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

Potential for Black Cutworm Damage to Field Corn throughout North and Central Missouri

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

Published: May 2, 2008

Each spring black cutworm moth flights are monitored in Missouri using wing and Texas cone traps. These traps are designed to capture migrating male moths using a pheromone attractant. At present, several trappers across Missouri monitor traps every few days to determine when intensive captures of moths occur at trap sites. An intensive capture occurs when eight or more moths are captured over a two night period in a wing trap or when 17 or more moths are captured in a single night in a Texas cone trap. These trap capture data are combined with a 30 year average of temperatures along with real time meteorological data to predict when first cutting of seedling corn by 4th instar larvae (worm stage) may occur in the area in which the moths were captured. This is the insect growth stage at which the larvae are capable of cutting corn plants above and below the soil surface. Smaller instars will often leaf feed causing minor defoliation of corn seedlings, but damage increases significantly as the larvae grow to 4th instar or larger stages and begin cutting plants. The predicted date of first cutting may change by location as current 2008 meteorological data are entered into the model. Scouting activities should occur from first emergence of corn plants and continue through the 5th leaf stage of plant development. If this is not possible, then scouting of fields should begin a minimum of one week prior to the predicted date of cutting.

At this time in the season, intensive captures of black cutworm moths have been reported in the following counties:

  • Vernon County (Nevada): Intensive capture date, 3/28/2008. Predicted first cutting, 5/10/2008
  • Henry County (Clinton): Intensive capture date, 4/4/2008. Predicted first cutting, 5/15/2008
  • Franklin County (Union): Intensive capture date, 4/10/2008. Predicted first cutting, 5/11/2008
  • Franklin County (Union): Intensive capture date, 4/11/2008. Predicted first cutting, 5/12/2008
  • Knox County (Edina): Intensive capture date, 4/17/2008. Predicted first cutting, 5/18/2008
  • Audrain County (Mexico): Intensive capture date, 4/18/2008. Predicted first cutting, 5/17/2008
  • Linn County (Linneus): Intensive capture date, 4/18/2008. Predicted first cutting, 5/19/2008
  • Linn County (Linneus): Intensive capture date, 4/21/2008. Predicted first cutting, 5/20/2008
  • Knox County (Edina): Intensive capture date, 4/21/2008. Predicted first cutting, 5/19/2008
  • Audrain County (Mexico): Intensive capture date, 4/21/2008. Predicted first cutting, 5/18/2008
  • Knox County (Edina): Intensive capture date, 4/22/2008. Predicted first cutting, 5/20/2008
  • Knox County (Edina): Intensive capture date, 4/23/2008. Predicted first cutting, 5/22/2008
  • Audrain County (Mexico): Intensive capture date, 4/23/2008. Predicted first cutting, 5/21/2008
  • Knox County (Edina): Intensive capture date, 4/24/2008. Predicted first cutting, 5/23/2008
  • Knox County (Edina): Intensive capture date, 4/25/2008. Predicted first cutting, 5/24/2008
  • Linn County (Linneus): Intensive capture date, 4/25/2008. Predicted first cutting, 5/25/2008

The potential for black cutworm damage is elevated in the state in 2008 due to several factors including (1) the late planting of corn, (2) the presence of substantial black cutworm moths as indicated by "intensive" captures, (3) the presence in some fields of heavy vegetation such as henbit prior to planting, and (4) the potential for large black cutworm larvae to be present when seedling corn plants are emerging or small in size. All of these factors favor the black cutworm population and may result in substantial cutting of corn seedlings in the northern 2/3 of Missouri. Areas represented by multiple "intensive" captures are most at risk of black cutworm damage, although corn producers in all northern and central Missouri counties should monitor emerging and seedling corn plants for damage. Black cutworm infestations may occur in scattered areas within a field or be found throughout the entire field. When scouting be sure to check all areas of the field, but focus some effort on those areas of the field where black cutworm infestations have been found in the past. Although the economic threshold for black cutworm varies from state to state, under normal conditions in Missouri, treatment is recommended when cutting of corn seedlings reach or exceed 2-4 percent of plants cut. Due to the location of the plant growing point, plants cut below ground level will sustain greater damage than plants cut above ground. Cut plants may be left on the soil surface or partially pulled into the soil by the larvae. If the economic threshold is reached, then treatment with a recommended insecticide is justified. It is possible for a field of corn to be infested more than once by black cutworm due to migratory patterns of arriving moths.

