• The Korean Journal of Pesticide Science
• /
• v.12 no.4
• /
• pp.375-381
• /
• 2008

A new disease causing skin sooty dapple symptoms on fruits, leaves, and young shoot of Asian pear occurred in Korea. However, no chemical control approaches has been developed to control this disease. To investigate ecological aspects of this disease, we conducted field surveys in the high or low disease occurred orchards. The years with heavy rainfall caused severe occurrence of the skin sooty dapple disease than the years with lower rainfall during all growth stages of pear fruit. Different fruit-wrapping bags did not prevent occurrence of skin sooty dapple disease, and lesion numbers were higher in lower parts of fruit equatorial line inside of fruit-wrapping bags. There is a direct correlation between occurrence of the skin sooty dapple disease and frequency of fungicide application in the orchards. Among the tested commercial fungicides, thiophanate-methyl WP and penconazole WP completely inhibited the growth of the Cladosporium sp. in in vitro studies but little protection was observed in the field following fungicide applications. However, application of lime sulfur combined with the use of fruit-wrapping bags most effectively reduced incidence of the disease in the field. Our results suggest that skin sooty dapple disease could be a serious problem in sustainable organic pear farms and effective control methods for this disease urgently required.

• Applied Biological Chemistry
• /
• v.31 no.3
• /
• pp.226-233
• /
• 1988

Some physico-chemical properties and biological activities of new fungicide formulations were tested to investigate a feasibility of water-floating formulation development for sheath blight control in rice. Pencycuron[1-(4-chlorobenzyl)-1-cyclopentyl-3-phenylurea] and flutolanil$({\alpha},{\alpha},{\alpha}$-trifluoro-3'-isopropoxy-O-toluanilide) were chosen as toxicants for the formulations. Vegetable oil and surface active agents were used as a floating agent and spreader, respectively. All the formulations tested showed an excellent spreadability on the water having over $35cm^2/mg$ and were chemically stable, which the degradation rates of active ingredients were less than 10% after 12 weeks of storage at $50^{\circ}C$. Most of the applied test formulation of pencycuron was retained within 0.5cm of the surface paddy water, while that of flutolanil was vertically dispersed in the water. Inhibition activity of the tested pencycuron formulation on the sclerotia germination of the pathogen in paddy water was maintained over 30 days after the formulation treatment. Control effect of 4% pencycuron water-floating formulated with surface active agent of hydro-lipophyllic balance 4.3 on the disease in rice was equal to the reference fungicide(pencycuron 25% WP) when the former was treated one day before the transplantation of rice seedlings. Overflowing the submerged paddy water after the formulation treatment resulted in a deterious effect on the disease control.

• The Korean Journal of Pesticide Science
• /
• v.10 no.2
• /
• pp.69-75
• /
• 2006

For the development of new agrochemical fungicide 3-amino-2-phenylimino-1,3-thiazolines 2 were designed through the molecular modification based on isostere concept of 3-methyl-2-phenylimino-1,3-thiazolines 1 which showed antifungal activity against rice blast. All the compounds 2 were fit Lipinski rule and they had higher solubility in water than that of 1 by virtual calculation. We constructed 195 kinds of focused library of 3-amino-2-phenylimino-1,3-thiazolines through 6H-[1,3,4]thiadiazines (195 compounds) which synthesized from the reaction of thiourea 4 with $\gamma$-chloroacetoacetanilides 5.

• Journal of the Korean Chemical Society
• /
• v.46 no.4
• /
• pp.330-336
• /
• 2002

For the purpose of development of new agrochemical fungicide of ${\alpha},{\beta}-unsaturated$ carboxanilide series a synthesis of 4-acetyl-3-methyl-N-phenyl-1,4-thiazine-2-carboxamide (6) is described. Pummerer reaction of sulfoxide 7 obtained by sulfoxidation of dihydro-1,4-thiazine methyl ester 11 gave ${\alpha}-acetoxy$ dihydro-1,4-thiazine 10a. Under the same reaction conditions, dihydro-1,4-thiazine carboxanilide sulfoxide 14 was converted to acetoxymethyl dihydro-1,4-thiazine 18 through vinylogous Pummerer reaction involving carboxanilide of sulfonium ion through intermediate 15.1,4-Thiazine carboxanilide 6 was synthesized from the treatment of ${\alpha}-acetoxy$ dihydro-1,4-thiazine 10a with acid cat-alyst followed by hydrolysis and then the reaction with aniline.

