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JOUENAL

OF THE

ROYAL HORTICULTURAL SOCIETY

ESTABLISHED A.D. 1804

EDITED BY THE

EE V. W. WILKS, M.A.

SECRETARY

VOL. XXVIII.

I903-I904

The whole of the Contents of this Volume are Copyright. For permission to reproduce any of the Articles application should be made to the Council of the Society in whom the Copyright vests.

LONDON

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ROYAL CHARTERS A.D. 1809, 1860, 1899

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BlJBUI moi.i ( « ANi-s. (The Garden.) (See p. lxvi.)

CONTENTS OF VOL. XXVIII.

PAGE

Fungoid Pests of the Garden. By Dr. Cooke, M.A., V.M.H 1, 313

Use of Ether and Chloroform for Forcing. By M. Emile Lemoine, F.R.H.S. 45

Little-known Trees and Shrubs. By Geo. Nicholson, V.M.H 52

Recent Trees and Shrubs from China. By James H. Yeitch, F.R.H.S 57

Darwinism and Evolution. By Rev. Professor George Henslow, M.A., V.M.H. 71

Ants, Green Fly, and Scale. By Dr. Bonavia, F.R.H.S 84

Blue Xymph.eas. By James Hudson, V.M.H 86

Horticultural Education in Greater Britain. By R. Hedger Wallace,

F.R.H.S 92

On Bottling Fruit. By Edith Bradley, F.R.H.S 101

Conifers in the Lower Thames Valley. By A. Wobsley, F.R.H.S 107

Peculiarities of the Cape Flora. By Rev. Professor Henslow, M.A., V.M.H. 112

Examination List, 1903 119

Future Development of Show Tulips. By J. W. Bentley, F.R.H.S 125

Fruit Culture at the Cape. By H. E. V. Pickstone 129

Modern Progress in Horticulture. By F. W. Burbidge, M.A., V.M.H 135

To Protect Cucumbers and Tomatos from Fungus. By Geo. Massee, V.M.H. 142

Horticulture in New Zealand. By Geo. Hunt, F.R.H.S 146

Root Growth in Daffodils. By W. Bartholomew, F.R.H.S 163

Ix Memoriam, Archibald F. Barron, V.M.H 181

Reports on German Iris, Poppies, Edible Peas, Dwarf, Climbing, and

Runner Beans, and Vegetable Marrows at Chiswick 183

Books Briefly Reviewed 205, 585

Commonplace Notes by the Secretary and the Superintendent 214, 591

Abstracts and Notes on Recent Research 225, 616

Judging Cactus Dahlias. By Chas. G. Wyatt, F.R.H.S 338

Vegetables All the Year Round. By W. H. Divers, F.R.H.S 344

Vegetables for Market. By W. G. Lohjoit, F.R.H.S 362

The Cooking of Vegetables. By Dr. Bonavia, F.R.H.S 369

Vegetables for Exhibition". By Edwin Beckett, F.R H.S 377

On the Productivity of Seeds. By F. J. Baker, A.R.C.Sc 385

Hardy Ornamental Vines. By James H. Veitch, F.L.S 389

The Hollyhock. By George Webb 398

Autumn Raspberries and Strawberries. By James Hudson, V.M.H 402

On Size in Flowers, Fruits, and Vegetables. By E. T. Cook, F.R.H.S 407

Germination of Amaryllide.e. By A. Worsley, F.R.H.S 420

Variation under Wild Conditions. By C. T. Druery, V.M.H 424

Medi.eval Medicine. By the Rev. Professor George Henslow, M.A.. V.M.H. 428

IV

CONTENTS.

PAGP

Thk Pruning ok Roses. By Monsieur Yiviand-Morel 487

luH K-tiAKi'KX \xi> \Vatki;sidk Irises. By Elkonoba Akmu age 481

Hardy boon. By W. J. Capaene, F.R.H.S 458

Alhixism. By John Bidgood, II. Sc., F.L.S 477

Heredity Experiments. By Chas. C. Hubst, F.L.S 483

Kmklk Fi x.. i. By Dr. Cookk. M.A.. V.M.H 495

Lkctckks to Students. By liev. Professor George Henslow, M.A., V.M.H. ... 511 Plaxtg hum. COUB Pbtbopolxs, South Brazil. By A. Worsley, F.R.H.S. ... 525

A«ii;< 'Nihik u. Notes on South Australia. By Dr. Krichauff, F.R.H.S 533

Thk Trust Deed of Wisley Gardens 538

Meteorological Observations. By Edward Mawley, F.R.H.S 543

I'kwis or the Hawaiian Islands. By the Rev. Canon Weymouth 552

Reports on Tomatos. Cactus Dahlias, Potatos, &c 554

Books, Plants, axd Seeds Presexted to the Society 606

Extracts from Proceedixgs of the Society :

General Meetings i, xiv, cvii, cxx, clix

Temple Show, 1*103 cviii

Holland House Show, 1903 cxiv

Exhiritiox of Edible Fungi cxxiv

British-grown Fruit Show, 1903 cxxv

Report of the Council for the Year 1902 iii

Scientific Committee Meetings xix, clxiii

Fruit and Vegetable Committee Meetings zl, clxxxvii

Floral Committee Meetings xlv, ccii

Orchid Committee Meetings lxviii, ccxxviii

Narcissus and Tulip Committee Meetings xci

Deputation to Cardiff cxxi

Notices to Fellows cii, ccl

Index to Illustrations cclxxiv

Index to Fungoid Pests cclxxvi

General Index cclxxxii

DIRECTIONS TO THE BINDER.

