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Wart disease of the potato
Wart Disease of the Potato. M. C. Potter.
247
WART DISEASE OF THE POTATO. PRELIMINARY EXPERIMENTS,
By M. C. Potter, Sc.D., M.A., P.L.S. For some time it has been recognised that certain plants are associated with acid and others with alkaline soils, and that soil acidity or alkalinity is a determining factor in the distribution of plants. Atkins has recently correlated the range of hydrogen ion concentration with the growth of over one hundred plants. In a similar manner it is found that micro-organisms are also sensitive to culture media. Potts showed in 1905 that the turnip disease known as Finger-and-Toe was absent from slightly alkaline soils; Jamieson and later Atkins have also noted that this disease is more prevalent in acid soils. A series of experiments have been instituted in the Botanical Department of Armstrong College to determine the limits of hydrogen-ion concentration between which the potato can live and also to determine the pH range of Synchytrium endobioticum, the causal organism of wart disease. The experiment consisted in growing a non-immune variety of potato in soils of varying pH concentration, and ordinary garden soil taken from an old allotment was employed for the purpose. In the previous year this soil had been infected with wart disease and a crop of badly infected potatoes grown upon it. It was therefore a soil in which wart disease would occur and was in every way suitable for the experiment. The variations of soil alkalinity were brought about by the applications of different amounts of washing soda crystals and of chalk. Large ten-inch flower pots filled with the treated soil were sunk in the ground out of doors and a seed potato was planted in each. Controls. Two controls were taken; one of the original soil and the other of this soil specially mixed with wart diseased potatoes. The potatoes planted in both these pots gave rise to tubers infected with wart disease. Washing soda. Six pots were used and to the soil in these pots was added respectively 14, z8, 56, IIZ, 168 and Z44 grams of washing soda. The soda was dissolved in water and poured over the surface of the soil. Any water running through was caught in a porcelain pneumatic trough and poured over the surface again, this operation being repeated until the water was all absorbed by the soil. The soil from each pot was then separately turned out, thoroughly mixed, and replaced. The pH of the soil in these six pots was found to be approximately 8, 9, 9'5, 10, 10'5 and II, the soil as taken from the garden being approximately 7'5.
248
Transactions British Mycological Society.
The non-immune variety Up-to-Date was used and a single tuber planted in each pot, about the middle of April. The shoots from the potatoes appeared above ground in the usual time, except in the pots with r68 and 244 grams of soda, In the former of these the shoot from the germinating potato was somewhat later in pushing its way through the soil and in the latter the shoot failed to appear. The tuber when removed from the soil showed that the eyes had commenced to germinate but had failed to develop and had died off; the roots had also failed to penetrate the soil. This tuber was encouraged to germinate and was again planted in the same pot. Later in the summer, when the excessive rain had leached some of the soda from the soil, a very stunted growth was produced, with a few tubers ranging from the size of a pea to that of a bean. The old tuber did not decay in the soil. It may be assumed that the higher limit of soil alkalinity had been attained by the application of such a large quantity of soda. The following table shows the pH concentration at the commencement and at the conclusion of the experiment and also the occurrence of the disease, It will be noted that the wart disease did not appear in the pot with r68 grams of soda. POTS
Grams of soda 14 28 56
112
pH conc;ntration Commencement 8 9 9'5
10
Conclusion 7 7'5
Wart disease
8'5
"
8
168 11'5 9'2 No wart disease (168 grams on a ten inch pot would be approximately 2 ozs, per sq. yard.)
The diminution of the pH concentration would be due to the leaching action of the almost continuous rains during the summer of 1922, A parallel experiment, neutralising the soil with chalk, was also carried out. Two pots were employed filled with soil similarly infected with wart disease, the one having i chalk and the other 1 chalk mixed with it. In the first the pH varied from ro at the commencement to. 9'5 at the conclusion and in the other .pot the same variation was from I I to ro. In neither of these pots was any wart disease to be discovered upon the tubers. From these experiments it may be inferred that Synchytrium endobioticum is sensitive to a high degree of alkalinity and fails to attack the potato when the pH concentration of the soil is in the region of pH 10'5. The experiment was not designed to form any idea of the influence of soil alkalinity upon the yield of tubers, but it may be remarked that soil alkalinity, while preventing wart disease, has a tendency to diminish the crop. .
Wart Disease of the Potato. M. C. Potter.
