PARASITIC AND OTHER INJURIOUS PARASITIC AND OTHER INJURIOUS PLANTS 75- The Chief Russian Species of Dodder. LARIONOW, D. Die Hauptarten der Russischen Seide und ihre Massregeln. der Samenprüfungsanstalten am kaiserlichen botanischen Garten zu St. Petersburg, Vol. I, Part 4, p. 27. St. Petersburg, 1912. This communication givs a description of the biological characters of Cuscuta. The writer considers Cuscuta to be an annual plant and attributes its passing the winter to the germination of its seeds in autumn producing winter forms. Cuscuta obtusiflora, H. B. K. var. breviflora Engelm. occurs in the Government of Astrakan on red pepper, onions and even on potatoes; this species is one of the rarest and occurs sporadically. C. Epithymum Murr. is met with on Papilionaceae, Labiatae, Daphne and Crupina vulgaris and is of very wide-spread occurrence. A classical district in which this species is abundant is the neighbourhood of Balaclava (Crimea). C. racemosa Mart. has begun to spread in the Governments of Ekaterinoslav and Chernigov. C. planiflora Ten. is abundant in the Crimea, Caucasus and Central Asia; the lucerne of Turkestan is much attacked by it. C. europaea L., which is common everywhere, injures hops, tobacco, hemp, poplars, alders, stinging nettles and Lycium barbarum L. C. Epilinum Weihe is found on flax in the Baltic Provinces and the Governments of Jaroslav and Kursk, on Camelina sativa in the Government of Kiev, on Lolium and Spergula; it occurs sometimes, but not often, in clover seed. C. cupuliformis Kroeker is found on garden trees and on lupins. This species, especially in the south, is very wide-spread. C. monogyna Vahl. is also parasitic in the south on Lycium barbarum, Prunus Amygdalus, Salix, Artemisia and Helianthus. The writer draws attention to the fact that it is necessary to take energetic measures for the control of dodders when the gardens are weeded in the spring. The fields should be ploughed over before sowing with buckwheat and millet, and burning should also be resorted to if necessary. It is very necessary that seed control stations be established and that sacks be sealed. The writer advises inspection on the frontiers for the purpose of preventing the introduction of dodder-infected clover seed to Russia. The sacks which have been sealed at foreign seed control stations, need not be subjected to inspection. 76- Bersim Dodder (Cuscuta aegyptiaca n. sp.). TRABUT, L. La Cuscute du Trèfle d'Alexandrie, Cuscuta aegyptiaca sp. n. - Bulletin de la Société botanique de France, Vol. LIX (Series 4, Vol. XII), 1912, 6, Séances de Juin 1912, pp. 489-491, plate XII. Paris, Nov. 13, 1912. In 1912, as a result of the importation of bersim (Trifolium alexandrinum) seed direct from Egypt, a dodder appeared in Algeria, which is very common in the Egyptian crops and is called by the natives "hamoûl ". Bersim dodder spreads very rapidly and grows at a remarkable rate. Unless energetically suppressed, this parasite hinders seed production, for it is especially the last spring shoots, which flower and bear the seeds, that this dodder attacks. The pest seems to follow bersim wherever it is cultivated. The species of Cuscuta in question was observed for the first time by Lippi, who named it Cuscuta aegyptiaca. Later, Fresenius called it C. arabica and described a specimen from Sinai; this name was used subsequently by other writers. The study of a large number of specimens decided the writer to separate bersim dodder from C. arabica Fres. It appeared to him, that the name C. aegyptiaca used by Lippi should be resumed to distinguish this dodder; though probably derived from C. arabica, it has already acquired red sufficiently distinctive characters to prevent its being confused, even with this very near ally. It is under the name of C. aegyptiaca n. sp. that M. Trabut gives a systematic description of the plant studied. 