Farming News - Post-emergence herbicides - Bruchid Beetle - Aphid monitoring - PGRO Update

Post-emergence herbicides - Bruchid Beetle - Aphid monitoring - PGRO Update

18 May 2018
Agronomy / Arable

Post-emergence herbicides ...

Some spring crops of peas and beans may be ready for post-emergence herbicide applications.

Bentazone is the only active ingredient available in beans for post-emergence broad-leaved weed control. Bentazone and MCPB are both options in peas. The maximum permissible dose rate of Basagran SG is 1.1kg/ha in both peas and beans and split applications are permitted.

There are various generic bentazone products available which generally can be used at a maximum 3.0 l/ha, but no split applications are permitted in peas with these. The option of two low dose applications can be very effective on small susceptible weeds, but it can be problematical fitting two applications in within the permitted application window.

Tank mixes of Basagran SG + MCPB are still supported, as are mixes of MCPB with alternative bentazone products.

Using bentazone when temperatures are low can give disappointing results. However, high temperatures shortly after application (> 20-21°C) can cause an increased incidence of crop damage. The tendency these days to use reduced rates of bentazone reduces the potential for crop damage.

Please read the individual product labels carefully before use.

Bruchid beetle ...

Bruchid beetles have been active in field bean crops, particularly winter beans that are flowering.

Image result for image bruchid beetle pgro

Winter beans may be close to first pod-set stage. Insecticide sprays should be applied when the temperature threshold of 2 consecutive days at 20°C has been reached and around 50% of pods on bottom trusses are 2 cm long.

Sign up for the Syngenta BruchidCast® forecasting service by going to

The forecast predicts when the temperature threshold has been reached and indicates suitable conditions for applications. Growers should check that first pods have set. BruchidCast® is currently indicating that the temperature threshold will be reached at the weekend in some areas. 

To avoid risk to foraging bees, spraying should be carried out very late in the evening or at night time.

Aphid monitoring ...

Aphid monitoring is carried out in the UK by Rothamsted Research, SASA and FERA.

Updates on suction trap catches and activity of crop aphid species can be found in the summaries provided by AHDB on the PGRO website at or at

The AHDB Aphid News bulletins provide information about when aphids are migrating at key times of the year. Information in the newsletters should be used to optimise the use of insecticides, time treatments better and reduce harm to beneficial insects. This will also lower the risk of selection for insecticide resistance by reducing unnecessary or wrongly timed sprays.

Support for this project is provided by BBSRC, The Lawes Agricultural Trust, PGRO, BBRO, AHDB and other industrial supporters