Phenylmercury Chloride Research Articles

Glasshouse experiments on apple scab

SUMMARYDilutions of various fungicides were compared on potted MM 109 clonal rootstocks in the glasshouse for protective (pre‐infection) and curative (post‐infection) activity against apple scab. The materials, as commercial preparations, included captan, copper (as ‘dry’ Bordeaux mixture), dichlofluanid, didecyldimethylammonium bromide (DDAB), dispersible sulphur, dithianon, dodine acetate, lime‐sulphur (LS), phenylmercury chloride (PMC), and thiram; they were assessed on the basis of percentage active ingredient in the dilutions.When acting at normal rates of use, many of the fungicides were much more effective protectively than curatively, but this contrast was less applicable to DDAB, dodine acetate, LS, and dichlofluanid. PMC, however, was an especially notable exception in proving curatively superior at unusually low rates. In addition, it was particularly active in vapour form, and was effectively translocated not only from one leaf surface to the other, but, especially at 0.005%, from sprayed to younger unsprayed leaves on the same shoots. Other standard fungicides showed little or no translocated activity, but isobutyl‐o‐coumarate was effective at the growing shoot‐tips in spring from a spray applied to the lower leaves.PMC reduced infection when applied once at any time during the scab‐incubation period, and especially 24 hr. after infection, when the control was almost complete. Longer intervals before spraying reduced the curative action, but not in proportion to the intervals; the infection pattern showed multi‐peak fungicidal activity and, after the later sprays, many lesions were practically infertile. The curative properties of PMC were matched by several other formulated phenylmercury salts compared at equivalent percentage mercury content, but the dimethyldithiocarbamate proved rather less effective. A preliminary attempt to supplement the curative properties of PMC with the protective properties of LS, by mixing these fungicides at low rates, showed evidence of fungicidal antagonism, and this needs further investigation.Several fungicides, notably the inorganic sulphurs, thiram, the phenylmercury compounds, dichlofluanid, and DDAB showed incidental activity against natural infection by powdery mildew.

Kinetics and mechanism of the reaction of isotopic exchange of phenylmercury chloride with mercuric chloride, labeled with Hg203

1. The isotopic exchange of phenylmercury chloride with mercuric chloride, labeled with Hg203, was studied in anhydrous toluene. 2. The kinetics of the isotopic exchange of phenylmercury chloride with mercuric chloride was studied in anhydrous toluene. The reaction possesses a total second order, and is first order with respect to each of the components. 3. The activation energy of the reaction was determined at 6093 cal/mole. 4. A mechanism was proposed for the reaction studied.

Mercury residues in apples from trees receiving organomercurial fungicide in the previous autumn and winter.

SUMMARYMercury residues have been measured in apples from trees receiving experimental applications of phenylmercury chloride in the previous autumn and/or in the dormant season. In the absence of organomercurial sprays in the succeeding summer, mercury could not be found in the fruit at harvest. Even when post‐harvest or dormancy applications preceded conventional summer schedules of an organomercurial fungicide, residues of mercury at harvest were not increased.

Phenyl derivatives of organotitanium compounds

Thermally unstable tetraphenyltitanium has been obtained by the interaction of 4 moles of phenyllithium with titanium tetrachloride in benzene solution at −70°. It reacts with mercuric chloride at the same temperature with quantitative formation of phenylmercury chloride. In ether-cyclopentadiene solution, because of the replacement of two phenyl groups, dicyclopentadienyldiphenyltitanium is formed. At −10° tetraphenyltitanium decomposes, 1 mole of biphenyl is formed, and black pyrophoric diphenyltitanium, stable at room temperature and in an inert atmosphere, has been isolated. The oxidation of diphenyltitanium in benzene labelled with 14C shows that both products of the oxidation, phenol and biphenyl, do not contain the label. A chloroform solution of diphenyltitanium decomposes at room temperature with the formation of benzene, titanium tetrachloride and biphenyl. A black crystalline precipitate of diphenyltitanium ammine has been obtained by the action of ammonia on a solution of diphenyltitanium in benzene. It is easily oxidised in air. Only about 40% of the theoretical yield of phenylmercury chloride is obtained by the action of mercuric chloride on a solution of diphenyltitanium in either. Phenylmercury chloride reacts with the organotitanium compound with formation of benzene, metallic mercury, calomel and ethylmercury derivatives. The formation of ethylmercury chloride was the result of a homolytical procedure with the solvent, diethyl ether.

