Synthesis and fungitoxicity of some pyrimidine derivatives
A series of 12 pyrimidine derivatives were prepared and testedin vitro against growth, sporulation and nucleic acid content ofFusarium oxysporum f. sp.lycopersici andHelminthosporium oryzae. Introduction of a thiazole ring together with two aryl groups into 2-aminopyrimidine brought about drastic toxicity for both fungi. Pyrimidine derivatives with aryl groups alone were less toxic. Nitro groups were found to enhance the toxicity of the pyrimidine derivatives especially when substituted in the ortho-position of the aryl groups. Inhibition of nucleic acid synthesis of both fungi was attributed mainly to the presence of the thiazole ring.
Suppression of Sclerotinia blight of peanuts with dinitrophenol herbicides.
PORTER, D. M., and 0. E. RUD. 1980. Suppression of Sclerotinia blight of peanuts with dinitrophenol herbicides. Phytopathology 70:720-722. Dinoseb and Dyanap incorporated into potato dextrose agar at I ug/ml hypogaea) when applied at postemergence but not when applied only at significantly reduced mycelial growth of Sclerotinia minor, the causal agent seedling emergence. Dinoseb reduced disease severity more than Dyanap. of Sclerotinia blight of peanut. Mycelial growth also was reduced on media Peanut pod yields were greater in plots receiving postemergent treatments containing 2,4-DB at 25 ug/ml. Growth of S. minor after 192 hr of of dinoseb or Dyanap than in plots treated at seedling emergence. Peanut incubation was not restricted on media containing benefin, vernolate, crop values was about 23% greater in plots treated at postemergence with alachor, or naptalam at 25 pg/ ml. Field applications of dinoseb or Dyanap dinoseb or Dyanap than in nontreated plots. significantly reduced the severity of Sclerotinia blight in peanuts (Arachis Additional key words: Sclerotinia scierotiorum, soilborne disease, disease control, dinoseb, Dyanap. Sclerotinia blight of peanut caused by the soilborne fungus naptalam (N-l-napthylphthalamic acid), Dyanap (a formulation Sclerotinia minor Jagger (10), was first discovered in Virginia in containing one part dinoseb and two parts naptalam), and 2,4-DB 1971 (12). This disease has since become widespread in both (4-[2,4,dichlorophenoxy] butyric acid) prepared in acetone. Virginia and North Carolina and causes severe economic losses to Desired quantities of these stock solutions of each herbicide were growers (13). All peanut plant parts on or near the soil surface are pipetted into flasks containing an appropriate volume of partially subject to attack. At present, all peanut cultivars available to cooled PDA. The contents of each flask were stirred during growers are susceptible to S. minor, and available fungicides addition of the herbicides, shaken for 60 sec to insure uniform provide only limited control. mixing, and then poured into sterile plastic petri plates (85 X 15 Several workers have shown that dinitrophenol herbicides mm). Solidified media were inoculated with 5-mm diameter agar reduce the severity of diseases caused by several plant pathogens. In plugs of mycelium taken from the periphery of 3-day-old colonies 1956 Chappell and Miller (4) showed that dinoseb and other of S. minor grown on PDA. Plates were incubated at room herbicides were effective against a wide range of peanut plant temperature (22 C). Radial colony growth was measured at pathogens. Dinoseb reduced the severity of stem rot of peanuts specified intervals. (caused by Sclerotium rolfsii Sacc. [2,5,7]), root rot of pea (caused A farm with a history of Sclerotinia blight was used for field by Aphanomyces euteiches Drechs. [8,14]), root rot of navy bean experiments. The soil type was an Altavista loamy fine sand. (caused by Fusarium solani [Mart.] Appel & Wr. f. sp. phaseoli Preplant-applied vernolate (1.9 kg/ha) and benefin (1.68 kg/ha) [Burk.] Snyd. & Hans. [16,17]), and root rot of snapbean (caused were used in all treatments. Peanuts (cultivar Virginia 72R) were by Pythium irregulare Buis. [15]). However, the severity of root planted in May of 1977 and 1978. A randomized block design with rot of soybean caused by Thielaviopsis basicola (Berk. & Br.) Ferr. four replications of four-row plots 12.2-m long and spaced 0.9-m was enhanced following application of dinoseb (11). Increases in between rows was used in all experiments. Dinoseb (1,361 g/3.785 peanut yield were attributed to weed control and not fungicidal L) was applied at seedling emergence at the rate of 1.68 kg/ha. activity of dinoseb against the stem rot pathogen (6). Dyanap was applied at seedling emergence at the rate of 5.04 The purposes of this research were to identify herbicides kg/ha. Single and multiple postemergent applications of dinoseb currently used in peanut production that might possess fungicidal or Dyanap at 0.84 kg/ha were made in the middle of the growing properties against S. minor and to determine whether the severity season. All herbicides were of commercial grade and were applied of Sclerotinia blight under field conditions could be reduced by with a C02 backpack sprayer equipped with 8004 flat spray tips and herbicide application. set to maintain a pressure of 4.3 kg/cm 2 and to deliver 262 L/ha. Plants were monitored for evidence of S. minor infection. Twice MATERIALS AND METHODS each year during the growing season twenty randomly selected The toxicity of commercial grades of herbicides to S. minor was plants in each of the two center rows in each plot were scored I to 5 measured as the inhibition of mycelial growth on potato dextrose on a scale of increasing symptom development and disease indices agar (PDA) and on herbicide-amended PDA. The herbicides were calculated. At the end of the growing season, plants in the two included dinoseb (2-sec-butyl-4,6-dinitrophenol), benefin (Ncenter rows of each plot were harvested, dried, and graded by butyl-N-ethyl-a,a,a-trifluoro-2,6-dinitro-p-toluidine), and standard procedures to determine pod value. vernolate (S-propyldipropylthiocarbamate) prepared in water, and alachlor (2-chloro-2',6'-diethyl-N-[methoxymethyl]acetanilide), RESULTS This article is in the public domain and not copyrightable. It may be freely Effect of herbicides on mycelial growth of S. minor. After 48 hr reprinted with customary crediting of the source. The American Phytopathoof incubation, mycelial growth on agar amended with alachlor, logical Society, 1980. benefin, naptalam, and vernolate at 25 pg/ ml was similar to that on
Effect of actinomycin D and chloramphenicol on the induction of the malate decarboxylase system in Lactobacillus thermobacterium 5 (CNRZ) 313.
This paper presents data on the induction of malate decarboxylase in Lactobacillus thermobacterium and the effect of chloramphenicol and actinomycin D on the induction.