Taking an environmentally sensitive approach to pest management


Integrated Pest & Crop Management



AUTHOR

Wayne C. Bailey
University of Missouri
Division of Plant Sciences
(573) 882-2838
baileyw@missouri.edu

Numerous Reports of Black Cutworm Damage to Corn and Soybean Seedlings

Wayne C. Bailey
University of Missouri
(573) 882-2838
baileyw@missouri.edu

Published: June 6, 2011

During the past 10 days many reports of black cutworm damage to seedling corn plants and soybean have been received. Larvae produced from late moth flights have reached the 4th instar or later stages of growth and are causing problems on seedling corn and soybean plants in fields scattered across the state. Black cutworm larvae occasionally cause damage to seedling soybean when their feeding activities result in high plant mortality. In most years, low populations of black cutworm larval in soybean go unnoticed as surviving plants often compensate for lost plants. However, moderate to heavy feeding by black cutworm larvae on soybeans seedlings may substantially reduce crop yields if high seedling mortality occurs. Although a good economic threshold for black cutworm feeding on soybean seedlings is lacking, 20% or more cutting of soybean seedlings has been used in past years. With the higher commodity prices for soybean, this economic threshold is probably too conservative. As commodity prices go higher, producers can afford to treat pest infestations at lower thresholds. With this in mind, an economic threshold of 10% or more cutting is a more reasonable economic threshold for black cutworm infestations in seedling soybean. Soybean producers are encouraged to monitor soybeans stands at least twice per week during the next month to make sure cutworm larvae are not reducing plant stands to unacceptable levels. Seed applied insecticide treatments on soybean should help reduce black cutworm larval numbers, but may not prevent economic damage in situations where larval feeding is severe. In corn, these seed treatments often control about 50% of black cutworm larvae under heavy infestations. They should work better in soybean where the treated seed is grouped closer together in the row. However, insecticide efficacy data on black cutworm in soybean is very limited for many of the new seed treatments. A list of rescue application insecticides for black cutworm control in soybean is as follows. Be sure to follow label directions concerning whether the insecticide selected for rescue or replant needs to be incorporated or simple broadcast over the soil surface.

Table 1. Black Cutworm - Soybean
Comments: Scout emerging plants and treat if cutting reaches or exceeds 10% and cutworms are present.
Common Name Trade Name Rate of formulated
material per acre
Placement REI Hours Pre-Harvest Intervals Days
esfenvalerate *Asana XL 5.8 to 9.6 fl oz foliage 12 21 (grain)
Do not graze or feed livestock
cyfluthrin *Baythroid XL 1.6 to 2.8 fl oz foliage 12 45 (grain, feeding dry vines)
15 (green forage)
bifenthrin *Brigade 2EC 2.1 to 6.4 fl oz foliage 12 18 (grain)
chlorpyrifos +
gamma-cyhalothrin
*Cobalt 13 to 26 fl oz foliage 24 30 (grain)
Do not graze or feed livestock
lambda-cyhalothrin +
thiamethoxam
*Endigo ZC 2.5 to 3.5 fl oz foliage 24 30 (grain)
Do not graze or feed livestock
zeta-cypermethrin +
bifenthrin
*Hero 2.6 to 6.1 fl oz foliage 12 21 (grain)
Do not graze or feed livestock
chlorpyrifos *Lorsban Advanced 1 to 2 pt foliage 24 28 (grain)
Do not graze or feed livestock
zeta-cypermethrin *Mustang Max 1.28 to 4.0 fl oz foliage 12 21 (grain)
Do not graze or feed livestock
chlorpyrifos *Nufos 4E 1 to 2 pt foliage 24 28 (grain)
Do not graze or feed livestock
carbaryl Sevin 4F 2 to 3 pt foliage 12 21 (dry grain or hay)
chlorpyrifos +
bifenthrin
*Stallion 3.75 to 11.75 fl oz foliage 24 Do not graze or feed livestock
14 (graze or forage)
cyfluthrin *Tombstone
Helios
0.8 to 1.6 fl oz foliage 12 45 (grain, feeding dry vines)
15 (green forage)
lambda-cyhalothrin *Warrior II with Zeon 0.96 to1.60 fl oz foliage 24 30 (grain)
Do not graze or feed livestock
* Designates a restricted-use pesticide. Use is restricted to certified applicators only. Read the label to determine appropriated insecticide rates. Be sure to follow all directions, precautions and restrictions.
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REVISED: November 11, 2011