or drought tolerant and tends to turn brown about mid August. Control nonselectively with glyphosate and reseed the area. Commercial applicators can control selectively in Kentucky bluegrass with a herbicide containing sulfosulfuron (Certainty).
Annual Bluegrass and Rough Bluegrass Control, Ohio State University
7. Chinch Bugs damage Buffalograss and Zoysiagrass usually in sunny locations during hot, dry periods. Damage appears as patchy areas which turn yellow, then dry out and turn brown. Chinch bugs feed by sucking juices from leaves and stems. While feeding, they inject a toxin which disrupts movement of water and nutrients. Chinch bug nymphs are red with a white band, then orangish, and finally brown to black. Short-winged adults are black and 1/10th of an inch long. Control thatch to reduce chinch bugs. If bugs exceed 20 per square foot, apply the insecticide containing bifenthrin for control.
Chinch Bugs in Buffalograss and Zoysiagrass Turf, University of Nebraska-Lincoln Extension
8. Cottonwood borers are large black and white beetles that emerge from cottonwoods and willows from late June to mid-August. Damage occurs primarily at the base of infested trees and consists of sawdust-packed tunnels up to ½ inch in diameter bored into the wood, which weakens trees and interferes with movement of water and nutrients. Damaged trees may blow over, breaking off at the base. Insecticide treatment is usually not needed due to rareness of attack.
Borers of Shade Trees and Ornamentals, University of Nebraska-Lincoln Extension
9. Euonymous scale Infested leaves turn yellow, then die and drop off. Undersides of leaves and stems are covered with a brown or white scale. Scale insects feed from beneath a protective scale, removing plant sap from stems and leaves. Controls are most effective when the insect is in the crawler stage, usually in May to early June and late August to early September (second generation). Monitor for the presence of crawlers by wrapping a few stems with black electrical tape, with the sticky side facing out, near present scales. Crawlers are yellowish to orange. When in the crawler stage, control with insecticidal soaps. Systemic insecticides are also effective. Read and follow label directions for effective application. Prune and remove heavily infested branches to the ground.
Euonymous Scale, University of Nebraska-Lincoln Extension
10. Leucanium (Fletcher) scales on yew are initially flattened and brown. As they mature, they become hardened and round. They attack a variety of trees and shrubs. With high populations, dieback of twigs, branches and lowered plant vigor result. Control by pruning heavily infested branches and/or applying insecticides just after egg hatch when insects are in the crawler stage in May and June.
Fletcher Scale, Michigan State University
11. Oak twig girdlers starting to cause twig dieback. Squirrels chewing leaves off tree may be confused with girdler damage. Twig girdler is a small, slender, bronze-to-black beetle that emerges from May to September and deposits eggs on twigs at the junction between current and previous year's growth. Larvae hatch and bore into twigs. As they grow, they mine spirally so terminal clusters of dead leaves ("flags") appear in August and September. During the next year, larvae continue to mine deeper into twigs and complete development, pupating in the fall. While damage is obvious, it is rarely severe, and there is rarely a need for control.
Flatheaded Borers, University of Nebraska-Lincoln Extension
12. Dutch elm disease is a wilt disease that causes branches, then entire trees to die. Black or brown streaks may be found in the wood. Remove dead trees and destroy the wood. Do not use it for firewood. A trunk injected fungicide is available. See resource for information.
Diseases of Broadleaf Trees, Nebraska Forest Service
13. Leaf Scorch A uniform yellowing or browning on leaf edges of broadleaf plants or the tips of evergreen needles is a symptom of a condition called scorch. This environmental problem commonly occurs on linden, maple, ash and cottonwood. Scorch is usually is more severe on the south or southwest side of a tree or on the side nearest a source of radiated heat, such as a brick wall or street. Severe scorch can result in premature leaf or needle loss. Prolonged dry periods accompanied by warm, dry winds can cause leaves to transpire moisture faster than roots can supply it to the leaves, resulting in drying out of plant tissue. Young trees with un-established roots, or any tree growing in soils that are not conducive to healthy root function (i.e. compacted clay soil or overwatered soil) can lead to leaf scorch. Properly siting trees, avoiding overwatering, and encouraging healthy root growth can decrease leaf scorch in some situations.
Leaf Scorch of Ornamental Trees and Shrubs, University of Missouri Extension
Leaf Scorch of Trees and Shrubs, Purdue University
14. Zimmerman pine moth larvae tunnel beneath the bark of pine trees, particularly in branch crotches, causing branches to die or break off readily in wind and snow storms. A pinkish mass may be found at the base of infested branches. Insecticides, such as bifenthrin or permethrin, applied during the second week of April and the second week of August are required for control. Use the label rate for borers and apply to the trunk and major branches.
