. Circular. Agriculture; Agriculture -- United States. meters in length (see fig. 2). Tlie development of the female takes place within the underground tis- sues of tlie host plant and its presence in these tissues is indi- cated by enlargements or mal- formations. Figure 3 show^s a potato which is badly infected with gall worms. The skin is roughened and broken in patches. Fig. of the nema- Not all infected potatoes show the same symptoms. Often tlie gallworm is found in potatoes of which the skin is nearly smooth, and in such cases the presence white spots showing approx- ^j ^j^^ ]
. Circular. Agriculture; Agriculture -- United States. meters in length (see fig. 2). Tlie development of the female takes place within the underground tis- sues of tlie host plant and its presence in these tissues is indi- cated by enlargements or mal- formations. Figure 3 show^s a potato which is badly infected with gall worms. The skin is roughened and broken in patches. Fig. of the nema- Not all infected potatoes show the same symptoms. Often tlie gallworm is found in potatoes of which the skin is nearly smooth, and in such cases the presence white spots showing approx- ^j ^j^^ ])arasite can be detected imately tlio natural size of -i only by cutting the potato. In the infected tubers there is usu- alh^ a ring of darkened tissue just under the skin, and a microscop- ical examination of this tissue ^vill reveal the i)resence of the mature females and the region of the worm \_ 1 11 1 showing blind young larvae. In figure 4 are showm the larvae and the eggs of the gallworm as seen through the microscope from a preparation made from a diseased potato. One of the eggs seen in figure 4 is shown still further enlarged in figure 5. LIFE HISTORY OF THE GALLWORM. todo gallworm (JJeterodera radicicola) magnified So di- ameters: a, Mouth; 6, spher- ical sucking bulb; c, c, ova-' ries, as seen through the body wall; d, anus; e, small jitesp lately these worms. They are usually wliite. It is gener- ally not difficult to isolate them in water by breaking open the galls containing them. (After N. A. Cobb.). Fig 2.—The adult male of Helerodera radicicola, or gall- worni: /, Worm in profile view; //, head of the same, more highly mag- nified;///.middle The larvae of the gallworm upon hatching from the egg, which liatching sometimes occurs within the body of the parent, ultimately escaj)e from the liost ])lant and live for a period in the surrounding soil. Tlicse larva;, although verj' active, have but little power of progressive locomotion, and the spread of infec
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Keywords: ., bookcentury1900, bookdecade1900, booksubj, booksubjectagriculture
