Green Industry Resources
Hort Update- Seasonal Information for the Green Industry
Hort Update for the Week of January 9, 2012
|1. Ice effects on turfgrass||Ice layer worse than snow, but avoid traffic on turfgrass.|
|2. Snow mold & snow piles||Disperse snow when shoveling for faster melting.|
|3. Avoiding winter traffic on frozen turf||Cosmetic damage to frosted or frozen grass|
|4. Added winter protection||Screen plants from salt/drying with burlap or other material.|
|5. Snow/ice build-up on plants||Remove snow by gently brushing; let ice melt naturally.|
|6. Dealing with storm damage||See NFS resources on repairing damage & choosing an Arborist.|
|7. Trees for windbreaks||See NRSC/NRD for tree lists.|
|8. Winter watering||Applied correctly can be beneficial when conditions are dry.|
|9. Check winter protection||Add mulch if needed; ventilate rose cones on warm days.|
|10. Great Plants for Great Plains||Five Great Plants for Nebraska in 2012|
|Fruits & Vegetables|
|11. Pruning fruit trees||Pruning best delayed until late February and March.|
|12. Vole damage||Monitor for voles and their damage.|
|13. Plant decline; leaf drop||Winter growing conditions acclimation response.|
|14. Fungus gnats||Small fly-like insects flying around houseplants.|
|15. Whiteflies||Small powdery white flies flying around houseplants.|
|16. Heating/ ventilation||Extension resources available.|
1. Ice effects on turfgrass- Snow is a good insulator for turf protecting it from winter drying and extreme cold. If a frozen layer of ice develops beneath snow, turfgrass may be smothered due to oxygen exchange problems. Turfgrass will withstand 90 days of snow cover, but only 60 to 70 days of ice cover. Avoid walking on snow covered grass to prevent compacting snow and development of an ice layer. An ice sheet developing on turf due to winter rain or snow melting and refreezing can damage crowns. The crowns hydrate and then the tissue refreezes, damaging the crown. Improving soil drainage is important to preventing ice sheet development.
Understanding Winter Kill of Cool Season Turfgrasses, University of Nebraska-Lincoln
2. Snow mold & snow cover- Gray snow mold requires extended periods of snow cover to develop. Long periods of compacted snow increase the incidence of gray snow mold. To reduce the length of time snow covers a turf area, avoid traffic across snow resulting in compacted snow/ice areas that melt more slowly. Also avoid shoveling snow into one large pile; spread it around for quicker melting.
3. Foot or vehicle traffic on frosted or frozen turf can cause cosmetic damage; resulting in foot prints, pathways or tire tracks across the turf that may not recover until late spring. Unlike actively growing grass, dormant grass does not have the capability to recover until growth resumes.
Stay Off Frosted Turf, University of Nebraska-Lincoln
4. Added winter protection may be needed for evergreens growing near pavement where de-icing salts are applied and for evergreens like Arborvitae and Japanese Yew growing in exposed locations or near the south or southwest side of a home. Construct a screen with canvas, burlap or polyethylene plastic screens to the south and west of evergreens or on the side closest to pavement. Burlap can be wrapped around an evergreen, but keep the top open for ventilation.
5. Snow/ice build-up on plants can lead to limb breakage. It can also result in less obvious splits and cracks in trunks and limbs which pose a risk long after the storm. As a general rule, let ice melt naturally from tree limbs. If it is safe to do so, gently remove snow from limbs. Hold onto the limb from below and gently brush off loose snow. Watch for falling limbs and ice from above. Do not hit a branch to knock off snow or ice. Always let ice melt naturally. Do not try to dig snow away from shrubs as this leads to damaged limbs.
6. Dealing with storm damaged trees- Before ice or snow damages trees, refer to the Nebraska Forest Service publication for helpful information on dealing with storm damage. The series will prepare you for a safe and quick response when needed. The series provides information on the immediate care for storm damaged trees, how to select an arborist or tree service and pruning storm damaged trees, along with other helpful information
Storm Damage Series, Nebraska Forest Service
7. Natural Resource District’s (NRD’s) offer a variety of tree and shrub seedlings for conservation plantings. When planning conservation plantings, like windbreaks, select a variety of plants for biodiversity. In place of planting two or three rows of the same tree, mix it up and plant each row to a different type of tree. It’s okay to mix species up within the row too.
For information on species available from Nebraska NRD’s, see Conservation Trees for Nebraska.
