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disease, he states, was due to Sclerotinia bulborum Wakker. He figures a Peziza form not unlike Sclerotinia libertiana Fckl., and a Botrytis form with globose conidia very similar to Botrytis cinerea Pers. Oudemans (1884) and others state that no Botrytis stage has been found for Sclerotinia bulborum (Wakk.) Rehm., which was described by Wakker (1883) as causing a disease of hyacinth and other bulbs, and that none occurs. At any rate the description and figures presented by Massee cannot apply to the fungus causing the neck rot of onions. Again, in 1903 and 1914, Massee restated that a destructive rot of onions due to Sclerotinia bulborum occurs. Until the connection between the Botrytis and the Sclerotium forms has been demonstrated these descriptions only lead to endless confusion.
In 1900 Smith pointed out that the onion bulb rot due to a Botrytis and observed by him near Munich was not typical J5. cinerea because of its low, dense manner of growth and smaller spores. This author also doubted the possibility of the onion rot being due to Sclerotinia bulborum Wakker as suggested by Massee.
Voglino (1903) made a careful study of a disease of Allium sativum which occurred in Italy and was able to prove conclusively that the onion disease caused by a Botrytis as described by Sorauer (1886) and Prillieux (1897) is not due to Sclerotium cepivorum Berk., but he suggested that it may be a Botrytis described by Schroter on Allium ursinum and one found by himself as occurring on onions and referred to Sclerotium ambiguum Duby. This author stated that due to the kindness of Professor P. A. Saccardo he was able to examine in the Exsiccati of Libert1 typical examples of Sclerotium cepivorum Berk. (S. cepae Berk, et Br.) and to determine the identity of these with those found on Allium sativum. This author further stated that the sclerotial form of Libert and of the specimens which develop in various parts of Italy are constantly spherical in form as is true of the form found by Garavaglio in rice plants and described by Cattaneo2 under the name Sclerotium oryzae. These correspond to the description by Berkeley as reported by Fries3 and by Saccardo4 for Sclerotium cepivorum Berk. (S. cepae Berk. et. Br.). "Minutum, sphaeroideum, gregarium, atrum, tegumento distincte parenchymatico fuligineo, intus cellulis varie ramosis intricatis albis farctum." Yoglino carefully worked out the eonidial form of this fungus which was very abundant on the bulbils and which he described as Sphacelia allii distinguishing it by the following characters: "Effusa bulbos, Allii sativi crustaeeo-pulvinata, roseola, sporophoris e strato proligero oriundis, ramulosis, hyalinis, dense fasiculatis septatis, 40-50 microns longis; conidiis sphaericis, hyalinis, quandoque catenulatis, 1-guttulatis 3-4.5 microns diam." This important work performed by Voglino and to which attention has been called by Delacroix (1909, p. 401) and others, places beyond all doubt the possibility of the neckrot disease of onions being due to the fungus Sclerotium cepivorum Berk.
1Cryptog. exs. Ard. n. 238.
2 Saccardo, Syll. Fung. 14:1153.
3 Summa Vegetabilia Scandinaviae, page 478. * * Syll. Fung. 14: 1151.
Clinton (1903-1904) in reporting a Botrytis as causing a serious onion bulb rot of white onions in Connecticut suggested that possibly it is the same as the Botrytis bulb rot of onions and hyacinths in Europe, where it is known in its perfect form as Sclerotinia bidboriim altho he stated that no perfect or ascospore stage has been noted in Connecticut. He further emphasized the possibility that it is not specifically different from the common Botrytis which is found so commonly on greenhouse plants. According to this author's description of the fungus and its behavior, supplemented by cultures which the writer has secured from diseased onions from Connecticut, no doubt is entertained but that it is identically the same fungus as is found in New York, Michigan, and elsewhere causing the neck rot of onion bulbs.
Bruck (1907) made note of a disease of onions in Europe due to a Botrytis with a sclerotial stage which he suggested is Sclerotium cepae Lib. This fungus was found both in the field and in the storage house.
