In 1981, bacterial leaf and flower spot of zinnia was found in Ishikawa pref., Japan. The disease first appeared on the leaves as yellowish small circular spots. Those spots slowly enlarged to angular shape about 5mm in diameter and became reddish or dark brown. Lesions of flower were dark or blackish brown spots. The bacteriological tests and host range indicated that the pathogen was Xanthomonas campestris pv. zinniae (Hopkins & Dowson 1949) Dye 1978.
A protozoa feeding on Pseudomonas syringae pv. mori was isolated from a subculture of the bacterial strain. The organisms formed plaques on culture of P. s. mori and the other bacteria including Xanthomonas campestris pv. citri and Erwinia carotovora subsp. carotovora. Some cultural conditions for plaque formation and the other properties of the organisms were also reported.
Isolates of Botrytis cinerea Persoon resistant to iprodione were obtained from three tomato fields in Kanagawa prefecture, Japan. The minimal inhibitory concentration value of iprodione for the isolates was about 25ppm. The isolates were cross-resistant to procymidone and vinclozolin. Resistance to benomyl was also found in all the iprodione resistant isolates in this experiment. The virulence of the isolates on broad bean leaves were correspond to that of sensitive isolates. One of the isolate had an ability to develop the disease even on the tomato leaves that treated with 500ppm solution of iprodione, procymidone, vinclozolin, benomyl or thiophanate-methyl.
A new disease of onion (Allium cepa) caused by mycoplasma-like organism (MLO) was found in Saga Prefecture. The typical symptoms of diseased onion leaves were yellowing and stunting with fasciculation. Hypertrophy of the diseased onion bulb was decreased while flower clusters of the bulb were teratoid. The diseased onion bulb during storage was sprouted earlier than healthy one. In ultrathin sections of the diseased onion, MLO was observed in the sieve tubes of diseased leaves. In transmission tests with 5 species of wild planthopper and leafhoppers, only Macrosteles orientalis could inoculate and transmit the MLO to onion seedlings. The inoculated seedlings expressed the typical symptoms 20-28 days after transmission tests and MLO was detected in the sieve tubes of the onion leaves. The transmission rate of MLO by naturally infested M. orientalis ranged from 3.3 to 33%. The results indicate that the causal agent of this disease seemed to be MLO, and this disease was proposed to name “Onion yellows”.