Creeping bentgrass (Agrostis palustris Huds. ; Bentgrass) and manilagrass (Zoysia matrella Merr.) were grown under turf condition mowed at 8 mm in height. Photosynthesis, dark respiration and the growth parameters in both turfs were periodically measured from February to August for bentgrass and from May to October for manilagrass in 1990, respectively. The differences of photosynthetic characteristics between both turfs in relation to climatic factors and mowing treatment were discussed. Turf photosynthesis and dark respiration were determined by the open system chamber method with core samples taken up from turfs. The results are as follows:
Gross photosynthetic rate (Pg) in bentgrass turf decreased accompanying with decreasing of dry matter weight (DMW) and chlorophyll content (CCA) of aboveground plant part by mowing. There were significant relationships between CCA and maximum Pg or dark respiration rate in bentgrass turf. Consequently, it was possible by growth parameters to know the response of photosynthesis to mowing.
On the other hand, the decreasing ratio of Pg by mowing was less than that of CCA, and Pg per unit chlorophyll content was higher at post-mowing in manilagrass turf. This is supposed to be caused by improving light-interception with the high relative efficiency of light utilization of turf at post-mowing, indicating high adaptability of manilagrass to intensive mowing than that of bentgrass.

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A sensitive field isolate (U0P392) ofPythium vanterpooliiwas compared with its acquired resistant isolate against metalaxyl (U0P393) for cultural characteristics and virulence. The results obtained are as follows.
(1) The disease development on grasses inoculated with UOP 392 in pot was protected by metalaxyl under grasshouse conditions, whereas this was not the case with UOP 393 under the same conditions.
(2) There was no significant difference between UOP 392 and UOP 393 in various cultural characteristics such as temperature, growth rate, pH and growth habit.
(3) There were some differences between the two isolates in zoospore, hyphal swellings, oogonium and oospore formation.
(4) There was no difference between the two isolates in virulence.
(5) The isolate UOP 393 retained its resistance during 2-years storage on CMA medium at 20°C.

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With a purpose to develop a biological method to control snow mold caused by Typhula ishikariensis, microorganisms, which were antagonistic to the pathogen and psychrophilic, were screened from sclerotia of the pathogen, grasses and soil of several golf courses in Sapporo and other places. Five isolates of bacteria, which could grow at 0°C and were strongly antagonistic to the pathogen, were selected by a step-by-step screening using artificial media, grass media and a newly devised sod cup test method. Significance of the new sod cup test in screening antagonists for snow mold was also discussed.

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As the first step to develop a turfgrass production system, urethane-foam has been chosen to culture turfgrass seedling. It has been confirmed that urethane-foam can culture the turfgrass seeding just as well as sand of conventional culture medium does, and urethane-foam sod provides superior mechanical handling proerity.
Futhermore, flexible polyurethane-foam F, semi-rigid polyurethane-foam SR 1, SR 2 and S have been developed with taking considerations of the degradation of urethanefoam and the soil hardness of turfgrass with urethanefoam as culture medium after transplantation.Urethane-foam F, SR 1 and SR 2 with thickness of 5 mm and 10 mm were used to culture Manilagrass and, F and S with thickness of 5 mm and 8 mm were used to culture Pencross, corn paring to sand in both cases. A series of experiment were conducted and the results are as follows:
1. Seeding growth
There was no significant difference at p<0.05 in dried shoot weight and hueangle of shoot in all experimental blocks. However, it was noted that the urethane-foam with thickness of 8 mm or 10 mm produced more dried shoot weight than 5 mm experimental blocks did.
2. Sod tensile strength and sod mass
The tensile strengths of Urethane-foam sods were 1.7-3.8 and 2.4-6.3 times that of sods for Manilagrass and Pencross respectively.
The masses of urethane-foam sods were about 70% and 50% of sand sod for Manilagrass and Pencross respectively.
3. Root growth after transplantation
For both Manilagrass and Pencross, the turfgrass root of urethane-foam sod grew just as well as sand sod's. It was observed that root Manilagrass and Pencross grew 10-15cm underground in 10 months after transplantation.
4. Soil hardness
For flexible urethane-form F, the soil hardness were 0.51-0.65 kg/cm² which was much less than 1.12-1.32 kg/cm² of sand experimental blocks in six months after transplantation. However, SR 1, SR 2 and S blocks provided a soil hardness of 1.09-1.32 kg/cm2 wich was equivalent for that of sand blocks.
5. Degradation of urethane-foam
Semi-rigid polyurethane-foam S degreded ultimately right after transplantation. The reduction rate of F, SR 1 and SR 2 were 31.1%, 55.4% and 61.1% with trampling in six months after transplantation, which were much higher than 7.1%, 19.5% and 28.7% without trampling respectively.

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