Significant progress has been made in the quest for a diagnostic kit to test potatoes for skin spot, the BPC has reported.

In a project funded by the BPC, researchers at Central Science Laboratory (CSL), have been developing assays - in-field and lab-based tests - that analyse the DNA or RNA in a seed tuber for the presence of the pathogen. These have been tested at SBEU.

“We’re almost at the stage where we have a test that can reliably predict the presence of skin spot in a crop before it’s harvested,” reports SBEU’s Jeff Peters. “The potential benefits are huge - the disease does not express itself in storage until after Christmas, by which time it is too late to do anything about it.”

Skin spot’s ability to be the unseen enemy can make it an in-store nightmare. Pimples form on the skin, which affect shelf appeal for the pre-pack market. The resulting discolouration can run deep into the tuber, causing rejections of crop destined for processing. The disease is primarily a problem for seed growers because it can affect the growth of the following crop.

Field-testing of the new diagnostic test is now nearing completion, reports Dr Peters. “We know the assay works - we’ve put it to the test over the last season and have a good correlation between symptoms expressed in store and tests that have shown up as positive several weeks earlier. The next stage will be to test it on tubers at harvest time so that we can quantify the risk and deliver a tool that growers can rely on as part of their in-store disease control strategy.”

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