Now, crop protection company Adama says it has a solution: Merpan (captan). Captan, a proven multi-site fungicide with a 30-year history in this country, now has its PHI (preharvest interval) down from 14 days to just three.

Bull’s eye rot is a significant problem for many of New Zealand’s high value export varieties, including Pacific Queen, Pink Lady and Ambrosia. Fruit becomes more susceptible to bull’s eye rot infection late season, with the distinctive, circular rot only showing-up during storage.

Protecting mature fruit against rots is challenging, as apples are successively picked and most product PHIs prevent application between picks to protect later harvested fruit. China has its own significant apple industry and is naturally highly motivated in its desire to stop bull’s eye rot before it reaches its borders.

To meet stringent import requirements, an application of Merpan within the last 20 plus or minus five days before harvest is a requirement for apples imported from NZ. However, this was not previously possible for successively picked fruit with a 14-day PHI. With a reduced PHI of three days for Merpan, growers will be able to treat fruit more effectively and consequently reduce risk to trade with China.

European canker, which is controlled by Merpan, is also of serious concern for the NZ apple industry, having been described by some growers as the number one threat to their business. Not only is it a quarantine pest for Australia, China and Taiwan, it also reduces productivity and can result in tree death in severe cases. European canker infection may occur at any time during the year, but harvest, leaf fall and winter pruning have been identified as critical infection periods where the fungus can enter host trees through exposed wound sites such as pedicel and leaf scars.

Prevalence and severity increases in high rainfall seasons as spores are dispersed by rainfall. Apple-producing areas including Riwaka and Lower Moutere can be especially susceptible. Adama technical services and development manager Claire Mills says, while European canker has been present in NZ for decades, it has become more prevalent due to changes in orchard management, including increased planting densities and changing varieties.

Mills says previously, the only products currently with label claims for canker were copperbased products such as copper oxide, copper oxychloride and Bordeaux mixture, and these may only be used postharvest due to the risk of phytotoxicity. “With European canker on the Merpan label, growers now have an effective tool to manage the disease. "What’s more, with the PHI reduced to three days, the risk of infection associated with picking scars can be significantly reduced.”

For more detail contact your local Adama commercial manager or visit www.adama.com.