A hot summer and earlier than usual harvest has meant that oilseed rape establishment has now taken priority for many growers. Cabbage stem flea beetle (CSFB) has become one of the most important pests in OSR, and since the loss of neonicotinoid seed treatments, growers are left with limited options.
Rob Adamson, technical support for Arysta LifeScience UK & Ireland looks at some of the issues: “With the recent moisture, following a hot, dry summer, our minds over the last couple of weeks have suddenly turn to getting oilseed rape in the ground. And unfortunately, this is accompanied by the haunting words ‘flea beetle’.
“In a bid to minimise the damage of Cabbage Stem Flea Beetle (CSFB), many plant oilseed rape increasingly early to optimise the rapidly declining daylength hours of September, and to avoid the migration of this notorious pest at crop emergence. Even more so this year, with timings less pressured that usual due to the unusually early harvest.
“During the past few years we have seen a host of concepts for CSFB control – including spraying at night, companion cropping and early drilling. The range of ideas and concepts the industry has investigated shows how important it is to grow a crop of oilseed rape away from this pest, which can lead to complete crop loss if unsuccessful.
“With the loss of neonicotinoid seed treatments for oilseed rape, chemical controls are restricted to foliar applications, and pyrethroid insecticides are a popular option. Despite resistance concerns in UK pests, this chemical group remains integral in protecting an oilseed rape crop – allowing it to grow to a less vulnerable stage without being munched to nothing.
“Cypermethrin, the active ingredient of Cythrin® Max, is one such pyrethroid, which in its high concentration formulation, can be used in this crop establishment battle. This synthetic pyrethroid targets the nervous system of the insect, causing rapid knock-down and ultimately, control. It not only provides contact knock down of the pest, but it also kills through ingestion.
“There is a third beneficial effect from these products which can make them a useful tool, and that is the repellence effect of the formulation. Cythrin Max discourages beetles from the treated plants, giving them more time to grow away from the feeding damage.
“This repellence effect is normally only considered when cypermethrin is used as a seed treatment such as Signal® 300 ES – acting as a repellent in the soil for wireworms and wheat bulb fly. This additional benefit should be taken into account however, as it makes cypermethrin a useful tool in the early control of CSFB.
“It is important that growers adhere to the label guidance currently in place for Cythrin Max. An 18m aquatic buffer zone is in place, and to protect non-target insects / arthropods, an untreated buffer zone of 5m to non-crop land should be respected.
The use of foliar insecticides should be as part of an IPM programme, and flea beetle thresholds, available from AHDB, should be adhered to.”