Volume XXVI II. has been issued in two numbers, each containing the / Urnal" proper, paged With Arabic figures, and " Extracts from the I'roeeetlinas," payed with Roman figures. This title and contents sheet should be placed first, and he followed by pages 1 to 312 and then by pages 313 to 728. After thai should come the " Extracts from the Proceedings," pages i to cvi and cvii to eclxxxvi, concluding with the three Indices.

JOURNAL

OF THE

Royal Horticultural Society.

Vol. XXVIII. 1903. Parts I. and II.

PESTS OF ORCHARD AND FRUIT GARDEN. By M. C. Cooke, M.A., LL.D., A.L.S., F.R.H.S., V.M.H.

Fbuit-geowees will find indicated in the following pages most of the pests which are likely to trouble them in their occupation. The arrangement is rather an artificial one, but it appeared to be best suited to the wants of practical men. Orchard trees will occupy the first portion, whilst the latter will be assigned to bushy and herbaceous plants with marketable fruits. Anomalies may be sometimes anticipated, as, for instance, placing Melons with Gourds and Cucumbers in the kitchen garden, and Tomatos in juxtaposition with Potatos. The Grape Vine and Pineapple, and similar tropical fruits, will have to be dealt with by themselves.

Apple-leaf Spot. Septoria pyricola (Desm.), PI. X. fig. 1.

Spotted leaves are common enough in the orchard and elsewhere, but they may have many causes, known and unknown, and cannot all be attributed either to insects or fungi. In most cases the spots on the leaves, although destructive to the leaf, unless very prevalent do not affect materially the general condition of the tree or the production of fruit, except in a few instances of a virulent kind.

In the present instance the spots occur on the upper surface of the leaves of Apple or Pear, and are of a greyish-white with a narrow brown margin. They are commonly somewhat rounded, from a quarter of an inch in diameter. The substance within the spot is killed by the mycelium and bleached, with the surface sprinkled or dotted with little black points not larger than the prick of a pin. Each of these points

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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY.

consists of a small nearly globose receptacle with a minute pore at the apex which encloses the fruit, or spores, of the fungus. When fully mature these minute sporules ooze out at the orifice in the form of a tendril and spread over the surface of the leaf.

The sporules in the present species are elongated and threadlike, with about two transverse divisions (60 x 3^ ^) of a very pale olive tint.

Found generally throughout Europe.

Sacc. Syll. iii. 2624 ; Cooke Hdbk. No. 1320 ; Seem. Journ. iv. f. 27.

A large leaf-spot {Pliyllosticta pyrorum) is known in the United State-, with much smaller sporules (10 x 2 /*).

Apple-leaf Black Mould. Coniothecium Quest ieri (Desm.).

This mould was first discovered in France nearly half a century ago on leaves of Cornus, and has appeared this season (1902) on fading leaves of Apple, although we have grave doubts of its being any other than a saprophyte. It occurs on the under surface of completely dead spots of the leaves, or on thoroughly dead and brittle leaves. The tufts are small and scattered in little black dots over the dead parts, but do not occur upon the merely discoloured and fading leaves.

The conidia are conglomerated in variously shaped clusters of from two to eight cells (about 10 a* diam.), of a pale brownish colour, mixed with occasional slender threads.

Sacc. Syll. iv. 2442; Trans. Br. Myc. Soc. (1903), p. 15.

Apple-thee White Mould. Oidium farinosu/m (Cooke), PL X. fig. 2.

This mould was first observed in 1870 and 1871 covering the young kwigfl and leaves of Apple trees with a mealy coating of white mould, so that they looked as if dusted with flour or powdered chalk. Since the above it lias he-come sufliciently common. Although it is a true epiphyte, r ifl capable of inflicting injury, causing the young leaves to curl, phoMriwg their growth, and distorting the tender twigs.

Tin iv is a thin and delicate but profuse mycelium from which ari-e tin fertile! branches, which are elub-shaped and divided by transverse Bpta into ihort joints, which gradually contract at the suture, and then the top j<»int ha\ing acquired an elliptical form falls away as a conidium. to be followed successively by the other joints, so that a continuous crop of mature 0 midia is ensured. They are externally quite smooth and eolourh ss (2H 30 x VI

Tin- habit and structure of this mould are quite similar to the Oidium of the \ine, that which precedes the Hose mildew, and the development of the different species of ilryaiphv.

In 1H!)0 this mould made it- appearance on Apple trees in South Wric.i, and possibly it is the same species as one which is common east Of the Mississippi in the I nited States.

