Hort Update for March 18, 2014

Hort Update for March 18, 2014

In This Issue:
1. Winter turf injury Winter conditions may cause damage to lower mowed golfcourse turf
2. Spring mower maintenance Service mowers before beginning another season

3. Tree selection

Selection of well-adapted trees critical for success
4. Emerald Ash Borer update EAB quaranties in Iowa, Missouri and Colorado
5. Pruning deciduous shrubs

Use shrub's bloom date as a guideline for pruning

6. Selecting summer bulbs Choose large, healthy bulbs for best growth
7. Selecting perennials Helping gardeners choose; Right Plant Right Place
8. Fruit cultivars for home planting Disease resistant cultivar recommendations
9. Importance of cross pollination Good fruit set relies on cross pollination between varieties
10. Promoting native bees Encouraging native pollinators will help ensure good cross pollination and fruit set
11. Apple diseases Apple Scab and Cedar Apple Rust are two common issues on NE apple trees
12. Planting vegetables Good planning and design as well as plant health will start your garden off right
13. Nebraska frost dates Offers a guideline for when to plant outside in the spring
14. Repotting houseplants
Spring is a good time to repot in a container about 1" larger than previous container
15. Swarming ants Normal occurrence, positively ID to ease concern of termites
16. English/Spanish language guides English/Spanish language guides available for the green industry
17. Upcoming programs Eastern Nebraska Tree Care Workshops, March 18-26

1.  Winter turf injury - Warm temperatures in the next few weeks will initiate turf green-up. UNL Turf Specialists are concerned that serious injury to lower mowed turf, particularly golf course greens, tees, and fairways, is very likely from this winter's conditions.  Damage results from the following conditions, which are most damaging to perennial ryegrass and annual bluegrass.

  • Dessication injury - open, dry, sunny winter conditions resulting in loss of moisture in leaf and crown tissues to the point of death.  Most common on exposed, winter sites.
  • Crown hydration injury - grasses that respond quickly to warm temperatures, like perennial ryegrass and annual bluegrass, rehydrate quickly and can be easily damaged by freezing temperatures. Damage commonly occurs in late winter or early spring, or during water periods in mid-winter.
  • Ice encasement injury- caused by lack of oxygen and toxic levels of carbon dioxide when grass is encased in ice for over a month.  Occurs in low lying or poorly drained areas.

While concern is high for lower mowed turf, higher mowed turf and home lawns will likely come through winter with little or no damage. As spring progresses, follow these action steps for turfgrass evaluation and recovery. 

  • Look closely for new leaf growth from plant crowns to determine grass recovery.
  • Reseed problem areas immediately so cool season grasses will start germination when surface soil temperatures reach the mid-50s F. Complete all reseeding no later than mid-May.
  • Don't rush into mowing low, trying to remove all of the protective brown tissue.  We still may have some winter left.
  • Avoid the application of any preemergence herbicides until the extent of turf damage is determined.

Much much more information is available on the UNL Turfgrass website.

Comprehensive guide to winter turf damage and recovery in the Northern United States


2. Spring mower maintenance - Before another mowing season starts, take time to service your mowers.  Before beginning any maintenance, disconnect the spark plug.

  • Examine spark plug contacts.  They should be smooth and shiny.  If the connections are rusty use emery cloth or 400 grit sandpaper to remove it, but be careful not to damage the contacts.  If the rust is severe, replace the spark plugs.
  • With the spark plug disconnected, check and sharpen the blade. 
  • Clean the undercarriage. Remove any rust with a stiff steel brush and steel wool.  Repaint the undercarriage with rust-resistant paint. 
  • Change the mower's oil.  Engine oil should be checked at least twice annually.
  • If your mower has them, check the blade brake, belts, or self propeller mechanism. 
  • Reset the mowing height if necessary
  • Reconnect the spark plug and fill with fresh gasoline, and you're ready to go for the next six months.


3.  Tree selection - When properly cared for, trees can provide benefits for generations.  When deciding which tree to plant, ask yourself the following questions:

  • Why am I planting the tree(s)?
  • What are the characteristics of the planting site?
  • What is the condition of the soil in the planting site?
  • How much time am I willing to spend maintaining the tree(s)?

The tree's function, form, size and location, as well as site characteristics such as soil & environmental conditions, and pest & disease problems, are all important to consider.  Choose plants well adapted to your site to maximize their chances of success.

Trees for Eastern Nebraska, Nebraska Forest Service
Trees for Western Nebraska, Nebraska Forest Service
Tree Selection & Placement, Nebraska Forest Service
Nebraska's Landscape Tree Information, Nebraska Forest Service
Right Tree, Right Place, NFS ReTree Nebraska


4.  Emerald Ash Borer update - By now many homeowners have heard of emerald ash borer (EAB) and are concerned about their ash trees.  Now EAB is found in 22 states from Massachusetts south to Georgia, and west to Minnesota and Missouri.  Closest to home, EAB was confirmed in Missouri 2008, Iowa 2010, Kansas 2012 and Colorado 2013.  The nearest confirmed sites are Kansas City, MO, Boulder, CO and Creston, IA.  It is inevitable that EAB will eventually make its way into Nebraska, probably within the next few years. 