Mercury residues in potatoes following application of a foliar spray containing phenylmercury chloride

AbstractA fungicide containing phenylmercury chloride (o.6% w/w mercury) and copper oxychloride was sprayed on to potato foliage at the normal rate of 3 lb. formulated wettable powder/100 gal./acre. Four and eight applications were made at 7–10‐day intervals although it is normal practice in this country to make not more than four applications. In the flesh of potatoes 0.02 p.p.m. of mercury was found half‐way through the growing season after four applications and 0.03 p.p.m. at the end of the growing season, whether four or eight sprays had been put on. Similar residues were found in the peel. Unsprayed controls contained less than 0.005 p.p.m. of mercury. Potatoes grown on ground where phenylmercury chloride had been sprayed the previous year were not contaminated. Pot experiments suggested that traces of mercury compounds can be both translocated from the foliage and taken up from soil into tubers.

AGloeosporiumBud-Rot and Twig-Canker Disease of Cultivated Hazel

An apparently unrecorded but devastating bud-rot and twig-canker disease of cultivated hazel (Corylus avellana L.) was investigated in a Kent orchard. Etiological studies established the causal organism as a possibly undescribed species of Gloeosporium. Spores released in spring and early summer from dead buds and twig cankers are inactive on most of the new buds over a long period, and the fully developed buds are killed only immediately before foliation in the following spring. A small proportion of immature buds may be infected and killed in early summer, but most bud invasion occurs after leaf-fall. The disease is widely distributed in wild and cultivated hazel in this country, and the causal fungus is pathogenic to apple fruit.Virtually complete control was given by a single high-volume spray, applied in October before leaf-fall, of a phenylmercury chloride wettable powder at 0∙005% p.m.c. ; a similar spray delayed until after leaf-fall gave partial control. Cropping was greatly improved by the October spray. Bordeaux mixture and captan wettable powders applied before or after leaf-fall, and tar-oil emulsion after leaf-fall, were all ineffective. The conspicuous superiority of the pre-leaf-fall mercury spray is explained by postulating the translocation of mercury from the leaves to the inner parts of the buds.

Experiments on the control of ripe spot on sturmer apples

Summary Satisfactory control of ripe spot of apples, a storage disease caused by one or both of the fungi Gloeosporium perennans Z. et C. and G. album Osterw., was obtained by the use of an orchard spraying programme which included phenyl mercury chloride until about mid-December, and captan for the remainder of the season. Storage of Sturmer apples at 36°–38°F inhibited considerably the development of ripe spot. A lapse of several days between picking and placing in cool store did not affect the amount of this disease in Sturmer fruit picked at normal harvesting date and stored for six months.

Synthesis and properties of trichloromethyl- and 3,3-dichloroallyl mercury compounds

1. Trichloromethylmercury bromide was synthesized by reaction between mercury and bromotrichloromethane in presence of radiation; the product was converted by the usual methods into trichloromethylmercury hydroxide, chloride, and iodide. 2. Phenyl(trichloromethyl)mercury was synthesized by reaction of trichloromethylmercury bromide with dichlorodiphenyltin in an alkaline medium. Reaction of the product with hydrogen chloride gave phenylmercury chloride, which indicates the high electronegativity of the trichloromethyl group, as compared with that of the phenyl group. 3. Trichloromethylmercury halides form complex compounds with pyridine. The double compound of pyridine with trichloromethylmercury bromide survives recrystallization and has the composition CC13HgBr · C5H5N. 4. The complex-formers ammonia and hydrogen sulfide completely destroy trichloromethylmercury halides. 5. 3,3-Dichloroallylmercury iodide was synthesized by reaction between 1,1-dichloro-3-iodopropene and mercury in presence of ultraviolet radiation; the product was converted by the usual methods into 3,3-dichloroallylmercury chloride and bromide.

OBSERVATIONS ON APPLE CANKER

Sodium pentachlorophenate and phenyl mercury chloride have been tested as eradicant sprays against apple canker. Trials with inoculated shoots showed that neither of these sprays would affect an established leaf‐scar canker. Both chemicals checked sporulation of Nectria galligena on cankers but phenyl mercury chloride was the more effective and reduced sporing up to 18 months after application.The incidence of leaf‐scar infection was diminished by treatments reducing sporulation, such as spraying with phenyl mercury chloride or the removal of diseased material from the tree. Bordeaux mixture used as a protectant winter spray was ineffective in reducing leaf‐scar infection.