Hort Update for February 19, 2014

Hort Update for February 19, 2014

black knot
In This Issue:
1. Recent snowmelt moisture May help alleviate dessication potential
2. Black knot removal Irregular hard black galls on branches and trunk of cherry and plum
3. Potting up tender bulbs Summer-blooming bulbs can be potted up 6 weeks before last frost
4. Order asparagus crowns Ordering now will ensure you have your asparagus for March planting
5. Dormant application for plum pockets & peach leaf curl Dormant sprays must be applied before leaves begin to expand
6. Great Plants for Great Plains 2014 selections have been named
7. All-America Selections for 2014 2014 selections have been named
8. Upcoming Programs

  • Eastern Nebraska Tree Care Workshops, Multiple dates and sites
  • Urban Pest Management Conference, February 18 - 19, Lincoln, NE
  • Beekeeping Workshop, February 22, Nebraska City, NE



1. Recent snow fall/melt - The open, dry, and windy winter of 2013/14, with wildly fluctuating temperatures, created perfect conditions for turf desiccation, especially on low-mowed, exposed slopes, sandy soils, new seedlings, etc. Recent snowfall provided cover and likely enough moisture to help minimize desiccation issues that have not yet occurred. However, damage may have already been done on some sites and thus it is still important to bring turf samples into your office window sill, water them, and determine green-up. More information is available at

Fighting Dessication: Should we Water Turf in Winter?, University of Nebraska-Lincoln
Warm Winter with No Snow Cover Could Increase Desiccation Damage, University of Nebraska-Lincoln


2. Black knot removal - Black knot is a fungal disease that caused hard, black woody growths to encircle the stems of infected plants, mainly plums. Established orchards or backyard trees should be scouted or examined each year for the presence of black knot, and infected twigs should be pruned out and destroyed or removed before bud break. It is important to prune at least 2-4 inches below each knot because the fungus grows beyond the edge of the knot itself. If pruning is not possible because knots are present on major scaffold limbs or the trunk, they can be removed by cutting away the diseased tissue down to healthy wood and out at least 1/2 inch beyond the edge of the knot. Burn or bury the prunings before April 1st. Fungicides can offer significant protection against black knot, but are unlikely to be effective if pruning and sanitation are ignored.

Black Knot of Plum, University of Nebraska-Lincoln


3. Potting up tender bulbs - Summer-blooming bulbs and bulb-like plants, such as canna, and caladium, and elephant ear, can be potted up 6 weeks before the last expected frost.  This time gives them a head start on growth and vegetative production, so they will be that much quicker to flower, or show off their attractive foliage.  None like wet, cold soil so don't plant outside too soon, or overwater while still indoors. 

Fill containers with good quality potting soil and plant bulbs at the following depths: canna 5-6 inches, caladium 1-1.5 inches, tuberous begonias 0.5-1 inch, dahlia 1 inch, elephant ears 1-2 inches, calla lily 1-2 inches.  Water well and place in a sunny, warm location to initiate growth.

Starting Tender Perennials Indoors, Iowa State University


4. Ordering asparagus now will ensure arrival of your asparagus for April-May planting.  Asparagus is a perennial, which means it returns year after year.  The first two years of growth, it's recommended to not harvest any spears from your asparagus patch, and then only lightly the third year.  Because of this, make sure you pick your site carefully!  There are many resources for growing and harvesting asparagus.  Following are some helpful links.

Asparagus, University of Nebraska-Lincoln Extension
Growing Asparagus, Ohio State University
Asparagus, Univeristy of Illinois Extension
Everything About Asparagus, Michigan Asparagus Board


5. Plum pockets & peach leaf curl are caused by Taphrina fungus. Dormant sprays of fungicides are effective controls if applied in late winter before buds begin to swell and when temperatures are above 40° F. These diseases cannot be controlled once leaves have started to expand. Use the fungicides ferbam, clorothalonil (Daconil), Bordeaux or liquid lime-sulfur. Do not add oil to lime-sulfur or spray oil treatments for three weeks after application of lime-sulfur. Lime-sulfur should not be applied to trees when temperatures are below 45 or above 80 F. Follow recommended label rates for all commercial fungicides.

Peach Leaf Curl, University of Nebraska - Lincoln Extension
Peach Leaf Curl and Plum Pockets, University of Kansas


6. GreatPlants for the Great Plains is a program by the Nebraska Nursery and Landscape Association and the Nebraska Statewide Arboretum that highlights some of the superb and little-used plants suited for growing in the Great Plains.  Each year, selections are made for a deciduous tree, a conifer, a shrub, a perennial, and an ornamental grass.  This year's featured plants include tuliptree, Korean fir, purple beautyberry, showy black-eyed Susan, and Gray's sedge. The 2014 selections, as well as those from previous years, can be found at:

GreatPlants for the Great Plains


7. All-America Selections (AAS) has completed 81 years of testing and introducing significantly improved new flowers and vegetables grown from seed and bedding plants.  Founded in 1932 to foster the development, production and distribution of new and improved horticultural and agricultural varieties of flowers, bedding plants and vegetables in North America, the organization evaluates plants at a network of almost 200 display gardens across the United States and Canada.  Selection as an AAS Award winner recognizes a flower or vegetable for significant achievements, proven to be superior to all others on the market.

Plant released through AAS are tested for at least two years in trial gardens across the United States.  Regional and National winners are named each year, after rigorous trials across the country.  You can find pictures and descriptions of the 2014 winners at:

All-America Selections  


8. 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. 

Urban Pest Conference
February 18 and 19, 2014
Lincoln, NE

Beekeeping Workshop
February 22, 2014
Nebraska City, NE

Eastern Nebraska Tree Care workshops
March 18, Hastings
March 19, Ord
March 20, Norfolk
March 25, Lincoln
March 26, Omaha