Zimmerman Pine Moth, Colorado State University
Zimmerman Pine Moth, Iowa State University
15. Bagworm Some homeowners mistake bagworm damage for general decline of trees. Close inspection is recommended when evergreens, especially spruce, are thinning or browning. At this time of year, bagworms are up to 2 inches long and there is only one larva per small “brown bag”; although there may be numerous bags throughout the tree. Larvae will pupate in mid to late August and insecticide applications will no longer be effective once they pupate. Check bags. If larvae are still feeding, insecticides, such as Bifenthrin, can be applied. If larvae are no longer active, remove and destroy bags to reduce the number of overwintering eggs.
Bagworms, University of Nebraska-Lincoln Extension
16. Fall webworms make the large 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; then follow up by spraying with a strong stream of water or an insecticide such as permethrin or Spinosad. Prune out webbed nests when feasible. There are natural parasites and pathogens of fall webworm that often bring these infestations under control; hence, trees with numerous webworm nests this year may have none or few next year. Outbreaks usually last two or three years.
Fall Webworm Management, Ohio State University
17. Cytospora canker With hail damage (western Nebraska), this fungus is causing twig dieback and gall-like canker formation, most commonly on Spruce trees. Branches near the base of trees or tops of trees die. Resin often oozes from branch or trunk cankers. There are no fungicide controls. Prune and destroy dead and dying branches during winter. The fungus of often spread during spring rains. Disinfect all pruning tools such as knives and saws by wiping them with rubbing alcohol. Avoid stress by spacing trees correctly, then mulching and watering correctly. Avoid wounds. Black Hills Spruce is less susceptible to this disease.
Diseases of Evergreen Trees, Nebraska Forest Service
18. Rose Fertilization Stop fertilizing roses and most other woody plants by August 15. Fertilization after this date can encourage succulent growth that will not have time to harden off before winter and increase the risk of winter injury.
19. Rose rosette, also known as witches’ broom of rose, is a virus spread by a very small, eriophyid mite, or by grafting. Its main host is the multiflora rose, which is considered a noxious weed throughout much of the USA. On these roses, the virus causes a witches broom symptom with leaves becoming deformed and crinkled with yellow mosaic and red pigmentation. Symptoms on cultivated roses are typically less severe and include thickened, succulent stems and a proliferation of thorns. Small plants are usually killed in about 2 years, while a large plant may survive for five years in a deteriorated condition. Control includes removing the entire plant, including the rootstock, of ornamental roses; planting ornamental roses as far away from known stands of multiflora rose as possible; and controlling the mite. Pesticides such as carbaryl (Sevin), bifenthrin, horticultural oils and insecticidal soap may provide some protection when applied at weekly intervals during the months of June and July.
Rose rosette, Missouri Botanical Garden
20. Common stalk borer attacks over 100 species of plants including flowers, tomato, pepper, corn, rhubarb, hibiscus, and broadleaf weeds. The stalk borer adult is a dull, grayish-brown moth. Young larvae are brownish-purple with three prominent white stripes at the front and rear ends of the body. The stripes are interrupted by a dark purple to black area at mid-body. Full grown larvae are a uniformly dirty gray color and up to 1 1/2 to 2 inches long. Plant symptoms include stunting, wilting or dieback. Control by controlling weeds and using good sanitation practices. Insecticides are only effective if applied before the borer enters the stem.
21. Bacterial canker/speck/spot on tomatoes is most common during wet summers. Bacterial canker causes lesions or cankers on any portion of the plant and may cause wilting, curling of leaflets, and yellowing or browning of leaves, often on one side or a portion of the plant. Fruit spots are dark and bordered by a distinct white halo which may disappear as fruit ripens.
Bacterial speck and spot cause small (1/8-1/4 inch) black lesions, usually with a yellow halo, on leaves. Bacterial spot causes small, slightly raised, water-soaked spots on the fruit which may enlarge to 1/4 inch in diameter and become very rough and cracked. Bacterial speck fruit lesions are also slightly raised but typically smaller (1/16 inch). Bacterial speck lesions do not crack or become scaly.
To control, use a 3 year crop rotation, practice good sanitation, and select bacterial free seed/transplants. Copper-based fungicides may be effective in suppressing bacterial speck and spot if applied at the first sign of leaf spotting or at the time of first blossom and applications continued at 7 to 10 day intervals. These fungicides will not control bacterial canker.
