The Department of Agriculture, Food and the Marine (DAFM) has granted two temporary herbicide licences for dock control purposes in newly established red clover swards.

The period of authorisation is from June 15 to October 15.

However, the reality remains that all newly established clover swards are very sensitive to herbicides. Perhaps the best way to ensure a dock-free sward is to deal with the offending weed in the period prior to sowing out the new crop.

Red clover

This issue was discussed in depth at a recent red clover farm walk, hosted in Co. Tyrone. Agri-Food and Biosciences Institute (AFBI) grassland agronomist, Dr. David Patterson, spoke at the event.

He explained that plans to establish a clover-based sward should kick-in 12 months, or even 24 months before the new ley is actually sown out.

“This approach gives sufficient time to sort out any weed-related issues that may be apparent within the existing sward,” he said.

“Dock control is a case in point. Getting soil pH up to a value of 6.5 is also critically important. Red clover will not meet its growth targets in acid soils.”

According to Patterson, red clover swards must be established in the late spring/early summer period.

“This approach ensures that soil temperatures are sufficiently high so as to encourage clover growth from the outset,” he continued.

“A firm, fine seed bed must be established. Red clover seeds are extremely small. So a very shallow sowing depth must be achieved.

“Another key advantage of a late spring sowing date is the opportunity it provides of creating stale seed beds. Taking this approach allows many of the weed seeds already in the soil to germinate before the new ley is established.”

“These weeds can then be effectively killed-off using a suitable herbicide prior to sowing.

The agronomist explained that this approach significantly reduces the weed challenge confronting the newly established swards.

He also confirmed that red clovers are very sensitive to most herbicides.

“Annual weeds, such as fat hen and fumitory, can be physically dealt with by taking a first cut of silage,” he said.

“Seedling docks, however, represent a challenge of a different magnitude. There is only a very selective range of herbicides now available that can be safely used to deal with this specific weed challenge in red clover swards.

“Farmers should get bespoke advice on this issue.”