Tobacco budworm populations have been booming in our research plots this summer, and as they often are, tobacco budworm larvae are present in fields at or 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. This is because budworm larvae prefer to feed on flowers and seed capsules when given a choice between these and leaves.  

These are the same plant parts (along with the youngest, smallest leaves) that are removed during topping.

Tobacco budworm feeding during the interval between buttoning (when the unopened flowers are visible outside of the bud) and flower does not damage plant tissue that will be harvested and has no economic impact. Therefore, any insecticide applied at this stage for tobacco budworm is a waste.  

Tobacco budworm will not re-infest tobacco after topping because the attractive buds and flowers are no longer there.

Tank mixing insecticides and sucker controls

Among some North Carolina tobacco growers, it has been standard practice to include an insecticide (most commonly acephate) in the first few applications contact sucker control.  

Contact sucker control materials are pesticides that, as their name implies, need to come into contact with a leaf axil in order to inhibit growth. Contacts are typically fatty alcohols, or soaps, which are commonly made from petroleum or, in the case of organic contacts, palm oil.

Fatty alcohols are also used in a number of industrial and cosmetic applications.

Foliar (sprayed on) insecticides in tobacco should only be used when insects are present at damaging levels (the economic threshold).  

Acephate is a broad spectrum insecticide, so it could potentially be used against a wide range of insect pests. The insect pests most commonly present at or near topping are tobacco budworm, the "tobacco form" of the green peach aphid, and, less commonly, tobacco & tomato hornworms.  

We already know that pre-topping treatments for tobacco budworms are not needed, but what about aphids and hornworms?

Aphids

Aphid management in tobacco has shifted dramatically in the last 15 years. Aphids used to be frequent pests which often reached treatment threshold (10 percent or more of plants with 50 or more aphids in the upper third) several times in a season.