Willows Ideal For North American Cut Stem Production

Willows are an ideal specialty cut branch for temperate North America.  They can be harvested in mid-winter to early spring when few other flowers are blooming.  They also tolerate poor soils and provide many years of harvest from the initial planting.  Researchers at The Ohio State University evaluated 150 willow taxa for ornamental vegetative and flowering characteristics to ultimately suggest 20 species with desirable traits that can be worked into a production schedule for continuous winter-to-spring harvest.
    

After obtaining 150 taxa as unrooted cuttings, the plants were grown for four years at two Columbus, Ohio, locations, both USDA zone 5.  Over four years, the following evaluations were made to aid in selection: production of abundant catkins with fuzzy “pussy-willow” effect and stems with bright colors or ornamental configuration.  Plants with these characteristics were further scrutinized as data were collected for: harvestable stem length, stem color or shape, bud color and density, catkin size, color, texture, and relative location on the stem.
    

The willows selected can be divided into three groups by branch size.  Seven are “short” averaging 1m (3.3ft) or less. Six are “medium” with a harvestable stem length of 1-1.5m (3.3-4.9ft). The remaining seven average a stem length of 1.5-2m (4.9-6.6ft) resulting in a designation of “long.” (Table 1.)
    

Willows might also be classified by catkin color (white, gray, green and black) or catkin size (small, medium and large). Interestingly, in most species the male specimens were showier than the female specimens due to longer bract hair and larger catkin size.  While some willows had insignificant catkins, they were valued for their stem color, bud color or stem shape.
    

From cuttings, two to three years of growth is necessary to obtain harvestable stems. On average, plants produce 10-30 stems per year. In order to promote thicker, straighter, longer single-stemmed branches, the shrub should be cut to the ground annually (known as coppicing). Coppicing can be done as the stems are harvested. The dormant season (harvest time) of late winter, early spring is ideal for coppicing in order to produce a vigorous plant the following year.
    

Using the selected species, the researchers also developed a schedule illustrating how using many different species can allow for continuous harvest from the beginning of January through the beginning of April (in Ohio).  This creates a broader market window and introduces new willows with interesting characteristics to the public.

Kuzovkina, Y. and M.F. Quigley. 2004. Selection of Willows for Floral and Stem Quality and Continuous Production Sequence in Temperate North America. HortTechnology 14(3):415-419.

Table 1. Section of 20 desirable willow (Salix) taxa categorized by harvestable stem length.   

ShortMediumLong
S. aegyptiacaS. ‘The Hague’S. acutifolia
S. amplexicaulisS. humilisS. babylonica ‘Tortuosa’
S. discolorS. koriyanagiS. caprea
S. gracilistyla ‘Melanostachys’S. kuznetzowiiS. gracilistyla
S. hookerianaS. x multinervisS. miyabeana
S. schweriniiS. x tsugaluensis ‘Ginme”S. undensis ‘Sekka’
S. x friesiana S. x wimmeriana


Affect of Salinated Water on Lupine Production

Recycled water, reclaimed municipal water, and brackish groundwater are alternative irrigation sources to fresh water; however they generally contain higher salt levels than fresh water and therefore may affect plant growth and development.  Since the fresh water supply is limited in some areas, researchers have started assessing the salinity tolerance of various plants. In many cases, plants grown for landscape use grow more compact when treated with these alternative water sources.  Compact growth is not desirable for cut flowers, therefore, researchers at Texas A&M University have studied two lupine species to assess the acceptable level of salinity before plant quality suffers. 

Lupinus havardii is an annual native in southwest Texas with cut flower potential.  It produces 40-55 cm (15.7-21.7 in) long racemes with fragrant, blue flowers. Lupinus texensis is a hardy winter annual commonly sold as a bedding plant.  Plants were started from seeds which were scarified with concentrated sulfuric acid for 90 minutes (L. havardii) or 45 minutes (L. texensis). The seeds were sown in early January and transplanted in early March into pots grown in the greenhouse. Plants were irrigated with a 20-20-20 nutrient solution.   

Sodium chloride (87%), magnesium sulfate (8%) and calcium chloride (5%) were used to prepare the saline treatments. Five salinity levels were tested: 1.6 (the control), 3.7, 5.7, 7.6, and 9.4 dS/m EC.  The saline solutions were applied through the irrigation water for 11 weeks (early March to late May).  To prevent rapid salt accumulation, the irrigation was applied so that a 30% leaching fraction was achieved.   

Plant height, canopy width, visual quality and shoot dry weight were evaluated. Quality was assessed using a scale of 1 to 5 with 1 being “severely stunted growth with over 50% foliage salt
damage (leaf necrosis, browning) or dead,” and 5 being “excellent with vigorous growth and no foliage damage.”
    

L. havardii displayed foliage salt damage at salinity levels of 5.7 dS/m. Salinity levels above 5.7 dS/m resulted in significant plant death. L. texensis showed no signs of foliage damage up to 7.6 dS/m. As expected, shoot growth decreased as salinity levels increased in both species.
    

The potential cut flower, L. havardii produced similar flower yield and quality at the control level (1.6 dS/m) and at 3.7 dS/m indicating some tolerance to saline waters.  Given that the average EC of reclaimed municipal water is 2.0 dS/m, this flower should perform equally well using fresh water or reclaimed water. L. texensis also performed well, perhaps with a positive side effect of compact growth in the landscape, when irrigated with saline water, up to 5.7 dS/m.

Niu, G., S. Rodriguez, L. Anginiga and W. Mackay. 2007. Salinity Tolerance of Lupinus havardii and Lupinus texensis. HortScience 42(3):526-528.



Gladiolus Response to Supplemental Boron and Zinc

Researchers in Bangladesh studied various rates of boron and zinc, applied singly and in combination to find the optimum rate for maximizing the flower yield of gladiolus.  Previous research indicated that boron and zinc positively affected the growth, flowers, yield and quality of gladiolus.   

Corms were sown in early December at two research farms in Bangladesh.  Nutrients, including phosphorus, potassium, sulfur, boron and zinc, were applied to the field prior to planting. Nitrogen was top-dressed at 30, 45, and 60 days after sowing.  Sixteen treatments consisted of four levels of boron (0, 1, 2, and 3 kg/ha) and four levels of zinc (0, 1.5, 3, and 4.5 kg/ha).    

Boron levels up to 2 kg/ha produced increased growth and flowers; however rates beyond 2 kg/ha produced a decline in growth and yield.  In fact, all the measured characteristics (plant height, effective leaves, length of spike and rachis, number of florets, size of floret, and weight of stem) significantly responded to a boron application rate up to 2 kg/ha. Zinc levels, up to 3 kg/ha produced a positive response in floret number, floret size and stem weight.    

The boron/zinc combination of 2 kg/ha B and 4.5 kg/ha Zn produced the most desirable characteristics overall at both test sites.  Plant height measured 79.8 and 94.1 cm (31.4 and 37.0 in) with a rachis length of 48.9 and 46.1 cm (19.3 and 18.1 in).  Both sites reported about 10 effective leaves and nearly 13 florets per spike.  Their results further support including boron and zinc, along with a balanced nutrient formulation, to maximize yield and flower quality of gladiolus.

Halder, N.K., Md. Rafiuddin, M.A. Siddiky, R. Gomes and K. Anju-Man-Ara Begam. 2007. Performance of Gladiolus as Influenced by Boron and Zinc. Pakistan Journal of Biological Sciences 10(4):581-585.

  

Megan Bame

Megan Bame is a freelance writer in Salisbury, North Carolina. Contact her at [email protected]