IN VITRO ACTION OF FUNGICIDES ON MYCELIAL GROWTH AND CONIDIUM GERMINATION OF ALTERNARIA SOLANI, CAUSAL AGENT OF TOMATO EARLY BLIGHT

ABSTRACT

In vitro tests were carried out with the aim of evaluating the inhibitory action of 16 fungicides on the mycelial growth and conidium germination of Alternaria solani, causal agent of tomato early blight. The fungicides were tested in the concentrations of 0, 1, 10 and 100 µg.mL-1 to both criteria, using the fungicide dilution in culture media and the cellophane techniques (NEELY, 1978), respectively. The best inhibition levels were obtained with specific fungicides that showed differential action on the different stages of the fungus life cycle. The fungicides iprodione, cyprodinil, procymidone, fluazinam, and pyrimethanil presented elevated inhibition levels for both criteria. Metconazole, tebuconazole, difenoconazole and prochloraz provided elevated inhibition of the micelial growth and partial inhibition in relation to conidium germination. Kresoxim methyl, azoxystrobin, pyraclostrobin+methiram, fenamidone and famoxadone+mancozeb presented intermediary inhibitory behavior of the growth micelial and complete inhibition of conidium germination starting from 1 µg.mL-1. Chlorothalonil and mancozeb promoted the minor inhibition levels, however their action was always superior to the control.

KEY WORDS:
Fungi; inhibition; Lycopersicon esculentum Mill.