The plant growth regulative application of Paclobutrazol [ (2RS, 3RS) -1- (4-chlorophenyl) -4, 4-dimethyl-2- (1H-1, 2, 4-triazol-1-yl) pentan-3-ol] was investigated in several species of turfgrass (Table 1.) .
Test plants of turfgrass are shown in table 2. It was observed thet the sensitivity of the plant growth retardants to the various kinds of turfgrass used in this experiment differs according to species.
With a concentration of 10^-4-10^-3Mol. or above, Paclobutrazol showed a tendency to inhibit germination (table 3) .
As concerns the effects of the Paclobutrazol treatment on the growth in elongation of the roots in the first stage of germination, it was discerned that it promoted an increase in the number of roots at a concentration of between 10^-7Mol. and 10^-11Mol. (Table 5) . In the case of a high concentration of 10^-9Mol. or above, it showed a tendency to inhibit the growth in elongation of the turfgrass (Table 4) .

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To keep the vigor of manilagrass during winter time, an antitranspirant (alkyl-polyoxyethylene-alcohol) was sprayed on the grass at the rates of 0, 0.2, 0.4, 0.8 and 1.6 g/m²in every other week from early October to late March at a golf club in Ichihara City, Chiba Prefecture. Monitoring of air-temperature and soil-temperature (1 cm deep) was also performed. Occasionally, core-samples of the grass with roots in sandy soil were taken and compared their gas-exchange activities under conditions of 20°C air-temperature, 500 μE/m²/sec light, 50% relative humidity and 350 ppm CO₂. The antitranspirant was very effective to maintain the photosynthetic activity of manilagrass during the wintering probably because of its effect on elevating soil temperature through the suppression of evaporation of water vapor from the plant surface.

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A fungal isolate obtained from Astria-bentgrass showing red thread symptom on a golf course of Hakone, Japan, exhibited pathogenicity on seedlings of bentgrass, Italian ryegrass, Kentucky 31 fescue, weeping lovegrass, while it exhibited no to weak pathogenicity on seedlings of Japanese lawngrass, centipedegrass, bahia grass, bermudagrass and perenial ryegrass. The isolate attacked leaves and stems of adult bentgrass at the temperature range of 10 and 25°C under the laboratory condition. At 20 and 25°C, the disease development was most rapid and produced on leaves typical sign of the red thread pathogen. On potato-dextrose agar, the fungus produced Chinese rose color, but produced no clamp connection. These results clearly indicate that the disease casued by this isolate is red thread, rather than pink patch. Some characteristic features of the isolate on culture media were observed in relation to the growth conditions of the pathogen. The most inhibitory fungicides on the mycelial growth on potato-dextrose agar were TPN and benomyl.

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1. It was already clearified thatZoysiaspring dead spot in this field was caused byRhizoctonia solani.
But it is not clear yet whether the fungi of this disease causes all occurence from fall to spring.
Therefore, research was made on the season of the disease occurrence and the vicissitudes of the number of the fungi and then on their relationship to the temperature. For this research, six sections were prepared: five with several different types of fungicides sprayed respectively and the other without any such treatment.
2. In the plots where fungicides with anti-Rhizoctoniaeffect were sprayed for four times such as the sections of Trichlophosmethyl 2g/2l/m², Iprodione 2g/2l/m²and TPN 2g/2l/m², the disease was not ditected at all at any time during this period. On the other hand, the sections of Echlomezol 2cc/2l/m², Hymexazol 4cc/2l/m² (These are not effective against Rhizoctonia.) and the nontreatment section saw the apparent occurrence of the disease.
In the plots where the disease activity was witnessed, the disease started showing up right before and at the early stage of the senescent period (Dec. 21 to Jan. 17) . Then right before and during the budding season (Mar. 7 to Mar. 20) a violent outbreak of the disease was witnessed.
The sympton of the disease would be characterized by the colors of the disease: in fall it was vazuely brownish, while in spring both gray-brownish and vivid brownish kinds were detected, although the latter occurred more frequently.
3. In the experiment where the occurrence of the disease during the senescent period was researched by the budding method, no sign of the disease was detected in the plots which were treated by anti-Rhizoctoniafungicides. On the other hand, both in the plots where fungicides withoutanti-Rhizoctoniaeffect were sprayed and in the non-treatment section, the disease was found in the place where the occurrence of the disease was witnessed even before the senescence. And even where there had been no such evidence of the disease before, new outbreaks of the disease took place. The occurrence of the disease centered on the period at the latter half of the senescence.
4. When the relationship betweenRhizoctoniaand the occurrence of the disease were seen, the disease did not take place whereRhizoctoniawas not detected because of the use of the anti-Rhizoctoniafungicides. On the other hand, the plots whereRhizoctoniawas detected were the non-treatment section and the plots in which fungicides without anti-Rhizoctoniaeffect were sprayed.
ButPythium, FusariumandCurvularia (includingHelminthosporium) were detected from all the plots. Therefore it can be said that, these have no direct relationship with the occurrence of the disease. Making a close look at the vicissitude of the number ofRhizoctoniawhich causes the disease, once during the period of mid-November to mid-December (the pre-senescence to immediately before the senescent period) and the period between mid-January and March (late senescence to pre-and post budding season) respectively, there was a time of sharpin crease in the mumber ofRhizoctonia.
5. On the relationship between the occurrence of the disease and the vicissitude of the number of the fungi on the one hand, and the temperature on the other, Rhizoctoniaincreases at the minimum temperature of 10°C during the pre-and post-senescent period of the turf, during which time partical occurrence of the disease takes place.
Although the fungi decreases in winter, foward spring when the maximum temperature reaches around 9°C the increase of the number of the fungi could again be detected. And then at around 12°C the activity of the fungi reaches to peak.