PESTS OF ORCHARD AND FRUIT GARDEN.

Fig. 1. Apple Mildew (Sphwrotheca maU).

As the mycelium'of the fungus appears to be perennial in the tissues, diseased shoots should be removed along the line marked f. Spraying does not check this disease. The point affected should be all cut away.

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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY.

In such cases dusting with dry sulphur is likely to be the most effectual treatment. In America the application of the ammoniacal solution of carbonate of copper is recommended.

QreviLleOy xvi. 10.

Apple-twig \Yhite Mildew. SpluerotJieca malt (Duby).

A century ago one of the fungi closely allied to that of the Rose and the Hop was imperfectly described in France under the name of Erysiphe viali, but very recently it has been revived by Dr. Magnus, who has seen and figured one of the conceptacles. It was said to be broadly eftused ; the thin arachnoid threads of the mycelium interwoven ; the conceptacles rare, and scattered, subglobose, rugulose, and black.

The mould already described here under the name of Oidium farinosum appears to be the mycelium and conidia of the above fungus, but at present the more perfect and complete condition with the con- ceptacles has not been met with in this country. In this instance we appear to have a " perennial mycelium in the host plant, which grows along with the shoot each season, stunting its growth and eventually killing the tree." (Fig. 1.)

Journ. B.II.S. (1902), xxvi. p. 737, fig. 310; Duby, Bot. Gail. 869.

Fruit-tree Pustule. Eutypella prunastri (Pers.).

This compound Splicer ia is only parasitic in the early stage, when spermogonia are evolved in tendrils through punctures of the bark. No one has seen the complete or true Eutypella stage, except on dead tissues. In this condition the perithecia are clustered together in definite pustules, some five or six, with long converging necks, which are sulcate or grooved at the extremity or ostiolum. The fructification is contained within the perithecia, consisting of eight sporidia, enclosed within a transparent MOU8, of which there are several. The sporidia are cylindrical, curved, and but slightly coloured (6-8 x 1! p).

Ttit spermogonia, which are developed earlier, ooze out in tendrila from the mouths of the receptacles, and are known in this stage under bhe name of Oytispora rubescensy. they are not more than half the length of the conidia. It is reported that this is a wound parasite, and enters through wounds made by pruning, finally causing discoloration in the centre of the stem (see figs. 2 and 8). The trees will continue to grow for several years after infection.

Destructive to Apple and other fruit trees, especially Plum and Cherry.

Sacr. Syll. i. 566; 0ool< /A/A/,-. No. 2460; Juiim. B.E.S. (1902), ml p. 742, fig. 818; Z bid. xwii. pp. 691, 986,1152; Gard. Ghron. 1908, ... 2:i:». lig. SO ; lirrlcsc Icon. iii. pi. 85.

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5

Fig. 2.— Eutypella prunastri.

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Brown Rot. Monti ia fructigena (Pers.), PI. X. fig. 12.

This rot is not confined to the Apple and Pear, but attacks most orchard fruits, especially the Cherry, to which we shall refer it later on. (See " Apricot Brown Rot.")

Thitm. Pom. p. 22 ; Joimi. B.H.S. (1902), p. 738, fig. 811.

Fruit Spot.

Septoria Balfsii (Berk.).

About the year 1854 Berkeley described a small fungus which accompanied spotting on ripe Apples ; but it never seems to have been demonstrated that it was the cause of the spotting, and as nothing has transpired since which leads to the conclusion that it is really a fruit disease we can dismiss it with a brief notice.

The appearance caused is that of black patches of an irregular form on the surface of ripe Apples. Over these patches are scattered the minute points, which indicate the receptacles of the fungus. The sporules are long and slender (30 n long) with six minute nuclei. Pears as well as Apples are said to have suffered from the same infliction.

Sacc. Syll. iii. 3028 ; Cooke Hdbk. No. 1307 ; Berk. Ann. K. H. No. 745, t. xv. f. G ; Thiim. Pom. p. 122.

Apple Scab. Fusicladium dcndriticum (Wallr.), PI. X. fig. 3.

This disease appears under different forms, but in all cases it seems to be caused by the same fungus. On the leaves it comes in small olive spots, which are somewhat rounded and gradually enlarge, and become velvety and irregular ; frequently two or three spots will run together and form a large irregular blotch. The mould also appears on the petioles and the young twigs. The threads of which the mould is com- posed have a radiating habit, from which its specific name is derived. On the fruit its appearance is similar, but as the spots increase in size the cuticle cracks and forms a light-coloured ring about their margin. The greatest vigour is towards the edge of the spots, where the fruit seems stimulated to the production of a kind of corky layer in its efforts to throw off the disease and the formation of scab. Generally the result is to produce on the fruit crackings with a thickened scabby edge.

Tin mycelium is rather superficial, and produces short erect brown threads at the apex of which the spores, or conidia, are produced. These bodies arc somewhat oval, attenuated towards each end, so as to be thickest in the middle, or they are of an elongated Pear shape, and coloured brown, like the threads, but varying much in form and si/e. Although ii mill) con isting of only B single cell, the conidia. BAG sometimes divided by a septum towards one end into two unequal cells (30 x 7-9 p).

