Hort Update for January 27, 2014

Hort Update for January 27, 2014

bugwood pruning
LawnsIn This Issue:
1. Welcome Bill Kreuser New UNL Turfgrass Specialist
2. Winter desiccation possible Chance of injury with continued dry conditions
3. Prepare for dormant seeding in March Broadcasting seed can work, soil preparation needed
4. Roundup over buffalograss Control of cool season weeds that have some green color
5. Emerald Ash Borer update Confirmations in Iowa, Kansas, Missouri and Colorado
6. Winter desiccation injury on evergreens Foliage browning on south or west side of evergreens
7. Shade tree pruning February and March ideal for pruning
8. Pruning tender plants Wait until spring, ideally mid-April
9. Maintain mulch on tender perennials 2-4" deep is best for winter protection
10. Starting seeds indoors Summer plants can be started now for a head start
11. Fungus gnats Small fly-like insects flying around houseplants
12. Whiteflies Small powdery white flies flying around houseplants
13. Keeping holiday plants Know which ones to rebloom; provide right conditions
14. Indoor roach control Identify roach type before attempting treatment

1. Welcome Bill Kreuser, new UNL Turfgrass Specialist

Bill has a 60% Extension appointment. His industry turfgrass focus will be turfgrass nutrition/fertilization and irrigation. Zac Reicher, UNL Turfgrass Specialist, will focus on weed control and herbicides for the green industry. Both specialists will help with homeowner related turf issues.


2. Winter desiccation injury to turfgrass

Winter desiccation injury to turfgrass may occur when there is little snow cover during winter. Desiccation injury is usually greatest on exposed or elevated areas where surface water runoff is great. It is also prevalent on poorly rooted turf that cannot take-up water from deeper in the soil profile.

Winter watering could minimize dessication, but could also lead to crown hydration injury. Crown hydration occurs when plants start absorbing water. If warm weather is followed by a rapid drop to freezing temperatures, water taken up by the crown freezes, causing ice crystals which can damage or rupture plant cells, and ultimately cause death.

If winter irrigation is used, only water when the soil is not frozen and air temperatures are above 40 degrees F. Apply water at mid-day so it has time to percolate into soil before colder nighttime temperatures and freezing may occur. Use a slow running sprinkler left in place long enough to moisten the top 4 to 6 inches of soil. To prevent crown hydration injury, avoid watering before a sudden temperature drop is forecast, when the ground is frozen, or in low areas where water might collect and stand due to frozen soil or poor drainage.

Winter Desiccation, University of Nebraska-Lincoln


3. Dormant seeding & soil preparation

Dormant seeding can take place when soil temperatures are 40 degrees F. or below. While dormant seeding can take place in January, it will be most effective in areas where soil preparation, such as core aeration, power-raking, tilling, or some other form of cultivation was done last fall. Simply broadcasting seed and allowing it to work into the soil naturally through frost-heaving might be effective; but having soil preparation done first to improve seed to soil contact is important for successful dormant-seeding. A risk with fall dormant seeding is too early germination and seedlings being killed by cold temperatures, and late seeding in late winter allowing seedlings to germinate during warm periods in January or February possibly leading to death when cold temperatures return. Dormant seeding should be done no later than March 15th.

Improving Success of Dormant Seeding, University of Nebraska-Lincoln


4. Round-up over dormant buffalograss for weed control

Dormant buffalograss can be sprayed with glyphosate (Roundup®) to control weeds that have some green color in them. Fall applications can be applied after the first hard killing freeze or when the buffalograss turns straw-brown. Don't apply glyphosate if the buffalograss is showing any green color. Glyphosate applications applied to semi-dormant buffalograss will significantly delay green-up and could severely injure the buffalograss. To insure no injury, do not spray glyphosate (Roundup) after Feb 15 through two weeks after the first hard killing freeze (25°F) in the fall.


