NDSU Crop and Pest Report

Entomology


ISSUE 6  June 5, 2003

EXEMPTION FOR MUSTANG ON MUSTARD TO CONTROL FLEA BEETLE

The ND Department of Agriculture declared a crisis exemption for Mustang® Max, enabling North Dakota producers of yellow and brown mustard to use the insecticide to control crucifer flea beetles.

The exemption allows a use rate of 2.24 to 4.0 ounces of active ingredient per acre with a maximum seasonal use rate of 0.05 lb of active ingredient per acre. The exemption extends to June 13, 2003.

Applicators must follow all other directions, restrictions, and precautions from the EPA-approved labeling for the product. A copy of the label must be in the possession of the user at time of application. One can be found at the NDSU Pesticide Certification webpage:

http://www.ag.ndsu.nodak.edu/aginfo/pesticid/sec18_2003.htm

 

APHTHONA FLEA BEETLES FIGHT SPURGE

It is time to prepare for collecting and redistributing Aphthona flea beetles for leafy spurge control. Several county weed control officers host field days during June for collecting and redistributing the flea beetles. Contact your county weed control officer for the date, time, and location of a field day in your area.

Beetle Collecting and Redistribution

The overwintering larvae are currently feeding on the spurge root system near the soil surface and soon moving to where they pupate. Expect to see adults feeding on the spurge foliage during the next few weeks.

Mid-June to early July is the best time period to collect adult flea beetles for redistribution. To collect the adult flea beetles you will need a sweep net, paper bag or paper container, and a cooler containing blue ice. It is best to collect beetles after 10 a.m. when the air temperature has warmed to at least 70EF and the spurge is dry. Beetles are easiest to collect when there is little or no wind.

Beetles can be collected from an established population only when the population has increased enough for redistribution. Using a sweep net, make five sweeps in a 10 square foot area and count the number of beetles in the net. If there are beetles to numerous to count individually, remove the vegetative trash and other insects and pour the flea beetles into a graduated container. Every 10 ml equals approximately 1,000 flea beetles. You need to redistribute flea beetles when an established population yields 500 to 1,000 adults per five minute sweeping period.

For redistribution, the beetles need be placed in the paper bag or container with some leafy spurge. Transport the beetles in a cooler with blue ice. Remember the beetles are living organisms and the containers of beetles should not be left in the sun or a hot vehicle. The beetles need to be released preferably the same day of collection into the new spurge location. If the beetles cannot be released as soon as possible, they can be stored, preferably a week or less, at 40EF.

The flea beetles usually establish and control spurge sooner when large numbers are released into habitats that are similar to the habitat where they were collected. A minimum of 1,000 adults should be released at a single point, marked with a stake, along the margins of the spurge when the weed infestation is dense. Make multiple releases in a large spurge infestation. The new flea beetle release should yield at least 50 beetles per five sweeps the following summer. If the population is less than 50 beetles, make additional releases.

The flea beetles do have limitations and do not have an equal impact across all habitats. Flea beetles will establish sooner when released in moderate spurge densities of 60-90 stems per square yard with little grass cover and thatch. The Aphthona flea beetles establish faster on the south facing slops followed by the western and eastern slopes and usually noticeably slower on north facing slops.

The black flea beetle, Aphthona lacertosa, establishes at sites ranging from high and dry to cooler and moister habitats with shade and denser stands of spurge, with silt loam, silt clay loam, clay loam, loam, or loam/fine sand loam soil conditions. The brown flea beetle, Aphthona nigriscutis, is more successful in areas that are higher and drier with well drained loam soil. When releasing beetles into a spurge infestation for the first time, release a mixture of both species to determine the species that is best suited for the spurge habitat.

Integrating Beetles With Other Management Methods

The Aphthona flea beetles can successfully be integrated with other management methods. Herbicides plus flea beetles have been shown to give better results than either control tactic used alone. Tordon (picloram) plus 2,4-D at 1 quart plus 1 quart per acre (0.5 + 1 pound per acre) can be applied during early September to mid-October on leafy spurge with an established flea beetle population. The herbicide treatment will help to open up the canopy, allowing for the flea beetles to deposit their eggs at the base of the spurge plants.

Grazing by sheep or goats, or fire can also be used to open up the spurge canopy and remove excess trash from the soil surface. When integrating these management tactics with an established flea beetle population, they should only be used after mid-August, when egg laying by the beetles is completed.

An important point to remember is that the Aphthona flea beetles do have limitations and are not a "quick fix" for controlling leafy spurge. The beetles may take several years to reduce a leafy spurge infestation. Every spurge infestation is different and the flea beetle population development will vary across habitats. The beetles may need to be integrated with other management tactic to achieve desirable results.

