The spectrophotometer was used for the numerical evaluation of the relation between the tone of rice leaf color and the susceptibility to rice blast. It was able to evaluate precisely the numerical value of the seven tone grades of the rice leaf color scale by analyzing the brightness, coloration, tonality and reflection rate at 550nm wave length. It was also used for the evaluation of the relation between the tone of rice leaf color and the degree of susceptibility to rice blast after the nitrogen application as topdressing. It was able to detect the delicate change of leaf color just after nitrogen topdressing. Values of brightness, coloration and reflection rate at 550nm wave length reached the minimum 3 days after topdressing and the value of tonality reached the maximum. The susceptibility to rice blast began to increase just after nitrogen topdressing and reached the maximum 3 days later. These results suggested that using the spectrophotometer for detection of the change of leaf color afternitrogen topdressing was effective for the evaluation of the degree of susceptibility to rice blast.
Pythium rot of cabbage, Brassica oleracea L., occurred in Tsukuba city, Ibaraki Prefecture in September, 1995. The stems just above the soil surface were affected and diseased tissues turned white in color, showing dry rot symptom. Both Pythium aphanidermatum (Edson) Fitzpatrick and Pythium sp. group ‘HS’ isolated from diseased plants were demonstrated as causal pathogens. This is the first report on stem rot of cabbage caused by Pythium species.
Sclerotinia rot of Brassica campestris L. (chinensis group), Angelica keiskei Koidz., beard-tongue Penstemon hybrids (P. gloxinioides hort.), bladder campion Silene vulgaris Garcke and verbena Verbena officinalis L. occurred in Tokyo Metropolis between 1990 and 1995. The causal fungus isolated from the diseased plants was identified as Sclerotinia sclerotiorum (Libert) de Bary by morphological observations and inoculation tests.
Strawberry Anthracnose (Glomerella cingulata) causes severe loses in strawberry nurseries throughout Japan, despite the use of recommended fungicide. This study was carried out to evaluate the activity of two rice blast granule chemicals on the disease. In the nursery bed, probenazole at 9g a. i./m2 and pyroquilon at 4g a. i./m2 controlled the disease by row application. In raising seedlings in pots (9cm in diameter, 300ml in capacity), only probenazole at 5g per pot adequately controlled the disease. Probenazole was the most active material against strawberry anthracnose in nursery bed and raising seedlings in pots.
Gray mold of Steirodiscus tagetes occurred in Saitama prefecture in 1995. A Botrytis species isolated from diseased plants was identified as B. cinerea. The inoculation experiment showed that the fungus was the causal agent of the disease.
Southern blight of Eupatorium fortunei occurred in Saitama prefecture in 1994. A Sclerotium species isolated from diseased plants was identified as S. rolfsii. The inoculation experiment showed that the fungus was the causal agent of the disease.
Verticillium wilt of balloonflower Platycodon grandiflorum A. DC. and safflower Carthamus tinctorius L. occurred in Tokyo Metropolis in 1995. The causal fungus isolated from the diseased plants was identified as Verticillium dahliae Klebahn by morphological observations and inoculation tests.
Southern blight of Cyrtanthus, Cyrtanthus mackenii Hook. f., moss phlox, Phlox subulata L., and beard-tongue, Penstemon hybrids occurred in Tokyo Metropolis in 1995. The causal fungus isolated from diseased plants was identified as Sclerotium rolfsii Saccardo by morphological observations and inoculation tests.
Leafblight of copper alternanthera, Alternanthera ficoidea (L.) R. Br. ex Roem. et Schult., lion'sear, Leonotis leonurus (L.) R. Br., Egyptian star-cluster, Pentas lanceolata (Forssk.) Deflers and stem and root rot of moss phlox, Phlox subulata L. occurred in Tokyo Metropolis from 1994 to 1995. A Rhizoctonia species isolated from the diseased plants was identified as Rhizoctonia solani Kühn. Inoculation tests showed that the fungus was the causal agent of these diseases.
The simplified diagnostic method has been developed for latent infection of strawberry anthracnose. We applied this method to latent infection of cyclamen anthracnose. After dipping into 70% ethanol for 30 seconds, the leaves were incubated at 22°C, 25°C, 28°C, 31°C and 34°C. Pink masses of sporulation which were signs of anthracnose highly developed at 28°C after 20 days. This result supports that the method is useful for detection of latent infection of cyclamen anthracnose.
Superparasitism and sex allocation in parasitized hosts in Itoplectis naranyae and the effects of superparasitism on offspring survival and sex ratio at wasp emergence were studied. Female wasps accepted the majority of parasitized hosts for oviposition and did not change sex allocation in response to them. There is no significant difference in the percentage of wasp emergence between singly and plurally parasitized hosts. Superparatisitism did not influence sex ratio at wasp emergence.
Larval competition in the solitary parasitoid wasp Itoplectis naranyae was studied. When superparasitism occurred, competition took place between 24h and 48h after parasitism. Early instar larvae attacked competitive eggs and larvae and killed them, using the mandibles. The elimination of competitive eggs by larvae could be advantageous for larvae in superparasitism and partly explains why superparasitism has no effect on the fitness of surviving larvae.
A 12μm-thickness low density polyethylene ⌈PE⌋ film without fatty acid ester was good for manufacturing artificial eggs for rearing Trichogramma sp. Ten μm-thickness high density PE, parafilm® (American Can Co Ltd), Fuji Sealon film (Fuji photofilm Co. Ltd) and Urethane resin film were not suitable for processing artificial eggs. 20-30μm thickness PE was good for processing, but Trichogramma wasps could not penetrate their ovipositors into them. Trichogramma wasps laid their eggs into a 12μm-PE artificial egg. Their larvae and pupae grew inside filled with culture medium containing 2.5ml of pupal fluids of Mamestra brassicae, 1.5ml of cow milk, 1.0ml of egg yolk, and 0.5ml solutions of mineral elements. The number of oviposited eggs was 55 among 58 tested ones. An average number of larvae grown inside an artificial eggs was 18.5, 5% of oviposited eggs could become adult with swollen abdomen and shrunk wings.