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1. The pathogen ofZoysiaspring dead spot found in Wakayama isRhizoctonia solani. In order to see whether the pathogen found in other regions is also the same kind, research was carried out using anti-Rhizoctoniafungicides which have a restraining effect on the disease.
2. To stndy the disease found in the Lake Biwa golf course in shiga-pref., research was carried out, in addition to the fungi, on the season of its Occurrence and the vicissitude of the number of the fungi. The research showed that the fungi were most often detected under the minimun temperature of 12°C to 13°C which corresponds to the period right before the senescence of the turf during the first part of October.
But in the period of senesceuce during the months of December and January, the activity of the fungi decreased at the maximum temperature of 5°C. Then the activity was detected again in the middle of February when the maximum temperaature reached 8°C. The disease occurred on a few occasions during the period of senescence. Then in the middle and the end of March, when the maximum temperature exceeds 10°C, the fungi were again detected quite often. Around April, right before and after the sprouting, the fungi activity became most bively.
3. It was made clear that the pathogen of the disease in Nara, Hyogo (both the Japan Sea and Inland Seasides), Kanagawa, Shiga and Osaka wasRhizoctonia.
4. Other Zoysia spring dead spot could be caused by other reasons not related to the pathogen.

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Ecological observations and experiments were carried out concerning the stimulation of fungicidal solution for the fairy rings, Lepista sordida (Fr.) Singer, in the soil. There results are as follows.
We cannot observe the myceria and the mycerial membrane of fairy rings with naked eyes in the soil under natural conditions after cutting off the turf with a cutter, so it is not difficult to let arrive the fungicides to the pathogens.
The most important factor is the moisture in the soil. Suitable moisture supports the stimuation of fungicidal solution to all portions of the soil containing the mycelia of rings. Dryness in the soil prevents the fungicides from permeating the soil. A good result was obtained to control the disease by sprinkling the fungicidal solution, 10l per m², with a watering pot in the soil with suitable moisture on the tee of golf course.

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Recently there have been a remarkable number of the GenusHopliain golf courses in the Kanto and Tokai districts. The GenusHopliahas the habit of being attracted by the color of white. Therefore, they gather around players wearing white clothes and they are a nuisance to the players.
As a result of our investigation, we have found that in Tomei Country Club the GenusHopliawinters in the 2nd or 3rd instar larvae, beings to pupate at the end of March, and becomes adult in May to mid June. The Adults eat the flowers and young leaves ofQuercus acutissima, Quercus serrata, Rhododendron indicumandCastanopsis spach.
When we investigated the number of larvae in winter, we found a maximum of 101 larvae (50 on the average) in tha erea of 30×30×20cm. Because turfgrass was in winter decay, there was no visible damage thereto. However turfgrass roots were considerably eaten. It seems that there is a very strong possibility of being affected by drying and chemicals.