249
A plan has been set on foot to extend this line of enquiry during the coming year, repeating these experiments and extending them to other varieties of potatoes. The problem of increasing the acidity of the soil has also been attacked and it is hoped to conduct experiments upon the relationship of soil acidity to wart disease. REFERENCES. ATKINS, W. R. G.-Notes from the Botanical School of Trinity College, Dublin, III, p. 133 (1922). JAMIESON, T. F.-Reports of the Agricultural Research Association. Aberdeen (1892).
POTTS, G.-Report of the British Association, South Africa, p. 596 (1905).
RECORDS OF FUNGI IMPERFECTI. With 4 Text-figures. By Jessie S. Bayliss Elliott, D.S~. and Olive P. Stansfield, M.Sc. During 1920 and 1921, in the course of collecting material for another investigation, we have met with the following fungi, of which Septocylindrium leucum, S. melleum, Patellina caesia, P. diaphana are new species; Lemalis aurea, Hadrotrichum virescens var. Poae, Penicillium silvaticum are new records for the British Isles, and Oospora ochracea, T etraploa aristata and Sporodesmium myrianum seem worthy of note. SEPTOCYLINDRIUM LEUCUM n.sp. *t The mycelium forms gregarious superficial white brittle tufts on the surface of pine cones. The hyphae are very short so that the entire tuft is a mass of conidia. These are produced basipetally in repeatedly branched chains and are cylindrical in shape with truncate ends; they measure IO-I5 x 1'5-211', are from one to three septate and are produced in great quantities. They are rough, being covered with minute granules which soon disappear in water. The conidia germinate easily in rain water in the course of 24 hours. . This fungus agrees in many details with Septocylindrium album (Preuss) Sacc., recorded (without size of spores) by Preuss (in Sturm, Deutsch. Fl. III, 29 and 30 (1851), pp. 73, t. 37) as growing on decaying stumps of wood near Hoyerswerda in Germany, but it is evidently not the same fungus for the conidia are described and figured as definitely spindle-shaped, * Septocylindrium leucum n.sp. Hyphis conidiophoris brevissimis, in fasciculos gregarios, superficiales, albos, fragilissimos digestis. Conidiis copiosis, cylindricis, truncatis, 1-3 septatis, 10-15 x l'S-2M catenas repetite ramosas efformantibus. Hab. in conis Pini sylvestris herba semisepultis toto anno, Tanworth-inArden. t Found also on pine cones sent by DrC. E. Fairman from Lyndonville,N.Y.
247
WART DISEASE OF THE POTATO. PRELIMINARY EXPERIMENTS,
By M. C. Potter, Sc.D., M.A., P.L.S. For some time it has been recognised that certain plants are associated with acid and others with alkaline soils, and that soil acidity or alkalinity is a determining factor in the distribution of plants. Atkins has recently correlated the range of hydrogen ion concentration with the growth of over one hundred plants. In a similar manner it is found that micro-organisms are also sensitive to culture media. Potts showed in 1905 that the turnip disease known as Finger-and-Toe was absent from slightly alkaline soils; Jamieson and later Atkins have also noted that this disease is more prevalent in acid soils. A series of experiments have been instituted in the Botanical Department of Armstrong College to determine the limits of hydrogen-ion concentration between which the potato can live and also to determine the pH range of Synchytrium endobioticum, the causal organism of wart disease. The experiment consisted in growing a non-immune variety of potato in soils of varying pH concentration, and ordinary garden soil taken from an old allotment was employed for the purpose. In the previous year this soil had been infected with wart disease and a crop of badly infected potatoes grown upon it. It was therefore a soil in which wart disease would occur and was in every way suitable for the experiment. The variations of soil alkalinity were brought about by the applications of different amounts of washing soda crystals and of chalk. Large ten-inch flower pots filled with the treated soil were sunk in the ground out of doors and a seed potato was planted in each. Controls. Two controls were taken; one of the original soil and the other of this soil specially mixed with wart diseased potatoes. The potatoes planted in both these pots gave rise to tubers infected with wart disease. Washing soda. Six pots were used and to the soil in these pots was added respectively 14, z8, 56, IIZ, 168 and Z44 grams of washing soda. The soda was dissolved in water and poured over the surface of the soil. Any water running through was caught in a porcelain pneumatic trough and poured over the surface again, this operation being repeated until the water was all absorbed by the soil. The soil from each pot was then separately turned out, thoroughly mixed, and replaced. The pH of the soil in these six pots was found to be approximately 8, 9, 9'5, 10, 10'5 and II, the soil as taken from the garden being approximately 7'5.
248
Transactions British Mycological Society.