PESTS OF ORCHARD AND FRUIT GARDEN.

Fig. 3. Eutypella prunastri, causing a Disease of Nursery Stock.

A young Peach branch becoming shrivelled, indicating that the stock is dying. (Natural size.) B. The conidial stage of fruit bursting through the bark. (Natural size.) C. The second or ascigerous condition of fruit, showing at the surface through transverse cracks in the bark. (Natural size.) D. Surface of view of the second form of fruit, surrounded by the ruptured bark. ( x 40.) E. Cruciate mouth of a perithecium. ( x 400.) F. Ascus and spores. ( x 400.) G. Section through ascigerous form of fruit. ( x 80.) H. Section through conidial form of fruit. ( x 50.) I. Conidia. ( x 1,000.) '

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The coniclia germinate rapidly in water or moist air, and scab spots on the fruit may be found covered with vast numbers of germinating spores. The germ tubes are rather thick and coloured, with frequent divisions, or septa ; sometimes the germ tubes will produce secondary sporos at their tips, which in turn germinate like the original spore. The conidia will germinate in pure water (50° Fahr.) within eight hours. It is believed that the mycelium is perennial, living in the fallen leaves and twigs, and especially in the fruit, during the winter.

It has been observed in America that the individual cells or joints of the mould, under favourable conditions, will push out germ tubes and develop new individuals of the species. " This method may be roughly compared to reproduction by root cuttings in higher plants."

In early spring spray thoroughly with sulphate of iron. As soon as the fruit is set apply Bordeaux mixture or a modified preparation of eau celeste.

In storing fruit especial care should be taken to separate all Apples which show any signs of " scab " from those which are sound and healthy, and store in a dry place.

This pest is recognised in France, Belgium, Germany, Austria, Italy, North America, and Australia.

Gard. Chron. Nov. 28, 1885, figs. 155, 156; Mass. PI Dis. 302. fig. SO; Sacc. Syll. iv. 1642; Sacc. Fun. Ital. t. 782 ; Cooke Hdbk.No. 17 '47 ; U.S.A. Dep. Agri. 1887, p. 341, with figs. ; Thilm. Pom. p. 15 ; Grevillea, xx. p. 27 ; Tubeuf, Dis. 219, fig.

Apple rot, after scab, causes serious trouble in the United States. It is attributed to the common mould, Ccphalothccmm roseum, which has always been regarded as a saprophyte in Britain.

Bitter Hot of Apple. Glozosporium fructigcnum (Berk.), Pi. X. fig. 4.

Under the above name a disease is known in the United States which is attributed to this fungus as a cause. In this country it is rather doubtful whether the fungus is the cause of disease, since it has been affirmed that in most observed cases the fruits have been decayed before the fungus made its appearance. Still it must be conceded that nearly all the species of the genus to which it belongs are active parasites.

The pustules are circularly arranged in a cluster of a dirty rose colour, at length splitting the cuticle at the apex to discharge the < intents. The conidia are cylindrical, sometimes curved, rounded at the ends and colourless (20 30 x 5-6 /«), produced at the tips of nearly equally long hyaline threads.

Notwithstanding that the fruit exhibits decay with us before the fungus is detected it may prove to be true that such decay has been caused by the ( i hrcs/xtrium. In America it is said that 'the affected Apple ut first hows one or more black, or usually brownish, spots on any part of the surface ; as these gradually enlarge their shape becomes more or less circular, and their borders somewhat sharply defined, sometimes tin pot - co;il< ci , or run together, and in this manner the entire Apple

PL. X.

PESTS OF ORCHARD AND FRUIT GARDEN.

9

is soon affected. Towards the centre of the diseased spot there is usually a very dark, frequently almost black, discoloration. The darker portions are studded with minute black points, which are slighly raised above the surrounding tissue, imparting to their surfaces a somewhat roughened appearance ; occasionally these points are arranged in circles or grouped in little clusters."

It is affirmed that the spores when sown in water germinate within ten hours by sending out one or more thickish germ tubes. In about twenty hours they will produce at their extremity globose bodies (8 n diam.), more or less dark-coloured, which are of the nature of secondary spores. These secondary spores germinate in like manner, and produce, in a third series, the same kind of bodies as the original primary conidia. So that by an alternation of generations the old type is reverted to.

In addition to the above it has been announced that thick-walled cavities have been found at the base of the conidia-pustules, which con- tain minute colourless bodies resembling spermatia ; what may be their purpose or destiny is still an open question. No wonder, then, that the Apple growers of the United States have been cautioned that they " have a dangerous foe to contend with," and they are on the alert.

The fungus is known in Britain, Italy, and the United States.

The remedies suggested are spraying with a solution of one half an ounce of sulphate of potassium to one gallon of water. Application at intervals of ten days. In some cases the disease was arrested after the first application. Another fungicide applied with success is the ammoniacal carbonate of copper solution.

Grapes are also liable to the same disease.

