Archive Article: 1997/09/20
• Leave set-aside untouched as long as possible, to reduce egg-laying. When cultivating, leave a fine seedbed.
• Early drilling, where feasible. Well established crops can survive attacks better in the spring.
• Use a high tillering variety, and a higher seed rate to increase shoot numbers. Early nitrogen can help plants tiller and grow away from the problem.
• Avoid deep drilling – this increases the size of the target. Rolling reduces the ability of larvae to move between plants.
• Monitor risk by having a soil sample checked for egg count. Mr Purslow is not convinced of the benefits of soil sampling, because attack is related to weather and crop conditions in the spring.
• Insecticidal seed treatment (fonofos, chlorfenvinphos) is effective on late sown crops. On early sowings it may run out of steam too soon. As yet there is no seed treatment approved against wheat bulb fly for spring barley, but tefluthrin (familiar as Force on sugar beet) is in the registration pipeline.
• Egg hatch sprays. Egg hatch usually peaks during early February, but it depends on temperature – so timing is critical. Options are: chlorpyrifos (Dursban, Spannit) and chlorfenvinphos (Birlane, Sapecron). There is a tank-mix recommendation for chlorpyrifos plus dimethoate as a two- pronged attack during late egg hatch – but this approach may compromise the best timing for both products. Beware: low temperatures, organic soils and high pH may limit effectiveness, says Mr Purslow.
• One option for spring barley might be using chlorpyrifos (Dursban), at the egg hatch rate at drilling, and incorporate into the soil. Spring barley appears included under the general recommendation for this product.
• For "deadheart" sprays later in the season, dimethoate is an option. A "deadheart" spray is less effective when larvae are in their final stages. Absorption can be improved by using LI700.