8. Winter watering- may be needed during open winters when we have warmer than average temperatures and dry spells. Monitor weekly precipitation, whether snow or rain, and water during dry periods when the soil is not frozen. Winter droughts need treatment with water just as summer droughts do. Deeply water trees with a slow running sprinkler left in place long enough to moisten the top 12 inches of soil. Do not use 'root feeders' or deep root watering devices. Apply the water slowly enough that it can soak in and does not run off or freeze around the plant stems or crown overnight.
9. Check winter protection on perennial and tender ornamentals like some rose. Mulch layers should be about six inches deep and not matted. After Christmas, recycle trees by pruning off branches and laying these around or over perennials for added winter protection. On warm winter days, check roses protected by rose cones. These may need to be ventilated to prevent heat build up inside of the rose cone which can dry plant tissue leading to winter kill. Ventilate by cutting the top off the rose cone. At night and on cold days, place the top back on the cone and weight it with a rock.
10. 2012 Great Plants for Great Plains - The Nebraska Statewide Arboretum and the Nebraska Nursery and Landscape Association, has identified the 2012 Plants of the Year. They are Shantung maple (Acer truncatum, Rocky Mountain Douglas-fir (Pseudotsuga menziesii var. glauca), Deam’s arrowwwood viburnum, Viburnum dentatum var. deamii, Pink turtlehead, Chelone lyonii), and Northwind switchgrass, Panicum virgatum ‘Northwind’. Consider carrying these plants for retail or planting one or more of these plants if they are adapted to the growing conditions of a planting site.
11. Fruit Tree Pruning is best done during late February through March when temperatures may be less extreme. A small amount of annual pruning encourages production of fruiting wood and opens trees to increased light penetration which increases fruit production and quality. When pruning fruit trees, understand what age wood the different species bear fruit on. Make proper pruning cuts and use sharp pruning tools. Do not use pruning paints or wound dressings on pruning wounds. If a fruit tree sustains storm damage, consider removing the tree if over 50% of the trees branches need to be removed due to breakage.
Pruning Fruit Trees, University of Nebraska- Lincoln Extension
Pruning Fruit Trees, Kansas State University
12. Vole Damage and Fruit Trees- Once we receive enough snow cover, voles may gnaw on fruit tree bark and roots. Keep tall grass and weeds removed from around the trunk of fruit trees and avoid mulch layers deeper than two to three inches. Check for and trap voles by placing baited mouse traps inside PVC or other pipe near trees. Insert the traps far enough so pets, birds and other animals are unable to reach the trap. Check the stations once a week and reset traps as necessary.
Vole Damage, University of Nebraska-Lincoln
13. Houseplants dropping leaves during winter is often a response to reduced day length, lower light intensities and dry winter air. Place houseplants near south facing windows. This will not be too much light even for low light plants. Do not fertilize during the winter semi-dormancy period. Keep the soil consistently moist. To increase humidity levels around plant leaves, group plants together and/or place them on pebbles in water filled trays.
14. Fungus gnats are small fly-like insects that may be noticed flying around houseplants. They are commonly associated with overwatered houseplants or those grown in poorly drained potting mixes. If a houseplant pot is harboring fungus gnats, treat the soil with insecticidal soap or incorporate diatomaceous earth in the soil to kill the maggots. Another approach is to cut back on watering so soil dries out between watering. Any maggots present in the soil will dry out, and lack of water will reduce fungal growth, reducing the food supply for adult fungus gnats. A third option is a combination of letting the soil dry between watering and then watering with a solution of water and insecticidal soap.
Fungus gnats, University of Nebraska- Lincoln Extension
15. Whiteflies are a common pest of poinsettia and hibiscus. They also infest other indoor plants. Whiteflies are first noticed when it appears small specks of white ash are flying up out of plants. Whiteflies feed on plant sap, causing leaf yellowing and sticky leaf surfaces. White flies are difficult to control. If a plant is heavily infested, consider discarding it. White flies are often found on leaf undersides. If insecticidal sprays are used, direct these to leaf undersides or select a systemic. Using insecticidal soap works to a point but needs to be applied often and on a regular basis for control. Use insecticidal soaps in combination with yellow sticky traps hung or placed near infested plants.
16.Greenhouse Energy Efficiency & Ventilation Resources
Greenhouse Energy Cost Reduction Strategies, Michigan State University
Greenhouse Ventilation, eXtension Missouri State University
Greenhouse Ventilation, University of Florida
Greenhouse Heating Checklist, Unversity of Florida