77 - On the Properties of Germination of the Seeds of Different Weeds. GÜMBEL, HERMANN. Untersuchungen über die Keinungsverhältnisse verschiedener Unkräuter. Landwirtschaftliche Jahrbücher, Vol. XLIII, Part 2, pp. 215-331. Berlin, 1912. The writer has made a series of experiments with regard to the germination properties of various weed seeds: charlock, wild radish, false oat, cornflower, etc. One result, among others, of these experiments was that the seeds of charlock should be numbered amongst those that germinate best under the influence of light. Comparative experiments made in light and in darkness showed the great importance of the condition of the seeds (age, stage of maturity, etc.) as regards the germination process and the secondary part played by temperature and its variations. Exposure to strong sunlight may be highly injurious to germination. Desiccation of the seeds, which should be carried at least to the degree of air-dryness, as a rule augments the germination percentage. But at great' depths in the soil even a whole period of drought has no influence on germination. Cold had an unfavourable effect on the seeds left on the surface of the soil in the open in winter: false oat, charlock, radish and cornflower. In the case of false oat, injury occurred even when the seeds were covered with soil. The depth at which the seeds germinate, and their development, depend much on the nature of the soil. Seeds of charlock may be of different colours, but black is their normal one, brown denoting abnormal maturation and arrested development. Under favourable conditions, charlock seeds develop beneath as much as 2.8 inches of soil. The optimum germination depth is, however 1.2 in. The writer considers that amongst the common graminivorous birds those of largest size may be considered important allies of the farmer in the control of weeds. In preparing the food for domestic animals it is advisable to boil or chop up finely all fodder containing weeds, but even without this precaution, the danger of the fields being infected by means of the live stock is less than it is supposed to be. 78- Tor-Grass or False Brome and its Eradication from Down Pastures. HUTCHINSON, HENRY P. in The Journal of the Board of Agriculture, Vol. XIX, No. 8, pp. 648-657 + fig. London, Nov. 1912. Large areas of Down pasture land have little grazing value owing to the presence of the weeds Brachypodium pinnatum L. or False Brome, and B. sylvaticum or Slender False Brome; the former is the species chiefly met with in pastures. Whilst they have a low value as forage they spread rapidly; being perennial and tufted in habit of growth they soon choke out the finer grasses and clovers. The plant is able to withstand excessive dryness owing to its extensive root system. It is spread from place to place by means of its seed which ripens in late summer and is carried by the wind. At the time of ripening sheep will eat the flower heads; in some districts advantage is taken of this fact to check the spread of the plant. Various measures have been tried with the object of eradicating the weed, but nothing entirely satisfactory has been accomplished. It is a regular practice in some parts to burn the grass annually, which renders the fresh growth more tender and more palatable to stock than the older shoots, and if the operation be carried out sufficiently early in the season, flowering is prevented, and further spread of the plant checked. At the farm of the South Eastern Agricultural College at Wye, the writer tried several methods of control. Quicklime. — In November some tufts of tor were covered with about 2 inches of quicklime. In the spring the young shoots failed to grow, but later in the summer growth proceeded as vigorously as before. Better results were obtained from the following treatments: 1. Application of Salt. In May, three small plots of tor, each about 2 perches in extent, were treated with brine of different strengths. These salted plots were much relished by the sheep and cattle and the grass was eaten down close, but after the salt had been washed away by the rains, grazing almost ceased on these plots and the tufts developed again, but no flowering occurred. 2. Digging. In the spring of 1909, 3 perches of tor-grass were cleared by digging. The turf was thrown aside the soil by this means being removed to a depth of 3 or 4 inches and the subsoil exposed. The latter was forked over, brought to a fine tilth and sown down with a suitable mixture. The seeds germinated satisfactorily, but the plants were weak and the sward ultimately formed was thin. This is what might have been expected, since the readily available plant food was removed with the turf, and the soil as a rule is thin on the hill sides. It is unnecessary to dig deeper than 3 inches in order to eradicate the weed. 3. Digging and Burning. In March 1910, 6 perches of tor-grass were cleared by digging. The turf was allowed to dry, then barrowed into heaps, and burnt