S. Keller et al., INFLUENCE OF FUNGICIDES ON THE INSECT PAT HOGENIC FUNGUS BEAUVERIA-BRONGNIARTII (SACC) PETCH, Anzeiger fur Schadlingskunde, Pflanzenschutz, Umweltschutz, 66(6), 1993, pp. 108-114
We tested 17 fungicides to check the hypothesis whether they could int
erfere with B. brongniartii applied in orchards to control the larvae
of the cockchafer Melolontha melolontha L. (Coleoptera, Scarabaeidae).
Incorporated into Sabouraud dextrose agar (SDA) at the recommended co
ncentration the fungicides Funginex (Triforin), Recop (Cu-oxychlorid),
Rondo (Captan + Pyrifenox), Systhane (Captan + Myclobutanil) and Topa
s (Captan + Penconazol) completely inhibited mycelical growth, Rondo e
ven at a 10 fold dilution. Germination of conidia did not take place w
hen they were produced on SDA incorporated with Baycor (Captan + Biter
tanol), Captan, Euparene (Dichlofluanid), Nustar + Delan (Flusilazol Dithianon), Ridomil F (Mancozeb + Metalaxyl) at the recommended rate
or Systhane (10 fold diluted). Growth of the fungus on barley kernels
(commercial preparation) on soils sprayed with fungicides showed small
er differences. They were more marked on native soil than on sterile o
ne. On both soils, Baycor and Rondo reduced fungal growth more than th
e other fungicides. The fungal material from these soil tests was used
in bioassays where they caused mortalities between 70 and 100 %. Bayc
or, Captan, Nustar + Delan, Rondo and Topas induced the lowest mortali
ties. These side effects on 'semi-field'' tests are considered as insi
gnificant. In orchards the situation for the fungus is much more favou
rable, because it is applied at a soil depth of some centimeters and d
irect contact with the fungicides is excluded. It is therefore conclud
ed that the tested fungicides have no significant side effects on B. b
rongniartii under practical conditions. Exceptions might, however, are
indicated where slowly degradable triazoles are applied repeatedly or
in soils accumulated with copper.