According to Jarvis (1909) a disease of onions in the form of a rotting of the bulbs at the neck before and after storing occurred in Connecticut. This author referred the trouble to the same fungus (a Botrytis) as reported by Clinton (1903) and also recommended a similar method of treatment.
Selby (1910) discussed a "dry or black neck-rot" of onions which occurs in Ohio and causes heavy storage losses when white onions are stored. Altho he does not state that a Botrytis stage occurs he figured a diseased specimen which is typical of the Botrytis neck-rot disease. He stated that the disease is due to Sclerotium cepivorum Berk.
In reporting for the state of Oregon, Jackson (1914) mentioned a serious storage rot of onions due to a Botrytis. The disease is known there as onion stem rot and gray mold, and is said to be favored by moist weather conditions, poorly ventilated storage houses, and immaturity of the stock.
According to Hanzawa (1914) a disease of onions due to a Botrytis which has a sclerotial stage occurs in Japan. Hanzawa figured a Botrytis with oval to oblong spores, and stated that they measure 8.4-16.8 microns long and 6.3-10.5 microns wide. The conidiophores are branched at the tips and are about 1 mm. long. He further stated that the fungus resembles Botrytis tinerea. The small, round or elliptical sclerotia germinate by forming the Botrytis stage but not the apothecial stage.
In a recent publication Humbert (1916) discussed the same onion disease as reported by Selby for Ohio at an earlier date. He stated that the disease is disseminated by means of spores, but does not intimate that the fungus is a Botrytis. However, he affirms that the causal organism is Sclerotium cepivorum Berk.
As far as the writer is able to determine from a thoro search of literature the following fungi from the genus Sclerotium have been reported upon species of Allium. These will be compared with the fungus studied:
1.— Sclerotium ambiguum Duby.1 For this species the sclerotia are described as being minute, ovate or orbicular, with the margins elevated, and having a dark interior. This species has no Botrytis stage and does not resemble the onion neck-rot fungus in the sclerotial stage.
2.— S. Brassicae Pers.2 which is reported as occurring on the scapes of Allium victorialis has no Botrytis stage, and has sclerotia which are oblong, flat, 4-8 mm. long, and the interior becoming black. Net at all similar to the onion Botrytis.
3.— S. cepivorum Berk. (S. cepae Berk, et Br.)3 A discussion of this fungus has been given in a previous paragraph. Its minute, round sclerotia which have as a conidial stage, a Sphacelia as found by Voglino (1903), exclude it from identity with the neck-rot fungus.
*Duby, Bot. Gall. 2:875; Saccardo, Syll. Fung. 14:1150. 2Saccardo, Syll. Fung. 14:1164; Lindau, Rab. Krypt. Fl. 19:674. 3 Saccardo, Syll. Fung. 14:1151; Lindau, Rab. Krypt. FL I9:661.
4.— S. durum Pers.1 has sclerotia which are 4-6 mm. long, sometimes 12 mm. long and as wide, at first under the epidermis then becoming free. This species is reported by Lindau to occur on the stem of Allium sp.; also, that Botrytis cinerea is said to develop from the sclerotia. It is not similar to the onion Botrytis sclerotia since the latter are in most cases inseparable from the host tissue.
5.— S. inconspicuum Lib.2 which is reported to occur on putrid onion bulbs has very small, brown sclerotia not at all like the sclerotia in question.
6.— S. pulveraceum Dur et Mont.3 has round-globose, small (0.2-0.5 mm.) sclerotia which have been found in the bulbs of Allium pollens. These cannot compare with the sclerotia found in the onion bulbs attacked by the neck-rot fungus because of their small size.
7.— S. tulipae Lib. var. Hyacinthi Guep.4 which is reported as occurring on the stems of Allium vineale has thin, ovate-oblong, minute sclerotia from which Botrytis parasitica Cav. is said to have been produced. Their occurrence on the stem, and their small size and thinness distinguish them from the sclerotia of the onion Botrytis.
