| Current Problems: | Major Symptom: |
| Lawns | |
| 1. It's Time to... | Lawn care practices for April |
| 2. Soil temperatures | Need to warm before many lawn care practices are done |
| 3. Water pollution prevention | Apply fertilizer responsibly and manage yard waste wisely |
| 4. Voles | Runways of clipped grass on lawn surfaces |
| 5. Gray snow mold | Matted, grayish patches in the lawn |
| Trees & Shrubs | |
| 6. Pruning ice damaged trees | Safety and correct pruning cuts are critical |
| 7. Shrub planting | Timing |
| 8. Planting | Plant bare root trees in April |
| 9. Emerald ash borer | NOT known to be in Nebraska yet. Informational website. |
| 10. Squirrel damage | Stripping of tree bark and chewing of larger buds |
| 11. Pine wilt | Dead Scotch Pine trees or rapid crown dieback - remove by April 30 |
| 12. Black knot | Black woody mass encircling the stems of plums, cherries & almonds |
| 13. Current pesticide recommendations | Updated listing of chemicals and timing for control of common forest and shade tree pest problems |
| Gardens/Ornamentals | |
| 14. Cutting back tops | Remove the dead tops of herbaceous perennials & grasses |
| 15. Mulch removal | Wait to remove mulch until just before new growth begins |
| 16. eXtension website | New national Extension website - http://www.extension.org/ |
1. It’s Time to…. slow down on lawn care, for the most part. April care practices of cool season turfgrass lawns include hand raking to remove debris and tree leaves, edging, mowing, power raking, core aeration and seeding or sodding. Mow the lawn at a height of about two and one-half inches. It is not necessary to “mow as low as the mower will go”. This can scalp turfgrass and result in root loss or slowed root growth. Power rake if the true thatch layer exceeds one-half inch. Core aerate to relieve soil compaction and encourage root growth. Seeding, overseeding and sodding of cool season grasses can take place throughout the month of April.
Kentucky Bluegrass Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g517.pdf
Tall Fescue Lawn Calendar, http://www.ianrpubs.unl.edu/sendIt/g558.html
Thatch Prevention and Control, http://www.ianrpubs.unl.edu/sendIt/g1618.pdf
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2. Soil Temperatures- While air temperatures may be warm, it is important to monitor soil temperatures. A minimum soil temperature of about 40 degrees Fahrenheit is needed for roots to begin to grow and function. A minimum soil temperature of 50 to 55 degrees is needed for crabgrass seed to even begin to germinate. Many plant care practices should begin after soil temperatures warm to optimum degrees.
To monitor soil temperatures across Nebraska, see the Crop Watch Soil Temperature Update at, http://citnews.unl.edu/cropWatch/soilTemperature.html
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3. Water Pollution and Lawns- Nutrients can pollute water when an overload of nutrients (mainly nitrogen and phosphorous) reach water resources. Nutrients come from many sources. They can come from fertilizer or yard waste washed from lawns, or more often from pavement next to lawns, in run-off water during a rain storm. To reduce water pollution from your yard, apply fertilizers at the correct rate and keep them off of paved areas. Avoid applying fertilizer just prior to forecasts of heavy, intense rain storms. Leave grass clippings on the lawn. If you catch clippings, recycle them. Do not dump them into street curbs or on stream banks. In many communities, it is illegal to discharge grass clippings onto pavement where they can be washed into storm drains and then surface water. After fertilizing, mowing, and applying pesticides, sweep grass clippings and granules off paved areas and onto the lawn. Do not hose them into the street.
Lawns and Water Pollution, http://www.platte.unl.edu/yardandgarden
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4. Prairie and Meadow Voles scar lawns by constructing surface runways (one to two inches wide) and clipping grass very close to the roots. Runways are most visible after snow melts. Small holes lead to underground runways or nesting areas. Vole damage to lawns usually repairs itself during spring growth and is not permanent. Voles are small, mouse-like rodents that exist throughout Nebraska. Their short tails (about 1 inch long), stocky build and small eyes distinguish them from true mice. Vole damage is costliest when they eat the inner green bark layer of trees and shrubs during winter. This gnawing can severely damage or kill young trees and shrubs. In gardens, voles can clip off young plants and dig up seeds. They also eat leaves, shoots, roots, tubers and seeds of most grasses, forbs and broadleaf flowering plants.
Controlling Vole Damage, http://www.ianrpubs.unl.edu/sendIt/g887.pdf
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5. Gray Snow Mold appears as grayish, roughly circular patches in infected lawns, especially where snow cover persisted for a period of time. The fungal mycelium may appear as a dry mat or papery crust. Repair snow mold damage by raking in early spring to disrupt the matted areas and lightly fertilize to encourage new growth.
Fungicides are not recommended for home lawns except in extreme situations. Though symptoms look dramatic, the turf will recover eventually. Use cultural practices described above. If needed, fungicides can be used preventively in November and repeated during mid-winter thaws, especially for high-value turf or areas prone to problems with snow mold.
Snow Molds on Turfgrass: http://www.plantpath.k-state.edu/DesktopDefault.aspx?tabid=632
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6. Pruning Ice Damaged Trees- Check trees that were damaged by ice storms this winter. If broken branches remain in the tree, or if branch stubs were left after quick removal of hazardous branches just after an ice storm; see to it that these broken branches and/or stubs are removed for safety and for tree health. Consider hiring a trained and certified arborist to prune large trees.