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The field and the greenhouse studies were conducted to determine the weed control spectra of seven dinitroaniline herbicides, trif luralin [2.6dinitro-N. N-dipropyl-4- (trifluoromethyl) benzenamine], benef in [N-buthyl-N-ethyl-2. 6-dinitro4- (trifluoromethyl) benzenamine], dinitramine [N³, N³-diethyl-2.4-dinitro-6- (trifluoromethyl) 1.3-benzenediamine], prodiamine [N³, N³-dipropyl2.4-dinitro-6- (trifluoromethyl) -1.3-benzenediamine], nitralin (4-methylsulfonyl-2.6-dinitro-N, N-dipropylbenzenamine), and oryzalin [4- (dipropylamino) -3.5-dinitrobenzenesulfonamide], for annual turf weeds.
These herbicides showed excellent pre-emergence annual grass control, such asEchinochloa sp., Digitaria cilialis, Poa annuaandAlopecurus aequalis. But these varied in the effectiveness of broad leaved-weed control. Pendimethalin and dinitramine showed the broad spectrum weed control including Compositae, Crucif erae, Scrophulariaceae, Chenopodiaceae, Leguminosae, Amaranthaceae, Polygonaceae, Caryophyllaceae. Nitralin, prodiamine and oryzalin showed narrower spectrum weed control than pendimethalin and dinitramine. Benef in and trif luralin showed effectiveness on a few broad-leaved weed species.

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The herbicidal effectiveness of four diphenyl ether herbicides, nitrofen [2.4-dichloro-1- (4-nitrophenoxy) benzene], chlornitrofen [2.4.6-trichl-oro-1- (4-nitrophenoxy) benzene], bifenox [methyl 5- (2.4-dichlorophenoxy) -2-nitro-benzoate] and chlomethoxynil [2.4-dichloro-1- (3-methoxy-4-nitrophenoxy) benzene], were studied in the fields and in the greenhouse.
The pre-emergence applications of these herbicides showed higher activity than post-emergence applications. When these herbicides were applied pre-emergence, these herbicides effectively controlled annnual grasses. And when applied postemergence, these herbicides controlled broadleaved weeds except Caryophyiiaceae, Criucferae, Compositae, and Leguminosae.
Bifenox and nitrofen controlled many weeds except Caryophyllaceae. When difenox plus simazine (6-chloro-N, N' -diethyl-1.3.5 -triazine-2.4diamine), or atrazine [6-chloro-N-ethyl-N, - (1-methylethyl) -1.3.5-triazine-2. 4-diamine] were applied pre-emergence, or post-emergence, the combinations showed a broad herbicidal spectrum.

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1. Chlorsulfuron (2-Chloro-N- [ (4-methoxy-6methyl-1, 3, 5-triazin-2yl) aminocarbonyl] benzenesulfonamide at 2g a.i./10a showed complete control on broadleaf weeds with preemergence treatment, but was not so effective on gramineious weeds and sedge. However, the chemical at 4 and 8g a, i./10a strongly inhibited the growth of Poa anua andCyperus iriarespectivety
2. No phytotoxicity was observed even at high rate of Chlorsulfuron onZoysia tenuifolicandAgrostis stronifera. Therefore, it was concluded that Chlorsulfuron was selectively safe on turf.
3. Test result in field was almost same as abovementioned result in greenhouse. Chlorulfuron at 2g a.i./10a provided excellent weed control on most broadleaf weeds, but, even at 8g a, i./10a it was not effective on crabgrass and barnyardgrass.
4. The chemical was applied on weeds grawn to the height of 10-30cm. As a result, Chlorsulfuron at 2-4g a.i./10a showed excellent weed control onTaraxacum officinale, Erigeron annusandErigeron philadelphicus. And at 8g a.i./10a it was effective onHydrocotyle sibthorpioidesandOxalis corniculatabut not so effective onPumex acetosellaandCayratia japonica.
5. Combination of Chlorsulfuron with Simazine, Atrazine or Siduron improved the efficacy of Chlorsulfuron on grass and Cyperus. The combination was useful for integrated weed control in truf.
6. Relative mobility of Chlorsulfuron in upland soil leached about 4-5 cm depth. The mobility was larger than that of Simazine and smaller than 2.4-D.

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