Action Thresholds for Silk Stage Sweet Corn

Based on Corn Earworm Blacklight Trap Catches (conservative system)

 

Number of Moths caught
per Seven Days
Silk Spray Schedule
<1
No Spray
1
6 Day
2
5 Day
3
4 Day
4
3 Day
38
2 Day

Based on Corn Earworm Pheromone Trap Catches

Generally used as a guideline in combination with light trap catch information. Requires use of a wire mesh trap and Hercon CEW pheromone lure placed with the base of the trap at silk height in fresh silking corn. Check traps at 3 times per week throughout the growing season.

 

Number of Corn Earworm Moths Caught
Per Day
Per 5 Days
Per Week
Spray Interval
<0.2
<1
<1.4
No Spray
0.2 – 0.5
1.0 – 2.5
1.4 – 3.5
6 Day
0.5 – 1.0
2.5 – 5.0
3.5 – 7.0
5 Day
1.0 – 13.0
5.0 – 65.0
7.0 – 91.0
4 Day
>13.0
>65.0
>91.0
3 Day

In some cases corn earworm catches are very low; however, corn borer and fall armyworm pressure is high. If no sprays are called for CEW, the following spray schedule should be used:

 

European Corn Borer/Fall Armyworm/Sap beetle
Spray Schedule
ECB light trap catch is > 100 per 5 days
4 Day
ECB light trap catch is 51-100 per 5 days OR FAW infestations in whorl stage corn is >30% infestation OR Sap Beetle infestation is greater than 10%
5 Day
ECB light trap catch is 25 to 50 per 5 days & FAW infestations in whorl stage corn is < 30% infestation & Sap Beetle infestation is < 10%
6 Day
ECB light trap catch is < 25 per 5 days & FAW infestations in whorl stage corn is < 30% infestation & Sap Beetle infestation is < 10%
No Spray