Slugging it out

 In previous years, I have been a regular user of Nemaslug to keep the kitchen garden's resident slug population under control. See, for example, this post where I discuss biological (nematodes) and non-biological methods of slug control.

Photo 1: Nemaslug 2.0

It is a couple of years since I last applied this product and I may not have bothered this year except Mary was keen to try a similar nematode product for vine weevils; these little critters continue to wipe out a significant number of our outdoor pot plants. Based on the previous success of Nemaslug, I suggested we give this Nemasys product a go.

Photo 2: Nemasys Vine Weevil Killer

I will report at a later date as to whether the above vine weevil treatment was successful or not.

Back to the job in hand - repelling the slug onslaught in the battle for the kitchen garden (⚔ 2024). A recent article suggested we should learn to love slugs a little more than I we do. Love seems a rather strange emotion to direct towards these molluscs though I definitely have some respect for their eating capabilities & capacity. Importantly, by using nematodes, I am only trying to control their population during the early growing season when the plants are young and tender. For the remaining 9 months of the year, slugs and snails can get on with their lives with little or no interference on my part. We are not trying to eliminate slugs, just control their population for a short period.

Nematodes are applied to the soil surface as a suspension in water; the soil should be damp before application and the nematodes should be watered in after application. The length of time taken to perform this task is considerably shortened by carrying it out after overnight rain, or between showers, or during light rain because steps 3 and 5 below can be omitted. Soil temperatures must be above 5 ℃ which is why April is the usual month for the first application.

First of all, I collect all the necessary equipment together: 10-litre and 5-litre watering cans, a coarse rose for the 5-litre can, a two-litre measuring jug, a plastic spoon (or similar), a stirring stick and a hose with spray adaptor (Photo 3). Note: you can buy a coarse rose specifically for this job or just drill some larger holes in an existing rose as I did.

Photo 3: Equipment for Nemaslugging

1. Transfer the nematodes (sufficient for 100 square metres) to the two-litre plastic jug with the plastic spoon. Add water to the jug and pour into the 10-litre watering can. Continue to rinse out the jug and transfer the washings to the watering can until it is full.
2. Give the contents of the 10-litre can a good stir with a stick and measure out 500 ml into the two-litre jug (use a pen or piece of tape to indicate the 500 ml volume mark). Transfer the jug contents to a 5-litre watering using additional washings until the 5-litre can is full.
3. Pre-wet the soil, if necessary, using the hosepipe with spray adaptor (alternatively, use a watering can).
4. Fit a coarse rose to the 5-litre can, giving the contents a brief stir, and apply to wet soil covering an  area of approximately 5 square metres (e.g. a 1 metre by 5 metre strip).
5. Water in the nematode suspension using the hosepipe with spray adaptor (alternatively, use a watering can).

Ideally, the Nemaslug treatment should be applied about a week before planting out your precious vegetable/flower seedlings so that the nematodes have sufficient time to 'clear' the ground of slugs. The nematodes can also be applied after planting as was the case this year with my potato and sweetcorn plot (Photo 4). Note that for the sweetcorn seedlings, I took the precaution of using both a physical slug barrier (Hosta Halos) and organic ferric sulfate pellets (blue dots in Photo 4) to provide protection prior to applying the nematodes.

Photo 4: The Potato/Sweetcorn Plot after Nemaslugging

Each Nemaslug treatment offers some (not 100%) protection from slugs for about 6 weeks. The initial application was on the 18th May 2024. At the beginning of July, I will make a decision on whether to carry out a repeat application. It may not be necessary if I'm no longer planting out tender seedlings.