- Soybean

Soybean Soybean

Tobacco Budworm

Insect

Chloridea virescens


In a Nutshell

  • Damage on buds, blossoms and tender terminal foliar growth.
  • Yellowing buds which abort from the plant.
  • Chewing holes at the base of 'fruits'.
  • Hollowed out 'fruit', and gouges on their surface.
  • Yellowish - greenish to brownish colored larvae with brown lateral band.

Symptoms

Symptoms will vary widely depending on the crop. Larvae tunnel into and feed on buds, blossoms and tender terminal foliar growth, causing damage to growing tissues. Other plant organs such as leaves, petioles and stalks may be attacked if no reproductive tissue is available. Attacked buds become yellow and may abort from the plant. In cotton and legumes, holes and moist frass may be seen at the base of bolls and pods. Gouges resulting from the superficial feeding of caterpillars are also common. In some instances, the 'fruits' are emptied from the inside and they may start to rot. In cotton, the pattern of damage and level of injury resemble that caused by corn earworm.

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Hosts

Trigger

Damage is cause by the tobacco budworm, Chloridea virescens. It is an important pest in several crops, among others soybean and cotton (generally in desert areas). The moths are brownish in color (wings inclusive), sometimes lightly tinged with green. The front wings are crossed transversely by three dark brown bands, sometimes with a whitish or cream-colored border. The hindwings are whitish, with a dark band along the margins. Females lay spherical, flattened eggs on blossoms, fruits and terminal growth. Mature larvae are the most destructive because they can damage more blossoms and fruits, and can also damage them until later in the season (harder for the plant to replace). Moths can live up to 25 days when held at temperatures of about 20°C.

Organic Control

Natural enemies like wasps (Polistes spp.), bigeye bugs, damsel bugs, minute pirate bugs (Orius spp.) and spiders should be promoted. Parasitoids include Trichogramma pretiosum and Cardiochiles nigriceps in vegetables and Cotesia marginiventris in other crop groups. Other parasitoids that may be used are: Archytas marmoratus, Meteorus autographae, Netelia sayi, Pristomerus spinator and several insects of the genus Campoletis spp. Products based on pathogens Bacillus thuringiensis, Nosema spp., Spicaria rileyi or nuclear polyhedrosis virus can be sprayed to effectively suppress tobacco budworm.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. Control of this pest has proven to be particularly difficult due a variety of factors. Insecticides containing chlorantraniliprole, flubendiamide or esfenvalerate can be applied to control the budworm. Resistance to some major insecticides is common, among others pyrethroid treatments. Broad-scale insecticides need to be avoided, as they may kill beneficial insects.

Preventive Measures

  • Plant resilient plants, if available in your area.
  • Plant short-season varieties or sow earlier in the season.
  • Start monitoring for signs of the pest about 1 to 2 weeks after peak flowering period.
  • Use traps baited with sex pheromone lures to monitor or to catch the moths.
  • Leave sufficient distance between plants at sowing.
  • Plan and implement a good weeding program.
  • Maintain a balanced fertilization.
  • Avoid excessive irrigation.
  • If possible, manage the crop for early maturing.
  • Clear all harvest residues after harvest to prevent carry-over.

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