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Controlling weeds in high value crops

When controlling weeds in high value crops, the focus should be on starting clean and staying clean to reduce the impact of weeds, diseases and pests.

When controlling weeds in high value crops, the focus should be on starting clean and staying clean to reduce the impact of weeds, diseases and pests.

When used as part of an integrated approach, soil sterilisation will help to decontaminate soils and keep pests, diseases and weeds at bay, throughout the season.

For growers of high-value, protected or outdoor vegetable crops, consideration of soil sterilisation as part of an effective ICM strategy is a good practice, according to Certis’ Technical Specialist, Alan Horgan.

Alan’s top tips for controlling weeds in high value crops 

Soil preparation

Start with preparation of the soil. Leave fallow, better known as a stale bed system, for weeds to establish and then cultivate with a shallow hoe to knock the weeds out. Or, use a non-selective contact herbicide, such as Finalsan.

However, be careful not to work the soil too far down, as this may bring more weed seeds to the surface.

Crop hygiene

To avoid carry-over of pests or disease inoculum, implement good crop hygiene. Wash down equipment using an approved disinfectant, such as Jet-5, clean boots and change gloves between fields or crops in glasshouses, to reduce recontamination risks.

Soil sterilant

Traditional residual herbicides can be applied to address weeds. But, applying a soil sterilant, such as Basamid, is particularly useful for vegetable crops that don’t compete well with weeds, such as brassicas and baby leaf crops. 

Providing Basamid has been used correctly there is no risk to the growing crop, whereas, residual herbicides can adversely affect the early stages of the developing crop.

It can also help to reduce damage to yields from free living nematodes (FLN), clubroot and Fusarium.

Best practice application

When using Basamid, ensure it’s applied into warm soils, ideally above 10°C with soil moisture of 60-70%.
Immediately smear-roll the surface of the soil or apply polythene sheeting, and keep this on for at least two to four weeks, depending on the soil temperature. 

This will help to ‘trap’ the released gas from the active ingredient within the soil profile and provide more effective weed control.

Test for product residues

After treatment, carry out a cress germination test to check for product residues in the soil. If you see a difference in germination between treated and untreated soil samples, you’ll need to work the soil again before drilling.