Now federal Animal and Plant Health Inspection Service (APHIS) quarantines apply to all of Iowa and Missouri.  In Colorado, Boulder County and portions of Jefferson, Larimer, and Weld Counties are quarantined. This means interstate movement of EAB-host wood and wood products are regulated, including firewood of all hardwood species, nursery stock, green lumber, waste, compost, and chips of ash species.

More information on USDA APHIS regulations and quarantines.

Below are recommendations 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.

Nebraska Forest Service Resources:
EAB Community Readiness
Emerald Ash Borer Treatment Options
Emerald Ash Borer: Guidelines for Nebraska Homeowners
Emerald Ash Borer: Frequently Asked Questions
Decline in Ash Trees: Borers and Bark Beetles - An Identification Guide
Decline in Ash Trees: Diseases & Environmental Stresses An Identification Guide


5.  Pruning deciduous shrubs - Use the shrub's bloom date to decide when it should be pruned.  If the shrub blooms in spring, then prune it after it blooms.  If it blooms in summer or fall, or doesn't bloom much at all, prune it in early spring.

Spring Bloomers - Forsythia, Lilac, Viburnum, Dogwood, Flowering Quince, Deutzia, Pearlbush, Witchhazel, Japanese Kerria, Flowering Almond

Summer/Fall Bloomers  (and non-bloomers) - Mockorange, Rose of Sharon, Winged Euonymous (burning bush), Barberry, Allspice/Spicebush, Cotoneaster, Hydrangea, Privet, Honeysuckle, Shrub Rose, Spirea, Weigela

Prune for size reduction, rejuvenation or renovation.

  • Size reduction - use heading back cuts, removing branch length to an outward facing side shoot at least 1/3 diameter of the branch removed
  • Rejuvenation - begin with 2-3 year old plants.  Remove 1/3 of the shrubs thickest, woodiest stems as close to the crown as possible.  Repeating this process every year results in a shrub that is shorter, fuller and has more flowers. 
  • Renovation - cut down the entire shrub down as close to the crown as possible.  Works well with many spirea.


6. Selecting summer bulbs - There are hundreds of bulbs to choose from that produce plants varying in flower color, flower form and height. When choosing bulbs or bulb-like plants, choose the largest available that are firm and solid to the touch.  There is a direct correlation between bulb size and flower size. To ensure health and vigor in your planting, make sure planting areas are well-drained and don't use fresh manure as a soil amendment.


  • Undersized bulbs.
  • Bulbs that are shriveled or lightweight.  This may indicate the bulbs have been held too long and/or are drying out. 
  • Bulbs with soft spots or mold.  This indicates the beginning of bulb rot. 
  • Bulbs with physical damage.


7. Selecting quality herbaceous perennials - Helping homeowners choose the right plant materials for their gardens will help them be successful, and bring them back to your nursery for more. Below are several NebGuides to assist with plant selection.


8. Fruit cultivars for home plantings - Many customers ask for tree or small fruit cultivar recommendations. Selecting the right cultivars in the beginning can save them a lot of headaches, money, and maintenance in the long run. Disease resistance, harvest dates, winter hardiness and plant size are important considerations.

Fruit Cultivars for Home Plantings, University of Missouri


9. Importance of cross pollination - When planting fruit trees like apples and pears, it is discouraging to see healthy-looking plants that never produce fruit.  Maybe the issue is your pollination, or rather, lack thereof.   Many fruit trees need cross-pollination to produce fruit.  Even some varieties that are able to pollinate themselves, actually produce more fruit if another variety is present for cross-pollination.   For example, 'Honeycrisp' apple needs another variety to pollinate it.  Not every variety is suitable, but 'Golden Delicious' is one good option.  It's important to know if your fruit tree varieties need a cross pollinator, and which ones would be suitable selections.  Keep in mind you'll need varieties that are blooming at the same time! 

For more information on pollinating fruit trees, including charts of appropriate cross-pollinators, check out the publication below.

Pollinating Fruit Crops, University of Missouri


10. Promoting native bees for pollination - While honeybees are the most common insect pollinator, there are over 3,500 bee species native to North America (honeybees are native to Europe, Asia, and Africa).  Bumblebees, for instance, are a great example of a native bee that plays a very important role in pollination.  Bumblebees make their nests in the ground, as do many other native bees.  Others will nest in rotting trees, or plants with pithy stems, such as raspberries and roses.  To encourage native pollinators, have flowers available in all three seasons.  Let the edges of your landscape or yard get a little messy - many of the plants we consider 'weeds' such as clover and dandelion, are great pollinator plants!  Because many bees nest in the ground, leave a little space unplanted or turf-free to encourage nesting.  Also, decrease pesticide use, as many are toxic to bees.