Bacterial Spot, Speck and Canker, Ohio State University
22. Early Blight and Septoria Leaf Spot are the two most common fungal diseases of tomatoes. Symptoms begin as leaf spots on lower leaves, with infections moving up the plant causing foliage to die; often leading to fruit sunscald. These diseases can be reduced with fungicides labeled for use on tomatoes. For best results, applications need to begin as soon as symptoms first appear on lower leaves, and applications made every 7 to 10 days. Avoid overhead irrigation and increase air circulation around plants with proper spacing and caging. Mulch the soil around tomatoes to reduce soil splash of fungus onto lower leaves. Plant resistant varieties and avoid planting tomatoes in the same area year after year. Severely infected plants are best pulled and destroyed. Use fall sanitation to reduce the amount of fungus overwintering.
Early Blight and Septoria Leaf Spot of Tomatoes, Kansas State University
Tomato Disease I.D. Key, Cornell University
23. Anthracnose on curcurbits is a fungal disease that spreads rapidly in warm, wet weather. Early symptoms usually appear on older leaves as small yellowish circular (angular on watermelon) spots. The dead tissue turns brown on cucumber and melon leaves, and nearly black in watermelon leaves. In warm, wet weather all the leaves may be rapidly attacked, giving the planting a "burned-out" appearance. Circular, sunken, water-soaked spots develop on the fruit. These spots turn dark green to brown.
Fungal spores are spread from plant to plant by running water, including splashing rain and individuals working in the garden when vines are wet. The anthracnose fungus overwinters on seed and on diseased crop refuse. Practice good sanitation by removing and destroying infected plants. Preventive measures are important, including use of good quality seed and crop rotation. The fungicides benomyl and chlorothalonil (Ortho Multi-Purpose Fungicide Daconil 2787) help to control the disease, but must be applied at the first sign of disease or as a preventive.
Disease Management in Homegrown Cucurbits, North Dakota State University
24. Black rot of grape causes developing berries to turn dark purple or black, shrivel and cling to the cluster. Routine fungicide applications are necessary to inhibit infection. Start control measures when new shoots begin to emerge from the vine. Mancozeb is one fungicide labeled for control of black rot by homeowners.
Black Rot of Grapes, Kansas State University
Midwest Home Fruit Production Guide , Ohio State University
25. Blossom end rot is a common problem of tomatoes, but also occurs on peppers, eggplant, squash and watermelon. It appears as a flat, dry, sunken, brown rot on the blossom end of the fruit, opposite the stem end. The size of the rotted area varies, but can cover up to 50% of the fruit. This problem is a physiological disorder associated with a calcium deficiency in the developing fruit. Rarely is the problem a lack of calcium in the soil. Drought stress, low daytime humidity, high temperatures and rapid, vegetative plant growth caused by excess nitrogen applications favor blossom end rot development. To reduce it, prevent drought stress, mulch with organic mulch and avoid excess nitrogen fertilization.
Blossom End Rot, University of Nebraska-Lincoln Extension
26. Cedar apple rust Small, yellow spots on upper leaf surfaces. Spots gradually enlarge and become a bright yellow-orange color. Heavily infected leaves drop prematurely. Cedar-apple rust requires two hosts: cedar trees, and apple or crabapple trees. Fungal spores can travel up to 2 miles so removal of cedar trees will not provide control. Plant disease resistant apple or crabapple cultivars. Fungicide sprays may be used to protect apples and crabapples from infection if applications begin at petal drop and continue according to label direction. Applications made now will not be effective.
Cedar Apple Rust, University of Nebraska-Lincoln Extension
27. Tomato spotted wilt commonly causes yellow rings on ripening fruit. Early symptoms of spotted wilt can be an inward cupping of leaves and off-color foliage. The top of infected plants occasionally wilt. Spotted wilt virus is transmitted by an insect called thrips. Virus diseases cannot be controlled once a plant is infected. Sanitation is most important in controlling virus diseases. Remove infected plants immediately to prevent spread. Control perennial weeds in and adjacent to the garden as these can serve as alternate hosts for viruses. Avoid planting tomatoes next to peppers, or other vegetables and flowers susceptible to these diseases. Control of insects, especially thrips, will reduce the likelihood of spotted wilt.
Tomato Spotted Wilt Virus, Kansas State University
28. Yellow jackets become a nuisance during fall as they scavenge for food. If yellow jackets are disturbed, give them plenty of room as they are capable of inflicting multiple stings. If yellow jackets become excited and appear about to attack, do not panic; retreat slowly and calmly. Yellow jackets construct paper nests, usually in underground cavities. Favorite nesting sites include rodent burrows, compost piles, wood piles and wall voids. Occasionally, yellow jackets build aerial nests in garages, crawl spaces or other enclosed areas. They feed on insects, spiders and a variety of food items. Most stinging wasps and bees are beneficial and should be preserved unless they pose a direct hazard to humans. Colonies of yellow jackets are annual and nests are not reused. Freezing temperatures in November and December kill all stinging workers and only fertilized queens survive the winter. If yellow jackets pose a hazard, recommendations for treating the nests safely are available in the following publication.
