Update from the MSU Extension field crops team

Here are some important highlights from the MSU Extension field crops team this week.

IPM BREAKFASTS

· Many wheat fields are very dry, probably should have been watered before the boot stage to fill the soil profile—some fields need as much as 4” of water in the profile—but now is not an ideal time to water in order to avoid head scab problems.

· Stripe rust of wheat has been much more severe than usual in MI this year and it has come on earlier…farmers with significant stripe rust pressure should consider making a separate fungicide application before the typical timing for head scab.

· Some farmers who planted soybean early are now making replant decisions – if planted in 30” rows, one option is to come back in and plant between existing rows or replant with 15” rows

· Some seed corn maggot has been detected on soybean that got planted early but was not growing well…the seed treatment was not effective because the plants were not actively growing and taking up the systemic insecticide

Michigan State University Extension field crop entomologist Christina DiFonzo presented timely information on insect pests of field crops at an integrated pest management (IPM) meeting on May 31, 2016, in St. Joseph County. DiFonzo answered several questions from participants on a wide range of topics and insect species, including corn rootworm, soybean aphid, alfalfa weevil, western bean cutworm, corn borer and even ticks. However, the overall emphasis was placed on careful scouting, particularly if pest pressure has been high in a given field or if regional reports warrant local investigation.

As DiFonzo noted in “Weeds, wet weather and cutworms” in early May, true armyworm and black cutworm moth captures were very high in Indiana in late-April with peak flight occurring the week of April 21–27 in Whitley and LaPorte counties, according to Purdue University Pest and Crop Newsletter, Issue 8. True armyworm and black cutworm moth captures appear to have peaked around mid-May in East Lansing, Michigan, this spring according to “Armyworm and black cutworm trap catches for May 2016” by DiFonzo.

During the meeting, DiFonzo noted that since St. Joseph County lies approximately halfway between the northern Purdue University sites and the MSU campus, peak moth flight times for black cutworm and armyworm were likely in early May. This estimation agrees with moth capture counts in traps located in St. Joseph County this spring (Table 1). Incidentally, the very high weekly trap catches at Purdue University sites cannot be directly compared with those from MSU trap counts as the types of traps were different. However, relative numbers can be used to estimate peak flight times in each area.

As DiFonzo noted previously, scouting for crop damage in corn from the larvae of black cutworm and armyworm should generally begin 300 degree-days after a significant moth capture. According to MSU Enviro-weather station data from south central Michigan, all station locations had received more than this many heat units during the month of May (Table 2). Begin scouting fields now, particularly if you have fields that had green vegetation (live cover crops, winter annual weeds, grasses) when significant moth captures were recorded in the area.

WANTED: MANURED CORN FIELDS

I HAVE BEGUN to conduct a mini-study to highlight the potential benefits of a PSNT (pre-sidedress nitrate test). The test was originally designed to help growers gauge how much nitrogen would be available to this year’s corn crop from existing soil organic matter in manured fields. The criteria for fields include: 1) history of at least one manure application (any species) OR a field that has just come out of alfalfa OR had cover crops that had clover as a significant part; 2) must be planted to corn this year; and 3) must not have had a broadcast application of inorganic nitrogen prior to sidedress (banding or pop-up is OK). If you have one or more fields that meet these criteria, please contact me. I will come and pull soil samples and pay for the PSNT analysis, and you will receive the results, no strings attached. I will use the data from your fields, without any personal/identifying information included, in an article this summer in the MSUE News.
Submitted by:

Eric Anderson

Michigan State University Extension

Field Crops Extension Educator – St. Joseph County