Science Into Practice - Lettuce crop aphid controls

Prior to the use of neonicotinoids, lettuce root aphid was a significant problem, particularly near areas with poplar windbreaks because the pest overwinters in poplar trees.

Since the use of neonicotinoid seed treatments lettuce root aphid has been effectively controlled. But no further research had been conducted to find alternative insecticide treatments or different modes of action to allow growers to diversify their aphid control strategies instead of neonicotinoid seed treatments.

In the UK lettuce root aphid is effectively controlled with neonicotinoid seed treatments imidacloprid (Gaucho) and thiamethoxam (Cruiser), which also provide control of foliar feeding aphids.

However, depending on the lettuce variety and planting density, the loading is often adjusted so that the maximum total dose of neonicotinoids per hectare per year is not exceeded. This practice has shown that varieties such as Little Gem, which are planted at higher densities using lower seed loadings, are still protected from aphids.

HDC project FV 435 - Lettuce: Evaluating aphid control strategies - aimed to investigate the persistence and efficacy of currently used seed treatments against those with lower pesticide loadings, dummy pills, spirotetramat (Movento) and other novel systemic insecticides on the control of lettuce root aphid and a foliar feeding aphid, the currant-lettuce aphid.

Results indicated that insecticide loading on Iceberg lettuce seed can be reduced to 80g/ha for Gaucho or 60g/ha for Cruiser because the lower neonicotinoid loadings gave the same level of control as standard treated seed or dummy pills.

Horticultural Development Company

For details on all HDC activity, visit www.hdc.org.uk.


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