Sunflower Performance Linked to Planting Date

Research at Cornell University’s Long Island Horticultural Research and Extension Center in Riverhead, New York, looked at how planting date of various sunflower cultivars affects the number of days to flower, the height of the flower stem and the bloom diameter.
Fourteen cultivars were planted on June 6, June 24 and July 16 at a spacing of 12 inches apart within the row and 24 inches apart between rows. Data were collected at the first full bloom (anthesis).
‘Prado Red’ and ‘Musicbox’ were the only cultivars demonstrating a significant delay in days to flower when planted June 24 compared to June 6. ‘Prado Red’ bloomed 5 days later, while ‘Musicbox’ bloomed 3 days later. Cultivars that displayed a delay (three or more days) in flowering when planted July16 compared to June 24 were ‘Moulin Rouge,’ ‘Ring of Fire,’ ‘Sunbeam,’ ‘Sunbright,’ ‘Sunbright Supreme’ and ‘Sunrich Lemon.’ Three cultivars bloomed earlier when planted later; these were ‘Pacino Cola,’ ‘Pacino Lemon’ and ‘Soraya.’
Comparing the cultivars’ days to flower from the first planting date and the last planting date suggest photoperiodic response for each cultivar. ‘Big Smile,’ ‘Moonbright’ and ‘Sonja’ appear to be day-neutral since there was little difference between the number of days to flower in group planted June 6 and those planted July 16. ‘Pacino Cola,’ ‘Pacino Lemon’ and ‘Soraya’ appear to be facultative short-day plants, while ‘Moulin Rouge,’ ‘Ring of Fire,’ ‘Sunbeam,’ ‘Sunbright,’ ‘Prado Red,’ and Sunrich Lemon’ appear to be facultative long-day plants. A facultative photoperiod response means that a plant will flower under either long or short days, but they will flower faster under the preferred facultative daylength.
Generally speaking, plant height (stem length) decreased as planting date was delayed. ‘Moulin Rouge’ and ‘Prado Red’ displayed no significant height difference between the first and second planting or the second and third planting. Given the typically long stem length of sunflowers, the majority of the cultivars remained 30 to 40 inches long at the latest planting date. ‘Big Smile’ and ‘Pacino Lemon’ were the only cultivars to grow less than 20 inches before flowering when planted July 16.
‘Moulin Rouge,’ ‘Musicbox’ and ‘Pacino Lemon’ were the only cultivars not to display a significant decrease in bloom diameter as a result of planting date. ‘Big Smile’ displayed the greatest decrease in flower size from a 7-inch diameter when planted June 6 to a 4-inch diameter when planted July 16.
Though sunflowers should be evaluated by cultivar, this research found that generally speaking, a later planting date may result in shorter stems and smaller blooms.

Kollman, E., and M. Bridgen. 2006. The Effect of Planting Date. Greenhouse Grower 24:8 pp. 128-130.

Hydrangea Allergy Identified

An allergic reaction in the form of contact dermatitis has been found in cut flower growers and florists who frequently handle hydrangeas. As early as 1992 an allergen in hydrangea was identified as hydrangenol. Cutting the stems, stripping the leaves and bundling the flowers results in repeated contact with the hydrangenol-containing sap. Prolonged, intensive contact with the hydrangea sap may lead to an allergic reaction.
The reaction manifests itself as an itchy, persistent hand and facial dermatitis. Symptoms include redness, small blisters and scaling of the fingers and palms. Similar, but less severe symptoms may appear on the face, around the eyes and mouth.
To avoid a reaction, growers are advised to use protective vinyl gloves with a cotton lining or undergloves for all contact with the hydrangea. The workspace should be kept clean and hand-face contact should be avoided. The dermatitis condition has been observed to improve when contact precautions are taken, and deteriorate when precautions are overlooked.

De Rooij, J., D.P. Bruynzeel and T. Rustemeyer. 2006. Occupational allergic contact dermatitis from hydrangea Contact Dermatitis 54 pp. 65-66.

Water Pussy Willow for Increased Yield

Researchers at North Carolina State University’s Mountain Horticultural Crops Research and Extension Center studied the effect of fertilizer and moisture availability on stem yield of Salix chaenomeloides, giant Japanese pussy willow.
S. chaenomeloides is a vigorous species with abundant large, silvery-white catkins. The stems can be harvested at lengths of four to five feet in mid- to late January in Fletcher, N.C.. The plants in the study were allowed to become established in the field for one growing season. No supplemental irrigation was provided given the humidity of the North Carolina mountain climate. S. chaenomeloides may be a suitable crop for land with poor drainage that may not support other crops. In late winter, they were cut back to within one foot of the soil surface, a cultural practice know as coppicing. Cut stems were harvested the following winter.
A fertilizer study looked at rates of 0.25, 0.5, 1.0, and 2.0 ounces of nitrogen from ammonium nitrate applied at 20 to 150 pounds per acre per year. The results indicated that the amount of nitrogen applied had no effect on the number of stems produced or the stem length.
The weather pattern over multiple seasons allowed the researchers to draw conclusions about the effect of available water on plant productivity. Typical summer weather was observed the first growing season including at least 1 inch of rainfall per week. An extremely hot and dry summer occurred the second growing season. With little rainfall, the plants produced significantly fewer stems even though the plants were older and larger. When the experimental plants were transplanted to commercial growing operations, the growth trend continued. Those plants that were in location that received higher rainfall amounts grew more and yielded more harvestable stems.

Bir, R. and J. Conner. 2006. Growing pussy willow for cuts GMPro 26:5 pp. 37-38.