The arrowhead scale, Prontaspis yanonensis KUWANA, is one of the most nacious insec's of citrustrees in Japan. For its control the mixture of lime sulphur and zinc sulphate Las hitherto been applied by citrus growers, resulting in the rapid decrease of the pest. With a view to making out the effectiveness of the said mixture, some series of experiments have been carried. out with the results, as given in the summary that follows.
1. So far as concern laboratory and field experiments carried out in order to test the effect of the mixture of lime sulphur and zinc sulphate on the arrowhead scale, the mixture exercises scarcely effect on the adult. However, the newly hatched larva, though capable of infesting the sprayed leaf of five-years-old tangerine tree only at about 1% against about 40% on the unsprayed leaf, becomes before long to fall bown dead, without causing any trace of growth. This state of thins holds not only good in the field observation, but also in the experiment with the leaf washed the mixture off. Judging from the facts just mentioned, it is selfevident that the mixture acts as an evasive factor for the attachment of larva on the one hand, ani affects the larva on the other, permeating the leaf tissue.
2. Nevertheless the entire absence of change in the leaf tissue dealt with either of zinc sulphate and lime sulphur, the pH value in the tissue dealt with the mixture is rapidly increased for the first 10 days to attain 7, and then gradually decreased to about 5.8, or the normal state.. These facts appear to point to that the mixture is capable of permeating the leaf tissue, differin_??_ from either of zinc sulphate and lime sulphur.
3. Taking into consideration the fact that the pH is weak acidic in zinc sulphate and alkaline in lime sulphur, it may be stated that the element exercising the change of the value is attributable to the latter.
For the purpose of determining this respect, some series of quantitative analysis and mechanical observation were carried out with the results as follows: the amount of sulphur in the sprayed leaf is about twice as much as that in the unsprayed, and sulphur is mainly deposited in the cortical tissue. Consequenily it may be said that sulphur acts as an element playing an important rôle in the changte of pH.
4. On accout of, application of zinc spray for its efficiency in the citrus plant, it is appropriate to presume that sulphur is capable of permeatin: the leaf Tissue with the aid of zinc, , nevertheless the entire absence of permeability.
5. On the presumption that the main element of the mixture is zinc sulphide and that it affects the larva, permeating the leaf tissue, some series of experiments were prosecuted with this compound extracted from the mixture, as well as with that for sale. As the results, it is revealed that the former, though more inferior as compared with the mixture, is still effective, , but the latter is not effective at all. Subsequently presuming that the uneffectiveness of the latter may be due to dryness, another series of experiments were made with zinc sulphide ob_??_ained by reacting sulphurated hydroeen upon zinc sulphate, devoid of dryness, and it was revealed that the said compound was effective in as much as the mixture, notwithstanding the entire loss of efficacy immediately after it was dryed at high or low temperature. Consequenly it may be concluded that zinc sulphide permeates the leaf tissue in the course of reaction of lime sulphur and zinc sulphate.
6. So far as experiments go, the mixture exerciss such lethal actions as in the following:
1) Besides its evasive action for the attachment of larva to the leaf, the mixture is of a contact insecticidal action especially at an early stage of larval life.
2) A close microscopic observation reveals that the larvae, exclusive ofa few, are found dead without insertin_??_ suckers into the leaf tissue

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Some leading Kaki varieties, especially “Fuyu”, have no male flower, and rarely set by parthenocarpy. To ensure the fruit set of such varieties, hani pollination method is recom-mended in Japan. This experiment was perfomed at Okitsu Hort. Exp. Sta. to ascertain the most effective method of hand pollination.
1. Before the male flowers open, the branches must be protected by paper bags, lest pollen grains shoud be dispersed.
2. The time when petals and anthers open has varied with varieties of the trees and with climatic conditions. Almost all flowers have opened in the morning, when it was fine wea her and the anthesis took immediately after that.
3. Without any paper bag protection, we can gather pollens easily, as followes: Gather the buds which are expected to open next morning, in the evening of previous day, when they do not bloom at all and preserve them next room. Anthesis will occur at about ten o'clock in the next morning.
4. The fertilizing, ability of the pollen grains, gathered as mentioned above, was examined by means of germination test and pollination test, and proved to be complete. Stored pollens holded practical ability within about five days in room temperature, while lower temperature (_??_°C) and dry condition were preferable, and higher temperature (30°C) was injurious.
5. Two hand pollination methods prevailing in Japan were compared in this study: One is to pollinize by means of writing brush with previously gathered pollens and other to pat the female flowers with male flowers of which petals are removed previously.
6. Pollen quantities were compared among several varieties. “Zenjimaru” had most profuse pollen per flowers.
7. In “Fuyu” variety more than 95 per cent of flowers has set by hand pollination un_??_il the color of petals changed to brown from cream-colored, that could be easily discriminative.