The non-immune variety Up-to-Date was used and a single tuber planted in each pot, about the middle of April. The shoots from the potatoes appeared above ground in the usual time, except in the pots with r68 and 244 grams of soda, In the former of these the shoot from the germinating potato was somewhat later in pushing its way through the soil and in the latter the shoot failed to appear. The tuber when removed from the soil showed that the eyes had commenced to germinate but had failed to develop and had died off; the roots had also failed to penetrate the soil. This tuber was encouraged to germinate and was again planted in the same pot. Later in the summer, when the excessive rain had leached some of the soda from the soil, a very stunted growth was produced, with a few tubers ranging from the size of a pea to that of a bean. The old tuber did not decay in the soil. It may be assumed that the higher limit of soil alkalinity had been attained by the application of such a large quantity of soda. The following table shows the pH concentration at the commencement and at the conclusion of the experiment and also the occurrence of the disease, It will be noted that the wart disease did not appear in the pot with r68 grams of soda. POTS
Grams of soda 14 28 56
112
pH conc;ntration Commencement 8 9 9'5
10
Conclusion 7 7'5
Wart disease
8'5
"
8
168 11'5 9'2 No wart disease (168 grams on a ten inch pot would be approximately 2 ozs, per sq. yard.)
The diminution of the pH concentration would be due to the leaching action of the almost continuous rains during the summer of 1922, A parallel experiment, neutralising the soil with chalk, was also carried out. Two pots were employed filled with soil similarly infected with wart disease, the one having i chalk and the other 1 chalk mixed with it. In the first the pH varied from ro at the commencement to. 9'5 at the conclusion and in the other .pot the same variation was from I I to ro. In neither of these pots was any wart disease to be discovered upon the tubers. From these experiments it may be inferred that Synchytrium endobioticum is sensitive to a high degree of alkalinity and fails to attack the potato when the pH concentration of the soil is in the region of pH 10'5. The experiment was not designed to form any idea of the influence of soil alkalinity upon the yield of tubers, but it may be remarked that soil alkalinity, while preventing wart disease, has a tendency to diminish the crop. .
Wart Disease of the Potato. M. C. Potter.
249
A plan has been set on foot to extend this line of enquiry during the coming year, repeating these experiments and extending them to other varieties of potatoes. The problem of increasing the acidity of the soil has also been attacked and it is hoped to conduct experiments upon the relationship of soil acidity to wart disease. REFERENCES. ATKINS, W. R. G.-Notes from the Botanical School of Trinity College, Dublin, III, p. 133 (1922). JAMIESON, T. F.-Reports of the Agricultural Research Association. Aberdeen (1892).
POTTS, G.-Report of the British Association, South Africa, p. 596 (1905).
RECORDS OF FUNGI IMPERFECTI. With 4 Text-figures. By Jessie S. Bayliss Elliott, D.S~. and Olive P. Stansfield, M.Sc. During 1920 and 1921, in the course of collecting material for another investigation, we have met with the following fungi, of which Septocylindrium leucum, S. melleum, Patellina caesia, P. diaphana are new species; Lemalis aurea, Hadrotrichum virescens var. Poae, Penicillium silvaticum are new records for the British Isles, and Oospora ochracea, T etraploa aristata and Sporodesmium myrianum seem worthy of note. SEPTOCYLINDRIUM LEUCUM n.sp. *t The mycelium forms gregarious superficial white brittle tufts on the surface of pine cones. The hyphae are very short so that the entire tuft is a mass of conidia. These are produced basipetally in repeatedly branched chains and are cylindrical in shape with truncate ends; they measure IO-I5 x 1'5-211', are from one to three septate and are produced in great quantities. They are rough, being covered with minute granules which soon disappear in water. The conidia germinate easily in rain water in the course of 24 hours. . This fungus agrees in many details with Septocylindrium album (Preuss) Sacc., recorded (without size of spores) by Preuss (in Sturm, Deutsch. Fl. III, 29 and 30 (1851), pp. 73, t. 37) as growing on decaying stumps of wood near Hoyerswerda in Germany, but it is evidently not the same fungus for the conidia are described and figured as definitely spindle-shaped, * Septocylindrium leucum n.sp. Hyphis conidiophoris brevissimis, in fasciculos gregarios, superficiales, albos, fragilissimos digestis. Conidiis copiosis, cylindricis, truncatis, 1-3 septatis, 10-15 x l'S-2M catenas repetite ramosas efformantibus. Hab. in conis Pini sylvestris herba semisepultis toto anno, Tanworth-inArden. t Found also on pine cones sent by DrC. E. Fairman from Lyndonville,N.Y.