Diverse amino acid antagonists (AAA) were investigated for control of black spot of Japanese pear caused by Alternaria kikuchiana. Inhibitory action of the AAA to fungus spore germination was rather weak. However, some of AAA induced abnormality or exhibited inhibitory action to the germ tube elongation. Control effect of known AAA, Eth derivatives, 2-amino-4-(ethylthio) butyronitryl (AETB) and its six kinds of salts on black spot of Japanese pear on the young trees grown in pots was studied under greenhouse conditions. The disease was effectively controlled by DL-ethionine (Eth) and DL-m-fluorophenylalanine (FPA) among known AAA. In a series of Eth alkyl esters of 1 to 5 carbon atoms controlled the disease without phytotoxicity, but any with alkyl group more than 6 carbon atoms, particularly n-nonyl ester, was less effective and phytotoxic. Eth Cu salt (Eth Cu) controlled the disease better than those of Zn and Mn salts. AETB was effective, but its salts less effective. In a Japanese pear orchard, 1000ppm solution of Eth, FPA, methy, ethyl and propyl esters of Eth, and Eth Cu were sprayed nine times at 10 to 14 days intervlas from May to August in 1968. All the compounds were effective for control of the disease development without phytotoxicity on leaves, fruits and whole of the trees. The best results were obtained by the treatment with Eth ethyl ester and Eth Cu.
The tobacco mosaic virus strains, C and W which were isolated from crucifer plants, were compared about their host ranges with those of the other TMV strains, HR, Lychnis strain Ly, two ordinary strains OM and O, cowpea strain BC-B, its tobacco form BC-T, and 06. Strains C and W infected all 18 kinds of crucifer plants systemically, and HR and Ly infected 11 and 15 kinds of them respectively. Sometimes OM infected 5 Brassica plants systemically, but their virus contents were very low. Strains 06, BC-B, and O were inoculated to 6 Brassica plants, but no plants were infected systemically. Strains HR, C, W, and Ly caused only local lesions on the leaves of petunia and most of Nicotiana plants including several tobacco varieties. Among cucurbitaceous plants tested, only M. Charantia showed local lesions by the inoculation of HR, C, W, Ly, and OM. Ph. vulgaris var. Kairyo-Otebo showed no local lesions by the inoculation of HR, C, W, and Ly. Strains HR, C, W, and Ly caused primary lesions on P. lanceolata, and HR and sometimes Ly caused systemic infection. From the similarity of the host ranges and the amino acid compositions of the coat proteins of HR, C, W, and Ly, the authors concluded that these strains should be classified as “HR group” and suggested that TMV strains having a similar native amino acid composition may have a similar host range.
Organophosphorus compounds, N-methylcarbamates, amide compounds, alcohols, phenols and other compounds were tested for joint action with phosphorothiolate (PTL) fungicides by crossing the paper strips impregnated with the test chemicals on agar plate uniformly seeded with rice blast fungus. Antagonism was found for phosphoramidothionate herbicide (amiprophos) and phosphorothiolothionate having carboxy ester structure (malathion and phenthoate). While synergism was found for some amide compounds, including propanil (3', 4'-dichloropropinanilide) and its derivatives. There would be specificity of chemical structure in these amide compounds for synergism with PTL fungicide. The synergism was not observed when the PTL-resistant lines of the fungus was used as a test organism. Mchanism of the synergism was discussed in connection with resistance of the fungus to PTL fungicides.
Water solution of DNA fraction of potatoes inhibited the conidial germination of Phytophthora infestans. Susceptible lesions were observed on the interspecific hybrid 96-56 (R1 gene) inoculated with the conidial suspension of Phytophthora infestans (Race 1) germinated both in the water solution of DNA fraction from interspecific hybrid 96-56 (R1 gene) and in that of 1506-b (9) (R1R4 genes).
Scions of potato interspecific hybrid 1506-b (9) (R1R4 genes) on the stocks of interspecific hybrid 96-56 (R1 gene) and vice versa showed both susceptible lesions and hypersensitive flecks by an inoculation of Phytophthora infestans (Race 1). Plants grown up from grafted potatoes (scions of susceptible Norin No.1 on the stocks of interspecific hybrid 96-56 and vice versa) showed both susceptible lesions and hypersenstive flecks by an inoculation of Phytophtora infestans (Race 0).
Cucumber mosaic virus (CMV) was purified by repeated precipitations with 8% PEG and 0.2M NaCl, followed by PEG solubility gradient (0∼6% PEG stabilized in 35∼5% sucrose) centrifugation. Virus yields ranged from 500 to 800mg per kilogram of fresh tissue. Purified preparation was highly infectious and contained uniform virus particles. Sedimentation pattern showing a single peak suggests that no aggregation occurred.