Influence of some food additive chemicals to Phomopsis Viticola Sacc.

Abstract

The effects of food additives potassium sorbate, sodium benzoate, sodium bicarbonate, and classical
mancozeb on mycelial growth and the yield of pycnidium and pycnidiospore production of Phomopsis
viticola were tested in vitro. Food additive chemicals were tested at five different dosages, 100; 300; 600;
1000 and 1600µg ml-1, mancozeb was tested only at recommended dose. Food additives showed inhibitory
effect at different levels on mycelial growth of fungus isolates. According to the ED50 values at the 5th day,
potassium sorbate (375 µg ml-1 for isolate İzmir 2 and 700 µg ml-1 for isolate Salihli 2) showed significant
inhibition effect on the radial mycelial growth of fungal isolates. Similar efficacy for İzmir 2 and Salihli 2
was obtained at the highest doses (990 µg ml-1 for İzmir 2 and 1150 µg ml-1 for Salihli 2) from sodium
bicarbonate and (1040 µg ml-1 for İzmir 2 and over 1600 µg ml-1 for Salihli 2) from sodium benzoate. MIC
values of food additives on mycelial growth of P. viticola were found higher than 1600 µg ml-1. The food
additives at increasing doses were more successful on the pycnidia and pycnidiospores inhibition than on
mycelial growth. The strongest inhibition among food additives on the pycnidia and pycnidiospores
production was determined in potassium sorbate with dose between <100 µg ml1 and 620µg ml-1. However,
ED50 values of sodium benzoate were found lower than potassium and sodium bicarbonate had. While MIC
of potassium sorbate was 1000µg ml-1 on pycnidium production; on pycnidiospore it was 600 µg ml-1.
Whereas MIC values of sodium benzoate and sodium bicarbonate were determined higher than potassium
sorbate. Data obtained from the research demonstrated that food additives may be used against P. viticola in
organic and traditional viticulture after field experiments.