Mary T. Franklin

Heterodera latipons n.sp., a cereal cyst nematode from the Mediterranean region.

Heterodera latipons n. sp., which was found on the roots of wheat and barley in Israel and Tripoli, can also infest oats and rye. The cysts resemble those of H. turcomanica Kirjanova & Shagalina, 1965, but lack the gland-like structures on the cyst wall and the eggs are larger, 112 X 48 μ, instead of 77 × 40 μ. Eggs and larvae are smaller than those of H. avenae and the fenestration of the cyst cone is different.

A root-knot nematode, Meloidogyne naasi n.sp., on field crops in England and Wales.

Meloidogyne naasi n. sp. is described from cereals, grasses and sugar beet in west and south-west England and Wales. It is distinguished by the perineal pattern and the forward position of the excretory pore in the female, by the long, slender tail of the larva and by the protruding first head annule in the male. In both larva and male there is a curious structure resembling a group of small vesicles in the anterior part of the median oesophageal bulb.

Aphelenchoides Composticola N.Sp. and a. Saprophilus N.Sp. From Mushroom Compost and Rotting Plant Tissues 1)

Aphelenchoides composticola n.sp., eine Ursache fur das Versagen der Pilzbeete, ahnelt A. parietinus, ist aber langer, relativ schlanker und hat drei Incisuren auf dem Seitenfeld anstatt vier. Mannchen sind haufig. A. saprophilus n.sp. tritt im Boden und in faulenden Pflanzenteilen auf. Er unterscheidet sich von A. composticola durch seine grossere Breite im Vergleich zur Lange, durch vier Langsincisuren und durch die Form der Spicula. Von A. parietinus unterscheidet er sich durch die Form des weiblichen Schwanzes, die relative Grosse der Eier, das haufige Auftreten von Mannchen und, wie A. composticola, durch die Leichtigkeit mit der er auf Agar in Verbindung mit dem Pilz Alternaria tenuis kultiviert werden kann.

Bursaphelenchus fungivorus n.sp. (Nematoda: Aphelenchoidea) from rotting gardenia buds infected with Botrytis cinerea Pers. ex Fr.

Bursaphelenchus fungivorus n. sp. is described and figured. It readily reproduces on cultures of Botrytis cinerea isolated from rotting gardenia buds in which it was found. Its larval stages and rate of reproduction are described.

A British root-knot nematode, Meloidogyne artiellia n.sp.

Roots of oats grown on sandy loam in Norfolk were observed by E. B. Brown of the National Agricultural Advisory Service, Cambridge, to have small galls associated with proliferation of the lateral roots. Close examination showed the presence of female Meloidogyne in the galls. The nematodes differed in some respects from the generally-known species and specimens were sent to the author for study.

On Heterodera cruciferae n.sp. of Brassicas, and on a Heterodera Strain infecting Clover and Dock

Heterodera cruciferae n. sp., parasitic upon Brassicas and other Cruciferous plants, is described and compared with H. schachtii , the sugar beet eelworm. The new species differs from the sugar beet eelworm in its host range, in the reaction of the larvae to root excretions of sugar beet and in the time of hatching of the larvae. The cysts are somewhat shorter and rounder than in the sugar beet eelworm and differ in having attached to the vulva a mass of jelly-like substance containing eggs and sometimes one or two males. The larvae are shorter than in H. schachtii . The males are similar but tend to be smaller and with shorter stylets. The results of infection experiments with cysts from the roots of dock and of clovers indicate that these cysts are of the same race, and are probably a biological strain of the sugar beet eelworm H. schachtii .

A Quick Method of Demonstrating Nematodes of the Genus Aphelenchoides in Leaves

When the presence of nematodes in plant tissues is known or suspected it is often useful to be able to show the exact situation of the parasites and their biological condition, i.e. whether they are quiescent or active. If plant tissues are teased apart in water active nematodes will be freed and will soon be seen swimming in the water, or, if they are in a state of quiescence, and yet viable, they will revive in an hour or more and become active in the water. Whichever is the case, there may occasionally be some doubt as to whether the nematodes were really in the tissues of the plant or were carried on the outside. The larvae and eggs of most parasitic eelworms are so small that they may easily be overlooked amongst the teased plant tissue, with which there may also be numbers of detached plant hairs closely resembling nematodes in their shape, size and transparency. If the parts of the plants likely to contain eelworms can be stained so that the worms take up the stain in contrast to the plant tissue, and can be seen in their natural position, a much more accurate picture of the situation may often be obtained than that derived from teasing the tissues in water.

Nacobbus serendipiticus n.sp., a root-galling nematode from tomatoes in England.

Nacobbus serendipiticus n.sp. verursacht Gallen an Tomatenwurzeln. Er unterscheidet sich von N. dorsalis durch die Form des reifen Weibchens, den Schwanz des Mannchens und die Lage der Vulva beim jungen Weibchen. Von N. aberrans weicht er in der Grosse des Oesophagus beim reifen Weibchen und der Lage der Phasmiden beim jungen Weibchen ab. Von N. batatiformis unterscheidet er sich durch das Fehlen einer Spermatheca beim reifen Weibchen, die Lage der Phasmiden beim jungen Weibchen, die Grosse der Eier, die Lange des Oesophagus und die Form des Seitenfeldes bei den Larven.

On the Structure of the Cyst Wall of Heterodera schachtii (Schmidt)

The examination under the high power of the microscope of the walls of Heterodera cysts found on the roots of Agrostis stolonifera L. (Franklin 1938) showed the presence of rows of markings having the appearance of small punctations, and led to the tentative diagnosis of these cysts as H. punctata Thorne. By the kindness of Dr. Thorne the writer has been able to compare her cysts with some of Dr. Thornes material, and has found that the surface markings have the same appearance. The writer would like here to acknowledge her indebtedness to Dr. Thorne for kindly lending his material. Cysts of several strains of H. schachtii have since been examined to find out if they also bear distinctive markings of any kind.

Population Changes and Development of Meloidogyne Naasi in the Field

Experiments show that soil samples, especially those taken between October and April, yield more larvae if they are incubated for a week at 20°C than if they are processed on the day they are taken. Samples taken in autumn after a host crop and kept at 0°C for a week before incubation yield more larvae than incubated, non-chilled samples. The numbers of free larvae in field soil are few during winter, increase greatly as the soil temperature increases in spring, decrease sharply when the host roots are invaded, remain low during summer and show a moderate increase when some of the newly formed eggs hatch in late summer. In the absence of a host crop numbers increase in spring and decrease gradually during summer. The rate of development of M. naasi in host roots depends on temperature and is the same in barley and ryegrass. The amount of energy in the form of heat required for development is approximately the same throughout the year but the time taken varies greatly.