Stinging Wasps and Bees, University of Nebraska-Lincoln Extension
29. 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. Cricket Hunters are blue black wasps that capture crickets for food or to lay eggs on for larval food. Both wasps are solitary (one wasp per nest) and do not protect their nest. They are very unlikely to sting humans unless provoked.
Stinging Wasps and Bees, University of Nebraska-Lincoln Extension
30. Grasshoppers are becoming large and causing damage. The western part of state is drying out so hoppers are moving into irrigated portions of landscapes- lawn & gardens. They are also affecting trees. They can severely defoliate garden and landscape plants. Effective control includes treating egg hatching areas (roadsides and weedy areas) at egg hatch when the grasshoppers are young. Adult grasshoppers are difficult to control.
A Guide to Grasshopper Control in Yards and Gardens, University of Nebraska-Lincoln Extension
| Current Problems: | Major Symptom: |
| Lawns | |
| 1. Brown patch | Roughly circular patches of brown and dying grass |
| 2. Dollar spot | Small, tan patches in lawns. Tan lesions with red margins on blades |
| 3. Stem rust (Kentucky bluegrass) | Yellowing turfgrass. Rust colored “powder” on shoes, mowers |
| 4. White grub damage (west) | General browning of turf areas in full sun; resembles drought |
| 5. Dormant Kentucky bluegrass | Some areas of KBG go dormant during hot, dry weather |
| 6. Cool season weed grasses dying | Annual weedy grasses dying and turning brown in a lawn |
| 7. Chinch bugs in zoysia & buffalograss | Patchy areas which turn yellow, then dry out and turn brown |
| Trees & Shrubs | |
| 8. Cottonwood borer | Adults, Large black and white beetles, emerging from Poplar trees |
| 9. Euonymus scale | Browning of leaves; twigs covered with scales |
| 10. Leucanium scale (yew) | Brown, rounded bumps (scales) on twigs; sapsucking insect |
| 11. Oak twig girdlers | Small clusters of brown leaves on twig tips |
| 12. Dutch elm disease (American elm) | Leaves yellow & turn brown; branches and finally entire tree dies |
| 13. Leaf scorch (maple) | Brown leaf edges on broadleaves and brown tips on evergreen needles |
| 14. Zimmerman pine moth | Dead branches and large pinkish pitch masses on Scotch & Austrian |
| 15. Bagworms- look closely | Damage being mistaken for general decline or disease |
| 16. Fall webworm | Large webs in honeylocust, crabapple, cottonwood, elderberry, etc. |
| 17. Cytospora canker (spruce) | Twig dieback, gall-like canker formation, bluish-white resin on bark |
| Landscape Ornamentals | |
| 18. Stop rose fertilization | Do not fertilize after August 15; may lead to winter injury |
| 19. Rose rosette | Deformed, crinkled leaves with red pigmentation; witches broom |
| 20. Common stalk borer | In ornamentals, vegetables, and flowers – affects many plant types |
| Vegetables & Fruits | |
| 21. Bacterial canker/ speck/ spot (tomato) | Tomato leaf spots and fruit spots with white or yellow halos |
| 22. Early blight/ Septoria (tomato) | Brown leaf spots with concentric rings, leaf yellowing from bottom up |
| 23. Anthracnose (cucurbits) | Black spots on leaves. Sunken, brown spots on fruit |
| 24. Black rot (grape) | Developing berries turn dark purple or black |
| 25. Blossom end rot | Still affecting tomato, pepper, squash, zucchini, etc. |
| 26. Cedar-apple rust leaf drop | Yellowish leaf spots on apple and crabapple leaves. Leaf spots and leaf drop symptom evident to homeowners now. |
| 27. Tomato spotted wilt virus | Yellow rings on ripening tomatoes |
| General Issues | |
| 28. Yellow jacket wasps | Become more aggressive at this time of year |
| 29. Cicada killer wasps & cricket hunters | Large wasps, cause fear in people; mostly docile |
| 30. Grasshoppers (west) | Chewing damage on fruits, vegetables & ornamentals |
1. Brown Patch causes roughly circular patches of dead and dying grass. Tan colored, irregularly shaped leaf spots with reddish margins are found on leaf blades. Fungicide applications are often not recommended after August 1. Preventive applications of Prostar (commercial use), Bayleton, and chlorothalonil (Daconil) do a fairly good job of suppressing the disease when applied at monthly intervals in June, July, and August. Curative applications of chlorothalonil beginning a few days after symptoms of brown patch develop may suppress injury. In many cases, lawns damaged by brown patch recover in two to three weeks, provided the outbreak is not sustained by continuous hot, humid weather; and treatment may not be necessary.
