Nineteen sites reporting this week. European corn borer numbers are starting to increase again with eight sites reporting ECB-E and four sites reporting ECB-Z. Two of the six sites reporting corn earworm (CEW) were over threshold, indicating a need for a spray, please see the chart at the bottom of this page to determine the correct spray interval for your field. Fall armyworm (FAW) catches were up this week as well, with ten sites reporting trap catches. The site in Erie County caught 77 total FAW. Western bean cutworm (WBC) was also up this week with fourteen sites reporting trap catches, one as high as 96 moths.
Michigan State University recommends scouting for WBC egg masses when cumulative trap catch numbers reach 100 moth/trap for field corn. Whether this guideline also pertains to sweet corn is not known. Therefore it is recommended that all fields that are in the whorl or early tassel stage be scouted for egg masses with a 4% threshold for processing sweet corn and a 1% threshold for fresh market sweet corn. I scouted one field this week that had a cumulative trap catch of only 5 WBC moths and found one egg mass. WBC will usually lay eggs on the upper side of the top 1-3 leaves of pre-tassel corn, close to the leaf base. After tasseling has finished WBC seek out younger corn or dry beans. To scout for egg masses check the top 3 leaves of ten corn plants in ten locations throughout the field. The eggs are easy to observe if you view the leaf while holding it towards the sun. The egg mass will appear as a distinct shadow (see photo).
It takes between 5-7 days for eggs to hatch. It is critical that sprays are timed before the larvae have a chance to enter the ear. The egg mass will become purple in color approximately 24 hours before egg hatch (see photo).
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- WBC egg mass shadow. Photo: T. Baute
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- WBC egg mass.
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- WBC eggs become purple prior to hatch. Photo: Marlin Rice
| Location | ECB-E | ECB-Z | CEW | FAW | WBC | Total WBC to date |
DD to date |
| Avoca (Steuben Co.) | 0 | 0 | 0 | 0 | 1 | 1 | 1265 |
| Avon (Livingston Co.) | 0 | 0 | 0 | 9 | 6 | 6 | 1452 |
| Baldwinsville (Onondaga Co.) | 2 | 0 | 0 | 1 | 11 | 11 | 1470 |
| Batavia (Genesee Co.) | NA | NA | NA | NA | NA | 0 | 1142 |
| Bellona (Yates Co.) | 2 | 2 | 0 | 4 | 2 | 2 | 1512 |
| Eden (Erie Co.) | 5 | 0 | 0 | 77 | 96 | 96 | 1361 |
| Farmington (Ontario Co.) | NA | NA | NA | NA | NA | 0 | 1386 |
| Hamlin (Monroe Co.) | 2 | 1 | 1 | 0 | 0 | 0 | 1360 |
| Kennedy (Chautauqua Co.) | 0 | 0 | 0 | 4 | 19 | 24 | 1159 |
| King Ferry (Cayuga Co.) | 5 | 0 | 0 | 3 | 1 | 1 | 1425 |
| Kirkville (Madison Co.) | 22 | 0 | 1 | 1 | 9 | 9 | 1532 |
| LeRoy (Genesee Co.) | 0 | 2 | 2 | 0 | 0 | 0 | 1260 |
| Lockport (Niagra Co.) | 6 | 0 | 0 | NA | 0 | 0 | 1282 |
| Oswego (Oswego Co.) | 0 | 0 | 1 | 3 | 2 | 5 | 1342 |
| Owego (Tioga Co.) | 0 | 0 | 0 | 0 | 0 | 0 | 1292 |
| Pavilion (Genesee Co.) | NA | NA | NA | NA | NA | 3 | 1260 |
| Penn Yan (Yates Co.) | 0 | 0 | 0 | 0 | 1 | 1 | 1469 |
| Plessis (Jefferson Co.) | 1 | 0 | 1 | 0 | 13 | 15 | 1274 |
| Preble (Cortland Co.) | 0 | 0 | 0 | 7 | 3 | 3 | 1417 |
| Seneca Castle (Ontario Co.) | 0 | 0 | 0 | 0 | 1 | 2 | 1395 |
| Sherwood (Cayuga Co.) | NA | NA | NA | NA | NA | NA | 1425 |
| Spencerport (Monroe Co.) | 0 | 0 | 2 | 1 | 0 | 0 | 1452 |
| Waterport (Orleans Co.) | NA | NA | NA | NA | NA | 0 | 1360 |
| Williamson (Wayne Co.) | 0 | 1 | 0 | 0 | 10 | 11 | 1296 |
| ECB – European Corn Borer CEW – Corn Earworm FAW – Fall Armyworm WBC – Western Bean Cutworm NA – not available DD – Degree Day (modified base 50F) accumulation |
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| trap catches for the week of 7.15.14-7.22.14 |
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Below is a graph of the average trap catches to date. The first flight of ECB happened in mid June and we are now seeing the beginning of the second flight of ECB as well as the beginning of WBC and FAW flights.
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Average trap catch to date.
