The entomopathogenic nematode, Steinernema kushidai is known to have high insecticidal activity as a biological control agent against scarab grubs. This study was focused on the tolerances of S. hushidai against insecticides and their synergistic effects against scarab grubs.
The toxicidal effects of 10 insecticides against S. kushidai were tested by estimating the activity of the nematodes in the insecticidal solutions. All insecticide treated with 200ppm made S. kushidai low activity. Especially, organophosphates were toxic to nematodes, and at 10ppm of each insecticides percentage of wave movement tended to decline. On the other hand, permethrin and teflubenzuron indicated weak toxicity to the nematodes.
The toxic effects of the 10 insecticides on S.kushidai were tested in the soil. Survival rates in the treatment of all organophosphates were lower than that of control. In the treatments of permethrin and IGRs both survival and wave movement rates showed similar to or more than that of control.
In the pot tests, S.kushidai showed slight synergistic effect in permethrin treatment but did not in teflubenzuron.

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The effects of the continuous treatment of pyroligneous acid (PA) on the growth of manilagrass (Zoysia matrella Merr) were evaluated in a field test.
1. The monthly application of PA at 0.1-5l/a for three years (36 times) from 1994 to 1997 dose-dependently increased the cumulative top fresh weight of manilagrass. Especially, marked promotive effects were observed at 1 and 5l/a.
2. The increases in the root weight were observed in the surveys on 12, 24 and 36 months after the first application of PA. A marked effect on the root growth was observed at 0.5l/a.
3. The continuous application of PA induced no significant change in the soil pH of the turf, indicating that the modes of growth promotive effects of PA on manilagrass are independent of its effect on soil pH.
4. After the last application of PA, its residual effect on top growth was observed for 8-9 months at 0.1 l/a, 16-20 months at 0.5l/a, 20-22 months at 1l / a and more than 23 months at 5 l/a. In the survey on 13 months affter the last application, a promotive effect on root growth was also observed in every plot treated with PA.
5. These results indicate that the monthly application of PA at 0.5-1l / a diluted in 50l of water, which is a standard applicable to turf management, exhibits beneficial and long-lasting effects on the top and root growth of manilagrass.

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The Optimal conditions of particle bombardment treatment were assessed by β -glucuronidase (GUS) transient gene expression using the cells of two turfgrasses, Zoysia japonica Steud. and Agrostis palustris Huds. cv. ‘Chiba green B- 1 ’.
In Zoysia cells, gene transfer was influenced by DNA precipitation methods, particle size and osmotic treatment of target cells. The highest transformation efficiency was obtained when particle bombardment was performed with PEG-mediated DNA precipitation, 1.0 μm gold particles, and osmotic treatment of cells in 0.5M mannitol. Under these conditions, it was about 6 times more gene expression as compared with conventional methods.
Gene transfer in Agrostis palustris cells, in particular, depends on the osmotic treatment of target cells. The maximum transfer of GUS gene was obtained with the treatment of 0.75M mannitol, resulting in about 5 times more gene expression compared to the untreated control.

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Plant growth-inhibitory effects were found in the aqueous extract of manilagrass shoots. A methanol extract of dried manilagrass leaves was used for the isolation of phytotoxins. To isolate the growth inhibitors, methanol extract of manilagrass shoots was partitioned into ethyl acetate soluble (AE), neutral (NE) and aqueous (AQ) fractions. AQ and NE fractions were inhibitory to seed germination and seedling growth of livid amaranth. AE fraction was also inhibitory but stimulatory at lower concentrations. The relative inhibitory effects of these fractions were higher than that of the original extract. Column chromatographies, HPLC and gas chromatography were the principal methods used to identify the phytotoxins. The active fractions from ODS-HPLC were derivatized (Me/TMS), and then analyzed by gas chromatography-mass spectrometry. The identities were finally confirmed by the comparison with known authentic compounds by GC-MS. Eleven compounds were identified as phytotoxins from manilagrass. Nine fatty acids (C₁₀ to C₁₈) and two phenolic compounds (p-coumaric and p-hydroxybenzoic acids) were the major compounds and were known to have growth regulatory activities.Bioassays were also conducted using the standard chemicals to determine whether similar phytotoxic effects were produced. The results showed that all of the fatty acids and phenolic compounds found in manilagrass significantly inhibited root growth of livid amaranth seedlings. p-Coumaric and p-hydroxybenzoic acids were highly inhibitory to the root growth of livid amaranth even at 62.5 ppm. The others reduced root growth significantly at concentrations between 250-500 ppm. In general, the bioassay results with the standard compounds were similar to those obtained with the plant-derived phytotoxins, and thus the identities of these phytotoxins were confirmed.

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The purpose of this study is to examine the cold-resistance of Stenotaphrum secundatum. During growth response to the freezing treatment, the comparison of cold-resistance and the effect of hardening treatment were discussed between green leaf and variegated leaf plants. The plant growth under freezing condition was evaluated by the existing leaf number and leaf water potential. As a result, the temperature causing the wither and the damage on every kind were as follows: A tip of shoot was at -3°C, and a bottom of shoot was at -9°C, in green leaf plants. On the other hand, a tip of shoot was at 3°C, and a bottom of shoot was at -3°C, in variegated leaf plants. As the result of hardening treatment, green leaf existed at -11°C and variegated leaf existed at -7°C. These results suggest that the cold-resistance of variegated leaf is inferior to that of green leaf and hardening treatment contributes to increase of the cold-resistance in Stenotaphrum secundatum.

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Responses to salinity of 29 genotypes of three Zoysiagrasses (Z. japonica, Z. matrella and Z.tenuifolia) were investigated in a feild experiment. Grasses were treated with 4% NaCl, and harvested 4 months later to measure their dry weights. According to the changes in dry weight, Z.matrella appeared to be generally salt tolerance, while Z.japonica was sensitive. In Z.japonica, their habitats (distances from the sea) and the salt tolerances seemed to be correlated. T / R ratios increased in some Z.matrella genotypes and in Z.tenuifolia by NaCl treatment. According to the changes in dry weight and T / R ratio, Zoysiagrasses were classified into three groups with respect to salt tolerance.

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