slowly, the heaps being completely burnt out after nine to twelve days. The fine ashes and burnt earth were spread over the cleared plots, which were then ready for seeding, and no new tor shoots appeared afterwards, as the digging had been done carefully and no small pieces of stem had been left in the ground. This method though is expensive, about £5 10s. per acre. 4. Application of Gas-lime. In March 1910 on about 12 perches of tor the turf was dug out and while still green built into heaps; gas-lime was mixed with it, being distributed between the layers of turf; the bare ground was also covered with gas-lime. About I cwt. of gas-lime per perch; was used in the mixing and cwt. spread. The heaps were allowed to remain about three months and in June were thrown back over the cleared The cost of the treatment was the following: areas. It is very probable that less gas-lime than the quantity used would have been efficacious. 5. Another Application of Gas-lime. - On another plot of tor-grass about 12 perches in extent, two loads (about 34 cwt.) of gas-lime were broadcasted over the area as evenly as possible. In June, two months after treatment, all the grass appeared to have been killed. The cost was the following: Other experiments were made to ascertain the minimum quantity of gas-lime required and it was found that it must be applied, as fresh as possible, at about 21⁄2 cwt. per perch. Five months, at least, should elapse from the time of application to the time of resowing. The lime can be applied effectively at any time during the year, but autumn and early winter seem to be the most favourable. Where gas-lime cannot be obtained, the best method of eradication would be to dig the tor-grass out with a suitable spade to a depth of three inches. Where large patches occur on land which is not on too steep a slope, the tor might be ploughed out. The turf would require to be knocked about with harrows until dry. It should then be burnt or left until killed by the weather. Flowering should always be prevented by mowing, grazing with sheep, or burning, and young tufts should be grubbed out and burnt when first seen. GENERALITIES MEANS OF PREVENTION AND CONTROL DAVIDSON, W. M. in Journal of Economic Entomology, Vol. 5, No. 5, pp. 404-411. The paper under review reports several plant-lice not heretofore found in California, of which three species are new to science. A few sexual forms are also dealt with and illustrated The species here recorded are the following: Cerataphis lantaniae Boisd., taken on ferns in greenhouses; Phyllaphis coweni Gillette (syn. Cryptosiphum tahoense Davidson); Calaphis betulaecolens Fitch, whose sexual forms occur in November on cultivated birch; Calaphis castaneae Buckton, whose. sexual forms occur in early November on chestnut; Euceraphis betulae Kalt., whose sexual female is abundant on cultivated birch in November; Euceraphis flava sp. nov., not uncommon on the under side of the leaves of Alnus rhombifolia Nutt.; Aphis cardui, forming colonies on the young growth of several thistles throughout summer; Aphis atriplicis L., occurring on the upper side of the leaves of Chenopodium murale L., the sexual forms appearing in August; Aphis salicicola, abundant on willows throughout the summer, preyed on by the larva of a Leucopis (Agromyzidae); Aphis maidis Fitch, colonizing corn; Amphorophora latysiphon sp. nov., occurring sparingly on the periwinkle (Vinca major) and Convolvolus arvensis; Phorodon carduinum Walker, on the under side of the leaves of artichoke becoming a pest; very susceptible in California to fungus diseases; Myzus varians sp. nov., occurring an wild clematis (Clematis ligusticifolia Nutt.); Amphorophora ruhi Kalt., colonizing the terminal shoots of cultivated blackberry and loganberry and occurring also on the wild thimbleberry (Rubus nutkanus Moc.); Macrosiphum chrysanthemi Oestl., on the young shoots of a composite; Macrosiphum granarium Kalt., on various grasses in spring; Macrosiphum solanifolii Ashm., on wild lettuce. 80 The Vine Moth Caterpillar Parasite (1). FRENCH, C. in: The Journal of the Department of Agriculture of Victoria, Vol. X, Part 9, During the period from January to April, 1912, many shrivelled-up and dark-coloured Vine Moth caterpillars were noticed on vine leaves, (1) The Vine Moth is Agarista glycine Lewin. See: FRENCH, Handbook of the Destructive Insects of Victoria, Part II, pp. 101-107. Melbourne, 1893. (Ed.) |