What is in this article?:
- Mid-season tobacco pests, the burning question of tank-mixes
- Typically appear near topping
• The logical questions that follow these tobacco budworm populations is whether or not they need to be managed.
• In general, if plants are within 2 weeks of topping or large enough that contact sucker controls are being applied, tobacco budworm treatments are unnecessary.
TOBACCO BUDWORM MOTHS lay their eggs in or near tobacco buds and flowers and are more attracted to flowers.
Typically appear near topping
If aphids are present in a field when contacts are being applied, it may be tempting to include an insecticide in with these materials, but this is totally unnecessary.
Contacts (soaps) can be excellent aphid control materials, because they dry out their soft bodies, and the application method for contacts actually results in decent coverage for aphid control.
In addition, aphids are less attracted to tobacco leaves as they "harden off" following topping and will rarely re-infest.
In an organic aphid management trial we conducted in 2009, none of the organic insecticides were effective against the large aphid populations present, but as soon as the grower started spraying organic contact and topping, the aphids disappeared.
Timely topping and good sucker management can eliminate an aphid problem, so insecticides in the contact do not provide any additional benefit.
Tobacco and tomato hornworms
Tobacco and tomato hornworms typically occur in their highest numbers just after topping and, from a timing standpoint, are perhaps the most logical insects to be targeted by an insecticide tank-mixed with contacts. However, I do not recommend tank-mixing insecticides with sucker control materials even for hormworms for two important reasons:
1.) Phytotoxicity may occur when insecticides are tank-mixed with oils and soaps, and more importantly,
2.) Contact sucker controls and insecticides should be applied to different parts of the plant and will be less effective with different coverage patterns.
The only time I have seen phytotoxicity associated with some of our newer, caterpillar active insecticides in tobacco is when they have been used in combination with contacts. Although I have never seen truly damaging phytotoxicity associated with either Belt or Coragen, it doesn't make sense to combine these with sucker controls.
Because contacts need to coat leaf axils to be effective, they are applied in a coarse spray, run down spray, sometimes using modified hoods, as described in the 17 June issue of the Tobacco Connection Newsletter.
This application method drives contacts down the stalk, but hormworms are leaf feeding insects and could be missed with a stalk spray or hood application. If a tank-mixed insecticide application fails, it means yet another treatment across the field. I would rather see one insecticide trip made, done correctly.
The last tobacco insects that may pop up in the mid-season are stink bugs, both brown and green. Stink bugs feed on the stalk and mid-veins of tobacco leaves, which can cause them to wilt.
This damage is rarely, if ever, economically significant, and insecticide treatments for stink bugs are not recommended.
In fact, so few insecticides are effective for stink bugs, it is unlikely any of the materials with workable pre-harvest intervals would provide control regardless of whether treatment was needed.