Cereals: Armyworm (True - Pseudaletia unipuncta, Fall - Spodoptera frugiperda)


Pub 812: Field Crop Protection Guide > Chapter 4: Cereals > Armyworm (True and Fall)

Field Crop Protection Guide 2011-2012, Order 2011-2012 publication

Table of Contents

  1. Description
  2. Integrated Pest Management Options
      • trichlorfon – Dylox 420 LC
      • carbaryl – Sevin XLR Plus
      • methomyl – Lannate Toss-N-Go
      • cyhalothrin-lambda - Matador 120 E
      • spinetoram - Delegate WG
  3. Related links...

Description

True armyworms, full grown, are 4-cm (1 1/2-in.) dull-green to brown larvae that can be easily confused with other caterpillars, including variegated cutworm and fall armyworm. Two distinguishing features that true armyworm possess are white-bordered stripes running laterally along the body and dark diagonal bands at the top of each abdominal proleg. The head is yellow-brown with a network of dark brown lines creating a pattern. The adult sand-coloured moth has distinctive white spots on the centre of each forewing.

Image 1. True armyworm larvae have black bands at the top of each proleg and the lighter brown head.
Image 1. True armyworm larvae have black bands at the top of each proleg and the lighter brown head.

Full-grown fall armyworms are 4 cm (1 1/2 in.) long, varying in colour from light tan or green to near-black. Three white, thin stripes run down the back with one thicker, yellow band with red spots running along the side, just above the legs of the larvae. Scattered along the body are black spots called tubercles that have spines coming from them.

Image 2. Fall armyworm larva damage on corn ear. Larvae leave entry holes on the exterior of ear. Note head is black wih a white, inverted "Y" on the front.
Image 2. Fall armyworm larva damage on corn ear. Larvae leave entry holes on the exterior of ear. Note head is black wih a white, inverted "Y" on the front.

Integrated Pest Management Options

Five to six larvae in a 30 cm x 30 cm area warrant chemical control. Treat if larvae are smaller than 2.0 cm long and threshold has been exceeded. if larvae have white eggs attached to them, they are parasitized and may not require treatment.

 
Active ingredient trichlorofon
Trade name Dylox 420 LC
Rate per hectare (product) 1.5 L per ha
Rate per acre (product) 0.6 L per ac
PHI* 21
Comments Ground application only. 24-hr re-entry period.

 
Active ingredient carbaryl
Trade name Sevin XLR Plus
Rate per hectare (product) 2.5-5.25 L per ha
Rate per acre (product) 1.0-2.1 L per ac
PHI* 14 (wheat, rye, oat) 28 (barley)
Comments See label precautions applying to honeybees.

 
Active ingredient methomyl
Trade name Lannate Toss-N-Go
Rate per hectare (product) 270-540 g per ha
Rate per acre (product) 108-216 g per ac
PHI* 20
Comments Ground and aerial application. 24-hr re-entry period.

 

Active ingredient cyhalothrin-lambda
Trade name Matador 120 E
Rate per hectare (product)

83 mL per ha

Rate per acre (product) 34 mL per ac
PHI* 28 (wheat, barley, oat) 14 (livestock foraging)
Comments Ground and aerial application. Use 100–200 L of water/ha. Allow 7-day interval between treatments. Maximum 3 applications/yr. Do not apply more than 2 applications by air. 24-hr re-entry period.

 

Active ingredient spinetoram
Trade name Delegate WG
Rate per hectare (product) 100–200 g per ha
Rate per acre (product) 40–80 g per ac
PHI* 21
Comments Ground application only. Use higher rate for heavy infestations or advanced pest stages. Spray tank solution pH should be between 6 and 8 for optimal control. Minimum 5 days between treatments. Maximum 3 applications/yr. 12-hr re-entry period.

 


Related links...

 


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 2 May 2011
Last Reviewed: 13 May 2011