Tuesday, 16 November 2021

Don’t let slugs cut your stock’s lunch


November is a key month for establishing winter forage crops, such as kale, swedes or rape, and we all know how devastating slugs can be to newly sown crops. It makes sense to check paddocks going into winter forage brassicas, so you can take necessary measures to manage the slug challenge.       

Check before you sow

Paddocks should be checked for slugs both before and after drilling. Walking paddocks and checking under objects like sticks, stones, cowpats or thick layers of trash can give an initial idea of slug presence.

However, a slug mat can give a much more accurate assessment of slug populations, which can be crucial in ensuring the solid establishment of your crop. Ravensdown’s Endure slug mat (available from your Ravensdown agronomist or agri manager) is made from an absorbent material, so it maintains humidity, and is black on the underside and silver on the topside – creating an attractive environment for slugs to shelter under during the day. When conditions favour slug activity, slug mats should be left out overnight and checked for slugs the next morning. A common ‘rule of thumb’ is that three to four slugs per mat means there are sufficient numbers to cause damage. The mats can then be moved to new locations to monitor what is happening with slug numbers over time.

Even after taking measures to limit slug numbers, it is imperative to monitor the crop until the risk of slug damage has passed. This is particularly important where slug populations are high or where conditions favour slug development.

Combine forces to manage slugs
Cultural practices can help reduce the opportunity for slug populations to increase to damaging levels. Remove trash from the previous crop to reduce their food source and minimise suitable habitats. Consider mob stocking, which closes cracks in the soil and tramples slugs. Slugs are not good at burrowing into soil, but they do like crawling down to shelter in cracks, so fine firm seedbeds are better than loose cloddy ones.

Cultivation helps reduce slug numbers, so minimum till or direct drill crops are more at risk.

Spray out resident vegetation and broadcast slug bait with your starter fertiliser before drilling. This way, bait is introduced at the same time as other slug food sources are drying up. Endure slug bait mixes and spreads evenly with fertiliser, saving on application costs.

Plan around drilling
In most situations, broadcasting bait is more effective, because it takes care of the slugs in between the drill rows.

In conditions where drill slots remain open after direct drilling, sowing slug bait down the spout will help control slugs that crawl into the open drill row.

Continue monitoring after drilling, particularly if slug populations are high or conditions are favourable. Where risk is high, it’s a good idea to apply a repeat application of bait after three to four weeks.
For example, two applications of 4-5kg/ha Endure slug bait would be more effective than a single application at 8kg/ha.

Remember that even if slugs are hard to find in the paddock, they can migrate in from the fence lines, making it worthwhile to broadcast bait on the outside round. With continued monitoring, you will know if a repeat application of bait treatment is required three to four weeks later.

Right tool for the job

Pasta-based Endure® slug baits have been developed for the best combination of attractiveness, palatability, spreadability, and durability for slug control in wet conditions, when slugs are more active.

The active ingredient metaldehyde will not harm beneficial insects, such as carabid beetle and earthworms, so it is possible to use repeat applications when necessary.

The size and shape of Endure slug bait means that it spreads evenly on its own, and it can be mixed and spread with fertiliser with ease, saving on application costs. Endure Mini baits have the same benefits but come in a smaller bait size, so you have the option of applying in the drill row alongside the seed.

So, keep an eye on slug presence, think about slug habits, pick the best bait with the right baiting strategy, and don’t let slugs cut your stock’s lunch.