Six species of Botrytis have been reported as occurring upon some parts of plants of Allium sp. These, also, will be critically compared with the onion Botrytis studied.
1.— B. aclada Fres.5 is reported as occurring on the dying scapes of Allium. However, it does not correspond to the onion Botrytis because it has ovoid-oblong conidia which are said to be one-half the size of those of B. acinorum Pers.; that is, 5-7 x 3.5-4.5 microns.
2.— B. carta Kze. et Schm.6 is reported to have large oval spores. According to Ward (1888, p. 360) Botrytis (Polyactis) carta Berk. (B. carta Schmidt) has conidia measuring 30-33 x 15-8 microns. The conidia of neither of these species compares at all with the long elliptical conidia of the onion Botrytis.
Saccardo, Syll. Fung. 14:1165; Lindau, Rab. Krypt. Fl. 19:674. 2Saccardo, Syll. Fung. 14:1151; Lindau, Rab. Krypt. Fl. 19:662. 3Saccardo, Syll. Fung. 14:1151.
4 Saccardo, Syll. Fung. 14:1172; Lindau, Rab. Krvpt. Fl. I9: 677.
5 Saccardo, Svll. Fung. 4:131; Lindau, Rab. Krypt. Fl. 18:285.
6 Myk. Hefte 1: 82; Saccardo, Syll. Fung. 4:129.
3.— B. cinerea Pers.1 has been reported on Allium sp. The writer has found this species growing upon dead parts of onion plants in a number of instances; but its roundish, oval conidia are not to be confused with the long elliptical conidia of the onion Botrytis responsible for the onion neck-rot disease.
4.— B. fulva Link2 which is reported as occurring upon the dead stems of Allium cepa has spherical, yellow-brown conidia measuring 4—4.5 microns in diameter and having fine spines.
5.— B. parasitica Cav.3 which is reported by Hohnel as occurring on Allium ursinum has conidia which are ovate and large, measuring 16-20 x 10-13 microns, or nearly twice the dimensions of the onion Botrytis conidia.
6.— B. vulgaris Fr. var. interrupta Fr.4 has been reported as occurring on scapes of Allium. This species has globular-elliptical conidia slightly longer than, those of the onion Botrytis. However, it has typical constricted or interrupted conidia, which definitely excludes it from being the onion neck-rot fungus.
From the foregoing statements it will be seen that the fungus causing the neck-rot disease of the onion has been incorrectly assigned under a number of different names none of which is available for it. Accordingly, the name Botrytis allii n. sp., is proposed with the following description:
Colonies dirty white shortly becoming smoke gray (Ridgway, 1912, pi. 46), old cultures approaching the drab of Ridgway, close, dense, feltlike; mycelium septate, coarse, with no definite method of branching, 4-9 microns in diameter, filled with fine-grained or minutely vacuolate protoplasm, giving rise to short erect conidiophores; conidiophores numerous, septate, erect, usually about 0.5 mm., rarely over 1 mm. high, occurring either singly or in clusters, not often branched on the host plant, but with a tendency toward branching in cultures, branches short and indicating a spiral arrangement, conidia-bearing on upper portion (i-f), conidial clusters approximate, not widely separated; conidia hyalin or very dilutely colored, elliptical, often slightly tapering at both ends, 7.1-16.2 x 3.8-6.3 microns, average 10.3x5.1 microns, attached by a short
1 Saccardo, Syll. Fung. 4:129; Lindau, Rab. Krypt. Fl. I8: 284.
2 Saccardo, Syll. Fung. 4:123; Lindau, Rab. Krypt. Fl. I8:280.
3 Saccardo, Syll. Fung. 10:536; Lindau, Rab. Krypt. FL I8:292.
4 Fr. Syst. Mycol. 3:398; Saccardo, Syll. Fung. 4:129.