Sacc. SylL hi. 3751 ; Mass. PI. Dis. 281, fig. 75 ; Gard. Chron. 1856, p. 245 ; U.S.A. Dep. Agri. 1890, pi. iii. ; Cooke Hdbk, No. 1411 ; Thilm. Pom. 59; Tubeuf, Dis. 482.

Apple Speck. Spilocaa pomi (Fr.).

An enumeration of the fungi which attack Apples and Pears would not be complete without reference to two or three obscure species which are reported to have occurred on the fruits. The little black specks upon ripe Apples which resemble fly-spots have not afforded any evidence of fructification. Known under the above name, they are probably only incipient conditions of " Apple scab."

The Spliceria malorum of Berkeley, found upon decaying Apples lying on the ground, would be outside the bounds of our inquiry, since it is clearly a saprophyte, and possibly only Diplodia malorum.

In 1878 Baron von Thiimen published a work entitled " Fungi Pomicoli," in which he enumerated thirty-one fungi as growing on Apple and twenty-three on Pear trees, or their fruit. It is consoling to find that the majority of these are in no respect parasitic, and many of them common to all kinds of vegetable matter. Hence it is no guide to orchard pests.

Ft. Sijst. Myc. iii. 504 ; Thilm. Pom. p. 9.

10 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY.

Apple-twig Tumour. Botryodiplodia pyrcnophora (Sacc), PI. X. fig. 5.

Little swellings are sometimes to be seen on Apple twrigs in which the bark cracks in an irregular manner and exhibits beneath a cluster of black perithecia, about the size of pins' heads, closely packed together, and seated upon a kind of cushion formed from the mycelium.

These perithecia when mature contain a mass of rather large elliptical sporules, at first one-celled and colourless, but afterwards divided across the centre into two cells, and then of a deep brown colour. Possibly this is only a condition of a more highly organised fungus in which the spores arc contained in asci.

Fig. 4 Bp&BBOPSXS malokuu.

It Beems rather doubtful whether the "chancre" attributed to SpharopstS malo rum (Bull, de la Soc. Myc. de France, 1903, p. 134) may in t be a condition, or stage, in the development cf this same disease . (Pig. 1.)

At jn< >cm this is a rare disease, and must be hunted after to be di>co\tre<l ; but it is quite possible for it to become a pest if it establishes itx lf in an orchard. Hitherto we have no record of its having become troublesome, and consequently no experiments have been made [or its eradication.

\\ i diould certainly recommend its destruction wherever found, since it i> quite capable of extending itself hold by its mycelium and sporules. Sit,, . Syll. iii. 2121 ; Cooke lldhk. No. 1201.

Then- is a small twig pustule, caused by Phoma mali, which is not so elustared or conspicuous on the twigs of Apple and Pear trees. The

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11

sporules (8 /x long) are expelled when mature, and in some places it is looked upon with suspicion.

Apple-tree Canker. Nectria ditissima (Tul.), PI. X. fig. 6.

Ten or twelve years since R. Goethe propounded the opinion that canker on Apple trees was produced by the growth of the above-named fungus, which is of the Sphceria kind, a little resembling those clusters of red Nectria which are so common on Currant twigs, but smaller. Goethe claims to have demonstrated his position by cultivating the parasite both from conidia and ascospores. The same fungus he contends produces canker on various kinds of Pear trees, and the sporidia of the Nectria from the Apple were found to produce canker on the Beech and Sycamore, and again from these trees on the Apple.

According to Hartig the fungus enters through wounds caused by hail or the puncture of an insect. The best remedy, according to these authorities, is to cut out the diseased tissues and anoint carefully with coal tar.

The fungus consists of a number of little red dots, scarcely so large as a pin's head, growing in clusters in cracks of the bark. These minute dots are spherical and smooth, seated on a white mycelium, and when mature enclosing a kind of pulpy nucleus, like a tiny drop of gelatin, and which consists of a great number of long cylindrical tubes, or asci, each enclosing a row of eight elliptical sporidia, which are divided by a trans- verse septum into two cells. When ripe they are capable of germination from each cell (14 x 5-6 fi).

Occurs in France and Germany.

GarcL Chroii. March 8 and April 19, 1884, p. 313 ; 1891, p. 300, figs. 66, 67 ; Sacc. Syll. ii. 4671 ; Mass. PL Dis. 127, fig. 24 ; Grevillea, ix. p. 116 ; Tubeuf, Dis. p. 187, figs.

Apple -bark Valsa. Valsa ambiens (Fr.), PI. X. fig. 7.

It is only during the past year or two that we have become satisfied that this usually saprophytic fungus has seriously affected living Apple trees at least during its early or conidial condition.

The bark of living branches and trunks was observed to be roughened with little elevations from the apex of which proceeded what appeared to be a long twisted yellow filament, not thicker than a horse-hair, entangled together into a mass of golden threads. When moistened these threads dissolved into myriads of minute curved conidia (5 jj. long) which had oozed out from minute punctures of the bark, and proved to be those of a fungus called Cytospora ca/rpkosperma, common on many orchard trees, but heretofore considered saprophytic.

