Hort Update for the week of 11/26/07
| Current Problems: | Major Symptom: |
Lawns |
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| 1. Rust | Yellowing in lawns. Orange powder may appear on shoes, mowers. |
| 2. Leaf removal | Accumulations of less than three inches can be chopped with a mower. |
| Trees & Shrubs | |
| 3. Winter wildlife damage prevention | Protect trees from rabbit, vole and deer feeding during winter. |
| 4. Winter watering | Prevent winter burn and winter drying with monthly soakings . |
| 5. Sunscald prevention with tree wrap | Use carefully on young, tender barked trees for a short time only. |
| 6. Anti-transpirants | On windy, exposed sites, apply to evergreens three times during winter. |
| 7. Pruning | Delay most pruning until after plants are fully dormant. |
| 8. Winter mulch | Apply winter mulch when soil temperatures reach 30s. |
| Ornamentals | |
| 9. Planting spring bulbs | Plant bulbs now to meet minimum chilling requirements. |
| Miscellaneous | |
| 10. Greenhouse ventilation | Manage moisture condensation within greenhouse structures. |
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""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 1. Rust is still being seen in western Nebraska. Lawns infected with rust may develop a yellow appearance and an orangish powder (spores) appear on grass blades, which often appear on shoes and mowers. Fungicide controls are rarely suggested for home lawns. Overseed lawns with a history of rust problems in spring with disease resistant cultivars. Rust Turns Lawns Orange, http://www.urbanext.uiuc.edu/turf/rustlawn.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 2. Leaf removal from turfgrass is recommended if the accumulated depth is more than 3-4 inches. However, a shallow layer of leaves, three inches or less, can simply be chopped up with a mower and allowed to sift back down to the soil surface and will not contribute to thatch builup in the lawn. Sharpen the mower blade before starting, to lessen the stress on the mower. Home Lawn Research: Chopping Up Leaves, http://www.turf.msu.edu/y.fallcontent/leaves.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 3. Winter wildlife damage protection. Barriers of hardware cloth placed around young trees and shrubs is the best means of protection from rabbit and vole damage. Make sure the barriers extend well above the usual snow line. Various taste repellants, such as Thiram or Miller's Hot Sauce, can be effective in reducing deer and rabbit damage as long as animals have other food sources to turn to. Scent repellants, such as bags of human hair or bar soaps on a rope, have been shown to be effective in some situations. eXtension Deer Damage Management, http://www.extension.org/pages/Deer_Damage_Management eXtension Vole Damage Management, http://www.extension.org/pages/Vole_Damage_Management eXtension Rabbit Damage Management, http://www.extension.org/pages/Cottontail_Rabbit_Damage_Management """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 4. Winter watering is important to prevent winter burn, browning of evergreen needles caused by rapid temperature changes, or winter drying, dessication of foliage and twigs by warm, dry winds when water conduction is restricted by the freezing of plant tissues or by frozen soil. All trees transpire, or lose, water, even during the winter months. Sometimes this loss is greater than the roots can replace and drying damage results. Minor damage results in reddening or browning of foliage, which may later recover; symptoms of more severe injury includes browning and subsequent death of branch tips or entire branches. The side of the tree facing prevailing winds is most susceptible to winter drying. Often, a combination of winter burn and winter drying will occur, occasionally complicated by drought. If damage is severe enough, affected branches may die. Sometimes, the entire tree may be killed. Water trees thoroughly in the fall, deeply soaking the root systems, ideally before winter mulch is applied. Continue watering monthly in winter when the soil is not frozen, during dry periods with little precipitation, particularly new plantings installed during the past spring and summer. Winter Dessication Injury, http://extensionhorticulture.unl.edu/Current/WinterInjury.shtml """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 5. Sunscald prevention with tree wraps. Sunscald commonly occurs on young, tender barked trees, such as Maples, during winter. It may be due to uneven heating of the trunk, however, there appears to be a correlation to root damage caused during transplanting. Proper planting and post planting care may be more important to protecting trees from sunscald than tree wrap. If used incorrectly, or left on too long, tree wraps can cause more harm than good. If used, tree wraps should be attached in November at the soil line and the tree wrapped upward with the wrap overlapping up to the first set of branches. Remove wrap in spring, since leaving it on too long may girdle or compress the trunk, reduce photosynthesis, and increase insect (borer) damage. Avoid the use of paint as these may cause chemical damage to the trunk. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 6. Anti-transpirants can help plants endure stressful periods. The most common types are an emulsion of wax, latex, or plastic that forms a thin film on foliage, which minimizes water loss. We recommend their use during winter only on broadleaf (holly, Mahonia) or coniferous (yew, Arborvitae) evergreens growing in stressful sites, although they can also benefit newly transplanted trees in some situations. Apply them once every six weeks in mid- to late-November, early January, and mid- to late-February. Avoid coating plants so heavily that their needles become sticky and glued together. Read and follow label directions. Select the right product for the plant species as there are toxicity issues. Clean sprayers thoroughly after each application to prevent clogging. Have warm, soapy water nearby and clean out the sprayer immediately or the sprayer may be ruined by the product. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 7. Pruning of non-flowering deciduous trees and shrubs is best done when the plant is dormant during winter, up to late Feburary through March. Flowering plants should be pruned based on when blooming occurs. Make correct pruning cuts and do not use a wound dressing or tree paint on the pruning wounds. Pruning Mature Trees, http://www.treesaregood.com/treecare/pruning_mature.aspx Pruning Trees and Shrubs, http://www.extension.umn.edu/distribution/horticulture/DG0628.html """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 8. Winter mulch should be applied around the base of woody plants, and over the crowns of semi-tender plants such as hybrid tea roses, chrysanthemums and strawberries, to insulate them from wide soil temperature fluctuations and from extreme cold temperatures. Mulch also prevents frost heaving of newly installed plants- those planted during the 2007 growing season. Frost heaving is caused by the alternate freezing and thawing of the soil, and can result in damage to plant roots and/or winter injury. A 3-4 inch layer of winter mulch keeps the underlying soil cold and delays thawing, thus prevents frost heaving. However, it is still too early to apply winter mulch. Wait until plants are completely dormant, or soil temperatures have dropped into the 30's. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 9. Planting spring bulbs. If you purchased closeout sales on spring bulbs recently, get them planted as quickly as possible. Bulbs must develop roots after planting to supply the plant with moisture and root growth of many bulb species stop when soil temperatures fall below 37° F. Plus, trying to plant bulbs in frozen soil is not fun! Bulbs also have a "chilling requirement" or a specific period of dormancy below a certain temperature that is required in order for them to initiate flowering. Planting too late in the season can cause inadequate bulb chilling and poor flower production in spring. """"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" 10. Greenhouse ventilation. Some ventilation of greenhouses and high tunnels is required in winter to replace warm, moisture laden air within the structure with cooler, drier outside air. If moist air is not ventilated high humidity and excessive condensation. Condensation occurs when warm, humid air in the greenhouse comes into contact with a cold surface, such as glass, fiberglass, plastic, or structural members. High humidity results in higher rates of fungal leaf, fruit and flower infections. Greenhouse Condensation, http://www.ag.auburn.edu/hort/landscape/greenhousecond.html Greenhouse Ventilation, http://edis.ifas.ufl.edu/AE030 |
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