STRAWBERRY growers could have a new option for tackling outbreaks of charcoal rot disease.
Gas company BOC, in conjunction with the CSIRO and LZD Czech Republic, has developed a new soil fumigant that has shown efficacy comparable to the formerly used methyl bromide.
The CSIRO, DPI Victoria and BOC's field studies with EDN Fumigas (Ethanedinitrile) have shown it to be effective on soil pathogens and weeds.
The Australian Pesticide and Veterinary Medicine Authority (APVMA) is expected to approve registration shortly.
EDN Fumigas is a broad spectrum fumigant that is highly toxic to insects, weeds, nematodes and soil-borne pathogen.
It is not listed as a greenhouse gas or ozone depleting substance and can be a suitable substitute for methyl bromide.
Charcoal rot disease is caused by soil borne pathogen Macrophomina phaseolina.
The pathogen has a wide plant host range and favours heat stress, soil water deficit and host plant susceptibility to develop.
Identification of charcoal rot symptoms in the field is sometimes difficult due to the overlap of similar symptoms caused by other soil borne pathogen.
The typical charcoal rot symptoms includes necrotic root and crown rot accompanied by plant wilting and chlorosis of leaves.
Deep examination of the plant crown shows dark to orange brown discoloration.
Control of charcoal rot is problematic due to heat tolerance and because microsclerotia remain in the soil and on the infected plant materials left over from the previous cropping cycle, reoccurring when the favourable condition prevails.
Methyl bromide has been used for number of years to keep the pathogen under control, however with it currently being phased out, there appears to have been an increase in the incidence of charcoal rot in strawberry fruit growing areas.
An efficacy soil fumigation study under APVMA trial permit was conducted by BOC at a customer site growing strawberry fruit crop in Palmview, Queensland.
This site had been experiencing severe charcoal rot disease.
Six beds, with a sandy soil type, measuring 90m long and 0.65m width were selected for the study.
Three beds were applied with EDN Fumigas at the rate of 50g/m2 at 5cm depth using drip application method and another three beds were used as a control.
Prior to application all the soil beds were covered with low density polyethylene plastic sheet.
Soil samples were collected from both the trial and control beds before application of the EDN Fumigas and 14 days after application using standard procedure.
The samples were then sent to SARDI, Urrbrae, South Australia for analysis.
Macrophomina was identified using soil dilution method.
Before fumigation, Macrophomina was found in all the selected beds.
Fourteen days after fumigant application, no colony forming units of the target soil borne pathogen was found in the EDN Fumigas applied beds while it was found in the control beds.
Sunrise Strawberries manager Josh Hendriksen, Park Ridge, Queensland, said prior to trialling EDN Fumigas he was struggling to retain his crops due to charcoal rot.
“The EDN Fumigas trial gave our strawberries a new lease on life, proving to be a clear solution to the issue of charcoal rot which was causing us to lose almost half our crops," Mr Hendriksen said.
"We found that all crops fumigated with EDN Fumigas were cured from charcoal rot.”