5. Emerald Ash Borer update

EAB was found in Boulder, CO in September and most recently in Union County in eastern Iowa prompting people to ask questions about treatment for their ash trees. Below is the recommendation from the Nebraska Forest Service and the University of Nebraska-Lincoln Extension:

  • Treatment is recommended when EAB is known to be within 15 miles of a location.
  • Treating trees beyond 15 miles will likely provide little or no benefit to the trees and will result in unnecessary exposure of the environment to pesticides.
  • State and federal agencies monitor EAB infestations and will provide updates on infestations in Nebraska.
  • Visit the Nebraska Forest Service for information about when to begin treatments ()

For people concerned EAB might already be here, but has gone undetected, it is important to know that trees already infested with EAB are treatable if the damage is not yet severe.

Emerald Ash Borer, Nebraska Forest Service

EAB Nebraska Information


6. Winter desiccation injury on evergreens

Winter desiccation injury on evergreens occurs when foliage loses moisture faster than it can be replaced by roots from frozen soil. Injury is typical on the south or southwest sides of a tree or shrub and fairly uniform, i.e. one inch of the tip of every needle has turned brown. Plants growing near pavement or the south side of light colored or brick homes are often most susceptible.

Correct summer and fall watering is most important to preventing winter dessication. If needed, winter watering can be used. Only water when the soil is not frozen and air temperatures are above 40 degrees F. Apply water at mid-day so it has time to percolate into soil before colder nighttime temperatures and freezing may occur. Use a slow running sprinkler left in place long enough to moisten the top 8 inches of soil.


7. Shade Tree Pruning

Shade tree pruning is ideally completed in February and March. Sharpen tools and memories about how to make correct pruning cuts in preparation for the pruning season.

Pruning Trees, Nebraska Forest Service


8. Pruning tender plants

Wait until spring, typically about mid-April, to prune tender plants like roses and suffrutescent shrubs. These types of shrubs retain a woody base from which new growth occurs each spring. Examples include Caryopteris (Blue False Spirea) and Buddleia (Butterfly bush). Wait until after these shrubs begin to grow before pruning them. This allows time to determine how far back the shrub has died that year and how much dead wood needs to be removed. Waiting also helps to avoid additional injury if pruning stimulates the plant to begin growth too early in spring.


9. Maintain mulch on tender perennials

Maintain mulch on tender perennials if removed by winter winds. During winter when we experience those harsh winds, keep an eye on tender perennials. If you had mulched them some, if not most, of the mulch might have disappeared in the wind. Reapply as needed, keeping at a depth of at least 2 inches, but no more than 4 inches.


10. Starting seeds indoors

Starting seeds indoors is a great way to start a vegetable or flower garden off right. Many seeds can easily be started now and into February, or even early March to then have healthy transplants for the spring garden. Tomatoes, cabbage, petunias, and peppers are just a few plants that appreciate an indoors start.


11. Fungus Gnats

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, Nebraska Extension


12. White flies

White flies 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. Whiteflies are difficult to control. If a plant is heavily infested, consider discarding it. Whiteflies 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.


13. Herbicide driftrisk increases with hotter weather

Keeping holiday plants - Holiday plants, Christmas cactus and Amaryllis, can be kept and will rebloom if provided the right conditions. The same is true for Poinsettia and Cyclamen, although reflowering these is more challenging. The key to success is knowing what conditions individual plants require and meeting those conditions. Does a plant need a dormancy period? Short days and long nights? Cool temperatures? High humidity? For information on reblooming these four holiday plants, refer to the Backyard Farmer website article:

Reblooming Holiday Plants, University of Nebraska-Lincoln Backyard Farmer


14. Powdery mildewshowing up heavily on ninebark shrubs and other plants

Cockroaches indoors can be an unfortunate situation, but one that is completely treatable. The first step to treating is properly identifying which type of cockroach has taken up residence. Wood cockroaches for instance, will not breed indoors, so other than killing existing ones, no treatment would be necessary. Other types of roaches can breed and thrive indoors, and will possibly warrant chemical control. The following publications can help with identifying, and treating for cockroaches.

Identifying Cockroaches, Nebraska Extension

Low Toxic Treatment Options for Cockroaches, Nebraska Extension