Bioactive compound isolated from Conyza canadensis combined with physical treatments for the control of green mould in Orange

Green mould, caused by Penicillium digitatum, is the major postharvest disease of citrus in all producing countries. The control of this disease is carried out by fungicides in postharvest treatments, which can leave toxic residues in fruits. Therefore, the interest in cleaner technologies and alternatives to the use of fungicides, such as biopesticides, has grown in recent years. Conyza canadensis, an herbaceous weed spread all over the world, contains compounds which have significant activity against P. digitatum. Thus, the present research aimed to evaluate (4Z)-lachnophyllum lactone (LACH), isolated from C. canadensis, in combination with hot water brushing (HWB) and UV-C treatments, to control green mould and to preserve the quality of the fruit. LACH efficiently controlled green mould in orange cv. Valencia. The level of control improved from 24% to 42% according to the dose of LACH adopted, ranging from 10 to 100 mu g ml(-1) respectively. When in combination with HWB or UV-C, the efficiency of the control was enhanced from 50% to 78% with the lowest dose of LACH (10 mu g ml(-1)) and UV-C at 1.5 kJ m(-2), which showed no significant difference when the highest dose of LACH (100 mu g ml(-1)) was applied alone. This treatment delayed the onset of the disease symptoms. A biofungicide based on C. canadensis combined with UV-C and HWB is a potential natural control of green mould.

Automated summary

Green mould, caused by Penicillium digitatum, is a major postharvest disease of citrus. Controlling this disease with fungicides may leave toxic residues. Recent research has found that a compound from Conyza canadensis can effectively control green mould. Combining hot water brushing or UV-C treatment enhances the control efficiency and delays disease symptoms.