2. Dollar Spot Small (three to six inch diameter), roughly circular patches in lawns. Spots may coalesce into a larger patch. Grass blades have tan, band-like lesions with red margins. Damage is usually most severe where nitrogen is deficient. With timely rains this year, nitrogen may have been leached out of the root zone. The best control can be nitrogen fertilization. Turfgrass can be treated with products containing benomyl, mancozeb, propiconazole, thiophanate-methyl.
Dollar Spot Disease in Turfgrass, University of Nebraska-Lincoln Extension
3. Stem Rust symptoms on Kentucky bluegrass include rust colored “powder” (fungal spores) on grass blades, shoes and lawn mowers. Heavily infected turfgrass may have yellowing grass blades. Stem rust typically develops on lawns with slow growth. Fall lawn care, including fertilization and proper irrigation, along with cooler fall weather promotes turfgrass growth and rust disappears. Stem rust is often a problem on compacted soils; hence core aerification is effective in reducing rust disease. Fungicide controls are rarely suggested for home lawns.
Note for Sports Turf- If stem rust occurs on sports fields, the fungal spores can cause problems for allergy/asthma sufferers. Control of stem rust is recommended on sports turfs using a combination of turf management and timely fungicide applications.
Rust Turns Lawns Orange, University of Illinois Extension
Rust on Sports Turf, Ohio State University
4. White Grub damage is showing up in Western Nebraska. Larvae feed on turfgrass roots causing lawn areas to turn brown and sometimes die if grubs damage a large percentage of roots. Most white grub eggs have hatched and their numbers should be similar to past years; however, in eastern Nebraska growing conditions have been conducive to Kentucky bluegrass and is likely preventing or delaying damage. Turfgrass should continue to be inspected for white grubs. If birds are feeding in a lawn, or browning occurs, roll the sod back to look for c-shaped, cream colored, red headed larvae. If eight (8) white grubs are found per square foot, an insecticide application may be justified. At this time of year, Dylox is the insecticide of choice. Do not apply Merit or Meridian at this time of year.
White Grubs in Turf, University of Nebraska-Lincoln Extension
5. Dormant Kentucky bluegrass- As a cool season turfgrass, KBG can go dormant in dryer, heat exposed areas. Homeowners may mistake summer dormancy for disease or death of turf and request treatment or reseeding. Positively confirm cause of browning before treating. Cooler weather and/or irrigation may be all that is needed.
6. Annual weedy grasses such as Canada bluegrass and annual bluegrass are weaker weedy bluegrasses that begin to die out during hot summer weather creating brown or thin patches in lawns. These may be confused for disease/insect injury. Annual weedy grasses are dying later this year due to cooler summer weather. Normally they would have started dying out 3 weeks ago. Overseed bare or thin areas to establish turfgrass that will compete with annual weedy grasses.
Rough Bluegrass (Poa trivialis) is a pale green, stolon-forming perennial grass that forms pale green patches in lawns, especially in shady, moist or overwatered areas. It is not heat or drought tolerant and tends to turn brown about mid August. Control nonselectively with glyphosate and reseed the area. Commercial applicators can control selectively in Kentucky bluegrass with a herbicide containing sulfosulfuron (Certainty).
Annual Bluegrass and Rough Bluegrass Control, Ohio State University
7. Chinch Bugs damage Buffalograss and Zoysiagrass usually in sunny locations during hot, dry periods. Damage appears as patchy areas which turn yellow, then dry out and turn brown. Chinch bugs feed by sucking juices from leaves and stems. While feeding, they inject a toxin which disrupts movement of water and nutrients. Chinch bug nymphs are red with a white band, then orangish, and finally brown to black. Short-winged adults are black and 1/10th of an inch long. Control thatch to reduce chinch bugs. If bugs exceed 20 per square foot, apply the insecticide containing bifenthrin for control.
Chinch Bugs in Buffalograss and Zoysiagrass Turf, University of Nebraska-Lincoln Extension
8. Cottonwood borers are large black and white beetles that emerge from cottonwoods and willows from late June to mid-August. Damage occurs primarily at the base of infested trees and consists of sawdust-packed tunnels up to ½ inch in diameter bored into the wood, which weakens trees and interferes with movement of water and nutrients. Damaged trees may blow over, breaking off at the base. Insecticide treatment is usually not needed due to rareness of attack.
