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

Bean Leaf Beetles in Soybean; Flea Beetles in Field Corn

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

Published: June 1, 2009

Bean leaf beetle adults leaving overwintering sites or moving from alfalfa fields after infesting them early season generally move to soybean fields. These beetles are capable of flying long distances and will seek seedling soybean plants on which they will feed, mate, and then oviposit eggs in the soil for the next generation of beetles. During this past week, bean leaf beetle numbers approached or exceeded economic levels in some Northern Missouri soybean fields. Most fields were early planted and received much precipitation following planting. Economic infestations of beetles were found in fields with and without insecticide treated seed. Insecticide trials conducted in Missouri and other states show that Cruiser and Gaucho are both very effective at controlling this insect pest under most environmental conditions. The problems encountered with control of early season bean leaf beetle in these few fields may be due to several factors including the long period of time between planting and the appearance of the beetles, the dilution of the insecticides by continuous wet soil conditions, or by excessive numbers of beetles migrating into these fields. We know first planted fields typically attract high numbers of beetles. In addition, laboratory research from Minnesota and field trials from Missouri, Nebraska and other states show that under normal conditions seed treatments are very effective at early season insect control for about a 45-day period followed by a reduction in efficacy over the next few weeks. It is likely that all of these factors had some influence on the economic infestations of bean leaf beetle adults observed in northern Missouri soybean fields. The following insecticides are recommended for bean leaf beetle control in soybean.

Similar to bean leaf beetle, some flea beetle problems were observed on corn plants produced from both nontreated seed and seed treated with the 250 rate of insecticide. Flea beetles often damage corn grown from nontreated seed if beetle populations are high coming out of winter. In contrast, plants from insecticide treated seed rarely experience problems with this early season pest. The factors discussed previously with bean leaf beetle are likely reasons for the economic damage seen with flea beetles in field corn. The problems encountered with seed-treated plants in northern Missouri soybean and corn fields are rare, but can occur when field conditions limit the efficacy of the insecticide seed treatments.

Table 1. Bean Leaf Beetle
Been Leaf Beetle
Comments: Treatment on seedling soybean is rarely needed. If necessary, treat when five or more beetles are present per foot of row and 1 or more plants per foot of row are destroyed. Cold, dry growing conditions may lead to increases BLB problems on emerging and seedling soybean. Before bloom treat when 5 or more beetles are present per foot of row and defoliation exceeds 30%. At stages from bloom to pod fill, treat when defoliations reaches 20% and beetles average 10 or more per foot of row (30-inch rows) or 1 to 3 beetles (7-inch rows). At seed maturity, treat when 5%-10% of pods are damaged, plants are still green and 10 or more beetles per foot of row are present.
Common Name Trade Name Rate of Formulated Material per acre Placement
permethrin *Ambush 25W 3.2 to 6.4 fl. oz. On foliage
esfenvalerate *Asana XL 5.8 to 9.6 fl. oz.  
cyfluthrin *Baythroid XL 0.8 to 2.8 fl. oz.  
bifenthrin *Brigade 2EC 2.1 to 6.4 fl. oz.  
chlorpyrifos + gamma-cyhalothrin *Cobalt 19 to 38 fl. oz.  
dimethoate *Dimethoate 4EC 1 pt.  
carbofuran *Furadan 4F 1/4 to 1/2 pt. 2(ee) label  
zeta-cypermethrin + *Hero 2.6 to 6.1 fl. oz.  
methomyl *Lannate LV 3/4 to 1 pt.  
chlorpyrifos *Lorsban 4E 1 to 2 pt.  
acephate Orthene 97 3/4 to 1 lb. On foliage
microencapsulated methyl parathion *Penncap-M 2 to 3 pt.  
permethrin *Pounce 3.2EC 2.0 to 4.0 fl. oz.  
lambda-cyhalothrin *Proaxis 1.92 to 3.2 fl. oz.  
carbaryl Sevin XLR Plus 1 to 2 pt.  
spinosad Success 3.0 to 6.0 fl. oz.  
spinosad Tracer 4SC 1.0 to 3.0 fl. oz.  
lambda-cyhalothrin *Warrior 1.92 to 3.2 fl. oz.  
* 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.

 

Table 2. Flea Beetles in Field Corn
Flea Beetles in Field Corn
Comments: Treat when 5 or more beetles per plant are present or when seedling plants are being severely damaged or killed and beetles are present.
Common Name Trade Name Rate of Formulated Material per acre Placement
permethrin *Ambush 25W 6.4 to 12.8 fl. oz. Spray over row
esfenvalerate *Asana XL 5.8 to 9.6 fl. oz. Spray over row
cyfluthrin *Baythroid XL 0.8 to 1.6 fl. oz. Spray over row
bifenthrin *Brigade 2 EC 2.1 to 6.4 fl. oz. Spray over row
chlorpyrifos + gamma-cyhalothrin *Cobalt 13 to 26 fl. oz. Spray over row
bifenthrin *Fanfare 2EC 2.1 to 6.4 fl. oz. Spray over row
zeta-cypermethrin + bifentrhin *Hero 4.0 to 10.3 fl. oz. Spray over row
methomyl *Lannate LV 0.75 to 1.5 pt. Spray over row
chlorpyrifos *Lorsban 4E 1 to 2 pt. Spray over row
chlorpyrifos *Lorsban Advanced 1 to 2 pt. Spray over row
zeta-cypermethrin *Mustang Max 3.2 to 4.0 fl. oz. Spray over row
chlorpyrifos *Nufos 4E 1 to 2 pt. Spray over row
microencapsulated methyl parathion *Penncap-M 2 to 3 pt. Spray over row
permethrin *Pounce 3.2EC 4.0 to 8.0 fl. oz. Spray over row
lambda-cyhalothrin *Proaxis 2.56 to 3.84 fl. oz. Spray over row
carbaryl Sevin XLR Plus 2 to 4 pt. Spray over row
lambda-cyhalothrin *Warrior 2.56 to 3.84 fl. oz Spray over row
Seed Treatments:
thiamethoxam Cruiser see product label commercially applied to seed
clothianidin Poncho see product label commercially applied to seed
tefluthrin Proshield with Force ST see product label commercially applied to seed
* 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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