The mature condition is to be found in spring on branches that have lain on the ground through the winter, and consists of clusters of receptacles, flask-shaped, with long converging necks, containing sporidia

12 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY.

which are cylindrical, curved, and rounded at the ends (16-18 x 3-4 fj), and of these ei^ht are produced together in a membranous sac or aseus. This m; ture condition is only arrived at after hibernation, and con- sequently upon dead branches, but the early stage is clearly parasitic and may become troublesome. The mature stage is called Valsa ambicns.

Certainly whenever seen oozing out of living trees the parts should be well rinsed with Bordeaux mixture, so as to destroy all the germinating power of the conidia.

Sacc. Syll, i. 512; Cooke Hdbk. No. 2475; Gurr. Linn. Trans, xxii. t. 48, f. 138.

Peak-leaf Cluster-cups. Bastelia canccllata (Reb.), PI. X. fig. 8.

There is hardly any parasite which appears to be such a puzzle to gardeners as the Bojstelia or " cluster-cups " of the Pear leaves. They

Fiu. 5. Peak-leaf Clubteb-cup.

A fungus growing on two different kinds of plant at different periods of its

life-cycle.

1. The spring stage of the fungus on a living Juniper branch, reduced in size. _'. Spurt' of same, < 300. 3,4. " Cluster-cup," or summer form of fungus fruit on living Pear leaves, reduced in size. 5. Two cluster-cups, one cut open, slightly x . 0. Spores of cluster-cup condition, x 300.

base al o been a puzzle to others who are not gardeners, as evidenced by the literature of the past quarter of a century. We can permit the discussion to rest and state a few conclusions.

The parasite thickens the Pear leaves at the infected spots by the internal growth of the mycelium upon this, and externally are produced a small cluster of flask-shaped pale brown bodies called pcridia, and these are omi q»lit len-tliwis* nearly to the base into thread-like filaments which are for a Ion- tunc united together at the apex. The contents of these flask-shaped bodies are the acidiospores, which are nearly globose

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13

and warted on the surface (25-40 x 18-25 m). These spores are produced in chains, readily separating from each other.

Spots are also to be seen on the opposite side of the leaf to that which bears the Bcestelia and corresponding to it. These are conspicuous by their orange colour, which becomes reddish, sprinkled with blackish dots, which indicate cells containing very minute bodies called spermatid, which are expelled when mature.

It is recorded in Hooker's "British Flora" that when young Pear trees are planted near old trees suffering from the Bcestelia the young trees have been observed to become much injured by the fungus. Mr. Knight sowed Pear seeds in soil infested with Bcestelia, and the very youngest of the seedlings showed the disease.

According to theory it is contended that this kind of cluster cups must also have a condition analogous to the Uredo and Puccinia forms. As this is not known to take place upon the Pear tree itself, it is inferred that it must take place upon some other plant. The plant selected as fulfilling the condition is the Savin, and it is contended that the cluster cups of the Pear tree produces those gelatinous exudations on the stems of the Savin which are known under the name of Gymno sporangium.

(Ersted originated this suggestion in 1865, when he intimated that he had learned that gardeners were of opinion that the Pear fungus was never seen except after the appearance of the fungus on Savin. Hence he set to work to prove by cultures that the Pear fungus would produce the Savin fungus by inoculation, and vice versa. (Fig. 5.)

Incidentally Stevenson records that the Savin fungus is found in Scotland, but that the other condition, the Pear-leaf fungus, is not a Scottish plant.

The advice given to gardeners by the theorists is to destroy all Savin bushes, root and branch, if they would save their Pear trees. Berkeley, however, wrote : " If picking the leaves off carefully and burning them will not do, we may feel secure that an onslaught against the poor Savin bushes will not avail us."

Known in France, Germany, Switzerland, Austria, and North America.

Sacc. Sytt. vii. 2608 ; Cooke M. F. 193, t. 2, f. 2021 ; Plowr. Br. Ured, p. 230; Mass. PI. Dis. 257; Thiim. Pom. 73; Cooke Hclbk. No. 1597; Gard. Chron. 1862, p. 689 ; Tubeuf, Dis. 399, fig.

Pear-leaf Blister. Exoascus bullatus (Tul.), PI. X. fig. 9.

The blister of Pear leaves is a disease which has long been known in this country, distorting the foliage in a similar manner to the "curl " on Peach leaves.

The under surface of the leaves is occupied by the external manifesta- tions of the fungus, but the mycelium penetrates the leaf. The glaucous appearance of the hollows of the blisters consists of tufts of small cylindrical cells, or asci, each containing eight small ovate uncoloured sporidia (5 /j. diam.). When these sporidia are mature the asci are ruptured at the apex, and they escape.

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When first discovered this fungus was called Oidium bidlatum, until the presence of asci was determined.

M In many cases these blisters formed two parallel lines on either side of the midrib, but sometimes they were irregularly scattered over the leaf. In some cases the blistered part had become black, and in others the portion of the leaf which had protruded had fallen out, so as to leave a regularly defined aperture. The cavities were found to be lined with a thin white stratum, consisting of myriads of confluent white specks of a waxy rather than a powdery appearance."

