The nature of the virus inducing crinkle mosaic in the potato variety Benimaru is reported in this paper.
Mottling of the upper six to seven leaves is distinct throughout the entire growth stages of the plant, although it may be masked in the hot season. It is followed by waviness of margins of leaflets. No streak was ovserved during the course of the experiment. Transmission experiments have proved that the causal virus is a complex of X-virus which is transmitted only by sap inoculation, and Y-virus which is transmitted by means of aphids as well as mutilation method. On inoculating with X+Y viruses or with Y-virus to apparently healthy plants of Benimaru potato, symptoms similar to the original crinkle mosaic were produced. The apparently healthy plants of Benimaru variety were demonstrated to be infected by a mild strain of X-virus.
As a result of arfificial inoculations, Turkish tobacco, Nicotiana longiflora CAV, N. glutinosa L., tomato, and Solanum nigrum L. were found to be infected by both X- and Y-virus. Datura stramonium L., pepper (Capsicum annum L.) and eggplant were susceptible to X-virus, but not to Y-virus.
Inoculations with juice from the affected tubers shortly after harvest, or stored tubers immediately before planting, succeeded in producing infection of tobacco plants by Y-virus, though the percentage of succesful inoculation was lower than that by X-virus.
The X-virus used in this experiment is tolerant to heating at 70-75°C for 10 minutes, to a dilution of 1:100, 000 and to aging in vitro for 72 days. It passed through the ZEITZ filter L₃ (Shofu). Y-virus is tolerant to heating at 55-60°C for 10 minutes, to a dilution of 1:500-1, 000, and to aging for 1-2 days. It did not pass through ZEITZ filter L₃ (Shofu).

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From July to September of 1949 apparentlo healthy potato plants in various districts of Hokkaido were examined for potato virus X by serological tests and inoculation experiments. The tubers obtained from thirteen more localities of Hokkaido were later grown in the green house and the plants were examined by the same methods during the months of February and March of 1950.
The following are the results of experiments.
In spite of a heathy appearance, the examined plants of the Irish Cobbler, Benimaru and Green Mountain were found to be affected as much as from 94 to 100% with potato virus X. It is worthy of note that the first two varieties are the most widely grown in Hokkaido. The virus was found in 50% and 83.3% plants of the varieties Norin No.1 and No.2, respectively and the affected plants were fewer in numer in 5 varieties of the Shima Line which amount to 20% in average. Another sixteen varieties tested showed a relatively high infection of 75% in average. The virus was found in only 3.8% of the plants raised from seed and it is probable that the newly bred varieties areal most free from virus for a few years. In most of the meterials examined, the virus was found more frequently in the leaves than in the tubers.
In the detection of the virus X, the precipitin reaction is more valuable than the inoculation experiment, because the former is more sensitive and the reaction occurs immediately. Unfortunately, the complement fixation is not quite so sensitive to the present material, as the precipitin reaction owing to its strong anti-complementary properties. The slide flocculation method is also highly sensitive, but the precipitin reaction is considered to be more suitable, as it gives a more accurate result.

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1. The present paper gives the results of morphological and physiological studies on the causal fungus (Cercospora sp.) of a new disease of tomato.
2. The symptoms of the disease closely resemble “leaf mould of tomato (Cladosporium fulvum), ” and it is almost impossible to find the difference between these two diseases except under microscope.
3. The present disease is widely distributed in Japan, and causes often serious damage to tomato.
4. The causal fungus is almost identical to Cercospora diffusa, ecxepting that the former has septated conidiophores.
5. The author proposes a new common name “Cercospora leaf mould” for the present disease.
6. Optimum temperature for germination of the conidia is about 26°C, and maximum about 36°C.
7. Mycelial growth of the fungus is very poor on common culture media forming minute colonies in island type, and saltation occurs very often.
8. Conidial formation is comparatively good on tomato plant decoction agar and optimum temperature for mycelial growth of the fungus seems to lie between 26-28°C and maximum 34-38°C.
9. Conidia on tomato leaves kept thier vitality under ordinary conditions in the laboratory until the end of the following June, but they all died after 40 days in moist condition. Therefore conidia may live over winter in natural conditions and cause primary infection in the next season.
10. The author made infection experiments of the fungus on tomato seedling with success and reisolated the same fungus from affected leaves.
11. Varietal susceptibility of tomato is still unknown, but the author found two resistant varieties “Dwarf Stone” and “Marglove” among 35 varieties in the field.
12. According to the spore germination test in vitro, Bordeaux mixture showed the strongest fungicidal power on the fungus, Zerlate and Fermate came next, while wettable sulphur (Soid No.1) was very weak.
Postscript:
The present fungus was lately identified to Cercospora fuligena Roldan by Dr. CHUPP.