Bee Aware: Protecting Pollinators from Pesticides, University of Nebraska - Lincoln Extension


11. Apple diseases - Two of the most important diseases of apples in Nebraska are Apple Scab (caused by the fungus Venturia), and Cedar Apple Rust (caused by the fungus Gymnosporangium).  Both of these can cause serious damage if not properly cared for. 

The fungus that causes apple scab prefers cool, wet conditions so scab is often a springtime issue, but can appear at other times of the growing season as well.  Fungal spores can over winter in infected leaves left on the ground.  Sanitation in the orchard is essential for control. Fungicides, such as copper formulations such as Liquid Copper Fungicide can give chemical control when needed as well.  If don't have any fruit trees, but are planning on purchasing some this year, choosing resistant varieties is the best place to start when making selections.  For more information on apple scab, and varieties resistant to it, see the link below.

Apple Scab, University of Nebraska, Lincoln Extension

Cedar Apple Rust, while also caused by a fungus, is a completely different disease.  For the disease to develop, both hosts need to be present - The susceptible apple, and the susceptible Juniperus (such as Eastern Red Cedar).  As with other diseases, the first line of defense is choosing resistant varieties to plant.  Of course, if you have an established orchard, sanitation and fungicides will be necessary components of treatment. 

Cedar Apple Rust, University of Nebraska, Lincoln Extension


12. Planting vegetables - Homeowners trying to grow their own transplants have some challenges. They need to provide the right conditions and not starting seed too early. Depending on the vegetable, start most transplants about 6 weeks prior to the expected outdoor planting date. To grow quality transplants, use a soilless potting mix and provide fairly high humidity, cool temperatures (60 to 70 degrees F) and 14 to 16 hours of bright light per day. Use a grow light or at least one cool white and one warm white fluorescent light, placed one to two inches from the plants. A little air movement, such as with a fan, can also lead to sturdier transplants.

Growing Transplants, University of Illinois Extension

While transplants are small, when planting them, as well as seeds, in the garden, it's important gardeners space the plants with full size in mind.  Proper spacing ensures good air circulation, which can cut down on disease occurrence.  Properly spaced vegetable plants will have less competition for water and nutrients.  It's also makes harvesting easier if plants aren't growing into each other!  The following Illinois publication has a great chart for vegetable spacing:

Plan Your Garden Layout, University of Illinois Extension


13. Nebraska average last spring freeze (32° F) dates indicate that half of all final spring freezes will occur before the dates shown and half will occur after, based on 47 years of data from 1949-1995. In southeastern Nebraska that average last spring freeze date is approximately April 30 and May 21 in the northwest corner of Nebraska's panhandle. These dates are guidelines only. Freezing temperatures may occur after the dates listed below. Also remember that local microclimate conditions can significantly affect the occurrence of frost in your landscape.  These dates can be used as guidelines for gardeners planting early spring crops. Frost sensitive plants will not tolerate freezing temperatures and must be protected if freezing temperatures occurs after planting.

Spring last frot date map


14. Repotting houseplants is needed to move houseplants up to larger containers and to refresh the potting mix. March and April, just as houseplants are emerging from winter semi-dormancy are good times to repot houseplants to a new container that is only about one inch larger than the previous container.

University of Illinois Extension has a great publication on Repotting Houseplants.


15. Swarming ants create concerns about termites. Termites also swarm in spring. When swarmers are seen near structures, positively identify. All swarmers have wings. Ants will have a constricted waist, making them appear to have three body parts. The wings of termites are longer than the body and termites do not have constricted waists and only have two main body parts.


16. Spanish/English guides available- University of Nebraska-Lincoln Extension is offering three guides to help improve communication between Spanish and English speaking individuals. Titled, español a ingles, English to Spanish, these communication guides are laminated and easy to keep with you, folding into a convenient quarter-fold size of 4.5" by 11".

The guides feature phrases and key words in both Spanish and English, including pronunciation guides for both languages. Each of the three guides has a unique focus area including a guide for the Green Industry, one for Landscaping and Grounds Keeping, and one for Golf and Pond Maintenance. They are currently available for by calling or e-mailing John Fech at jfech@unlnotes.unl.edu or 402-444-7804. They can also be ordered on-line at Garden Center Update.  The cost is $8.99, not including shipping and handling; there are bulk discount rates available if you order more than 10.

John Fech, University of Nebraska-Lincoln Horticulturist coordinated the making of the Spanish guides. Fech's goal is to help native English speakers communicate with native Spanish speakers, and vice-versa. This guide is unique because it facilitates the two-way communication.


17. Upcoming Programs - Late winter is the time to brush up on forgotten information, or learn something new!  The following are just a few of the upcoming programs and/or conferences that you can attend.

Eastern Nebraska Tree Care workshops

March 18, Hastings
March 19, Ord
March 20, Norfolk
March 25, Lincoln
March 26, Omaha