GLOSSARY. 



403 



RusTOFCoMPOsiTiE. riicciuia Tanaceti, 

 Puccinia compositarum. — -This rust, injuri- 

 ous to conipositie, especially to Artemisia 

 dracunculus. Absinthium ft vulgare, Tana- 

 cetum imlgare, to the growth of chrysanthe- 

 mums, is characterized by small round, brown 

 and black cusl)ions which spot the leaves. 



Rdst of Gooseberries. Puccinia Ribis. 

 — The rust causes great damage by attacking 

 gooseberry leaves and fruit. 



RosT OF THE Leaves of the Mulberry. 

 Cylindrosporium Mori. — Tlie leaves of the 

 mulberry have, from the first of spring, 

 brown, pale, irregular spots, limited by the 

 veius. On these spots pustules are to be 

 seen, in which conidia form, by which this 

 fungus multiplies all the year round. The 

 peritheca appear on the leaves, which fall at 

 the end of the season. The disease does not 

 cause great damage ; but it renders the leaves 

 unfit for feeding silk-worms. 



Rust of Oats. Puccinia Coronata. — 

 This rust is peculiar to oats. It has, like 

 the preceding rusts, the uredo and puccinia 

 forms on oats, but on the contrary the 

 aecidium form on different plants of the 

 Rhamnacea;, particularly buck-thorn and 

 black alder. 



The rust of cereals often cause a con- 

 siderable decreased yield when the tempera- 

 ture is warm and tlie air humid ; the great 

 number of pustules exliaust the plant and 

 prevent the normal formation of grains, living 

 at the e.xpeuse of the substances accumulated 

 for that purpose. Garola found that 1000 

 grains of wheat from the rusted plant only 

 weighed 22'2 grammes, whilst the same 

 number of grains from healthy plants 

 weighed 42"8-65-5 grammes. According to 

 Gregoire the decreased yield is 8 per cent 

 to 2'i per cent for straw, and 21 per cent to 

 47 per cent for grain. 



Rust, Spotted. Puccinia Rubiyo vera. 

 — The uredo pustules formed on the leaves 

 and the stems of cereals are more oval than 

 those of the linear species. It is the rust of 

 wheat, altiiough it also attacks ri/e and barlej/. 

 On wheat it develops abundantly in the 

 spikelets, on the glumes where it can cause 

 great damage by stopping the growth of the 

 grain. Spotted rust does not fructify like 

 linear rust but as uredo and puccinia on the 

 cereal, and produces seeidium on the plants 

 of the family of Boragiuse : vipers' bugloss, 

 bugloss, officinal borage, comfrey, Ij'copods 

 of the fields, officinal cynoglossum (hound's 

 tongue). 



Rust ok Spruce Needles. Chrysmnyxa 

 Abies. — The young needles attacked in the 

 course of summer, from mid-June to mid- 

 July, turn yellow where the fungus is local- 

 ized. In autumn there are formed on these 

 yellow parts projecting elongateil gohlen- 

 yellow cushions, consisting of a mass of 

 teleutospores. In the spring the epidermis 

 splits above these cushions, the spores issue, 

 give off a promycelium charged with sporidia 

 and reproduce Ihe dust on the new shoots. 



Rust of Stone-fruit Trees. Puccinia 

 Pruni. — This rust attacks the plum-tree, 



apricot-tree, almond-tree, and peach-tree. 

 It is recognized by its cinnamon-brown tufts 

 consisting of uredospores on the under sur- 

 face of the leaves and the rapid alteration of 

 the latter. The trees attacked lose their 

 leaves prematnrely. 



Rust (Vesicular) of the Bark of the 

 Pine. Peridermium Pini, I'ine Cluster 

 Cups. — In May bladders or whitish mem- 

 branous sacs, which split to let the aecidium 

 spores which they contain, and which form an 

 orange dust, escape, are seen to appear on the 

 pines, chiefly at the foot of the stem of the 

 young plants, or on the branches of adult 

 plants. The mycelium extends between the 

 bark and the liber, and sinks into the wood 

 through the medullary rays. Tlie mycelium 

 is perennial and forms new receptacles each 

 year until the branch is exhausted and dead. 

 Under the influence of this fungus, the 

 starch in the cells is converted into turpen- 

 tine, which flows througli the holes in the 

 dead bark, and resinifies on the surface of 

 the diseased parts. On the young pines 

 the mycelium soon invades the whole stem, 

 and kills the tree, thus producing great 

 ravages in young plantations. The adult 

 trees resist longer, but, owing to the great 

 ilamage to the bark, and the cambium layer, 

 they languish, gradually lose their branches, 

 and top and finally die. This urediueie is 

 heteroic ; its uredo and teleuto forms are 

 found, according to Klebahn, on the swallow- 

 wort ( Vincetuxicum officinale) under the 

 name of Cronartium- ascejjliadeicm (Fries). 



Rust (Vesicular) of Pine Needles. 

 Peridermium oblongispoHum. — This rust is 

 similar to the preceding, but it is localized 

 in the needles. It develops secides in such 

 large numbers that the trees become per- 

 fectly yellow, but the damages caused to 

 the trees are less perceptible than those 

 caused by the preceding fungus. 



Rust, White, of Ckuciker>e. Cystopus 

 Candidas. RusT, White, of Composite. 

 Cystopus Cubicns. — The hyphie of the 

 mycelium of these diseases glide between 

 the cells of the nurse plant and there sink 

 their suckers. The conidiophora form white 

 pustules which are found indifferently on 

 the surface of the leaves, stems, flowers, and 

 fruit, for the fungus invades all the plant 

 and causes it to undergo very curious de- 

 formations. These diseases can only be 

 transmitted when their spores succeed in 

 introducing themselves through the stomata 

 into the cotyledons of the young plant. It 

 is then that they invade the plant during 

 its growth and infect all the organs. The 

 first of these diseases is injurious to water- 

 cress, to turnips, and to cabbages. The 

 second to viper-grass, and to salsifis. 



Rusts. UredincE. — The urediuae are 

 parasitic fungi the mycelium of which grows 

 exclusively in the interior of the body of 

 green plants. Their spores are generally 

 formed under the epidernns of the nurse 

 plant, whence it spreads outwards through 

 the tearing of the epidermis which occurs. 

 It is from the orange-brown colour of tlieir 



