File:The journal of the Ministry of Agriculture. (1920) (14783718642).jpg

Identifier: journalofministr2611grea (find matches)
Title: The journal of the Ministry of Agriculture.
Year: 1919 (1910s)
Authors: Great Britain. Ministry of Agriculture
Subjects: Agriculture Agriculture
Publisher: London : Ministry of Agriculture and Fisheries
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: BHL-SIL-FEDLINK

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ince the term dry rot is usually associated withforms of decay occurring in storage, and as the present diseaseattacks the growing crops and seldom, if ever, causes troublein storage, this term appears to be somewhat inappropriate.For this reason, therefore, another popular name, viz., WhiteRot (derived from the abundance of white mould at the baseof diseased bulbs in the early stages) has been adopted, and thesame name is employed in the Ministrys Plant Disease SurveyReport for 1918. In Bedfordshire, where this disease is wide-spread, it is termed Mouldy Nose, and in the north it isoften, though erroneously, termed Mildew (see later, p. 1098). Description of the Disease.—Onions become attacked withWhite Rot when the soil in which they are sown or planted iscontaminated with the fungus. They usually first showsymptoms of attack at the end of May or early in June. Asmight be expected in the case of a disease contracted from the * Ann. andl^Mag. Nat. Hist., VI., January, 1841, p. 359.
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Fig. 2. Fig. 3. Fig. 2.—Spring-sown Onion Plant attacked by White Rot, showingthe white mycelium around the base of the bulb. Fig. 3.—A pure culture of the White Rot fungus grown on potatoagar in a test tube. The culture is about a fortnight old, and showsthe production of numerous black sclerotia amongst the white mycelium. 1920.) The White Rot Disease of Onion Bulbs. 1095 soil, the attack commences with individual plants locatedindiscriminately over the beds, but if the soil is heavily con-taminated practically all the plants will be affected. Autumn-sown plants appear to be the earliest to suffer, but spring-sownonions suffer equally and, being smaller, are more quicklykilled and are sometimes destroyed in large numbers. The earliest visible symptom is one of wilting and yellowingof the foliage. The oldest leaves turn yellow and fall over,and later the other leaves also collapse. If the diseased plantsare gently pulled they will be found to come up very readily,and closer exami

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