Nebraska Forest Tree Pruning, http://www.nfs.unl.edu/treecare/pruning.asp
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7. Shrub pruning- As a general rule, spring blooming shrubs are pruned after they bloom and summer blooming shrubs are pruned while dormant. Spring blooming shrubs develop flower buds the previous year. Pruning before blooming will not harm the shrub, but will reduce blooming. Common spring blooming shrubs include lilac, forsythia, some Spirea, dogwood and Viburnum, Deutzia, beautybush (Kolkwitzia) oakleaf Hydrangea, most climbing roses, spring blooming Clematis, and mockorange. When pruning shrubs, it is important to thin out stems along with reducing the shrubs height.
Pruning Ornamental Shrubs, http://extension.missouri.edu/explore/agguides/hort/g06870.htm
Pruning Shrubs, http://hgic.clemson.edu/factsheets/HGIC1053.htm
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8. Planting : April is a good time to plant bare root tree stock. A key to future success is to spread out the roots to avoid circling roots that may eventually girdle the tree and to not plant too deep. The root flare, or location where the first roots grow off of the trunk, should be at the soil line.
How to Plant a Bare Root Tree, http://www.arborday.org/trees/NineNum8.cfm
Care of Newly Planted Trees, http://www.ianrpubs.unl.edu/sendIt/g1195.pdf
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9. Emerald Ash Borer is a borer that is killing thousands of green and white ash in eastern states and has reached as far west as Illinois. EAB is not known to be in Nebraska as of yet, but is expected to reach Nebraska at some time in the near or distant future.
For this reason, UNL Extension and the Nebraska Forest Service have stopped recommending the planting of any green or white ash trees in Nebraska. A common way for this borer to move into a state is through the transportation of firewood across state lines. It is important for people to know this and to not transport ash firewood across state lines. It is important to remain up to date on Emerald Ash Borer.
Emerald Ash Borer, http://www.emeraldashborer.info
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10. Squirrel Damage- During late winter, when stored food runs short, squirrels may eat bark. In the spring, squirrels prefer swelling tree buds. It is difficult to avoid this damage to trees as we cannot exclude squirrels from trees.
Squirrel Damage to Trees, http://www.ext.colostate.edu/ptlk/2303.html
Tree Squirrels, http://icwdm.org/handbook/rodents/TreeSquirrels.asp
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11. Pine Wilt mainly infects Scotch pine trees. Scotch pine that have recently died or are dieing fairly rapidly in the tree crown may have pine wilt. If this is suspected, these trees need to be removed by April 30 to slow the spread of this disease.
Pine wilt is a fatal disease of Scotch pine, which should no longer be planted in Nebraska. The disease has already killed thousands of Scotch pines in southeastern Nebraska and has been found mostly from Grand Island east, but it is also found in western Nebraska.
Pine wilt is caused by a microscopic organism called a pinewood nematode, which is spread by pine sawyer beetles which can carry thousands of nematodes on their bodies when they fly to other trees to feed. Trees infected with pine wilt cannot be saved They must be cut down and burned, buried or chipped before beetles emerge from the wood in May. Do not save the wood from these trees firewood.
Greyhound (abamectin) had been tested and shown to provide some control of pine wilt through a trunk injection. Contact a Nebraska Certified arborist for more information.
Recently a recommendation for the use of
Talstar (permethrin) has been seen for control of pine wilt. Presumably this control is targeted at killing the pine sawyer beetles, and hence, reduce the spread of the pine wood nematode. However, much research has been done attempting to reduce pine wilt by controlling the pine sawyer beetle and the research shows that Talstar is not effective at preventing pine wilt and is not a good insecticide for killing pine sawyer beetles.
Nebraska Forest Service Pine Wilt, http://www.nfs.unl.edu/documents/foresthealth/pinewilt.pdf
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12. Black knot - a black fungal mass in a hard knot wrapped around stems. Affects plants in the Prunus genus, including plums, cherries, almonds. Prune out the galls, going back at least 2-4" below each knot, or into healthy tissue. Lime sulfur applications in spring, combine with pruning, is the best control method. The knot takes 2 years to show up. The first season there is a canker, the 2nd year the black mass develops.
Black Knot,
http://ohioline.osu.edu/hyg-fact/3000/3011.html
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13. Current Pesticide Recommendations. An updated listing is now available of chemicals and the time of application for control of common forest and shade tree pest problems. Evergreen and deciduous tree insect and disease problems are addressed.
Chemical Control of Common Forest & Shade Tree Pest Control, http://www.nfs.unl.edu/program-foresthealth.asp
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14. Cutting back herbaceous perennials. Remove the tops of herbaceous perennials (plants whose tops naturally die to the ground each year) and ornamental grasses prior to the start of new growth. The overwintering stems and leaves are dead. Their removal makes room for new growth and improves the plants appearance. It is also a form of sanitation which can help reduce overwintering disease organisms and insects.
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15. Delay Mulch Removal on plants such as strawberries, roses, or Chrysanthemums that have been protected with winter mulch. Early removal may cause new growth to begin too early and be susceptible to cold temperature damage. Ideally, delay mulch removal as long as possible but do remove it before new growth begins. If warm temperatures cause new growth to begin earlier than usual, rake the mulch to the side of the plant so it can be raked over the plants if freezing temperatures are forecast.
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16. eXtension is a new national website offering research based information from Extension on a variety of topics referred to as "Communities of Practice." The current Communities of Practice include Gardens, Lawns and Landscapes; Wildlife Damage Management; and Beef, Cotton, Dairy, Disaster Education, Diversity, Entrepreneurship, Family Caregiving, Fire Ants, Livestock & Poultry, Map@syst, Parenting, Personal Finance, and Youth SET for Life.
eXtension is brought to you through a unique partnership of more than 70 universities found in every state and territory throughout the United States. These land-grant universities have as their missions research, teaching, and outreach to Americans. eXtension brings the best of the best from these institutions.
For more information, visit eXtension, http://www.extension.org/
