1. In a field experiment, the effects of MH (maleic hydrazide) treatment by seasons on growth retardation and appearance of several turfgrass species were studied.
2. Manilagrass maintained normal leaf colors but showed little retarding effects.
3. A significant suppression on growth of Japanese lawngrass was observed when it was treated in May at a rate of 0.5cc (product) /m² but a reddish discoloration of the tips of leaves was found at higher temperature.
4. For Bermudagrass, the treatments during May to June were effective.
5. Effects of autumn treatment on cool season turfgrass lasted till next spring which might suggest a better result with an early spring treatment.
6. The retarding effects decreased remarkably by rain or irrigation shortly after MH application.

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1. To clear the stands of cool season grasses overseeded in autumn for a smooth re-establishment of the turf with Tifton-328, the putting greens were treated with various substances on April 27 and June 24.
2. A salt injury induced by a heavy application of urea and a liquid fertilizer showed no effect on killing the cool season grasses but increased the survival rates for some cases, on the contrary.
3. A broadcast of calcium cyanamide showed uneven effect on killing of the cool season grasses and its effect did not last long. However, it favored the re-establishment of Tifton-328 to some extent.
4. An excellent result was found in plots treated either with Kerb alone at a rate of ai 0.5g/m² or Kerb and Mataway in combination, showing hardly any remaining stands of the overseeded grasses and a smooth turf establishment with Tifton-328.
5. Treatment in April showed a better effect in the turf establishment with Tifton-328.
6. In this trial, no top-dressing of fertilizers was done after the treatments which might have delayed the turf establishment with Tifton-328. A further study changing combinations of grass species, fertilizer treatments, etc. is needed to ensure an evergreen turf of high quality in this area.

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In my previous paper, it was shown that electron microscopic examination of ultra-thin sections of leaves of Zoysia materella (L.) Merr. infected by yellow leaf disease revealed none of Mycoplasma-like organisms in the phloem cells. Inoculation tests to Zoysia materella (L.) Merr. by Fusarium sp. which was isolated from the yellow leaf disease were not successful. Further experiments were carried out to ascertain that the disease is cured with some chemicals or microelements. Results of this experiment were as follows.
A yellow leaf disease of sweet-flag (Acorns Calamus L. var. angustatus Bess.) having symptoms quite similar to that of Zoysia spp. was found at Higashi-Hiroshima City. The diseased plant was recovered quite easily in Knop's solution containing the inorganic microelements, whereas the plant affected with the yellow leaf disease of Zoysia materella (L.) Merr. did not recover from the disease in the same solution.
The SNK Koso— a kind of organic microelement containing about 40% of several kinds of enzymes, 15% of iron and other microelement—was dissolved in distilled water at the concentrations of 1 to 500, 1, 000, 2, 000, 3, 000, 4, 000, 5, 000, 10, 000 and 20, 000. Diseased turfgrass plants (Zoysia materella (L.) Merr.) were cultured in the Knop's solution containing the SNK Koso. The SNK Koso was effective to cure the disease at the concentrations of 1 to 500, 1, 000, 2, 000, 3, 000, 4, 000 and 5, 000, it showed some effect at the concentrations of 1 to 10, 000, but none at 1 to 20, 000.
The disease was cured after spraying the golf course with the SNK Koso at the concentrations of 1 to 200, 400 and 1, 000, when sprayed with the amount of 1, 000ml per 30cm², but not with FePO₄ and MgSO₄ at the concentration of 1 to 1, 000. The SNK Koso cured the disease when sprayed with the amount of 500ml per 30cm² and appeared to have some curing effect by spraying 250ml, but no effect with 100, 50 and 25ml.
It is likely that the yellow leaf disease of Zoysia materella (L.) Merr. is not caused by the deficiency of inorganic microelements, but may be due to the deficiency of some organic microelements or due to some functional disorder in the growing process of plants.

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This paper presents the results of investigations on the isolation and inoculation tests of fungi isolated from leafspot of turfgrasses (Zoysia spp.) The disease is regarded to be based on Helminthosporium.
(1) From lesions of diseased leaves, Helminthosporium spp, were isolated with a high frequency, and Curvularia app. and Nigrospora spp. were also isolated frequently. In addition, Phoma spp. Mucor spp., Fusarium spp., Penicillium spp. and others were isolated with a low frequency.
(2) According to the inoculation tests of fungi isolated to turfgrasses, the pathogencity of Helminthosporium sp. was most vigorous and large brown lesions were produced on leaves but lesions caused by Curvularia sp. and Nigrospora sp. were rather small.
(3) When conidia suspension of Helminthosporium sp. mixed with those of Curvularia sp. or Nigrospora sp. were inoculated to leaves of turfgrsses, number of lesions porduced by Helminthosporium sp. reduced markedly. In this case conidia suspension of Helminthosporium sp. mixed with those of Curvularia sp. showed marked reduction in the number of lesions.
(4) When conidia of Curvularia sp. or Nigrospora sp. were inoculated to leaves of turfgrsses, after inoculating conidia of Helminthosporium sp., they did not give an influence upon lesions production by Helminthosporium sp.

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In order to clarify the life history, number of generations in a year and behavior of a Crambinae sp., every generations of the moth were collected by light traps in 1972 and each stages of them were reared under various conditions.
(1) Imago stage
Wing expanse and body length of adult male and female are about 19, 22mm and 8, 9mm respectively. They are covered with gray scales. Longevity of male and female is 3-5 days and 5-7 days respectively and oviposition period is 2-3 days. They start to fly at 7 : 20 p.m. and the most active time is from 8 : 00 to 8 : 30 p.m.. The activity decreases rapidly after that period. In case of the 3rd generation, flight activity occurs earlier than in case of the 2nd one. After the peak time of flight activity, the moth come down on turfgrass to copulate and oviposit. The number of generations of this species is 4 in a year. The 1st generation was collected from the middle of May to the last 10 days of June and the number was 503 ; the 2nd, from the last 10 days of June to the first 10 days of August and 841 ; the 3rd, from the first 10 days of August to the middle of September and 13426; the 4th, from the last 10 days of September to the first 10 days of November and 1872. The density of the moth increases rapidly in a short time because of their large number of eggs deposited and 4 generations in a year.
(2) Egg stage
The size of egg is 0.525×0.328mm in average. They hatch at a regular interval and hatchability is very high.
(3) Larval stage
Body length of the larvae is 0.8-1.0mm and they are covered with bristle and colored dark brown at the time they hatch. Mature larvae measure about 20mm. At room temperature, the larval period of the 1st, 2nd, 3rd and 4th genera-tion were 37, 26, 31 and about 230 days respectively. The degree of damages caused by larvae differs according to the kind of cultured turfgrass. That of Zoysia japonica Steud. is slightly less than those of Tifgreen, Tifway and Zoysia matrella Merr..
(4) Pupal stage
The pupal period at 30°C and 25°C was 7.2 and 9.2 days respectively.
(5) The damage by this species is most rampant from August to September and this is caused by the 3rd generation. Sometimes, turfgrass of green and fair way of golf-links is blasted yellow within 2-3 days. When many larvae overwinter, the damage may occur by the 2nd generation from July to August. By the time one can notice the damage, it would be impossible to suppress by splaying insecticides. Therefore, it is necessary to detect the occurance of the 1st and 2nd generation and initiate the control measures before their density become high.

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