Results of trial work in fruit and vegetables show that in addition to the disease control of bacteria and virus infection by the two fungicides involved - pyrastrobin and boscalid - they can also play an equally key role in boosting a crop’s own defence mechanisms.
BASF, architect behind their own product development, say that these non-fungicidal benefits could have significant economic advantages, once they have been further evaluated in a wide range of fruit and vegetables. The strobilurin fungicide pyraclostrobin and the fungicide boscalid, together form Signum.
But hitherto, there has been the largely unexplained benefit of increasing the crop’s own defence mechanism as well as boosting yields.
It has been known that Signum (as a dispersible granule containing both boscalid and pryraclostrobin) inhibits the development of ethylene, so leaving the plant less stressed by disease
BASF field vegetables manager Dave Marris said that the company’s early research was to identify and illustrate the non-fungicidal effects of their fungicides since the introduction of their first strobilurin - kresoxim-methyl, known commercially as Stroby WG for the control of apple scab and for powdery mildew in strawberries and blackcurrants.
“These plant health benefits contribute positively to yields, quality and storage life as well as the economic performances of products,” he said. “And that recent research demonstrates that pyraclostrobin represents the most powerful compound to date in terms of non fungicidal benefits.”
He added that the fact pyraclostrobin was the only compound of the ‘strob’ which had a label statement regarding increased yields in the absence of disease, clearly pointed to these unique characteristics.”
Bill Clark, plant pathologist at ADAS Boxworth, who has been closely involved in this research, said that some aspects, such as greening of the plants following applications of pyrastrobin, could be explained, the disease control and yield responses could less so.
Trial work had been carried on Cucumber Green Mottle Mosaic - a highly infectious mechanically transmitted disease and Tomato Spotted Wilt Virus (TSWV) - a significant and worldwide disease that affect many horticultural crops and is transmitted by western flower thrips, as well as Xanthomonas campestris - a major bacterial disease of brassicas.
“Pre-treatment of plants with pyrastrobin significantly reduced the severity of all three diseases by triggering the plants own defence, we believe,” said Clark.
Though exact measurements of benefits had some way to go, Simon Townsend of BASF said it was clear to see that the healthier crops going into store like top fruit and cauliflower mean they came out healthy.
“A healthy crop into store increases marketable yields. It increased the chlorophyll content, resulting in more efficient photosynthesis, greener leaves and better quality of salads in particular,” he said.
The combined pyrastrobin and boscalid Signum formulated as a WDG (water dispersible granule) was protectant and systemic fungicide, recommended for the control of white blister in brussel sprouts, ringspot in cabbage and in cauliflower for the control of dark leaf spot and ringspot; and in carrots for the control of sclerotinia, powdery mildew and alternaria
It is also recommended in protected and outdoor lettuce and strawberries.
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