Borers of Shade Trees and Ornamentals, University of Nebraska-Lincoln Extension
9. Euonymous scale Infested leaves turn yellow, then die and drop off. Undersides of leaves and stems are covered with a brown or white scale. Scale insects feed from beneath a protective scale, removing plant sap from stems and leaves. Controls are most effective when the insect is in the crawler stage, usually in May to early June and late August to early September (second generation). Monitor for the presence of crawlers by wrapping a few stems with black electrical tape, with the sticky side facing out, near present scales. Crawlers are yellowish to orange. When in the crawler stage, control with insecticidal soaps. Systemic insecticides are also effective. Read and follow label directions for effective application. Prune and remove heavily infested branches to the ground.
Euonymous Scale, University of Nebraska-Lincoln Extension
10. Leucanium (Fletcher) scales on yew are initially flattened and brown. As they mature, they become hardened and round. They attack a variety of trees and shrubs. With high populations, dieback of twigs, branches and lowered plant vigor result. Control by pruning heavily infested branches and/or applying insecticides just after egg hatch when insects are in the crawler stage in May and June.
Fletcher Scale, Michigan State University
11. Oak twig girdlers starting to cause twig dieback. Squirrels chewing leaves off tree may be confused with girdler damage. Twig girdler is a small, slender, bronze-to-black beetle that emerges from May to September and deposits eggs on twigs at the junction between current and previous year's growth. Larvae hatch and bore into twigs. As they grow, they mine spirally so terminal clusters of dead leaves ("flags") appear in August and September. During the next year, larvae continue to mine deeper into twigs and complete development, pupating in the fall. While damage is obvious, it is rarely severe, and there is rarely a need for control.
Flatheaded Borers, University of Nebraska-Lincoln Extension
12. Dutch elm disease is a wilt disease that causes branches, then entire trees to die. Black or brown streaks may be found in the wood. Remove dead trees and destroy the wood. Do not use it for firewood. A trunk injected fungicide is available. See resource for information.
Diseases of Broadleaf Trees, Nebraska Forest Service
13. Leaf Scorch A uniform yellowing or browning on leaf edges of broadleaf plants or the tips of evergreen needles is a symptom of a condition called scorch. This environmental problem commonly occurs on linden, maple, ash and cottonwood. Scorch is usually is more severe on the south or southwest side of a tree or on the side nearest a source of radiated heat, such as a brick wall or street. Severe scorch can result in premature leaf or needle loss. Prolonged dry periods accompanied by warm, dry winds can cause leaves to transpire moisture faster than roots can supply it to the leaves, resulting in drying out of plant tissue. Young trees with un-established roots, or any tree growing in soils that are not conducive to healthy root function (i.e. compacted clay soil or overwatered soil) can lead to leaf scorch. Properly siting trees, avoiding overwatering, and encouraging healthy root growth can decrease leaf scorch in some situations.
Leaf Scorch of Ornamental Trees and Shrubs, University of Missouri Extension
Leaf Scorch of Trees and Shrubs, Purdue University
14. Zimmerman pine moth larvae tunnel beneath the bark of pine trees, particularly in branch crotches, causing branches to die or break off readily in wind and snow storms. A pinkish mass may be found at the base of infested branches. Insecticides, such as bifenthrin or permethrin, applied during the second week of April and the second week of August are required for control. Use the label rate for borers and apply to the trunk and major branches.
Zimmerman Pine Moth, Colorado State University
Zimmerman Pine Moth, Iowa State University
15. Bagworm Some homeowners mistake bagworm damage for general decline of trees. Close inspection is recommended when evergreens, especially spruce, are thinning or browning. At this time of year, bagworms are up to 2 inches long and there is only one larva per small “brown bag”; although there may be numerous bags throughout the tree. Larvae will pupate in mid to late August and insecticide applications will no longer be effective once they pupate. Check bags. If larvae are still feeding, insecticides, such as Bifenthrin, can be applied. If larvae are no longer active, remove and destroy bags to reduce the number of overwintering eggs.
Bagworms, University of Nebraska-Lincoln Extension
16. Fall webworms make the large 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; then follow up by spraying with a strong stream of water or an insecticide such as permethrin or Spinosad. Prune out webbed nests when feasible. There are natural parasites and pathogens of fall webworm that often bring these infestations under control; hence, trees with numerous webworm nests this year may have none or few next year. Outbreaks usually last two or three years.
