The effect of some commercial pesticide carrier formulations on the germination of Pseudoaegerita matsushimae propagules

Propagules of Pseudoaegerita matsushimae, an aero-aquatic hyphomycetous fungus commonly occurring on the surface of woodland ponds, were shown to germinate readily on moist surfaces. After an initial latency period of approximately 3 h during which less than 5% germination occurred, the ensuing 2–3 h saw 97% of all propagules germinate. This figure did not increase after 16 and 24 h. Using this information as a control, germinability was tested in many situations that simulated the application of pesticides and also their carriers. Oil emulsions or emulsifiable oil concentrates containing surfactants were up to 30% more toxic than mineral oils which did not contain such additives. The surfactant itself (Tween 80) did not significantly inhibit germination. Our initial studies indicated that aromatic carriers such as xylene or turpentine are highly toxic to Pseudoaegerita matsushimae propagules, whereas aliphatic carriers such as kerosene produce no significant reduction of germination. Key words: aero-aquatic fungus, pesticide carriers, aliphatic hydrocarbons, aromatic hydrocarbons, environmental impact.