• The Korean Journal of Pesticide Science
• /
• v.9 no.2
• /
• pp.122-131
• /
• 2005

For development of new agrochemical fungicide, syntheses of pyrrolo[2,1-b]thiazole carboxanilide derivatives 9 and antifungal screening against 6 kinds of plant pathogens were carried out. Functionalization of carboxylic acid on C-2 into carboxanilide in the pyrrolo[2,1-b]thiazole resulted in new 20 candidates, in which are ${\alpha},{\beta}$-unsaturated carboxanilide and methyl groups that are in cis relationship. Treatment of acetoxy-1,4-thiazin with magnesium in refluxing methanol gave pyrrolo[2,1-b]thiazole ethyl ester 4 in higher yield than that of the previous report. Hydrolysis of this compound afforded the corresponding acid 5, which reacted with aniline derivatives in the presence of coupling reagent, DIC to give pyrrolo[2,1-b]thiazole carboxanilides 9. As the result of in vivo antifungal assay of 9 against rice blast, rice sheath blight, cucumber gray mold, tomato late blight, wheat leaf rust, and barley powdery mildew, some compounds showed selectively antifungal activities against the rice blast and wheat leaf rust.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.8
• /
• pp.2627-2634
• /
• 2012

Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel ${\beta}$-methoxyacrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, $^1H$ nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds (1a-1h) exhibited potent antifungal activities against Colletotrichum orbiculare, Botrytis cinerea Pers and Phytophthora capsici Leonian at the concentration of 50 ${\mu}g/mL$. Exhilaratingly, compound 1d (R=3-trifluoromethylphenyl) showed better antifungal activity against all the tested fungi than the commercial strobilurin fungicide azoxystrobin.

• Mycobiology
• /
• v.48 no.1
• /
• pp.44-50
• /
• 2020

Calonectria pseudonaviculata and C. henricotiae are two closely related fungal species responsible for boxwood blight disease of ornamental shrubs (Buxus spp.) in the U.S. and Europe. A previous study has shown isolates of the latter species, which is restricted to Europe, to be less sensitive to tetraconazole, an azole fungicide. In this study, we have analyzed the CYP51 paralogs for polymorphism in 26 genomes, representing geographically disparate populations of C. pseudonaviculata (n = 19) and C. henricotiae (n = 7), from the U.S., Europe, Asia, and New Zealand. The presence of a CYP51A pseudogene and lack of a functional CYP51A paralog in all C. pseudonaviculata genomes examined is a novel discovery for fungi and could have implications for the evolution of resistance to antifungal chemicals.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2004.10a
• /
• pp.36-38
• /
• 2004

Ethaboxam is a new fungicidal active ingredient that inhibits growth of plant pathogens specifically belonging to Oomycetes with protective, curative, systemic and translaminar activity in plants. Modes of action studies revealed that ethaboxam simultaneously inhibits cytoskeleton formation and mitochondrial respiration of Phytophthora infestans at low concentrations. There have been no indications of resistance development when tested for baseline resistance monitoring to 261 isolates of P. infestans in Korea and Europe and 150 populations of Plasmopara viticola populations in Europe for 3 years since 2000. In a selective study with vine trees artificially inoculated with P. viticola repeatedly for 10 generations in greenhouse, there have been no changes in sensitivity to ethaboxam among four natural populations of P. viticola. Furthermore, ethamoxam has not shown any cross resistance with azoxystrobin, mefenoxam, dimethomorph and cymoxanil. Based on the study results from modes of action and resistance development, ethaboxam appears to be unlikely to develop resistance in field applications.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.11
• /
• pp.3341-3347
• /
• 2010

A series of oxazolidinone-based strobilurin analogues were efficiently synthesized by the reaction of 3-(2-bromomethylphenyl) oxazolidin-2-one with 1-substituted phenyl-2H-pyrazolin-3-one. Their structures were confirmed and characterized by $^1H$-NMR, $^{13}C$-NMR, elemental analysis, and mass spectroscopy. In addition, the crystal structure of the target compound 3-(2-((1-phenyl-2H-pyrazol-3-yloxy)methyl)phenyl) oxazolidin-2-one was determined by single crystal X-ray diffraction. The bioassay results of these compounds indicated that some of the oxazolidin-2-one derivatives containing N-substituted phenyl 2H-pyrazol ring exhibited potential in vivo fungicidal activities against M. grisea at the dosage of $1\;g\;L^{-1}$.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.2
• /
• pp.149-153
• /
• 2001

A new methodology for construction of dihydro-1,4-dioxin skeleton was described. Introduction of thio group at the ${\alpha}-position$ of 8 followed by chlorination gave 11, which was to prevent an enolization as well as to promote the facile nucleophilic substitution reaction of ethylene glycol giving 16 in equilibrium with cyclic ether 19. Removal of thio group of 19 and dehydration in the presence of an acid catalyst gave dihydro-1,4-dioxin 21. In case of electron withdrawing trifluoromethyl group is subsituted in C-2, 18 was converted to the corresponding dihydro-1,4-dioxin 20 by the halogenation of hydroxy followed by treatment of triethylamine.