Fall Webworm Management, Ohio State University
17. Cytospora canker With hail damage (western Nebraska), this fungus is causing twig dieback and gall-like canker formation, most commonly on Spruce trees. Branches near the base of trees or tops of trees die. Resin often oozes from branch or trunk cankers. There are no fungicide controls. Prune and destroy dead and dying branches during winter. The fungus of often spread during spring rains. Disinfect all pruning tools such as knives and saws by wiping them with rubbing alcohol. Avoid stress by spacing trees correctly, then mulching and watering correctly. Avoid wounds. Black Hills Spruce is less susceptible to this disease.
Diseases of Evergreen Trees, Nebraska Forest Service
18. Rose Fertilization Stop fertilizing roses and most other woody plants by August 15. Fertilization after this date can encourage succulent growth that will not have time to harden off before winter and increase the risk of winter injury.
19. Rose rosette, also known as witches’ broom of rose, is a virus spread by a very small, eriophyid mite, or by grafting. Its main host is the multiflora rose, which is considered a noxious weed throughout much of the USA. On these roses, the virus causes a witches broom symptom with leaves becoming deformed and crinkled with yellow mosaic and red pigmentation. Symptoms on cultivated roses are typically less severe and include thickened, succulent stems and a proliferation of thorns. Small plants are usually killed in about 2 years, while a large plant may survive for five years in a deteriorated condition. Control includes removing the entire plant, including the rootstock, of ornamental roses; planting ornamental roses as far away from known stands of multiflora rose as possible; and controlling the mite. Pesticides such as carbaryl (Sevin), bifenthrin, horticultural oils and insecticidal soap may provide some protection when applied at weekly intervals during the months of June and July.
Rose rosette, Missouri Botanical Garden
20. Common stalk borer attacks over 100 species of plants including flowers, tomato, pepper, corn, rhubarb, hibiscus, and broadleaf weeds. The stalk borer adult is a dull, grayish-brown moth. Young larvae are brownish-purple with three prominent white stripes at the front and rear ends of the body. The stripes are interrupted by a dark purple to black area at mid-body. Full grown larvae are a uniformly dirty gray color and up to 1 1/2 to 2 inches long. Plant symptoms include stunting, wilting or dieback. Control by controlling weeds and using good sanitation practices. Insecticides are only effective if applied before the borer enters the stem.
21. Bacterial canker/speck/spot on tomatoes is most common during wet summers. Bacterial canker causes lesions or cankers on any portion of the plant and may cause wilting, curling of leaflets, and yellowing or browning of leaves, often on one side or a portion of the plant. Fruit spots are dark and bordered by a distinct white halo which may disappear as fruit ripens.
Bacterial speck and spot cause small (1/8-1/4 inch) black lesions, usually with a yellow halo, on leaves. Bacterial spot causes small, slightly raised, water-soaked spots on the fruit which may enlarge to 1/4 inch in diameter and become very rough and cracked. Bacterial speck fruit lesions are also slightly raised but typically smaller (1/16 inch). Bacterial speck lesions do not crack or become scaly.
To control, use a 3 year crop rotation, practice good sanitation, and select bacterial free seed/transplants. Copper-based fungicides may be effective in suppressing bacterial speck and spot if applied at the first sign of leaf spotting or at the time of first blossom and applications continued at 7 to 10 day intervals. These fungicides will not control bacterial canker.
Bacterial Spot, Speck and Canker, Ohio State University
22. Early Blight and Septoria Leaf Spot are the two most common fungal diseases of tomatoes. Symptoms begin as leaf spots on lower leaves, with infections moving up the plant causing foliage to die; often leading to fruit sunscald. These diseases can be reduced with fungicides labeled for use on tomatoes. For best results, applications need to begin as soon as symptoms first appear on lower leaves, and applications made every 7 to 10 days. Avoid overhead irrigation and increase air circulation around plants with proper spacing and caging. Mulch the soil around tomatoes to reduce soil splash of fungus onto lower leaves. Plant resistant varieties and avoid planting tomatoes in the same area year after year. Severely infected plants are best pulled and destroyed. Use fall sanitation to reduce the amount of fungus overwintering.
Early Blight and Septoria Leaf Spot of Tomatoes, Kansas State University
Tomato Disease I.D. Key, Cornell University
23. Anthracnose on curcurbits is a fungal disease that spreads rapidly in warm, wet weather. Early symptoms usually appear on older leaves as small yellowish circular (angular on watermelon) spots. The dead tissue turns brown on cucumber and melon leaves, and nearly black in watermelon leaves. In warm, wet weather all the leaves may be rapidly attacked, giving the planting a "burned-out" appearance. Circular, sunken, water-soaked spots develop on the fruit. These spots turn dark green to brown.
