Whether one is a farmer or has landscape or garden aspirations around the home, now is a critical time to scout for pests.
Around the yard as mentioned during the past few weeks, it is high time to be scouting for those bagworms that continue to become big and ugly ornaments on trees by August. Also Japanese beetles can damage plants in a hurry. So far, spider mites have not been an issue locally.
On the farm scene, Western Corn Rootworm (WCR) has been an increasing threat to county farmers as variant WCR adult beetles have developed that lay large numbers of eggs in soybean fields rather than only in corn fields. This is a significant change from several years back when WCR was not a problem for any corn fields except those that were continuous corn.
Since several non-farm clientele comment they like reading this column, I would like to point out that farmers do not like to use insecticides for several reasons. These include but are not limited to cost and the fact that most insecticides are more dangerous to the farmer who handles the product relative to other pesticides like herbicides used for weed control.
Due to the development of variant WCR beetles initially in northern Illinois and northwest Indiana, this situation has crept to the south and east to the point during the past couple of years in our area that most corn fields north of I-70 following beans were recommended to be treated with insecticide for WCR when no WCR beetle pressure data during the previous bean season was available.
This past week, sticky traps were set out to monitor WCR beetles to assist with decisions for next year. Most likely, numbers will be low this year as many larva drowned during this year's flood events. This will help farmers in decision making of whether or not an insecticide will be needed next spring in corn planted following beans.
While the traps contain no lures or pheromones, they are a bright yellow color attracting the beetles to the sticky surface where they remain to be counted. Beginning no later than July 24, one should place six PheroconŽ AM (unbaited) yellow sticky traps with the sticky side away from a wooden stake schematically throughout the soybean field. Traps should be kept 100' away from field edges or borders or waterways.
Large fields greater than sixty acres particularly with varying soil types, weed pressure, etc. may require more traps. Long and skinnier fields can have six evenly spaced traps in a row whereas a field that is squarer can have two rows of three evenly spaced traps. Since many Clay and Owen fields are irregularly shaped, an arc of six traps or two arcs of three traps may be a good distribution for trap placement. The traps should be placed just above the soybean canopy.
The soybean plants around the stake should be removed so the soybean leaves don't stick to the trap. In drilled soybean, consider placing the traps in wheel tracks. The traps will be checked each week for a total of six weeks unless the beetle threshold indicating necessary treatment is reached prior to six weeks.
Each week the trap will be removed for counting beetles and a new trap set up for the following week. Therefore 36 traps are needed to monitor a field over the span of six weeks. Other insects, litter, etc. will accompany the WCR beetles on the traps each week.
Count the WCR beetles each week and record for each trap. Sum the total beetles for all traps in the field. Divide by the number of traps (as previously mentioned ideally six). Next you will divide by the number of days (ideally seven days if checking the traps weekly) to arrive at the average number of beetles per trap per day in the field. The economic threshold is five or more WCR beetles per trap per day during any of the six trapping weeks.
If this level is reached earlier than the sixth week, an alternative management plan should be implemented and you will not need to continue trapping in that particular field. An alternative management plan would be to either use insecticide for WCR in corn next spring or rotate to a crop other than corn. Also you should not use a single trapped field to estimate WCR numbers in surrounding fields.
If you would like to purchase sticky traps, call the Owen or Clay County Extension office (numbers below) for assistance in obtaining traps.
Purdue publication E-218 entitled "Monitoring and Decision Rules for WCR Beetles in Soybean" and annual updates in E-49 entitled "Managing Corn Rootworms" are also available at no cost and our county Extension website found at www.ext-ension.purdue.edu/ and click on county offices and then either Owen or Clay and go to the agriculture area on the left hand menu.
You can contact the local Purdue Extension Office by calling 829-5020 x14 in Owen County or 448-9041 in Clay County for more information or publication copies regarding this week's column topic or to RSVP for upcoming events. It is always best to call first to assure items are ready when you arrive and to RSVP for programs. While most publications are free, some do have a fee. All times listed are Eastern Time.
July 30 No-till Program w/ Jill Clapperton, Cayuga, 9 a.m.
August 1 No-till Program w/ Jill Clapperton, Cayuga, 9 a.m.
August 6-17 Indiana State Fair