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(1) In the both year of 1947 and 1948, the period and proeress of the fruit bud formation of the 11 leading apple varieties were researched for the duration from late June to late August in the Aomori Apple Experiment Station.
(2) The varieties which form their flower parts in the bud in earlier petiod are the Yellow Transparent, Early McIntosh, Mclntosn Red, Indo and American Summer Pearmain. The Golden Delicious, Ralls Janet and nTewton Pippin follow them, and the Delicious, Winesap and Jonathan are the latest in the period of fruit bud formation
(3) Each variety has its own period of bud formation, and is various in the velocity of its progress. Moreover, it seems that the velocity of its progress is not always fast because of the variety with which the beginninz of differentiation is earlier. Therefore, the period and progress of fruit bud formation of the varieties is peculiary themselves.
(4) In 1948, the period of fruit bud formation was earlier about 5 to 10 days than those in 1947. It appears to be affected wich high temperature, much sunshine and drying in June in 1948.
(5) In Aomori Prefecture, the relationship between the period of bud formation and the maximum temperature through all the year is not _??_ecognized.
(6) With the earliest maturing varieties, flower parts seem normally to be formed in the bud in early period, but, as to the middle and late maturing varieties, there is no confirmed relationship between the ripening season and the period of fruit bud formation.
(7) Excepting the Mclntosh Red and Newtown Pippin apple out of 11 varieties, there is a strong tendency that the stronger the alternate bearing character of varieties is, the earlier is the period of fruit bud formation.
(8) The terminal bud on about 30cm long fruiting twig is later about 20 to 30 days in the period of fruit bud formation, compared with those on spurs.

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1. In September of 1939 the scions of a Satsuma oran, e strain are double-grafted on the scion part of those previously (1937) had been grafted by three different s'rains of Satsuma orange, yudzu and tachibana on seedling stocks of trifoliate orange.
2. The growth of the top scion part have been influenced by growing characters, weak or vigorous. of the intermediate stocks. The effects are found in the diameters of stems, and volumes of crowns as measured in the top scion part as well as in the stem diameters of intermediate or stock parts.
3. The tops grafted on the same strain intermediate stocks are compared with those on the vigorous strain (Tanikawa) intermediate stocks. The former surpassed the latter at the end of. this investigation, when they are ten years old, though they had been inferior in the beginning.
4. Though the stem diameter of intermediate stock of yudzu had been the largest of all, before and several years after the graftin of top scion parts, its growth declined gradually, and consequently showed the minimum diameter of all in both intermediate part and stock. The volume of the crown was one ninth of that with the same intermediate part.
5. In the tachibana grafted plot at the beginning, the diameter of intermediate stock had been smallest, and the scion part the same amont the other Satsuma strain plots. Afterwards, its growth out-ran the others, and consequently, gained the neat rank to the Tanikawa plot. When it is ten years old, its crown volume and stem diameter are nearly same to those of the latter plot.
6. The connections were smooth and gradually more slender to the top in three Satsuma plots. In yudzu plot, stems of the tops were suddenly small. In tachibana plot, both were same or slightly larger in the top stems, and the connected parts smelled a little.

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Studies on the effects of pinching treatments and the differences of fruit settinz position were performed with variety “Higata.”
1. At the plot which was pinched immediately above the fruit, both fresh and dry weight of fruits and the rate of dry weigh: were less than any other plot.
No remarkable difference was found among the pinched plots which had two or four or six leaves above the fruit.
2. At the pinched plots, except ont which was pinched immediately above the fruit, fresh weight of fruit was more than no pinching plot, but dry weight of fruit and the rate of dry weight were less. This may be depend upon the fact that the accumulation of carbohydrates is happened a_??_ the later period of rrowint season than the increse of fruit size and the function of no⁺ pinched leaves is declined as the result of pinching.
3. No remarkable difference of numbers of seeds per fruit was found between the pinched plots and no pinching plot.
4. The weigtht (both fresh and dry) of fruit, numbers of seeds per fruit and the size of leaf were the most at the third flower plot in which the third flower was only set. The second flower plot was the second and the first flower plot was the third.
This is perhaps chiefly depend on the fact that squash plant growing is more sufficient enough at the later flowering plot.
5. No remarkable difference of the rate of dry weight was found between these three plots.

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