Potato Review

46 POTATO REVIEW MAY/JUNE 2022 SLUG CONTROL G rowers are urged to take a proactive approach to tackling slugs in potato crops, with early season risk assessments and timely and accurate slug pellet application key to protecting marketable yield from this damaging pest. Potatoes are a high value crop but very costly to grow and with recent inflationary pressure pushing cost up further, growers need to remain particularly vigilant against threats that could dent returns this season. One of those threats is the slug, with markets having a relatively low tolerance to its impact and the possibility of feeding damage ever present on more bodied soil types and where irrigation is applied. Risk assessments That’s why Agrii’s potatoes and irrigation services technical and development manager Nick Winmill highlights the importance of slug risk assessments ahead of the two critical control periods for slugs and actively encourages growers to carry them out. The first of those control periods is between 50% and 75% canopy closure when a moist, shady microclimate encourages slug activity near the surface of potato ridges, and the second at early bulking when slugs move down to gorge on developing tubers. Further attention to slugs can also be required soon after desiccation programmes commence, depending on the season, adds Nick. This is particularly the case following the loss of diquat, with other methods of haulm destruction potentially slower if conditions are cool and dull. “On particularly high-risk sites and where it takes a long time to burn crops down, moist conditions can encourage slugs to the surface to feed. “That means you may need to take action so the population hasn’t got a free Proactive approach key to optimising slug control As planters finish 2022 planting, attention will soon turn to crop protection programmes. Potato Review gets some advice on protecting tubers from slug damage this season. rein at the crop while skins are setting ahead of harvest,” explains Nick. Risk assessments should be based on soil type, previous crops, and variety, with some cultivars like Maris Piper much more prone to feeding damage than others, although little independent data exists on varietal susceptibility. Brassica review Although too late for this season, Nick says rotations should be looked at strategically and crops that encourage slug activity reduced or eliminated from cropping plans. This could mean scaling back oilseed rape or brassica veg on land where potatoes will be grown or taking out brassica components of cover crops. The ability to do this may depend on the purpose of the cover crop, as some brassica species like caliente mustard can be used for biofumigation against other important pests like potato cyst nematode (PCN). “When we talk about IPM [integrated pest management], we need to take a Mike Simmons Harry Raley