Fungal spores are spread from plant to plant by running water, including splashing rain and individuals working in the garden when vines are wet. The anthracnose fungus overwinters on seed and on diseased crop refuse. Practice good sanitation by removing and destroying infected plants. Preventive measures are important, including use of good quality seed and crop rotation. The fungicides benomyl and chlorothalonil (Ortho Multi-Purpose Fungicide Daconil 2787) help to control the disease, but must be applied at the first sign of disease or as a preventive.
Disease Management in Homegrown Cucurbits, North Dakota State University
24. Black rot of grape causes developing berries to turn dark purple or black, shrivel and cling to the cluster. Routine fungicide applications are necessary to inhibit infection. Start control measures when new shoots begin to emerge from the vine. Mancozeb is one fungicide labeled for control of black rot by homeowners.
Black Rot of Grapes, Kansas State University
Midwest Home Fruit Production Guide , Ohio State University
25. Blossom end rot is a common problem of tomatoes, but also occurs on peppers, eggplant, squash and watermelon. It appears as a flat, dry, sunken, brown rot on the blossom end of the fruit, opposite the stem end. The size of the rotted area varies, but can cover up to 50% of the fruit. This problem is a physiological disorder associated with a calcium deficiency in the developing fruit. Rarely is the problem a lack of calcium in the soil. Drought stress, low daytime humidity, high temperatures and rapid, vegetative plant growth caused by excess nitrogen applications favor blossom end rot development. To reduce it, prevent drought stress, mulch with organic mulch and avoid excess nitrogen fertilization.
Blossom End Rot, University of Nebraska-Lincoln Extension
26. Cedar apple rust Small, yellow spots on upper leaf surfaces. Spots gradually enlarge and become a bright yellow-orange color. Heavily infected leaves drop prematurely. Cedar-apple rust requires two hosts: cedar trees, and apple or crabapple trees. Fungal spores can travel up to 2 miles so removal of cedar trees will not provide control. Plant disease resistant apple or crabapple cultivars. Fungicide sprays may be used to protect apples and crabapples from infection if applications begin at petal drop and continue according to label direction. Applications made now will not be effective.
Cedar Apple Rust, University of Nebraska-Lincoln Extension
27. Tomato spotted wilt commonly causes yellow rings on ripening fruit. Early symptoms of spotted wilt can be an inward cupping of leaves and off-color foliage. The top of infected plants occasionally wilt. Spotted wilt virus is transmitted by an insect called thrips. Virus diseases cannot be controlled once a plant is infected. Sanitation is most important in controlling virus diseases. Remove infected plants immediately to prevent spread. Control perennial weeds in and adjacent to the garden as these can serve as alternate hosts for viruses. Avoid planting tomatoes next to peppers, or other vegetables and flowers susceptible to these diseases. Control of insects, especially thrips, will reduce the likelihood of spotted wilt.
Tomato Spotted Wilt Virus, Kansas State University
28. Yellow jackets become a nuisance during fall as they scavenge for food. If yellow jackets are disturbed, give them plenty of room as they are capable of inflicting multiple stings. If yellow jackets become excited and appear about to attack, do not panic; retreat slowly and calmly. Yellow jackets construct paper nests, usually in underground cavities. Favorite nesting sites include rodent burrows, compost piles, wood piles and wall voids. Occasionally, yellow jackets build aerial nests in garages, crawl spaces or other enclosed areas. They feed on insects, spiders and a variety of food items. Most stinging wasps and bees are beneficial and should be preserved unless they pose a direct hazard to humans. Colonies of yellow jackets are annual and nests are not reused. Freezing temperatures in November and December kill all stinging workers and only fertilized queens survive the winter. If yellow jackets pose a hazard, recommendations for treating the nests safely are available in the following publication.
Stinging Wasps and Bees, University of Nebraska-Lincoln Extension
29. 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. Cricket Hunters are blue black wasps that capture crickets for food or to lay eggs on for larval food. Both wasps are solitary (one wasp per nest) and do not protect their nest. They are very unlikely to sting humans unless provoked.
Stinging Wasps and Bees, University of Nebraska-Lincoln Extension
30. Grasshoppers are becoming large and causing damage. The western part of state is drying out so hoppers are moving into irrigated portions of landscapes- lawn & gardens. They are also affecting trees. They can severely defoliate garden and landscape plants. Effective control includes treating egg hatching areas (roadsides and weedy areas) at egg hatch when the grasshoppers are young. Adult grasshoppers are difficult to control.
A Guide to Grasshopper Control in Yards and Gardens, University of Nebraska-Lincoln Extension
