Abstract
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.