For more information on using the Aphthona flea beetles for leafy spurge control, refer to Leafy Spurge Control Using Flea Beetles (W-1183) at

http://www.ext.nodak.edu/extpubs/weeds.htm  

Denise Olson
Research Entomologist
Denise.Olson@ndsu.nodak.edu

 

GRASSHOPPER TREATMENTS UNDERWAY

Grasshopper hatch has become steady. Numerous people are reporting feeding around field margins. Decisions are being made to treat hatching sites and prevent/delay movement into fields.

Here is a listing of Insecticides Currently Available for Use Against Grasshopper in Crop and Non-crop areas.

Field Corn and Sweet corn
Asana XL, Capture, Cythion, Diazinon, Mustang Max, Penncap_M, Sevin, and Warrior.

Field Corn Only
Dimethoate, Furadan 4F, Lorsban 4E, methyl parathion.

Soybean
Asana XL, Baythroid, Dimethoate, Furadan 4F, Lorsban 4E, Penncap_M, Scout X-Tra, Sevin, Warrior.

Sunflower
Asana XL, Baythroid, Furadan 4F, Lorsban 4E, Scout X_Tra, Sevin, Warrior.

Dry Bean
Asana XL, Dimethoate, Mustang Max, Orthene 75S, Sevin.

Potato
Asana XL, Dimethoate, Penncap-M, Sevin.

Sugarbeet
Asana XL, Cythion, Diazinon, Lorsban 4E, methyl parathion, Mustang Max, Sevin.

Wheat
Cythion, Dimethoate, Furadan 4F, Malathion 57EC, Mustang Max, methyl parathion, Penncap-M, Sevin, Warrior.

Barley
Cythion, Furadan 4F, Malathion 57EC, methyl parathion, Penncap-M.

Oat
Furadan 4F, Malathion 57EC, methyl parathion, Penncap-M.

Alfalfa

Baythroid, Cythion, Dimethoate, Furadan 4F, Lorsban 4E, Malathion 57EC, methyl parathion, Mustang Max, Penncap-M, Sevin,Warrior.

Clover
Cythion, methyl parathion, Sevin.

Grass and Grass hay
Cythion, Penncap-M.

Pasture and Range
Cythion, Dimilin, Orthene 75S, Penncap-M, Sevin,.

Non-Crop areas with grass cut for hay
Cythion, Malathion 57EC, Sevin.

Non-Crop areas NOT cut for hay
Asana XL, Orthene 75S, Warrior.

Grain Sorghum
Baythroid, Dimethoate, Lorsban 4E, Sevin, Warrior.

Lentils and Chick Pea
Baythroid, Mustang Max

Proso Millet, and Flax
Sevin.

Canola
Capture, Warrior.

Field Peas
Mustang, Sevin

Phillip Glogoza
Extension Entomologist
pglogoza@ndsuext.nodak.edu

 

SUGARBEET ROOT MAGGOT: FLIES EMERGING - PEAK APPROACHING SLOWLY

Sugarbeet root maggot flies have been captured on sticky stakes in previous-year beet fields for about one week now. The NDSU root maggot model suggests that peak fly activity in current-year beet fields is just around the corner. Significant emergence from soil in last year’s fields likely in the next 5 days or so. Also, degree-day (DD) unit accumulation will likely be sufficient for peak activity (600) in current-year beets very soon in most Red River Valley monitoring sites. However, an 80-degree Fahrenheit (or above) day will be needed after that for the actual peak because the flies prefer warm weather for mating, moving into new beet fields, and laying eggs. The extended weather forecast suggests that the first chance for breaking 80 degrees is not until Monday, and that cool and intermittent rainy conditions are likely for the next few days. Thus, an additional delay of the actual peak in this year’s beet fields is expected.

 

SPRINGTAILS IN SUGARBEET

Springtails have caused significant plant stand losses and have forced the replanting of several sugarbeet acres in the central and southern Red River Valley and also along the North Dakota/Montana border. Springtails are tiny (1/32 to 3/32"), blind, wingless insects (Fig. 1).

The springtails affecting these fields are subterranean (live below the soil surface). Although they are usually considered beneficial because they help break down organic matter and feed on soil fungi, they occasionally build up into high enough numbers to injure and kill sugarbeet seedlings. Typically, springtails cause problems in cool, wet springs. Heavy-textured (clay loam to silty clay) soils are especially at risk. Springtails do well in nearly saturated soils. Saturation usually results in poor plant development so young seedlings can be especially vulnerable to attack. Rescue treatment with a liquid insecticide may be possible, but will be highly dependent on getting a good rain (at least 1/4") shortly after the application. The best option is usually prompt replanting and applying a planting-time insecticide using modified in-furrow placement. Historical evidence suggests that insecticides containing chlorpyrifos as the active ingredient.(Lorsban & Nufos) will not provide sufficient protection from subterranean Sspringtails. Anecdotal information also indicates that Counter 15G will give good levels of root protection from this insect. NDSU research is currently underway to develop more options for controlling springtails in sugarbeet.

Mark Boetel
Research & Ext. Entomologist
mboetel@ndsuext.nodak.edu


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