THE INFLUENCE OF NUTRITION ON FUSARIUM BASAL ROT OF NARCISSUS AND ON FUSARIUM YELLOWS OF GLADIOLUS

Abstract

THE MOST serious disease of narcissus on the East Coast of the United States is a basal rot of the bulbs caused by Fusarium oxysporum f. narcissi (Cke. et Mass.) Snyder and Hansen. Some rot may be evident at the time of digging but the majority of the bulbs appear to be sound even though many are infected. After 6 to 8 weeks in storage many of the infected bulbs become rotted, particularly if high temperature and moisture conditions prevail and the bulbs cure slowly after digging. The closely related species Fusarium oxysporum f. gladioli (Massey) Snyder and Hansen, causes one of the most serious diseases of gladiolus, yellows, or corm rot, which in recent years has been responsible for annual losses of as much as 60 per cent in the extensive Florida plantings. As a result of commercial advertising, bulb growers have recently become interested in the possibility of using growth-regulating substances to flower and bulb production and to control disease. Some manufacturers of synthetic hormones and purine compounds have recently advocated the use of their products on bulbs to increase and accelerate root production. An advertisement by one of these companies alsoadds that their material controls serious bulb and tuber rots. This material contains allantoin, one of the purines. Another material4 consisted largely of sucrose, uric acid, and naphthalene acetamide at the time our tests were made. A third material is a rather widely used proprietary fertilizer containing 60 to 800 mg. of a synthetic hormone, indolebutyric acid or naphthaleneacetic acid, per ton of fertilizer, in addition to nitrogen, phosphorus, and potassium, and a number of minor elements. Our investigations of fertilizer requirements of narcissus and gladiolus have shown that fertilizers, synthetic growth regulators, and the nitrogen bases markedly affect the severity of the Fusarium diseases of these crops. In narcissus, basal rot is increased greatly when certain of the synthetic growth regulators and nitrogen bases are used in dips and in powders on the bulbs. It was also found that these materials stimulate the growth of Fusarium oxysporum f. narcissi in culture and a short note was published to this effect (Stuart and McClellan, 1943). A more complete account of the investigations is reported in this paper. FIELD RESULTS WITH GROWTH REGULATORS AND NITROGEN BASES.-On September 21, 1940, King Alfred narcissus bulbs 12 to 14 cm. in circumference