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The twig of peach infected by anthracnose fungus, Gloeosporium laeticolor, usually dies till March, and conidia may be formed on these killed twigs in April. On the twig, conidiophores develop sparsely and not mucilaginous, giving quite different appearance from acervuli on the fruits.
Primary infection occurs on the trichomes of young peach fruit. Spore, stuck on the trichome, germinates within about 12 hours, and forms appressorium at the apex of germ tube and penetrates the cell wall. About 2 days later, acervuli develop over the surface of the trichome. Affected trichomes turn brown in colour. They are easily detatched and blown off by the wind. Accordingly these infected trichomes play an important role as a source of initial secondary infection. In addition, the fungus may invade into the young fruit tissue through the affected trichomes.
The anthrachose fungus can also invade both young peach leaf and nectarine fruit, without forming appressorium at the entry point.
On the young fruit, acervuli are formed 48 hours after inoculation. Acervuli on the leaf are faded brown in colour and pulverlent, while the acervuli on the young fruit are light brown or light salmon in colour and mucilaginous.
Peach fruits may be infected at any time during their growth period from May to August, if the weathers are favorable to the dissemination of the pathogene. The conidia are hardly blown off by the wind unaccompanied with rain. But if it rains, conidia will be suspended in the rain droplets, which will be splashed by the wind. This infections of fruits on a peach tree spread conically, in a form of “Infection cone” (DUNEGAN, 1932). The conidia fallen on the soil surface may remain alive for about 7 days in summer.

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1. In this paper, the results of the following investigations which were done on the pedicels of panicles (“Hokubi”) of the rice plants grown on the flooded soil with the temperatures, 15.3°-28.2°C.(the lot of low temperature), and 16.5°-34.8°C(the lot of natural temperature), are mentioned:- (1) Inoculation experiments of Piricularia Oryzae CAVARA, (2) Appresorium formation of the fungus on the epidermal cells (3) Entrance of the fungus into the epidermal cells. (4) Infection (determined by the appearance of necrosis) of the epidermal cells by the fungus., (5) Microscopical examinations on some anatomical characters of the pedicels of panicles.
2. Throughout all the experiments, “Kameji” and “Mubo-aikoku” were used as a resistant variety and “Omachi” and “Kokuryomiyako” as a susceptible one. The rice plants of these varieties in the lot of low temperature continued very weak growth, and their panicles appeared about ten days later than those in the lot of natural temperature which did very strong and vigorous development.
3. The pedicels of panicles in the both lots were inoculated with the spore suspension from the pure culture of the fungus when the plants in the lot of low temperature began to bloom. From the macroscopic observation of the experiments, the disease development in the lot of low temperature showed 75-100 per cent. for the both susceptible and resistant varieties, while that in the lot of natural temperature did 0-13.3 per cent. for the resistant varieties and 20-33.3 per cent for the susceptible ones.
4. After the epidermal tissues of the pedicels of panicles inoculated with the fungus had been treated with 0.01 per cent. of safranin and concentric phenol, the appressorium formation, the entrance and the infection were microscopically examined on the epidermal cells. These examinations gave the results that without regard to the varieties and the kind of the cells tested, the number of the epidermal cells, on which the appressoria were formed, as well as that of the cells penetrated and infected, were larger in the lot of low temperature than in that of natural temperature. Regardless of the kind of the cells examined, they were also larger in the susceptible varieties than in the resistant ones, and this difference was more obviously in the lot of natural temperature than in the other lot. Furthermore, it was found that regardless of the varieties, the lot, and the kind of the cells, the epidermal cells, on which the appressoria were formed, gave the largest number, those into which the fungus entered the next, and those infected by the fungus the smallest, and whatever the varieties and the lots were concerned, the numbers were the greatest in the long cells in the non-stomatal zones of the tissues, the next in the long and short cells in the stomatal zones, and the smallest in the accessory cells of stomata, although this difference was obscurely observed in the lot of low temperature as compared with the other lot.
5. It was comfirmed that the low temperature of the soil, on which the plants are grown, seems to decrease the resistance of the pedicels of panicles to the disease owing to the reason that it makes the fungus to form abundant appressoria on the host cells in addition to easily enter into the cells and to easily infect them.
6. The comparative anatomical studies were made on the epidermis of the healthy panicles in the both lots which were not inoculated. The thickness of the outer wall of the epidermal cells was measured on the transversal sections by the usual method, while that of the silicated layer of the wall was done by the method of mounting the sections in concentric phenol.

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