It is incumbent upon the cultivator to pick oft' all the blistered leaves and burn them, so as to keep a check on reproduction. Spraying young trees with Bordeaux mixture at intervals of a fortnight may be pre- ventive.

Joiirn. B.H.S. ix. p. 48 ; Sacc. %//. viii. 3343 ; Mass. PL Dis. 90, fig. 13 ; Cooke Hdbk. No. 2232, fig. 342.

Peak-leaf Blight. Entomosporium maculatum (Lev.), PI. X. fig. 10.

This disease is very destructive in the nurseries of the United States, although its presence in this country is rather doubtful.

Small red spots on the leaves first appear : these increase in size and become brown, or it may extend over the leaf, which then shrivels and falls to the ground.

The conidia, or sporules, have a very peculiar form, consisting of two nearly equal uncoloured cells attached end to end, and two smaller cells on opposite sides at the point of attachment, so as to present an unequal cross-shaped body. These conidia are produced superficially, in consider- able numbers upon the leaves, extending also to the fruit (18-20 x 12 ll).

It also attacks the leaves of the Quince. Pear fruits when attacked are liable to crack ; hence a common name for the disease is "cracker."

Spraying with Bordeaux mixture holds the disease in check, using a V&py dilute solution. Dead leaves should be collected and burnt.

Sacc. Syll. iii. 3501 ; Mass. PL Dis. 276, fig. 73 ; Galloway, Rep. Ag\ :. U.S.A. 1889, p. 357, pis. viii. ix. ; Tubeiif, Dis. 480.

Pear-leaf spots, as distinct from those on Apple, are also recorded as Phyllosticta pvrina and PJu/llosticta piricola in Southern Europe, Asco- chyta piricola in Italy, and Scptoria n'ujcrrima in Germany.

Pear Scab. Fusicladitm pvriwum (Lib.), PL X. fig. 11.

lietweon the Pear scab and the Apple scab there seems to be very little diU'cnnee except in name. The conidia are the same in size, and the little dim -roiicr in form can scarce; bo material.

Tlx external map 1 f efltatlODB) both on the leaves and the fruit, are very imilar: in the former case both form irregular velvety olive patches, which are apt to have a dendritic appearance on Apple leaves.

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The threads are short and rather robust, and the conidia are typically rather fusiform, being attenuated towards each end (28-30x7-9 /*), and we have never met them with a transverse division, whereas those of the Pear scab are usually of a club shape, and often divided into one large cell and one small one.

Known in Germany, Austria, Italy, Portugal, and France.

For remedies see also Apple Scab. 1

Sacc. Syll. iv. 1643 ; Mass. PL Dis. 304, fig. 81.

A mould with fusiform conidia, not unlike Fusarium, is recorded as affecting ripening Pears in France. It has been named Discocolla pirina.

Ameeican Pear Blight. Micrococcus amylovorus (Burr.), PI. X. fig. 25.

Pear blight, or fire blight, is known only in North America, and was first observed in 1780, but no description of it until 1817. " It frequently destroys trees in the fullest apparent vigour and health in a few hours, turning the leaves suddenly brown, as if they had passed through a hot flame, and causing a morbid matter to exude from the pores of the bark of a black ferruginous appearance." The results of epidemics have been most disastrous, especially the memorable year of 1844.

Various conjectures have been made as to its cause, the last of which, the bacterial, advocated by Professor Burrell, was supported by a long series of experiments by inoculating healthy branches with the juices of diseased ones and producing the disease, since which time the experi- ments have been confirmed.

The organism named Micrococcus amylovorus consists of single cells, of oval or roundish shape (1—1 J x J-f ju) and quite colourless. For the most part they remain single, but may often be found in pairs, rarely a series of four or more, but never extending to chains.

Sacc Syll. viii. 3887; Amer. Nat. xvii. 1883, p. 319; Arthur, History and Biology of Pear Blight, 1886, plate ; Grove, Syn. Bact. p. 10.

Medlar Cluster-cups. Mci&ium mespili (DC).

This species of cluster-cups appears now to be recognised as distinct and alone, without Uredo or Puccinia to keep it company. It is only reported to occur on the leaves of Mespilus and Cotoneaster.

Rounded or irregular spots are formed upon the leaves, which are yellowish or reddish on the upper side, with a yellow border, thickened in the centre. The cups are cylindrical, splitting at the edge into narrow teeth or threads. iEcidiospores angular (19-24 [x diam.), very minutely warted and brown.

There is a suspicion of this species having been found in Britain, but it evidently has never given any trouble as a pest. It occurs also in France and in Germany.

Sacc. Syll. vii. 2773 ; Plowr. Br. Ured. p. 232 ; Mass. PL Dis. 258.

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An anthracnose attacks the leaves of the Quince (Glceosporhun Cydonia) in Southern Europe, as well as two or three kinds of leaf-spot, and Oidium Cydon'ue in Italy.

