I started getting more calls and questions regarding snails on pecan trees. We had this issue last year as well. Rather than “reinventing the wheel”, below is an article written in 2020 by Angel Acebes-Doria (UGA) in consultation with Dr. Lenny Wells (UGA), Dr. Will Hudson (UGA), Dr. Ted Cottrell (USDA), and Dr. Capinera (UF) that gives some good information about snails and control options in pecans.
In recent days, we have heard several reports of snails associated with young irrigated pecan trees. They have been seen congregating on tree trunks and on the foliage. Some have reported seeing snails in and around irrigation emitters.
Normally, snails are not considered pests in pecan orchards, but rain can encourage their activity. The moist and wet conditions in irrigated orchards (especially during hot weather conditions) can be attractive to snails. Even in fertigated orchards, these snails still seem to thrive.
The snails found on pecan trees appears to be Bulimulus sporadicus, a non-native species which has also been reported to be established in FL, AL and MS. It is unclear if they can feed on living plant tissues but based on anecdotal observations and reports, they are associated with decaying vegetation.
Given the generally less common occurrence of snails in pecan orchards, the options for their management is limited. Below are some potential management strategies that growers can use to address the issue:
1. Physical Removal
Under low infestation levels, removing snails by hand is a feasible option. This has to be done regularly whenever aggregations are found. You can place them in a plastic bag, seal and dispose. You can also put them in soapy water to kill them and dispose accordingly.
2. Barrier Trap
Copper foil barrier band may be applicable for bigger trees. It should be carefully done to avoid girdling the tree. Copper tapes may be used for smaller trees that are vulnerable to snail infestation.
3. Beer-baited traps
Another option to passively trap for snails. They need to be serviced regularly as other organisms (like your neighbor) attracted to fermented products can be captured in them. It can be labor-intensive and may not be practical for bigger affected areas.
There are snail and slug baits available that could be used. These normally contain iron phosphate and metaldehyde. Iron phosphate, an organic active ingredient, causes the snails to stop feeding therefore indirectly killing them while metaldehyde (non-organic) causes the snails to die within a day after ingestion/contact. Metaldehyde can be poisonous to dogs and cats.
Important Note: Please read the labels and follow them accordingly. Although these products are labelled for tree crops such as citrus, apples and peaches, it is NOT specifically labelled for pecans. Some of them do include usage in surrounding agricultural areas including: fallow land, barrier strips and buffer zones around agricultural crop areas.
5. Repellent Sprays
Copper acts as a repellent to snails. Sprays as bands targeting trunks can act as a barrier. Do not mix copper products or other products with the baits to try to improve their performance as copper is highly repellent to snails and slugs and they will not eat a bait that has been contaminated with it.
If you are using sprays when you want to bait, apply the spray first, wait for it to dry, then apply the baits so they are not contaminated by the spray. Barriers can be created around tree trunks to prevent snail movement onto trees. Products containing copper silicate are applied to the trunk and act as a repellent.
During extended dry and hot weather conditions, snail populations will naturally die off. Therefore, growers need to assess accordingly if control measures (which can be costly and/or labor-intensive) are needed for these snails that appear to be non-damaging to pecan trees.