Results of Forcing Hot Water Treated Narcissus Bulbs

Abstract

The treatment of dormant narcissus bulbs in hot water for a period of 3 hours at a temperature ranging from 110° to 111.5° F. is today recognized as a means of controlling infestation by the nematode, Tylenchus dipsaci Kuhn, the bulb flies, Merodon equestris and Eumerus spp., and the bulb mite, Rhisoglyphus hyacinthi Boisd. The results of the first year's experience, however, with this treatment of both home grown and newly imported narcissus bulbs were variable, success being attained in some sections while in others disastrous effects were noted. The causes of these failures, however, have not been clearly established. In some cases they were thought to be due to planting the bulbs while still hot and wet, i. e., without properly drying them before planting. In others they were attributed to very early planting, at a time when the soil temperatures were high and accompanied by either-excessive moisture or dryness. Under such conditions it was thought that the bulbs were weakened and rendered more susceptible to attack by diseases such as basal and other rots which ultimately hastened their destruction. Some growers thought failure was due to possible overheating of bulbs, which may have occurred while the bulbs were in transit, or to improper storage before and after treatment. These facts forced attention to the need of carefully studying the many details involved in the hot water method as a basis for definite recommendations as to time and manner of treatment for the different localities where bulbs are grown. Experiments conducted during the past year, using paperwhite narcissi which were treated at 110° to 111.5° F., indicated that there was a general tendency toward better flower production in bulbs treated about August 11, as compared to those treated on September 1 and October 1. It was also determined that paperwhites will not tolerate the higher temperature of 115° F. At this temperature the number of individual flowers produced per spike was greatly reduced. In case of the trumpet narcissi, including Golden Spur, Emperor, King Alfred, Victoria, and Spring Glory, a very satisfactory crop of flowers was produced in both the treated and untreated lots. In general these tests indicate that the varieties of bulbs mentioned above can be given the hot-water treatment without materially reducing the degree and quality of flowering. It is also evident that when stock is treated at the right stage of growth, and handled properly before and after treatment, it may safely be shipped from one section of the country to another without great risk of loss from the treatment. A detailed account together with illustrations of these experiments, written from the viewpoint of the grower, was published in the August 4 and September 15, 1927. issues of the Florists' Review.