Medlar White Mould. Oidium mespilinum (Thiim.).

This white mould occurs on the living leaves of Mespilus in Austria, forming broad white thin patches on the upper surface, which consists at first entirely of an epiphytal web of mycelium. From this shortly arise the fertile branches, which are at first simple and club-shaped. After- wards two or three elliptical cells or conidia are cut off from the upper portion of the branches, and form the short chain of spores (10 x 6 fi) which ultimately acquire a pale grey colour.

It is clear that this is an epiphyte of the same character as the various species of Oidium which precede such mildews as that which attacks the Hop, Rose, Gooseberry, Maple, Garden Pea, and many other plants.

In the case of any trouble the application of dry powdered sulphur is the safest remedy.

Sacc. Syll iv. 208 ; Grevillea, xvi. 58.

Another white mould (Ovularia necans) has damaged Quince and Medlar trees in Italy and France. Two kinds of leaf-spots are known on Medlar leaves, but neither is recorded as British. Phyllosticta mespili and Septoria mespili are both of them European.

Plum Powdbri Miu>i:w . Uncinula pruuastri (DC), PI. XI. fig. 17.

This mildew resembles externally the previous species so much that it is scarcely possible to detect the difference by the naked eye. However, it is more commonly found on the wild Sloe than on the cultivated Plum.

The mycelium is thin, and spreading over the surface of the leaves, giving them a frosty appearance, but never very dense. The conidia, in tin early stage, are of the Oidium form, and are produced in short chains.

The receptacles are globose and minute, scattered over the mycelium, and Mara Iv visible to the naked eye. The appendages which surround the base of the receptacles are very numerous and peculiar in their character, inasmuch as they are unbranched and curved at their tips in a hook-like manner, and are about twice as long as the diameter of the red ntacle. Each receptacle contains from twelve to sixteen transparent IN ar -maped .acs, or asci, each of which contains six sporidia.

Tin- sjmc'h i found also in France, Belgium, Germany, and Italy.

As an cpiphUc, should this species threaten to give trouble, it should be t with i he uilphur treatment.

Sacc. Syll. i. ; Cooke M. F. 289.

PL. XI.

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Plum Gummosis. Cladosporium epiphyllum (Link.), PI. XI. fig. 18.

Gumming, as exhibited in Prunus japonica, was made the subject of investigation by Massee in 1899, and the features were so apparently identical with those which takes place ordinarily in Plum and Cherry trees as to indicate the possibility of the cause being the same.

Stout branches were mostly attacked, and the disease was indicated by tear-like drops of almost colourless gum oozing from the branches. The drops increase in size so as to form irregular masses as large as a Walnut. Soft in damp weather, but in dry shrinking and horny, they gradually change in colour from grey to black as they increase in size ; but this is external, as the colour diminishes towards the centre.

A black mould [Cladosporium epiphyllum) was traced as the cause of this disease, as a wound parasite, entering through small wounds in the bark, or where buds have been broken off. An olive patch of the mould first appears at the wounded point, and after the conidia are dispersed the drop of gum appears, and into this gum the threads of the mould extend. The threads are at first colourless and slender, but as the masses increase the tips of the threads nearest the circumference become olive, and broken up into chains of cells, many of which produce small sclerotia or compact masses of cells with thick dark brown walls. If the mass remains damp at this stage myriads of very minute conidia are produced by the large brown cells. If the conditions remain unchanged the conidia increase rapidly by gemmation. When the mass is dissolved away to the ground the conidia continue to reproduce themselves by gemmation.

Keio Bulletin, 1899, p. 1, pi. ; Mass. PI. Dis. 306 ; Sacc. Syll. iv. 1718.

Plum-tree Rust. Puccinia pruni (Pers.), PI. XI. fig. 15.

Nearly all kinds of Plum trees are subject to the ravages of the Plum- tree rust, but those attacks are not in all cases equally virulent. One tree may be seen in an orchard with hardly a leaf untouched, whilst another tree at twenty yards' distance will scarcely reveal a pustule.

The under side of the leaves are generally closely sprinkled with the pustules, which split irregularly and discharge the spores, light brown or rusty brown for the uredospores, dark brown for the teleutospores, in both cases powdery, and soon sprinkled over the leaf.

The uredospores are egg-shaped or Pear-shaped, and the whole sur- face minutely spiny (20-35 x 12-16 fx). These are the ordinary uredo- spores, or, as we might call them, the true uredospores. In order to meet a difficulty certain authors have recently professed that two kinds of uredospores are known, the second and last invented kind being elongated and of a Uromyces type, so much so that it has acquired the name of Uromyces amygdali. Whether this is also a Uredo form of Puccinia pruni does not interest us much, as we intend, in this place, to treat them as distinct diseases.

The teleutospores are divided in the centre into two cells, each of

c

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which is nearly globose, except at their junction, where they are flattened, the lower cell being a little the smaller. The cell coat is chestnut brown and thickly covered with rather rigid obtuse spines (30-45 x 17-25 At first the short uncoloured pedicels are distinct, but these finally dis- appear.

Known in </