Protect your investment from flowering pest attack in rape

If pest thresholds for seed weevil are reached and attack from pod midge also threatens, it makes sense to protect the investment made to date in winter rape crops and apply an effective and reliable insecticide, such as Contest, warns BASF.

"The overall risk from seed weevil attack is increasing with mild winters and more oilseed rape being grown. The recent warm spring conditions have also favoured migration of this pest from its over-wintering sites into the crop. Experts advise that insecticides should only be applied when the pest threshold is reached. For seed weevil this is one or more adults per plant or 0.5 adults per plant in the North, where the risk and damage has been higher. As pod midges lay their eggs through the egg-laying punctures made in the pods by seed weevils, the threshold and control measures needed for both pests is inextricably linked," says Diane Heath, BASF Oilseed Rape Product Manager.

"Insecticide timing against seed weevil and pod midge is generally around mid-flowering. A persistent product is needed to make sure that the crop is protected against egg-laying and larval invasion throughout the risk period and the pyrethroid Contest has been shown to be more effective and more persistent than other pyrethroids. In trials where the untreated crop had 150 pod midge larvae per 100 pods, Contest reduced this to just 2 larvae per 100 pods, with lambda-cyhalothrin treatment resulting in 23 larvae per 100 pods. Additionally, Contest also reduced the number of seed weevil larvae and pod damage. The superior control levels and longer persistence is largely due to the unique tablet formulation of Contest," points out Mrs. Heath.

Diane explains that pyrethoids are mainly contact-acting insecticides, with pests picking the product up on the plant surface. "The unique formulation of Contest optimises the availability of the active ingredient by improving its coverage of leaves and pods and through improved retention on the plant surface. In contrast, other pyrethroids leave uneven leaf deposits with erratic coverage, making the active component less available to the insect pest. Contest is available as a micro-tablet formulation which is designed to be safe and easy to use."

Diane Heath reminds that Contest should only be applied when pest thresholds are reached. She also points out that growers should adopt good practice to minimise any risk to bees by applying Contest when bees are less active in the early morning or late evening. "Bee keepers should also be informed. Contest has been shown to have minimal impact on bees and beneficial populations of Trichomalus, the parasitic wasp which attacks seed weevil larvae."

"Seed weevil and pod midge can result in premature pod shatter and significant yield losses of up to 0.5 t/ha and so their impact on yield and returns can be considerable. If you have been taking care of your rape crop to date, you will want to protect the investment you have made and to maintain the crops’ yield potential," concludes Mrs. Heath.