We have seen and heard reports of snails and slugs across the state this week (June 5th). We normally can expect some issues in cool, wet years and in reduced till fields, particularly when cover crops are involved.
Slugs can pose much more of a threat to stands than snails. Little information is available on snails, but many species are detritivores – they feed on dead plant matter, not living plants and do not feed on or damage cotton.
Slugs on the other hand will feed on developing seedlings.
There are a couple of easy ways to tell the difference.
- Snails have shells and slugs do not.
- Slugs tend to hide out under the soil surface once the sun comes out, while snails will stay on plants during the day.
Slug feeding typically results in irregularly shaped holes on the edges of leaves and slugs may cut plant stems in heavy infestations. Slug damage is often worse in situations where the furrow is not closed, leading to “slug highways” where they will work their way down the furrow clipping several plants in a row.
In some rare occasions, snails may damage plants from the number of snails on the leaves weighing the plant down and bending it to the soil surface.
Short On Solutions
The question remains: what do we do about this? The answer, not much at this point. Snails and slugs are not insects, so insecticides do not have activity on them.
We know these issues tend to be more likely in reduced-tillage fields, but it is too late for that.
Some baits are available containing metaldehyde or iron phosphate. These products can be effective but are quite expensive and not always readily available. Baits can be broadcast at 10-40 lbs per acre but should be done when no rain is in the forecast.
If a re-plant is warranted, tilling the field is important to kill the population of slugs in the field. Otherwise, you are planting into the same situation. Making “trash cleaners” more aggressive at-planting may help remove plant debris from the row, which may lead to reduced injury from slugs on emerging plants.
If possible, increasing seeding rates by 5% to 10% may also help minimize stand loss.
The best answer to this problem is hot, dry growing conditions which are conducive for seedling growth and bad for slugs.
- Slugs may cause damage, snails very likely will not.
- Insecticides won’t help. Hot weather will.
- We need to plan ahead with at-risk fields.