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

Green Cloverworm Problems in Soybean

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

Published: September 19, 2011

Numerous soybean fields located in southwest Missouri are experiencing problems with green cloverworm larvae. This insect is traditionally a rare to occasional pest in Missouri, where it is usually controlled by the beneficial fungal pathogen Nomuraea rileyi. The moths of this insect may overwinter in more southern areas of the state, but most migrate into Missouri during spring each year. Two generations are produced annually with both generations susceptible to the fungal pathogen if conditions are favorable. Larvae feed on leaf tissue, but not on pods. Larvae killed by the fungal pathogen often take a posture of rearing up off the leaf and then turn white in color as the fungal pathogen produces white fruiting bodies which will blow in the wind to infest additional larvae.

Control is justified when foliar damage reaches or exceeds 20% and five larvae or more are present per foot of row. Larvae are most easily monitored using a ground sheet measuring 36" x 42" with a stick wound around each edge on the 42-inch sides. The sticks are used to twist the ground cloth to a size that fits the area between rows. Although you calculate the number of larvae per foot of row, generally one to three feet of row on both sides of the ground cloth are vigorously shaken to dislodge larvae and allow them to drop onto the cloth for collection and counting. Divide the total number of larvae collected per location by the number of feet of row of soybean shaken to determine number of larvae per foot. A minimum of 5 different locations within the field should be sampled to determine a reliable estimate of larvae numbers per foot of row.

Drought may be the contributing factor allowing the high numbers of green cloverworms observed this year. The fungal pathogen is always present at low levels in the soil, but works best when precipitation is present and field conditions are somewhat damp or wet.

GREEN CLOVERWORM - Hypena scabra (Fabricius)

Common Name Trade Name Rate of formulated
material per acre
Placement REI Hours Pre-Harvest Intervals Days
esfenvalerate *Asana XL 2.9 to 5.8 fl oz foliage 12 21 (grain)
Do not graze or feed livestock
cyfluthrin *Baythroid XL 0.8 to 1.6 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 7 to 13 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 + *Hero 2.6 to 6.1 fl oz foliage 12 21 (grain)
Do not graze or feed livestock
methomyl *Lannate SP
*Lannate LV
1/4 to 1/2 lb
3/4 to 1 1/2 pt
foliage 48 14 (grain)
3 (forage) 12 (hay)
Imidacloprid +
cyfluthrin
*Leverage 2.7 3.8 fl oz foliage 12 45 (grain, feeding dry vines)
15 (green forage)
chlorpyrifos *Lorsban Advanced 1/2 to 1 pt foliage 24 28 (grain)
Do not graze or feed livestock
zeta-cypermethrin *Mustang Max 2.8 to 4.0 fl oz foliage 12 21 (grain)
Do not graze or feed livestock
chlorpyrifos *Nufos 4E 1/2 to 1 pt foliage 24 28 (grain)
Do not graze or feed livestock
acephate Orthene 97 3/4 to 1 lb foliage 24 14 (grain)
Do not graze or feed livestock
microencapsulated
methyl parathion
*Penncap-M 2 to 3 pt foliage 96 20 (grain)
carbaryl Sevin 4F 2 to 3 pt foliage 12 21 (dry grain or hay)
14 (graze or forage)
spinosad Tracer Naturalyte 1 to 2 fl oz foliage 4 28 (grain)
Do not graze or feed livestock
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 ZT 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. Regardless of the formulation selected, read the label to determine appropriated insecticide rates, directions, precautions, and restrictions.
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REVISED: January 5, 2012