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The Pamphlet Collection of Sir Robert Stout: Volume 14

The Ear Cockles (Or Purples) Worm. Vibrio tritici Tylenchus tritici. Bastian

page 47

The Ear Cockles (Or Purples) Worm. Vibrio tritici Tylenchus tritici. Bastian.

Fig. XXII.

Fig. XXII.

Adult Vibrio; eggs with worms escaping; section of gall; Floret with galls it. situ.

Although this is not an insect it causes frequent and serious injury to corn plants and grasses, and should it is considered be treated of in this Report. Curtis describes it in Farm Insects, and Taschenberg also in his Praktische Insekten Kunde, so that there are eminent precedents for this course.

The chief and most dangerous consequences of the attack of this Nematoid, or thread worm, a species of the order Nematoide œ, is the replacement which it causes of the grains of corn by a black or dark brown substance known as "ear cockle" or "purples," of a round shape. It is commonly supposed that it is the grain that is actually converted into this dark mass of cellular tissue; but it is in fact a foreign body, an excrescence, or gall, and contains what appears to be a mass of small fibres. This is, as the miscroscope reveals, a cluster of tiny thread worms.

Corn plants are also attacked by this, or as Mr. Carruthers, the Consulting Botanist of the Royal Agricultural Society, thinks, by another, species of Nematoid, in their stems, so that they are seriously weakened, and in some instances prevented from flowering.*

page 48

In the case of the ordinary attack in the ears of corn not only is the crop reduced but the sample is more or less spoilt, and besides there is the great danger of the extensive reproduction of nematodes from the galls being sown with the seed com.

* Dr. Bastian found specimens of Plectus Tritici between the lower part of the sheaths of wheat-stalks at Broadmoor.