Microbial, chemical and physical aspects of citrus waste composting.

Citrus waste supplemented with calcium hydroxide and with a C/N ratio of 24:1, pH of 6.3 and moisture content of 60% was composted by piling under shelter. With regular turning over of the pile and replenishment of moisture, the thermic phase lasted for 65-70 days and composting was completed after 3 months. Compost thus prepared had an air-filled porosity of 14%, water-holding capacity of 590 ml l(-1), bulk density of 1.05 g cm(-3) and conductivity of 480 mS m(-1). Phosphorus content (in mg l(-1)) was 15, potassium 1,170, calcium 362, magnesium 121, sodium 32, chloride 143, boron 0.31, and water-soluble nitrogen and organic matter 126 and 4788, respectively. Total carbon amounted to 8.85% and total nitrogen to 1.26% of the dry weight, giving a C/N ratio of 7. Mature compost showed some, but acceptable, levels of phytotoxicity. Raw citrus waste was predominantly colonised by mesophilic yeasts. Thermophilous microorganisms present during the thermic phase mainly comprised the bacterial species Bacillus licheniformis, B. macerans and B. stearothermophilus and, to a lesser extent, fungi such as Absidia corymbifera, Aspergillus fumigatus, Emericella nidulans, Penicillium diversum, Paecilomyces variotii, Rhizomucor pusillus, Talaromyces thermophilus and Thermomyces lanuginosus. Bacteria prevalent in the final product included B. licheniformis, B. macerans, Proteus vulgaris, Pseudomonas aeruginosa, P. fluorescens, P. luteola and Serratia marcescens, whereas fungi isolated most frequently comprised Aspergillus puniceus, A. ustus, E. nidulans. Paecilomyces lilacinus, T lanuginosus, yeasts and a basidiomycetous species, probably Coprinus lagopus.

Field Sprays of Bacillus subtilis and Fungicides for Control of Preharvest Fruit Diseases of Avocado in South Africa.

In 3 consecutive years, preharvest applications of Bacillus subtilis field sprays integrated with copper oxychloride or benomyl consistently reduced severity of avocado black spot (BS), caused by Pseudocercospora purpurea at Omega, Republic of South Africa. Control was equal to that obtained with copper oxychloride or benomyl-copper oxychloride in the first and third years of spraying at Omega. In the second year, only the integrated treatment controlled BS, while copper oxychloride proved ineffective. The antagonist was applied on its own or integrated with copper oxychloride sprays at two other geographically distinct locations, Westfalia Estate and Waterval. The integrated and biological treatments at these localities were less effective than copper oxychloride sprays in controlling BS disease. Integrated control was more effective than B. subtilis sprays at Westfalia. On continuation of the biological spray program at Waterval for an additional three seasons, control was as effective as copper oxychloride in the last 2 years of spraying. Sooty blotch (SB), caused by an Akaropeltopsis sp., was reduced by the integrated treatment at Omega during the second season and at Westfalia during the first season. Although the two fungicide treatments reduced SB at Omega in the first season, copper oxychloride increased it above that of the control in the third season. Only the copper oxychloride treatment reduced SB at Waterval in the third season, while the B. subtilis treatment increased disease above that of the control in the fourth season.

Rind Stippling on Valencia Oranges by Copper Fungicides Used for Control of Citrus Black Spot in South Africa.

Four copper sprays and copper mixtures with dithiocarbamates aggravated stippling of the fruit rind of Valencia oranges if sprayed in succession at registered rates during the recommended protection period from October to January for control of citrus black spot in South Africa. Copper stippling was more severe on treatments in which copper oxychloride was sprayed in succession, individually, or in combination with mancozeb or maneb/ZnO. On the other hand, less copper stippling was observed on treatments in which three mancozeb applications were altered with a single copper oxychloride as tank mixtures with or without mancozeb, which was sprayed during midsummer (December and January). Cupric hydroxide resulted in more general copper stippling lesions than any other copper oxychloride spray program. Four successive applications of the wettable powder copper oxychloride formulation resulted in more copper stippling when compared with the suspension concentrate formulation. Stippling was calculated to be more severe with late applications of copper fungicides during December and January. In another experiment, all contact fungicides tested were effective in controlling citrus black spot.

Production of monoclonal antibodies against Xanthomonas campestris pv. mangiferaeindicae and their use to investigate differences in virulence.

Four Xanthomonas campestris pv. mangiferaeindicae isolates from mango black spot lesions were grouped according to differences in virulence and used to raise monoclonal antibodies (mAbs). Two immunization approaches were followed. In the first, four groups of mice were immunized, each with a different isolate and the spleens from each group homogenized together for cell fusion. The second approach entailed immunization of a single group of mice with bacteria pooled from all four isolates. The resultant mAbs were characterized with regard to the antigen binding specificity and antibody class. A relationship between mAb binding specificity and virulence of the bacteria was shown by Western blot analysis.

The role of the ambulance service as part of the health profession.

The provincial ambulance services have developed into highly trained professional emergency medical services over the last few years. This rapid development seems to have caught the medical profession by surprise, so much so that in recent months some medical practitioners were of the opinion that ambulance personnel were being trained to do more than they should. Unfortunately many doctors still seem to view the ambulance service as mainly a patient transport service and not as the emergency medical service it has become. It would be in the interest of the patient if a sound working relationship between pre-hospital, hospital and private medical practitioners could be established and that each group becomes familiar with the capabilities of the other. It is equally important that ambulance personnel be welcomed into the health profession of which they are now an integral part.

Antagonism of Lactic Acid Bacteria against Phytopathogenic Bacteria.

A variety of lactic acid bacteria, isolated from plant surfaces and plant-associated products, were found to be antagonistic to test strains of the phytopathogens Xanthomonas campestris, Erwinia carotovora, and Pseudomonas syringae. Effective "in vitro" inhibition was found both on agar plates and in broth cultures. In pot trials, treatment of bean plants with a Lactobacillus plantarum strain before inoculation with P. syringae caused a significant reduction of the disease incidence.