Management of the black cutworm with insecticides may occur by several methods. (1) Seed treatments are the most common method used as a very high percentage of corn seed planted in Missouri will contain either Poncho 250 or Cruiser 250 applied on seed. These products do kill some larvae, but may not be able to keep large larvae or high numbers of larvae from causing economic to field corn. In Missouri insecticide evaluations using heavy black cutworm pressure found an average of about 50 percent control when seed treatments were the only management strategy employed. (2) Most transgenic events using Bt do not provide control of this insect in field corn. The exception is Hercules, which provides good control under most situations. (3) Another management option is the destruction of any weedy vegetation in the field at least 10-14 days prior to planting. The destruction of the larval food source is an effective control strategy, but with the high moisture conditions and late planting dates experienced in spring of 2008, it may not be a feasible insect management option for use at this time. (4) A fourth option is to apply a preplant or planting time granular or liquid insecticides in order to reduce numbers of black cutworm larvae if present in the field at time of planting. This is not a preferred IPM method as it goes against the IPM philosophy of monitoring the crop and applying an insecticide when pest populations reach or exceed economic threshold levels. However, in those areas with high potential for damage, this is a viable option. (5) The preferred IPM management option would be to scout the emerging corn seedlings to determine damage levels. If the economic threshold of 2-4 percent cutting is reached or exceeded in a field, then a foliar applied insecticide may be used to rescue the crop. Regardless of what management option selected, producers are encouraged to actively scout corn fields from time of emergence through the 5th leaf stage of corn growth.

For more information on the black cutworm predictive model and the counties currently monitoring for black cutworm, please visit our Web site at: http://ppp.missouri.edu/pestmonitoring/bcw/index.htm.

Insecticides Recommended for preplant, planting-time, & rescue applications for Black Cutworm larval
Control in Field Corn
Chemical name Trade name Rate of Formulated Material/Acre Placement/Comments
esfenvalerate *Asana XL 5.9 to 9.6 fl oz/acre foliar broadcast - rescue
tebupirimfos plus cyfluthrin *Aztec 2.1G
*Aztec 4.67G
6.7 oz/1000 ft row
3 oz/1000 ft row
Aztec 4.67G only applied
T-band, see label for placement
T-band, see label for placement
through Smartbox system
beta-cyfluthrin *Baythroid XL 0.8 to 1.6 fl oz/acre foliar broadcast - rescue
bifenthrin *Capture 2EC 1.47 to 2.2 fl oz/acre
(2ee MO label)
foliar broadcast - rescue
bifenthrin *Capture LFR 3.4 fl oz/acre foliar broadcast - rescue
bifenthrin *several products see specific labels
0.15 to 0.30 fl oz/1000 ft row
foliar broadcast - rescue
planting in 5- to 7-inch T-band
chlorpyrifos plus
gamma-cyhalothrin
*Cobalt
*Cobalt
13 to 38 fl oz/A
1.89 fl oz/1000 ft row
broadcast
T-band
deltamethrin *Delta Gold 1.0 to 1.5 fl oz/A broadcast
tefluthrin *Force 3G
*Force CS
4 to 5 oz/1000 ft row
0.34 to 0.46 fl oz/1000 ft row
see label for placement
see label for placement
chlorethoxyfos *Fortress 2.5G 6 to 7.5 oz/1000 ft row T-band or in-furrow, incorporate
chlorethoxyfos *Fortress 5G 3 to 3.75 oz/1000 ft row
5G applied only through the
T-band or in-furrow, incorporate
Smartbox system
chlorpyrifos *Lorsban 4E 2 to 4 pts/acre
see specific labels
foliar broadcast - rescue
preplant soil surface broadcast
chlorpyrifos *numerous products see specific labels
see specific labels
foliar broadcast - rescue
preplant soil surface broadcast
chlorpyrifos *Lorsban 15G 8 oz/1000 ft row T-band
zeta-cypermethrin *Mustang Max EC 1.28 to 2.8 fl oz/acre foliar broadcast - rescue
permethrin Pounce 3.2EC 4.0 to 8.0 fl oz/acre foliar broadcast - rescue
permethrin *numerous products see specific labels foliar broadcast - rescue
permethrin *Pounce 1.5G
*Pounce 1.5G
6.7 to 13.3 lb/A
8 oz/1000 ft row
preplant incorporate/broadcast
4- to 15-inchband at planting
gamma-cyhalothrin *Proaxis 1.92 to 3.20 fl oz/acre foliar broadcast - rescue
Lambda-cyhalothrin *Warrior 1.92 to 3.20 fl oz/acre foliar broadcast - rescue
Read and follow all label direction, precautions, and restrictions. * Designated a restricted use product.
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REVISED: June 7, 2012